Agunloye_2017_J.Complement.Integr.Med_15_

Background Donepezil hydrochloride commonly used in the management of Alzheimer's disease (AD), exhibiting its inhibitory effects on acetylcholinesterase and butyrylcholinesterase activity thereby enhance cognitive function. Caffeic acid member of hydroxycinnamic acid is widely present in human diet. This study aims to investigate influence of caffeic acid on acetylcholinesterase and butyrylcholinesterase inhibitory properties of donepezil (in vitro). Methods 5mg of donepezil was dissolved in 50mL distilled water while 10mg of caffeic acid was dissolved in 100mL distilled water. Therefore, mixtures of samples were prepared as follows: A2=donepezil 0.075mg/mL+caffeic acid 0.025mg/mL; A3=donepezil 0.050mg/mL+caffeic acid 0.050mg/mL; A4=donepezil 0.025mg/mL+caffeic acid 0.075mg/mL. All samples were kept in the refrigerator at 4 degrees C for subsequent analysis. Results The result showed that all the combinations show an inhibitory effect on acetylcholinesterase and butyrylcholinesterase activity in vitro, with the combination A4=donepezil 0.025mg/mL+caffeic acid 0.075mg/mL had significant (p<0.05) highest inhibitory effect on acetylcholinesterase and butyrylcholinesterase activity in vitro. More so, all the samples were able to prevent pro-oxidants (FeSO4 and sodium nitroprusside [SNP] ) induced lipid peroxidation in rat brain homogenate, with the combination A4=donepezil 0.025mg/mL+caffeic acid 0.075mg/mL and A3=donepezil 0.050mg/mL+caffeic acid 0.050mg/mL had highest inhibitory effect against FeSO4 and SNP induced lipid peroxidation in rat brain homogenate in vitro respectively. Moreover, all the samples exhibit antioxidant properties as typified by their ability to chelate iron (II) ion (Fe2+), hydroxyl radical (OH) radical scavenging ability and ferric reducing property (FRAP). Conclusions Therefore, the combination of caffeic acid with donepezil enhances the antioxidant properties of donepezil. The combination of caffeic acid with donepezil could be a therapeutic aid in the management of AD, possibly with fewer side effects of donepezil. Nevertheless, the combination donepezil 0.025mg/mL+caffeic acid 0.075mg/mL acid look promising.