Antibacterial and cytotoxic phenolic metabolites from the fruits of Amorpha fruticosa

Fourteen new secondary metabolites; 2-[(Z)-styryl]-5-geranylresorcin-1-carboxylic acid (1), 8-geranyl-3,5,7-trihydroxyflavanone (2), 8-geranyl-5,7,3′-trihydroxy-4′-methoxyisoflavone (3), 6-geranyl-5,7,3′-trihydroxy-4′-methoxyisoflavone (4), amorphispironones B (5) and C, amorfrutin D, 4-O-demethylamorfrutin D, 8-geranyl-7,3′-dihydroxy-4′-methoxyisoflavone, 3-O-demethyldalbinol, 6a,12a-dehydro-3-O-demethylamorphigenin, (6aR,12aR,5′R)-amorphigenin, resokaempferol 3-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside, and daidzein 7-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside, together with 40 known compounds, were isolated from the fruits of Amorpha fruticosa. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopic analysis as well as from the mass spectrometry data. ECD calculations were performed to determine the absolute configurations of optically active compounds. New compounds 1, 2-4, and some other known metabolites showed potent to moderate antibacterial activities against several Gram-positive bacteria with MIC values ranging from 3.1 to 100µM. In addition, some of isolated metabolites were significantly cytotoxic against the L5178Y mouse lymphoma cell line and exhibited IC₅₀ values from 0.2 to 10.2µM.