Amaryllidaceae alkaloids with nitric oxide inhibitory activity from the leaves of Crinum asiaticum L. var. asiaticum.

Forty-two Amaryllidaceae alkaloids, including eleven previously undescribed alkaloids, crinasiaticines C-M, and three undescribed naturally occurring alkaloids, (+)-dihydroepivittatine, (+)-dihydrovittatine and (+)-dihydrohamayne, were isolated from the leaves of Crinum asiaticum L. var. asiaticum. Their structures and configurations were elucidated using NMR and MS spectroscopic techniques, along with the comparison of experimental electronic circular dichroism spectra to calculated data. The anti-inflammatory activity against nitric oxide (NO) production in lipopolysaccharide-stimulated RAW264.7 cells was evaluated for most of the isolated alkaloids. Compounds 39, 21, 22, and 35 exhibited considerable NO inhibitory activity, with IC50 values of 2.5-2.6 μM, compared to positive control dexamethasone (IC50 2.7 μM). However, these compounds demonstrated cytotoxic effects on cells. Compound 15 also possessed the highest selectivity index of 22.5 with minimal cytotoxicity.