Pipersarmenoids, new amide alkaloids from Piper sarmentosum.

A chemical investigation of the aerial parts of Piper sarmentosum resulted in the isolation and identification of 14 amide alkaloids, including three new amide alkaloids, pipersarmenoids A - C (1-3), three new natural amide alkaloids, pipersarmenoids D - F (4-6), and 8 known analogues, N-p-coumaroyltyramine (7), piperlotine C (8), piperlotine D (9), pellitorine (10), sarmentine (11), aurantiamide acetate (12), 1-cinnamoyl pyrrolidine (13) and sarmentamide B (14). Their structures were determined by spectroscopic analysis including HRESIMS and 1D and 2D NMR. The cytotoxicity, neuroinflammation-inhibiting and acetylcholinesterase (AChE) inhibitory activities of those compounds were tested. Compounds 1, 2 and 12 inhibited NO production induced by LPS in BV2 cells with IC50 values of 9.36, 12.53 and 10.77 μM, respectively. Moreover, 1, 2, 7 and 11 showed moderate inhibitory activity on AChE with IC50 values ranging from 37.56 to 48.84 μM.