Prenylated Flavonoids from the Roots of Desmodium caudatum and Evaluation of Their Antifungal Activity

Two new prenylated flavonoids (1, 4) and two new prenylated C-methyl-flavonoids (6, 7), together with four known flavonoids (2, 3, 5, 8), were isolated from the roots of Desmodium caudatum. The structures of the new compounds were elucidated by extensive spectroscopic analyses including 1D-, 2D-NMR and MS. The antifungal activities of five compounds (1, 2, 4, 6, 8) as well as nine flavonoids (9-17) previously isolated from this plant against Aspergillus niger, Penicillium sp., Rhizopus sp., and Trichophyton sp. were evaluated. Compound 6 showed potent antifungal activity against Trichophyton sp. with a minimum inhibitory concentration (MIC) value of 1.95 mu g/mL.