Two new megastigmane glycosides, (6 R,7E,9R)-3-oxo-α-ionyl-9-O-α-L-rhamnopyranosyl-(1''→4')-β-D-glucopyranoside (1) and (6 R,7E,9R)-3-oxo-α-ionyl-9-O-β-D-glucopyranosyl-(1''→6')-β-D-glucopyranoside (2), together with six known analogues (3-8) were isolated from the leaves of Nicotiana tabacum. The structures of all metabolites were determined by comprehensive analysis of NMR and MS spectroscopic data as well as by comparison with those of previously reported. The in vitro anti-inflammatory activity of all isolates was evaluated using a lipopolysaccharide (LPS)-induced RAW264.7 cell inflammatory model, and the compounds 1, 3, 7, and 8 exhibited inhibition of LPS-induced NO production in RAW264.7 macrophage cells with IC50 values of 42.3-61.7 μM (positive control, dexamethasone, IC50 = 21.3 ± 1.2 μM).
Keywords: IC50; Megastigmane glycosides; Nicotiana tabacum; anti-inflammatory; structural determination.