Antibacterial and cytotoxic phenolic metabolites from the fruits of amorpha fruticosa

Abstract

Fourteen new natural products, namely, 2-[(Z)- styryl]-5-geranylresorcin-1-carboxylic acid (1), amorfrutin D (2), 4-O-demethylamorfrutin D (3), 8-geranyl-3,5,7- trihydroxyflavanone (4), 8-geranyl-5,7,3′-trihydroxy-4′-methoxyisoflavone (5), 6-geranyl-5,7,3′-trihydroxy-4′-methoxyisoflavone (6), 8-geranyl-7,3′-dihydroxy-4′-methoxyisoflavone (7), 3-O-demethyldalbinol (8), 6a,12a-dehydro-3-O-demethylamorphigenin (9), (6aR,12aR,5′R)-amorphigenin (10), amorphispironones B and C (11 and 12), resokaempferol 3-O-β-Dglucopyranosyl-( 12)-β-D-glucopyranoside-7-O-α-L-rhamnopyranoside (13), and daidzein 7-O-β-D-glucopyranosyl-(12)- β-D-glucopyranoside (14), together with 40 known compounds, were isolated from the fruits of Amorpha f ruticosa. 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 11 and 15. Compounds 1, 4.6, and 16.23 showed potent to moderate antibacterial activities against several Gram-positive bacteria with MIC values ranging from 3.1 to 100 μM. In addition, compounds 11 and 24.33 were significantly cytotoxic against the L5178Y mouse lymphoma cell line and exhibited IC50 values from 0.2 to 10.2 μM.