The investigation of the fruits of Solanum nigrum led to the isolation of four previously undescribed steroidal alkaloids, named solanine A, 7α-OH khasianine, 7α-OH solamargine and 7α-OH solasonine, together with six known ones. The structures of the isolated compounds were elucidated unambiguously by spectroscopic data analyses and chemical methods. Solanine A represents an unusual steroidal alkaloid with an unprecedented 6/5/6/5/5/6 hexacyclic ring system, and its structure was confirmed by X-ray single crystal diffraction analysis. Compounds 2-4 were rare naturally occurring steroidal alkaloid glycosides bearing a hydroxyl group at C-7 position. Solanine A showed the most potent inhibitory activity against the LPS-induced NO production in murine RAW264.7 macrophages with an IC50 value of 3.85 ± 0.71 μM and significant cytotoxicity against MGC803, HepG2 and SW480 cancer cell lines with IC50 values of 6.00 ± 0.52 μM, 9.25 ± 0.49 μM and 6.23 ± 0.26 μM, respectively.
Keywords: Anti-inflammatory activity; Cytotoxic activity; Solanum nigrum Linn.; Steroidal alkaloids.
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