Anti-inflammatory steroids from the stems of Solanum nigrum L.

Sixteen previously undescribed steroidal sapogenins along with two known ones were isolated from the stems of Solanum nigrum L. (Solanaceae). Their structures were identified using a combination of 1D and 2D NMR, HR-ESI-MS spectroscopy, the Mosher method, and X-ray diffraction analysis. Compounds 1-8 have an unusual F ring and 9-12 have a derived A ring, both of which are rare skeletons found in natural products. The biological evaluation showed that the isolated steroids exhibited inhibition of nitric oxide in the LPS-induced RAW 264.7 macrophages with IC50 values from 7.4 to 41.3 mu M. Further studies revealed that compounds 6 and 10 exhibited anti-inflammatory activity by blocking the nuclear translocation of NF-kappa B, and down-regulating the expression of iNOS, COX-2, IL-1 beta, and IL-6 in a concentration-dependent manner. These results suggest that the stems of S. nigrum may serve as a source of anti-inflammatory agents for use in healthy or medicinal products.