Schottiin, a new prenylated isoflavones from and antibacterial synergism studies between methicillin and fremontone against methicillin-resistant ATCC 1708.

Bioactivity guided isolation of an ethanol extract of the root of (Family Fabaceae) afforded a new prenylated isoflavone, named schottiin (5,7,5'-trihydroxy-4'--methyl-6'-(3,3-dimethylallyl)-isoflavone) (), together with four other isoflavones, including fremontone (), 5,7,4',5'-tetrahydroxy-2'-(3,3-dimethylallyl)-isoflavone (), glycyrrhisoflavone () and fremontin (), of which and identified as isomeric mixture. Structures of - were determined by full spectroscopic analyses. A comprehensive 2 D NMR spectral data has allowed revising the structure of fremontone as from previously reported Compound showed weak antibacterial activity against methicillin-resistant (MRSA). A combination study using a checkerboard assay between fremontone () and methicillin exhibited a synergistic activity with 8-fold decrease in MIC of methicillin, as well as an additive effect with vancomycin against MRSA ATCC 1708. Compounds and also showed moderate antiplasmodial activity against chloroquine-sensitive (D6) and -resistant (W2) strains of with no cytotoxicity to mammalian Vero cells.