New unsaturated fatty acids from the aerial parts of Lycopodiastrum casuarinoides

Two new unsaturated fatty acid esters (1 and 2) and five new unsaturated fatty acids (4–8), together with two known analogs (3 and 9) were isolated from the aerial parts of Lycopodiastrum casuarinoides. Their structures were unambiguously elucidated by obtaining extensive spectroscopic data and comparing them with data in the literature. The absolute configurations of 1 and 2 were established by a modified Mosher's method. All compounds were evaluated in vitro for their inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Compound 8 exhibited the most potent inhibitory activity against AChE with an IC50 value of 1.16 ± 0.13 μM.