Konrath_2013_J.Enzyme.Inhib.Med.Chem_28_218

The alkaloid extracts of four Huperzia and one Lycopodiella species, from Brazilian habitats, were tested for their in vitro anticholinesterase activities. IC(50) values showed a potent acetylcholinesterase inhibition for H. reflexa (0.11 +/- 0.05 mug/mL), followed by H. quadrifariata (2.0 +/- 0.3 mug/mL), H. acerosa (5.5 +/- 0.9 mug/mL), H. heterocarpon (25.6 +/- 2.7 mug/mL) and L. cernua (42.6 +/- 1.5 mug/mL). A lower inhibition of butyrylcholinesterase was observed for all species with the exception of H. heterocarpon (8.3 +/- 0.9 mug/mL), whose alkaloid extract presented a selectivity for pseudocholinesterase. Moreover, the chemical study of the bioactive extracts performed by GC-MS, revealed the presence of a number of Lycopodium alkaloids belonging to the lycopodane, flabellidane and cernuane groups. Surprisingly, the potent acetylcholinesterase inhibitors huperzines A and B were not detected in the extracts, suggesting that other alkaloids may be responsible for such an effect.