Inhibitor Report for: Berberine

Herein we present a comparative study of the effects of isoquinoline alkaloids belonging to benzo[c]phenanthridine and berberine families on beta-amyloid aggregation. Results obtained using a Thioflavine T (ThT) fluorescence assay and circular dichroism (CD) spectroscopy suggested that the benzo[c]phenanthridine nucleus, present in both sanguinarine and chelerythrine molecules, was directly involved in an inhibitory effect of Abeta(1-42) aggregation. Conversely, coralyne, that contains the isomeric berberine nucleus, significantly increased propensity for Abeta(1-42) to aggregate. Surface Plasmon Resonance (SPR) experiments provided quantitative estimation of these interactions: coralyne bound to Abeta(1-42) with an affinity (K(D) = 11.6 microM) higher than benzo[c]phenanthridines. Molecular docking studies confirmed that all three compounds are able to recognize Abeta(1-42) in different aggregation forms suggesting their effective capacity to modulate the Abeta(1-42) self-recognition mechanism. Molecular dynamics simulations indicated that coralyne increased the beta-content of Abeta(1-42), in early stages of aggregation, consistent with fluorescence-based promotion of the Abeta(1-42) self-recognition mechanism by this alkaloid. At the same time, sanguinarine induced Abeta(1-42) helical conformation corroborating its ability to delay aggregation as experimentally proved in vitro. The investigated compounds were shown to interfere with aggregation of Abeta(1-42) demonstrating their potential as starting leads for the development of therapeutic strategies in neurodegenerative diseases.

A dataset of 67 berberine derivatives for the inhibition of butyrylcholinesterase (BuChE) was studied based on the combination of quantitative structure-activity relationships models, molecular docking, and molecular dynamics methods. First, a series of berberine derivatives were reported, and their inhibitory activities toward butyrylcholinesterase (BuChE) were evaluated. By 2D- quantitative structure-activity relationships studies, the best model built by partial least-square had a conventional correlation coefficient of the training set (R(2) ) of 0.883, a cross-validation correlation coefficient (Qcv2) of 0.777, and a conventional correlation coefficient of the test set (Rpred2) of 0.775. The model was also confirmed by Y-randomization examination. In addition, the molecular docking and molecular dynamics simulation were performed to better elucidate the inhibitory mechanism of three typical berberine derivatives (berberine, C2, and C55) toward BuChE. The predicted binding free energy results were consistent with the experimental data and showed that the van der Waals energy term (DeltaEvdw ) difference played the most important role in differentiating the activity among the three inhibitors (berberine, C2, and C55). The developed quantitative structure-activity relationships models provide details on the fine relationship linking structure and activity and offer clues for structural modifications, and the molecular simulation helps to understand the inhibitory mechanism of the three typical inhibitors. In conclusion, the results of this study provide useful clues for new drug design and discovery of BuChE inhibitors from berberine derivatives.

Three new serratene-type triterpenoids (1-3) and a new hydroxy unsaturated fatty acid (13) together with nine known compounds (4-12) were isolated from Lycopodiella cernua. The chemical structures were established using NMR, MS, and Mosher's method. Compound 13 showed the most potent inhibitory activity against acetylcholinesterase (AChE) with an IC50 value of 0.22muM. For butyrylcholinesterase (BChE) inhibitory activity, 5 showed the most potent activity with an IC50 value of 0.42muM. Compound 2 showed the most potent activity with an IC50 of 0.23muM for BACE-1 inhibitory activity. The kinetic activities were investigated to determine the type of enzyme inhibition involved. The types of AChE inhibition shown by compounds 4, 5, and 13 were mixed; BChE inhibition by 5 was competitive, while 2 and 6 showed mixed-types. In addition, molecular docking studies were performed to investigate the interaction of these compounds with the pocket sites of AChE. The docking results revealed that the tested inhibitors 3, 4, and 13 were stably present in several pocket domains of the AChE residue.

Berberine is an isoquinoline alkaloid, found in several plants. Diabetes induces erectile dysfunction (ED) via reduction in some hormones and enzymes implicated in sexual function. This study aimed to investigate the role of berberine on crucial biomolecules linked to penile function in diabetic rats. Sixty-three (63) adult male rats were used and distributed into nine groups (each = 7). Group I-IV normal rats administered with citrate buffer (pH 4.5), sildenafil citrate (SD, 5.0 mg/kg), 50 and 100 mg/kg of berberine, respectively, via oral gavage. Rats in groups V-IX were diabetic rat with ED treated with buffer, SD, 50 and 100 mg/kg of berberine, and acarbose (25 mg/kg ACA) respectively. The result revealed that histological architecture in penile tissues were altered in diabetic groups treated with berberine, sildenafil citrate and acarbose when compared to the diabetic control group. Treatment with berberine, increased testosterone, luteinizing hormone and follicle-stimulating hormone in diabetic rat with ED. Also, reduced prolactin level and acetylcholinesterase, angiotensin-1 converting enzyme, adenosine deaminase and arginase activities were observed in berberine treated diabetic rat with ED. Molecular docking analysis revealed that berberine had strong binding affinities for these enzymes. Thus, berberine could represent a potential therapeutic agent for diabetes-induced ED.

OBJECTIVES: Several studies had been conducted to examine the link between diabetes and diabetes encephalopathy. This study was conducted to examine the potency of berberine (BER) on the restoration of impaired neurochemicals in the brain of streptozotocin (STZ)-induced diabetic Wistar rats. METHODS: Fifty-six (56) adult rats weighing between 200 and 230 g were randomly divided into seven groups (n=8) as follows; Group I is normal control; Groups II and III were normal rats treated with 50 and 100 mg/kg respectively; Group IV-VII were STZ-induced rats, but Groups V-VII were treated with acarbose (25 mg/kg), 50 and 100 mg/kg of BER, respectively. RESULTS: The result of the study showed that untreated STZ-induced diabetic rats have increased acetylcholinesterase (AChE), butyrylcholinesterase (BChE), monoamine oxidase (MAO) activities, and malonylaldehyde (MDA) level, with concomitant decrease of superoxide dismutase (SOD), glutathione peroxidase (GPx) activities, and glutathione (GSH) level. However, daily treatment with 50 and 100 mg/kg BER and ACA significantly reversed these effects. CONCLUSIONS: The findings of this study clearly indicated that BER possesses neuro-protective and antioxidative potentials and normalize neurochemical impairment distort by diabetes.

OBJECTIVES: This study examined effect of berberine and piperine on neuroprotective potential of neostigmine in the management of neurological disorders. METHODS: Berberine and neostigmine were weighed (30 g), dissolved in distilled water (30 mL) separately, while, 30 mg piperine was dissolved in ethanol (0.45 mL), made up to 30 mL with distilled water. Antioxidant activities in 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH), 2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonate) radical (ABTS), Fe-chelation, ferric reducing properties (FRAP), nitric oxide (NO) and hydroxyl (OH) radical scavenging abilities and Fe(2+), cisplatin and sodium nitroprusside (SNP) induced lipid peroxidation (LPO), and acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and monoamine oxidase (MAO) activities were assessed in vitro. RESULTS: The result revealed that tested compounds inhibited enzymes activities dose-dependently. However, berberine (IC(50)=0.17 mg/mL) had slight higher AChE inhibitory effect than piperine and neostigmine (p<0.05). Also, berberine had the highest BChE inhibitory effect (IC(50)=0.16 mg/mL) while piperine exhibited the highest MAO inhibitory effect (IC(50)=0.21 mg/mL). Berberine, piperine and neostigmine exhibited high antioxidant properties and inhibited Fe(2+), cisplatin and SNP induced LPO. CONCLUSIONS: Both alkaloids demonstrated antiradical scavenging ability comparable to neostigmine action against Alzheimer's disease (AD). The modulatory and antioxidant berberine and piperine properties on these enzymes (AChE, BChE and MAO) could be possible underlying mechanisms in employing these compounds as a complementary therapy in neurodegenerative diseases (NDDs) management.

Acetylcholinesterase (AChE) plays a vital role in Alzheimer's disease (AD), which is one of the most common causes of dementia. Discovering new effective inhibitors against AChE activity is seen to be one of the effective approaches to reduce the suffering from AD. Protoberberine alkaloids isolated from natural resources have previously been reported as potent AChE inhibitors. In order to gain insights into how these alkaloids could inhibit AChE, berberine, palmatine, and cyclanoline were selected to investigate in terms of binding orientation and their key interactions with AChE using molecular docking and molecular dynamics simulations and quantum chemical calculations. The results revealed that the molecular dynamics structures of palmatine and berberine indicated that their equilibrated structures did not occupy the gorge but they slightly moved away from the catalytic site (CAS). For cyclanoline, the binding mode was quite different from those of donepezil and the other protoberberine alkaloids: it preferred to stay deeper in the CAS site. Interaction energies and residual interaction energies confirmed that the key interactions for palmatine and berberine were Pi-Pi interactions with Trp286 and Tyr341 and H-bond interactions with Tyr124. Cyclanoline formed Pi-Pi interactions with Trp86 and H-bonds to the amino acids in the CAS site. The results suggested the importance of aromaticity in the core structure and the flexibility of the core structure or the substituents in order to fit into the narrow gorge. The HOMO, LUMO, bioavailability, drug-likeness and pharmacokinetics were also predicted. The results obtained will be useful for further AD drug development.

Berberine is a promising botanical pesticide against fungal plant pathogens. However, whether berberine inhibits the invasion of fungal pathogen across plant surface remains unclear. Here we demonstrated that the enzyme activities of purified cutinase from fungal pathogen Colletotrichum capsici were partially inhibited in presence of berberine toward different substrates. Molecular dynamics simulation results suggested the rigidity of cutinase was decreased with berberine added into the system. Interestingly, aggregations of berberine to the catalytic center of cutinase were observed, and stronger hydrophobic interactions were detected between key residue His 208 and berberine with concentrations of berberine increased. More importantly, this hydrophobic interaction conferred conformational change of the imidazole ring of His 208, which swung out of the catalytic center to an inactive mode. In summary, we provided the molecular mechanism of the effect of berberine on cutinase from C. capsici.

Herein we present a comparative study of the effects of isoquinoline alkaloids belonging to benzo[c]phenanthridine and berberine families on beta-amyloid aggregation. Results obtained using a Thioflavine T (ThT) fluorescence assay and circular dichroism (CD) spectroscopy suggested that the benzo[c]phenanthridine nucleus, present in both sanguinarine and chelerythrine molecules, was directly involved in an inhibitory effect of Abeta(1-42) aggregation. Conversely, coralyne, that contains the isomeric berberine nucleus, significantly increased propensity for Abeta(1-42) to aggregate. Surface Plasmon Resonance (SPR) experiments provided quantitative estimation of these interactions: coralyne bound to Abeta(1-42) with an affinity (K(D) = 11.6 microM) higher than benzo[c]phenanthridines. Molecular docking studies confirmed that all three compounds are able to recognize Abeta(1-42) in different aggregation forms suggesting their effective capacity to modulate the Abeta(1-42) self-recognition mechanism. Molecular dynamics simulations indicated that coralyne increased the beta-content of Abeta(1-42), in early stages of aggregation, consistent with fluorescence-based promotion of the Abeta(1-42) self-recognition mechanism by this alkaloid. At the same time, sanguinarine induced Abeta(1-42) helical conformation corroborating its ability to delay aggregation as experimentally proved in vitro. The investigated compounds were shown to interfere with aggregation of Abeta(1-42) demonstrating their potential as starting leads for the development of therapeutic strategies in neurodegenerative diseases.

BACKGROUND: Berberine (BBR), an isoquinoline alkaloid, acts as a multipotent active pharmaceutical ingredient to counteract several types of dementia based on its numerous pharmacological actions including antioxidant, anti-inflammatory, cholesterol-lowering effect, and inhibition of Abeta production and AChE. However, BBR suffers from poor absorption, bioavailability and brain drug uptake. The present study is directed for the formulation and characterization of Chitosan BBR-Nanoparticles (BBR-NPs) as well as the estimation of its neuroprotective effects against scopolamine induced cognitive impairments. METHODS: BBR-NPs were formulated using the ionic gelation method, and tripolyphosphate was chosen as a crosslinker. Nanoparticles size, zeta potential, encapsulation efficiency and releasing profile were estimated. To investigate the neuroprotective effects, adult fifty-six Wistar male rats were randomly distributed into three control groups, received saline, polyethylene glycol or Chitosan- NPs, respectively; induced group, received scopolamine (2 mg/ kg, i.p.) and three treated groups were orally administrated BBR (50 mg/ kg), BBR- NP (7 mg/ kg) and donepezil (2.25 mg/ kg, as positive control) followed by scopolamine injection after 40 min, daily for 4 weeks. Morris water maze test, oxidative stress parameters, cholinergic and amyloid-beta processing intermediates, as well as neuroplasticity markers and histopathological examination were assessed. RESULTS: Our results showed that BBR- NPs were better than BBR and donepezil as BBR- NPs were powerful inhibitory ligands towards AChE and Abeta42 formation and significantly down-regulated Tau, iNOS and BACE gene expression in rats' hippocampus. BBR-NPs administration, at 1/6 of BBR therapeutic recommended dose, significantly improved learning and memory function. This could be accredited to the diminution of oxidative stress and amyloid-beta toxicity in addition to the improvement of the neuroplasticity markers. CONCLUSION: The enhancing effect of BBR- NPs could be related to the enhancing of its bioavailability, absorption and brain drug uptake, which need more investigation in future work.

Berberine is an isoquinoline derivative alkaloid extracted from Chinese herbs. Recent studies have demonstrated the therapeutic effect of berberine on glucose metabolic disorders. However, its specific mechanism is still unclear. Our study aimed to research the glucose-lowering effect of berberine in diabetic rats and to reveal the possible role of the cholinergic anti-inflammatory pathway. Diabetic rats induced by administration of a high-calorie diet and streptozocin tail vein injection were assessed by the oral glucose tolerance test. Then, the diabetic rats were divided into two groups, those with or without the alpha7 nicotinic acetylcholine receptor gene downregulated, respectively, followed by treatment including berberine for 6 weeks. Results of this study show that the administration of berberine downregulated levels of fasting blood glucose and fasting insulin, and ameliorated insulin resistance in diabetic rats. Treatment with berberine inhibited acetylcholinesterase activity, and upregulated acetylcholine levels in the serum and alpha7 nicotinic acetylcholine receptor gene expression in the liver tissue. Meanwhile, berberine reversed elevated expression of cytokines interleukin-1beta and TNF-alpha in the serum and downregulated nuclear factor kappaB expression. However, berberine administration showed no glucose-lowering or anti-inflammatory effect in diabetic rats in which alpha7 nicotinic acetylcholine receptor gene expression was downregulated, and acetylcholinesterase activity was also significantly inhibited. In conclusion, berberine may ameliorate glucose metabolism by activating the alpha7 nicotinic acetylcholine receptor-mediated cholinergic anti-inflammatory pathway.

As isoquinoline alkaloid naturally occurs in Coptis and Berberis species, berberine (BER) has shown anti-oxidant, anti-tumour, anti-bacterial and hepatoprotective activities and beneficial effects against digestive, cardiovascular and neurological conditions. Also, BER antiinflammatory, pain-relieving and anti-cholinesterase activities were widely studied. The present overview discusses the analgesic effects of BER. Based on the literature, BER exerted pain-relieving activity against diabetic and chemotherapy-induced neuropathy, and sciatic nerve injury-induced pain via down-regulation of transient receptor potential vanilloid 1, suppression of NF-kappaB and modulation of and opioid receptors. Besides, BER could repress inflammatory markers tumour necrosis factor-alpha, interleukin-6 and IL-1beta, as well as prostaglandin E2, inducible nitric oxide synthase and cyclooxygenase-2. The modulatory effects of BER on dopamine and N-methyl d-aspartate systems were also noted. Moreover, BER could induce Nrf2 expression but inhibits p38-MAPK and STAT3 phosphorylation. Noteworthy, anti-cholinesterase activity, which may potentially contribute to BER analgesic properties, warrants particular attention.

Berberine, a naturally occurring compound, possesses an interesting multipotent pharmacological profile potentially applicable for Alzheimer's disease (AD) treatment. In this study, a series of novel 22 berberine derivatives was developed and tested in vitro. Berberine core was substituted at position 9-O of its aromatic ring region. All the hybrids under the study revealed multi-targeted profile inhibiting prolyl oligopeptidase, acetylcholinesterase and butyrylcholinesterase highlighting 4a, 4g, 4j, 4l and 4s possessing balanced activities in the micromolar range. The top-ranked candidates in terms of the most pronounced potency against POP, AChE and BChE can be classified as 4d, 4u and 4v, bearing 4-methylbenzyl, (naphthalen-2-yl)methylene and 1-phenoxyethyl moieties, respectively. In vitro data were corroborated by detailed kinetic analysis of the selected lead molecules. 4d, 4u and 4v were also inspected for their potential to inhibit aggregation of two abberant proteins in AD, namely amyloid beta and tau, indicating their potential disease-modifying properties. To explain the results of our study, we carried out docking simulation to the active sites of the respective enzyme with the best berberine derivatives, along with QSAR study. We also investigated compounds' potential permeability through blood-brain barrier by applying parallel artificial membrane permeation assay and addressed their cytotoxicity profile.

Rhipicephalus microplus is responsible for high economic losses in livestock and its control has become difficult due to the establishment of tick populations resistant to commercial acaricides. This study aimed to evaluate the in vitro larvicidal effect of the alkaloids berberine and piperine, and also to investigate their inhibitory mechanisms against the acetylcholinesterase enzyme. The effects of the alkaloids on larvae were observed through the immersion test at the following concentrations: 1.5; 3; 6; 12; 16 and 24 mM. Berberine and piperine presented larvicidal activity greater than 95 %, not differing from 100 % for the positive fipronil control (p > 0.05). Of the two alkaloids, piperine had a lower effective concentration (EC), with an EC(50) of 6.04 mM. The acetylcholinesterase enzyme used in the study was obtained from R. microplus larvae (RmAChE) and the anticholinesterase activity was determined spectrophotometrically. The highest anticholinesterase activity, measured as inhibition concentration (IC), was observed for berberine (IC50 = 88.13 microM), while piperine showed lower activity (IC50 > 200 microM). Docking studies in RmAChE, followed by 10 ns molecular dynamics simulation, suggest that berberine stabilizes the RmAChE at lower Root-Mean-Square Deviation (RMSD) than Apo protein. Few hydrogen-bond interactions between berberine and RmAChE residues were balanced by hydrophobic and -type interactions. Berberine fills preferentially the peripheral anionic site (PAS), which correlates with its non-competitive mechanism. These results suggest that berberine and piperine alkaloids have an in vitro acaricidal action on R. microplus larvae, and the likely mechanism of action of berberine is related to RmAChE inhibition when accessing the PAS residues. These findings could help the study of new natural products that could inhibit RmAChE and aid in the development of new acaricides.

Systemic lipopolysaccharide (LPS) triggers neuroinflammation with consequent development of behavioral and cognitive deficits. Neuroinflammation plays a crucial role in the pathogenesis of neurodegenerative disorders including Alzheimer's disease (AD). Berberine is an isoquinoline alkaloid in Berberis genus with antioxidant and anti-inflammatory property and protective effects in neurodegenerative disorders. In this research, beneficial effect of this alkaloid against LPS-induced cognitive decline was assessed in the adult male rats. LPS was intraperitoneally administered at a dose of 1 mg/kg to induce neuroinflammation and berberine was given via gavage at doses of 10 or 50 mg/kg, one h after LPS, for 7 days. Treatment of LPS group with berberine at a dose of 50 mg/kg (but not at a dose of 10 mg/kg) improved spatial recognition memory in Y maze, performance in novel object recognition task (NORT), and prevented learning and memory dysfunction in passive avoidance tasks. Furthermore, berberine lowered hippocampal activity of acetylcholinesterase (AChE), malondialdehyde (MDA), protein carbonyl, activity of caspase 3, and DNA fragmentation and improved antioxidant capacity through enhancing glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase, and glutathione (GSH). Besides, berberine attenuated inflammation-related indices, as was evident by lower levels of nuclear factor-kappa B (NF-kappaB), toll-like receptor 4 (TLR4), tumor necrosis factor alpha (TNFalpha), and interleukin 6 (IL-6). Berberine also appropriately restored hippocampal 3-nitrotyrosine (3-NT), cyclooxygenase 2 (Cox 2), glial fibrillary acidic protein (GFAP), sirtuin 1, and mitogen-activated protein kinase (p38 MAPK) with no significant alteration of brain-derived neurotrophic factor (BDNF). In summary, berberine could partially ameliorate LPS-induced cognitive deficits via partial suppression of apoptotic cascade, neuroinflammation, oxido-nitrosative stress, AChE, MAPK, and restoration of sirtuin 1.

Background: Cognitive impairment caused by diabetes has been recognized. Berberine is well known for its resistance to peripheral lesions, but it is rarely used for the treatment of spatial learning and memory caused by diabetes. This study explored the mechanism of berberine to alleviate cognitive impairment via the cholinergic anti-inflammatory and insulin signaling pathways. Methods: Morris water maze was used to appraise spatial learning and memory. Positron-emission tomography (PET) imaging was adopted to detect the transport of glucose, and blood/cerebrospinal fluid (CSF) glucose was checked using commercial blood glucose meter. Insulin level was measured by ELISA kit and beta-Amyloid (Abeta) formation was observed by Congo red staining. Western-blot was performed to appraise protein expression. Results: We found that berberine rectified some aberrant changes in signal molecules concerning inflammation, and cholinergic and insulin signaling pathways in the hippocampus. Furthermore, CSF/blood glucose, inflammatory response or acetyl cholinesterase enzyme (AChE) activity were reduced by berberine. Additionally, acetylcholine levels were enhanced after berberine treatment in diabetic rats. Finally, Abeta formation in diabetic hippocampus was inhibited and spatial learning memory was ameliorated by berberine. Discussion: In conclusion, berberine clears Abeta deposit and consequently ameliorates spatial learning memory impairment via the activation of the cholinergic anti-inflammatory and insulin signaling pathways in diabetic rats.

BACKGROUND: Berberine is an isoquinoline alkaloid extracted from various Berberis species which is widely used in East Asia for a wide range of symptoms. Recently, neuroprotective effects of berberine in Alzheimer's disease (AD) animal models are being extensively reported. So far, no clinical trial has been carried out on the neuroprotective effects of berberine. However, a review of the experimental data is needed before choosing berberine as a candidate drug for clinical experiments. We conducted a systematic review on AD rodent models to analyze the drug effects with minimal selection bias. METHODS: Five online literature databases were searched to find publications reporting studies of the effect of berberine treatment on animal models of AD. Up to March 2018, 15 papers were identified to describe the efficacy of berberine. RESULTS: The included 15 articles met our inclusion criteria with different quality ranging from 3 to 5. We analyzed data extracted from full texts with regard to pharmacological effects and potential anti-Alzheimer's properties. Our analysis revealed that in multiple memory defects animal models, berberine showed significant memory-improving activities with multiple mechanisms, such as anti-inflammation, anti-oxidative stress, cholinesterase (ChE) inhibition and anti-amyloid effects. CONCLUSION: AD is likely to be a complex disease driven by multiple factors. Yet, many therapeutic strategies based on lowering beta-amyloid have failed in clinical trials. This suggest that the threapy should not base on a single cause of Alzheimer's disease but rather a number of different pathways that lead to the disease. Overall we think that berberine can be a promising multipotent agent to combat Alzheimer's disease.

Secondary metabolites from natural products are a potential source of acetylcholinesterase inhibitors (AChEIs), which is a key enzyme in the treatment of many neurodegenerative diseases. Inspired by the reported activities of isoquinoline-derivative alkaloids herein we report the design, one step synthesis and evaluation by capillary enzyme reactor (ICER) of benzyl analogs (1a-1e) of the tetrahydroprotoberberine alkaloid stepholidine, which is abundant in Onychopetalum amazonicum. Docking analysis based on the crystal structure of Torpedo californica AChE (TcAChE) indicated that pi-pi interactions were dominant in all planned derivatives and that the residues from esteratic, anionic and peripheral subsites of the enzyme played key interaction roles. Due to the similarities observed when compared with galantamine in the AChE complex, the results suggest that ligand-target interactions would increase, especially for the N-benzyl derivatives. From a series of synthesized compounds, the alkaloids (7R,13aS)-7-benzylstepholidine (1a), (7S,13aS)-7-benzylstepholidine (1b), and (S)-10-O-benzylstepholidine (1d) are reported here for the first time. The on flow bioaffinity chromatography inhibition assay, based on the quantification of choline, revealed the N-benzylated compound 1a and its epimer 1b to be the most active, with IC50 of 40.6 +/- 1 and 51.9 +/- 1 muM, respectively, and a non-competitive mechanism. The proposed approach, which is based on molecular docking and bioaffinity chromatography, demonstrated the usefulness of stepholidine as a template for the design of rational AChEIs and showed how the target-alkaloid derivatives interact with AChE.

Berberine has multiple clinical applications, including the treatment of tumors, diabetes, cardiovascular diseases, hyperlipidemia, inflammation, bacterial and viral infections, cerebral ischemic injuries, mental diseases, Alzheimer's disease and osteoporosis. In the present study, the neuroprotective effect of berberine agonist rescue learning and memory in severe traumatic brain injury (TBI), and the possible mechanism underlying these observations was explored. The protective effect of berberine agonist significantly recovered learning and memory skills, attenuated brain edema and inhibited matrix metalloproteinase3 and 9 protein expression in mice with severe TBI. Berberine agonist significantly reduced inflammation, oxidative stress and apoptosis levels in mice with severe TBI. Berberine agonist promoted choline acetyltransferase activity and inhibited the activity of acetylcholinesterase. Collectively, results of the present study revealed that the neuroprotective effect of berberine agonist rescues learning and memory skills in severe TBI.

A dataset of 67 berberine derivatives for the inhibition of butyrylcholinesterase (BuChE) was studied based on the combination of quantitative structure-activity relationships models, molecular docking, and molecular dynamics methods. First, a series of berberine derivatives were reported, and their inhibitory activities toward butyrylcholinesterase (BuChE) were evaluated. By 2D- quantitative structure-activity relationships studies, the best model built by partial least-square had a conventional correlation coefficient of the training set (R(2) ) of 0.883, a cross-validation correlation coefficient (Qcv2) of 0.777, and a conventional correlation coefficient of the test set (Rpred2) of 0.775. The model was also confirmed by Y-randomization examination. In addition, the molecular docking and molecular dynamics simulation were performed to better elucidate the inhibitory mechanism of three typical berberine derivatives (berberine, C2, and C55) toward BuChE. The predicted binding free energy results were consistent with the experimental data and showed that the van der Waals energy term (DeltaEvdw ) difference played the most important role in differentiating the activity among the three inhibitors (berberine, C2, and C55). The developed quantitative structure-activity relationships models provide details on the fine relationship linking structure and activity and offer clues for structural modifications, and the molecular simulation helps to understand the inhibitory mechanism of the three typical inhibitors. In conclusion, the results of this study provide useful clues for new drug design and discovery of BuChE inhibitors from berberine derivatives.

Berberine (BBR) is an isoquinoline alkaloid extracted from Rhizoma coptidis and has been used for treating type 2 diabetes mellitus (T2DM) in China. The development of T2DM is often abetasociated with insulin resistance and impaired glucose uptake in peripheral tibetasues. In this study, we examined whether BBR attenuated glucose uptake dysfunction through the cholinergic anti-inflammatory pathway in HepG2 cells. Cellular glucose uptake, quantified by the 2-[N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)-amino]-2-deoxy-D-glucose (2-NBDG), was inhibited by 21% after HepG2 cells were incubated with insulin (10(-6) mol/L) for 36 h. Meanwhile, the exprebetasion of alpha7 nicotinic acetylcholine receptor (alpha7nAChR) protein was reduced without the change of acetylcholinesterase (AChE) activity. The level of interleukin-6 (IL-6) in the culture supernatant, the ratio of phosphorylated I-kappa-B kinase-beta (IKkappabeta) Ser181/IKKbeta and the expression of nuclear factor-kappa B (NF-kappaB) p65 protein were also increased. However, the treatment with BBR enhanced the glucose uptake, increased the expression of alpha7nAChR protein and inhibited AChE activity. These changes were also accompanied with the decrease of the ratio of pIKKbeta Ser181/IKKbeta, NF-kappaB p65 expression and IL-6 level. Taken together, these results suggest that BBR could enhance glucose uptake, and relieve insulin resistance and inflammation in HepG2 cells. The mechanism may be related to the cholinergic anti-inflammatory pathway and the inhibition of AChE activity.

The present study aimed to investigate the effects of berberine (BRB) on spatial and learning memory, anxiety, acetylcholinesterase activity and cell death in an experimental model of intracerebroventricular streptozotocin (ICV-STZ) induced sporadic Alzheimer's-like dementia. Sixty male Wistar rats were randomly divided into six groups: control (CTR), BRB 50mg/kg (BRB 50), BRB 100mg/kg (BRB 100), streptozotocin (STZ), streptozotocin plus BRB 50mg/kg (STZ+BRB 50), and streptozotocin plus BRB 100mg/kg (STZ+BRB 100). Rats were injected with ICV-STZ (3mg/kg) or saline, and daily oral BRB treatment began on day 4 for a period of 21days. Behavioral tests were carried out on day 17, and rats were euthanized on day 24. Cell death analysis and determination of acetylcholinesterase activity was performed on the cerebral cortex and hippocampus of the brain. Administration of BRB prevented the memory loss, anxiogenic behavior, increased acetylcholinesterase activity and cell death induced by ICV-STZ. This may be explained, in part, by a protective effect of BRB on ameliorating the progression of neurodegenerative diseases, including Alzheimer's disease, and the results of this study provide a better understanding of the effect of BRB on the brain. Thus, BRB may act as a potential neuroprotective agent.

It was demonstrated that treatment with beta amyloid (Abeta) led to extreme alterations in the intrinsic electrophysiological properties of CA1 pyramidal neurons. Also, malfunction of the cholinergic system is correlated to the memory and cognitive impairments. Several new studies have suggested that Berberis vulgaris can act as a cholinesterase inhibitor. The present study aimed to investigate the effects of berberine (BER) on the Abeta-induced impairments in learning and memory. The male Wistar rats were divided into 4 groups of Sham, BER, Abeta and Abeta+BER. The administration of BER or its vehicle started immediately after the injection of Abeta and followed by 13 days. Then, the animals were tested for learning and memory performance using the Morris water maze (MWM) and passive avoidance tests. Then, they were sacrificed for the whole cell patch clamp recording. The results of the MWM and passive avoidance tasks indicated that administration of the BER in the Abeta+BER group prevented the memory impairment induced by Abeta. The results of the whole cell patch clamp also showed that administration of the BER restored the Abeta-induced impairments in the firing frequency, half-width and rebound action potential. These results suggested that administration of the BER could ameliorate neurotoxicity induced by Abeta. However, this neuroprotection impact could be resulted from the balance effect of the Ca(2+) entry. The optimal level of Ca(2+) entry by BER could be a major factor that modified the function of the Ca(2+)-activated K(+) channels and decreased the half-width in the Abeta treated rats.

Three new serratene-type triterpenoids (1-3) and a new hydroxy unsaturated fatty acid (13) together with nine known compounds (4-12) were isolated from Lycopodiella cernua. The chemical structures were established using NMR, MS, and Mosher's method. Compound 13 showed the most potent inhibitory activity against acetylcholinesterase (AChE) with an IC50 value of 0.22muM. For butyrylcholinesterase (BChE) inhibitory activity, 5 showed the most potent activity with an IC50 value of 0.42muM. Compound 2 showed the most potent activity with an IC50 of 0.23muM for BACE-1 inhibitory activity. The kinetic activities were investigated to determine the type of enzyme inhibition involved. The types of AChE inhibition shown by compounds 4, 5, and 13 were mixed; BChE inhibition by 5 was competitive, while 2 and 6 showed mixed-types. In addition, molecular docking studies were performed to investigate the interaction of these compounds with the pocket sites of AChE. The docking results revealed that the tested inhibitors 3, 4, and 13 were stably present in several pocket domains of the AChE residue.

Memory impairment induced by ethanol in rats is a consequence of changes in the CNS that are secondary to impaired oxidative stress and cholinergic dysfunction. Treatment with antioxidants and cholinergic agonists are reported to produce beneficial effects in this model. Berberine, an isoquinoline alkaloid is reported to exhibit antioxidant effect and cholinesterase (ChE) inhibitor activity. However, no report is available on the influence of berberine on ethanol-induced memory impairment. Therefore, we tested its influence against cognitive dysfunction in ethanol-induced rats using Morris water maze paradigm. Lipid peroxidation and glutathione levels as parameter of oxidative stress and cholinesterase (ChE) activity as a marker of cholinergic function were assessed in the cerebral cortex and hippocampus. Forty five days after ethanol treated rats showed a severe deficit in learning and memory associated with increased lipid peroxidation, decreased glutathione, and elevated ChE activity. In contrast, chronic treatment with berberine (25-100mg/kg, p.o., once a day for 45days) improved cognitive performance, and lowered oxidative stress and ChE activity in ethanol treated rats. In another set of experiments, berberine (100mg/kg) treatment during training trials also improved learning and memory, and lowered oxidative stress and ChE activity. Chronic treatment (45days) with vitamin C, and donepezil during training trials also improved ethanol-induced memory impairment and reduced oxidative stress and/or cholinesterase activity. In conclusion, the present study demonstrates that treatment with berberine prevents the changes in oxidative stress and ChE activity, and consequently memory impairment in ethanol treated rats.

Alzheimer's disease is a multi-factorial neurodegenerative disorder devastatingly affecting the aged population worldwide. Previous studies have shown that medicinal herbs used in traditional Chinese medicine might be benefit to Alzheimer's disease patients. Berberine and palmatine, two isoquinoline alkaloids found in several medicinal herbs, were used for memory enhancement in China. In this study, the inhibitory effects of combined berberine and palmatine on acetylcholinesteras were evaluated using recombinant human acetylcholinesterase. Our results showed that the combination of berberine and palmatine inhibited acetylcholinesterase in a mixed competitive pattern. By the median-effect principle, the calculated combination index of the combination was less than 1, suggesting that berberine and plamatine inhibited acetylcholinesterase synergistically. Furthermore, the drug-reducing index of berberine and palmatine were 2.98 and 2.66, respectively. Taken together, the results showed that the combination of the two alkaloids might potentially be developed as a more effective therapeutic strategy for Alzheimer's disease patients.

BACKGROUND: Berberis vulgaris is a well known plant with traditional herbal medical history. The aims of this study was to bioscreen and compare the in vitro biological activity (antioxidant, cholinergic, antidaibetic and the anticancer) of barberry crude extract and berberine active compound.
METHODS: The effect of B. vulgaris extract and berberine chloride on cellular thiobarbituric acid reactive species (TBARS) formation, diphenyle--alpha-picrylhydrazyl (DPPH) oxidation, cellular nitric oxide (NO) radical scavenging capability, superoxide dismutase (SOD), glutathione peroxidase (GPx), acetylcholinesterase (AChE) and alpha-gulcosidase activities were spectrophotometrically determined. On the other hand, the effect of extract and berberine as anticancer was estimated on three different cell lines which were MCF-7, HepG-2, and Caco-2 cells by using neutral red uptake assay which compared with control normal cells (PBMC).
RESULTS: Our results showed that barberry crude extract contains 0.6 mg berberine/mg crude extract. Barberry extract showed potent antioxidative capacity through decreasing TBARS, NO and the oxidation of DPPH that associated with GPx and SOD hyperactivation. Inhibitory effect of berberis crude extract on alpha-glucosidase was more potent than that of berberine chloride, while both had the same AChE inhibitory effect. Besides, different concentrations of both berberine chloride and barberry ethanolic extract showed to have no growth inhibitory effect on normal blood cells (PBMC). Otherwise, both berberine chloride and barberry ethanolic extract showed to have inhibitory effect on the growth of breast, liver and colon cancer cell lines (MCF7, HepG2 and CACO-2, respectively) at different incubation times starting from 24 hrs up to 72 hrs and the inhibitory effect increased with time in a dose dependant manner. CONCLUSION: This work demonstrates the potential of the barberry crude extract and its active alkaloid, berberine, on suppressing lipid peroxidation, suggesting a promising use in the treatment of hepatic oxidative stress, Alzheimer and idiopathic male factor infertility. Beside, berberis vulgaris ethanolic extract is safe non-toxic extract as it was not inhibit the growth of PBMC that can induce cancer cell death that could return to its powerful antioxidant activity.

Various potential molecules with putative positive role in stroke pathology have failed to confer neuro-protection in animal models due to their insufficient bioavailability in brain. Efflux of these molecules by P-glycoprotein (P-gp), on blood brain barrier (BBB) is one of the reasons of their poor bioavailability. Berberine, have anti-inflammatory, antioxidant, anti-apoptotic properties, but also having low oral bioavailabilty. Verapamil, which increased the central nervous system uptake of few drugs, when concomitantly administered with berberine was evaluated in this animal model. Wistar rats were subjected to bilateral common carotid artery occlusion to induce acute cerebral ischemia for 15min followed by reperfusion resulting in transient global cerebral ischemia. For 19 days berberine (5, 10, 20mg/kg, p.o.) alone and in similar doses concomitantly with verapamil (2mg/kg, p.o.) was evaluated employing various neuro-behavioral test, biochemical parameters and molecular estimations. The adjunction of berberine with verapamil improved the neurological outcome in a battery of behavioral paradigms, improved spatial memory in Morris water maze task, ameliorated the oxidative-nitrosative stress, increased acetylcholinesterase (AChE) activity, as well as improved mitochondrial complex (I, II, and IV) activity, reducing tumor necrosis factor-alpha, interleukin-1 beta and caspase-3 levels in brain tissues as compared to berberine alone group in ischemic rats. There is a strong possibility of improved brain bioavailabity of berberine when combined with verapamil. The findings suggested that the combination of berberine with verapamil, which could enhance its brain uptake, will surely provide a greater impact in neroprotection drug discovery for search of such combination.

A series of berberine-phenyl-benzoheterocyclic (26-29) and tacrine-phenyl-benzoheterocyclic hybrids (44-46) were synthesised and evaluated as multifunctional anti-Alzheimer's disease agents. Compound 44b, tacrine linked with phenyl-benzothiazole by 3-carbon spacers, was the most potent AChE inhibitor with an IC(50) value of 0.017 muM. This compound demonstrated similar Abeta aggregation inhibitory activity with cucurmin (51.8% vs 52.1% at 20 muM, respectively), indicating that this hybrid is an excellent multifunctional drug candidate for AD.

The natural isoquinoline alkaloid berberine possesses potential to treat Alzheimer's disease (AD) by targeting multiple pathogenic factors. In the present study, docking simulations were performed to gain deeper insights into the molecular basis of berberine's inhibitory effects against the important pathogenic enzymes of AD, that is, acetylcholinesterase, butyrylcholinesterase, and two isoforms of monoamine oxidase. It was found that the theoretical binding affinities of berberine to the four enzymes are very close to the experimental values, which verify the methodology. Further inspection to the binding modes found that hydrophobic interactions between the hydrophobic surface of berberine and neighboring hydrophobic residues are the principal forces contributing to the ligand-receptor interactions. Although berberine cation also has potential to form electrostatic interaction with neighboring residues, it is interesting to find that electrostatic force is excluded in the four cases unexpectedly. These results have important implications for the berberine-based anti-AD drug design.

Memory impairment induced by streptozotocin in rats is a consequence of changes in CNS that are secondary to chronic hyperglycemia, impaired oxidative stress, cholinergic dysfunction, and changes in glucagon-like peptide (GLP). Treatment with antihyperglycemics, antioxidants, and cholinergic agonists are reported to produce beneficial effect in this model. Berberine, an isoquinoline alkaloid is reported to exhibit anti-diabetic and antioxidant effect, acetylcholinesterase (AChE) inhibitor, and increases GLP release. However, no report is available on influence of berberine on streptozotocin-induced memory impairment. Therefore, we tested its influence against cognitive dysfunction in streptozotocin-induced diabetic rats using Morris water maze paradigm. Lipid peroxidation and glutathione levels as parameters of oxidative stress and choline esterase (ChE) activity as marker of cholinergic function were assessed in the cerebral cortex and hippocampus. Thirty days after diabetes induction rats showed a severe deficit in learning and memory associated with increased lipid peroxidation, decreased reduced glutathione, and elevated ChE activity. In contrast, chronic treatment with berberine (25-100mg/kg, p.o., twice daily, 30 days) improved cognitive performance, lowered hyperglycemia, oxidative stress, and ChE activity in diabetic rats. In another set of experiment, berberine (100mg/kg) treatment during training trials also improved learning and memory, lowered hyperglycemia, oxidative stress, and ChE activity. Chronic treatment (30 days) with vitamin C or metformin, and donepezil during training trials also improved diabetes-induced memory impairment and reduced oxidative stress and/or choline esterase activity. In conclusion, the present study demonstrates treatment with berberine prevents the changes in oxidative stress and ChE activity, and consequently memory impairment in diabetic rats.

Berberis darwinii is native to South America but has been widely distributed in Europe and other continents following its discovery by Charles Darwin. Herewith, the therapeutic potential of stem-bark of the plant for treating Alzheimer's disease was studied using an in vitro acetylcholinesterase inhibition assay. It was found that the methanolic extract of the stem-bark was a potent inhibitor of the enzyme with an IC50 value of 1.23 +/- 0.05 microg/mL. An HPLC-based berberine quantification study revealed an astonishing 38% yield of the dried methanolic extract.

We designed and synthesized a series of hybrid molecules, in an effort to identify novel multifunctional drug candidates for Alzheimer's disease (AD), by reacting berberine with benzenediol, melatonin, and ferulic acid. The products were evaluated for: (i) the ability to inhibit multiple cholinesterases (ChEs); (ii) the capacity to prevent amyloid beta (Abeta) aggregation; and (iii) antioxidant activity. All of the derivatives were better antioxidants, and inhibited Abeta aggregation to a greater extent, than the lead compound, berberine. Two of the hybrids, in particular, have the potential to be excellent candidates for AD therapy: the berberine-pyrocatechol hybrid (compound 8) was a much better inhibitor of acetylcholinesterase (AChE) than unconjugated berberine (IC(50): 0.123 vs 0.374 muM); and the berberine-hydroquinone hybrid (compound 12) displayed high antioxidant activity, could inhibit AChE (IC(50) of 0.460 muM), and had the greatest ability to inhibit Abeta aggregation.

A series of 9-N-substituted berberine derivatives were synthesized and biologically evaluated as antioxidant and inhibitors of acetylcholinesterase (AChE), butyrylcholinesterase and amyloid-beta aggregation. Most of these compounds exhibited very good antioxidant activities, inhibitive activities of AChE and amyloid-beta aggregation. Among them, compound 8d, (o-methylphenethyl)amino linked at the 9-position of berberine, was found to be a good antioxidant (with 4.05 muM of Trolox equivalents), potent inhibitor of AChE (an IC(50) value of 0.027 muM), and high active inhibitor of amyloid-beta aggregation (an IC(50) value of 2.73 muM).

A series of novel triazole-containing berberine derivatives were synthesized via the azide-alkyne cycloaddition reaction. Their biological activity as inhibitors of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were evaluated. Among them, compound 16d, which featured a diisopropylamino substitution at the 4-position of triazole ring, was found to be a potent inhibitor of AChE, with IC(50) value of 0.044 uM. Compound 18d, which beares a butyl at the 4-position of the triazole ring, showed the highest potency of beta-amyloid aggregation inhibition (77.9% at 20 uM). Molecular modeling studies indicated that the triazole moiety of berberine derivatives displayed a face-to-face - stacking interaction in a 'sandwich' form with the Trp84 (4.09 ) and Phe330 (4.33 ) in catalytic sites of AChE.

BACKGROUND: Berberine (BER), the major alkaloidal component of Rhizoma coptidis, has multiple pharmacological effects including inhibition of acetylcholinesterase, reduction of cholesterol and glucose levels, anti-inflammatory, neuroprotective and neurotrophic effects. It has also been demonstrated that BER can reduce the production of beta-amyloid40/42, which plays a critical and primary role in the pathogenesis of Alzheimer's disease. However, the mechanism by which it accomplishes this remains unclear. RESULTS: Here, we report that BER could not only significantly decrease the production of beta-amyloid40/42 and the expression of beta-secretase (BACE), but was also able to activate the extracellular signal-regulated kinase1/2 (ERK1/2) pathway in a dose- and time-dependent manner in HEK293 cells stably transfected with APP695 containing the Swedish mutation. We also find that U0126, an antagonist of the ERK1/2 pathway, could abolish (1) the activation activity of BER on the ERK1/2 pathway and (2) the inhibition activity of BER on the production of beta-amyloid40/42 and the expression of BACE. CONCLUSION: Our data indicate that BER decreases the production of beta-amyloid40/42 by inhibiting the expression of BACE via activation of the ERK1/2 pathway.

Berberine derivatives with substituted amino groups linked at the 9-position using different carbon spacers were designed, synthesized, and biologically evaluated as inhibitors of acetylcholinesterase. Compound 10b, with a cyclohexylamino group linked to berberine by a three carbon spacer, gave the most potent inhibitor activity with an IC(50) of 0.020 muM for AChE. Kinetic studies revealed mixed inhibition of AChE, and molecular modeling simulations of the AChE-inhibitor complex confirmed that compounds bound to both the catalytic active site and the peripheral anionic site.

By targeting the dual active sites of acetylcholinesterase (AChE), a new series of berberine derivatives was designed, synthesized, and evaluated as AChE inhibitors. Most of the derivatives inhibited AChE in the sub-micromolar range. Compound 8c, berberine linked with phenol by a 4-carbon spacer, showed the most potent inhibition of AChE. A kinetic study of AChE and BuChE indicated that a mix-competitive binding mode existed for these berberine derivatives. Molecular modeling studies confirmed that these hybrids target both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. This is the first report where AChE inhibitory activity has been associated with berberine as a lead molecule.

A series of novel berberine derivatives were designed, synthesized, and biologically evaluated as inhibitors of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Among these derivatives, compound 48a, berberine linked with 3-methylpyridinium by a 2-carbon spacer, was found to be a potent inhibitor of AChE, with an IC(50) value of 0.048 microM and compound 40c, berberine linked with 2-thionaphthol by a 4-carbon spacer, acted as the most potent inhibitor for BuChE with an IC(50) value of 0.078 microM. Kinetic studies and molecular modeling simulations of the AChE-inhibitor complex indicated that a mixed-competitive binding mode existed for these berberine derivatives.

Glucagon-like peptide (GLP)-1 is a potent glucose-dependent insulinotropic gut hormone released from intestinal L cells. Our previous studies showed that berberine increased GLP-1 secretion in streptozotocin-induced diabetic rats. The aim of this study was to investigate whether berberine affected GLP-1 release in normal rats and in NCI-H716 cells. Proglucagon and prohormone convertase 3 genes regulating GLP-1 biosynthesis were analyzed by RT-PCR. Effects of pharmacological inhibitors on berberine-mediated GLP-1 release were studied. In vivo, 5-week treatment of berberine enhanced GLP-1 secretion induced by glucose load and promoted proglucagon mRNA expression as well as L cell proliferation in intestine. In vitro, berberine concentration-dependently stimulated GLP-1 release in NCI-H716 cells. Berberine also promoted both prohormone convertase 3 and proglucagon mRNA expression. Chelerythrine (inhibitor of PKC) concentration-dependently suppressed berberine-mediated GLP-1 secretion. Compound C (inhibitor of AMPK) also inhibited berberine-mediated GLP-1 secretion. But only low concentrations of H89 (inhibitor of PKA) showed inhibitory effects on berberine-mediated GLP-1 release. The present results demonstrated that berberine showed its modulation on GLP-1 via promoting GLP-1 secretion and GLP-1 biosynthesis. Some signal pathways including PKC-dependent pathway were involved in this process. Elucidation of mechanisms controlling berberine-mediated GLP-1 secretion may facilitate the understanding of berberine's antidiabetic effects.

A new protoberberine alkaloid, 3-hydroxy-2-methoxy-9,10-methylenedioxy-8-oxo-protoberberine, along with three known compounds, was isolated from Rhizoma Coptidis. The new compound displayed weak antispasmodic activity against acetylcholine-induced contraction in isolated guinea-pig ileum with an IC50 of 83.7 microm.

OBJECTIVE: To investigate the protective effects of the total base from rhizoma coptis chinensis (CTB) and berberine (Ber) on neurodegeneration induced by aluminum overload in rats. METHODS: The study took place in the Department of Pharmacology, Chongqing Medical University, Chongqing, China, between February 2005 and May 2007. Wistar rats were divided into control group, model group, Ber-treated group, CTB (55 mg/kg and 110 mg/kg)-treated group, and nimodipine-treated group (n=20). A rat brain damage model was established via intragastric administration of 400 mg/kg element aluminum once a day, 5 days a week for 12 weeks. The CTB, Ber, and nimodipine were intragastrically administered 4 hours after each aluminum administration for 12 weeks. The morphological changes of the neurons of the rat hippocampus and the changes of rat learning and memory functions were observed. The superoxide dismutase (SOD), choline acetyltransferase (ChAT), acetylcholinesterase (AchE), and monoamine oxidase-B (MAO-B) activities and malondialdehyde (MDA) content, as well as the MAO-B expression in the rat brain were examined. RESULTS: The CTB, Ber, and nimodipine significantly improved the learning and memory ability impairment and hippocampal neuronal death. The CTB, Ber, and nimodipine also significantly blunted the decrease of SOD and ChAT activities, and the increase of MDA content, AchE activities, and MAO-B expressions and activity in the aluminum-overload rats. CONCLUSION: The CTB and Ber have protective effects on neurodegeneration induced by aluminum overload. The CTB (110 mg/kg) has more powerful neuroprotection than Ber.

Prolyl oligopeptidase is a cytosolic serine peptidase that hydrolyzes proline-containing peptides at the carboxy terminus. This peptidase has been associated with schizophrenia, bipolar affective disorder, and related neuropsychiatric disorders, and therefore may have important clinical implications. Among the strategies used to find novel prolyl oligopeptidase inhibitors, traditional Chinese medicinal plants provide a rich source of unexplored compounds. We used (19)F NMR spectroscopy to search for new prolyl oligopeptidase inhibitors in a library of traditional Chinese medicine plant extracts. Several extracts were identified as powerful inhibitors of this peptidase. The alkaloid berberine was the prolyl oligopeptidase inhibitory molecule isolated from Rhizoma coptidis extract. Berberine inhibited prolyl oligopeptidase in a dose-dependent manner. As berberine is a natural compound that has been safely administered to humans, it opens up new perspectives for the treatment of neuropsychiatric diseases. The results described herein suggest that the initiation of clinical trials in patients with schizophrenia, bipolar affective disorder, or related diseases in which cognitive capabilities are affected should be undertaken with either the extract or pure BBR.

A methanol extract of Coptidis Rhizoma effectively enhanced the outgrowth of neurite in PC12 cells induced by nerve growth factor (NGF). Following solvent partition and preparative HPLC, berberine was isolated as the major active compound. Berberine enhanced the proportion of neurite-bearing cells in a dose-dependent manner without cytotoxicity. Its structural relatives, palmatine and coptisine, showed a slightly weaker NGF-enhancing effect than berberine. These three alkaloids inhibited acetylcholinesterase activity at a level comparable to that of physostigmine, but this inhibition was not responsible for the potentiation of NGF-induced neurite outgrowth. It is demonstrated for the first time that protoberberine alkaloids potentiated the NGF-induced differentiation of neural cells.

The effect of berberine (BER) on scopolamine (SCOP)-induced amnesia was investigated in a step-through passive avoidance task in rats. It was observed that BER at the doses of 0.1 and 0.5 g/kg after 7-day or 14-day administration significantly improved SCOP-induced amnesia. The anti-amnesic effect of BER after 14-day administration on the SCOP-induced amnesia was significantly augmented by physostigmine or neostigmine, and completely reversed by scopolamine N-methylbromide. These results suggest that the antiamnesic effect of BER after 14-day administration may be related to the increase in the peripheral and central cholinergic neuronal system activity.

The alkaloids berberine, palmatine and sanguinarine are toxic to insects and vertebrates and inhibit the multiplication of bacteria, fungi and viruses. Biochemical properties which may contribute to these allelochemical activities were analysed. Acetylcholine esterase, butyrylcholinesterase, choline acetyl transferase, alpha 1- and alpha 2-adrenergic, nicotinergic, muscarinergic and serotonin2 receptors were substantially affected. Sanguinarine appears to be the most effective inhibitor of choline acetyl-transferase (IC50 284 nM), while the protoberberines were inactive at this target. Berberine and palmatine were most active at the alpha 2-receptor (binding with IC50 476 and 956 nM, respectively). Furthermore, berberine and sanguinarine intercalate DNA, inhibit DNA synthesis and reverse transcriptase. In addition, sanguinarine (but not berberine) affects membrane permeability and berberine protein biosynthesis. In consequence, these biochemical activities may mediate chemical defence against microorganisms, viruses and herbivores in the plants producing these alkaloids.

The effects of berberine on guinea-pig ileum contractility were studied in both transmurally-stimulated and unstimulated preparations. Transmural stimulation (80 V, 0.5 ms, 0.05 Hz) of the guinea-pig ileal segments produced a twitch response. Berberine (10(-8)-10(-5) M) enhanced this response dose-dependently. Atropine (10(-7) M), but not mecamylamine (10(-5) M), abolished this response. Acetylcholine (3 x 10(-9) and 10(-8) M) also enhanced the response to transmural stimulation. Pretreatment with hemicholinium (3 x 10(-5) M) antagonized the effect of berberine but failed to change that of acetylcholine. Berberine (10(-5) M) also antagonized the alpha 2-adrenoceptor agonist xylazine (10(-8) and 10(-7) M)-induced inhibition of the twitch response to transmural stimulation. In unstimulated ileal preparations, berberine (10(-5) M) produced contractile responses. In these preparations, atropine (10(-6) M), but not mecamylamine (10(-4) M), abolished the response to berberine. Furthermore, berberine (10(-6)-10(-4) M) inhibited dose-dependently the cholinesterase activity of the guinea-pig blood. The results suggest that berberine increases ileal contractility by: 1) increasing acetylcholine release from the postganglionic parasympathetic nerve terminal, 2) increasing acetylcholine retention through an inhibition of cholinesterase activity, and 3) blocking alpha 2-adrenoceptors, possibly in the postganglionic parasympathetic nerve.

The effects of berberine on the contractions of the longitudinal muscle of the guinea-pig isolated ileum were investigated. Lower concentrations of berberine (less than or equal to 5 x 10(-5) M) induced a parallel rightward shift of the dose-response curve of acetylcholine, suggesting that berberine is antagonizing the actions of acetylcholine at the receptors competitively. At higher concentration, berberine (1 x 10(-4) M) facilitated a rightward shift of the dose-response curve of acetylcholine with a reduction of maximum response, indicating that the interactions of the two agents changed from competitive to noncompetitive antagonism. The competitive antagonism is due to the actions of acetylcholine at the muscarinic receptors, while the noncompetitive antagonism is probably due to the action of berberine at other sites in addition to the muscarinic receptor sites. Berberine dose-dependently antagonized the effects of muscarine, a specific muscarinic receptor agonist, in a fashion similar to the antagonism of acetylcholine, providing evidence that the site of action of berberine is at the muscarinic receptors. Hexamethonium (7.5 x 10(-4) M) did not influence the effect of berberine on the concentration-response curve of acetylcholine and berberine had no effects on the contractions of the preparation elicited by histamine, suggesting its specificity for muscarinic receptors. Berberine also concentration-dependently reduced electrically induced cholinergic contractions, corresponding with its effects at the muscarinic receptor sites. Berberine had no effects on the contractions elicited by KCl, which acts at postreceptor sites. The action of berberine was reversible and dependent on the duration of incubation with the preparation; the longer the time of incubation with the tissues, the slower the recovery. The results of this series of experiments support the hypothesis that berberine blocks muscarinic receptors and this might be part of the explanation of its efficacy in the reduction of intestinal motility and in the treatment of diarrhea.