Constituents of Desmodium salicifolium (Poir.) DC (Fabaceae) with antifungal activity

Abstract

Phytochemical investigation of the roots of Desmodium salicifolium led to the isolation of two new compounds (Desmoflavanone A: 5,2',4'-trihydroxy-4'',4''-dimethyl-2 H -dihydropyranoisoflavanone ( 1 ) and desmodioside A: (22 R )-3 β ,22,23-trihydroxyolean-12-en-3- O - α - L -rhamnopyranosyl-(1→2)-β- D -glucopyranosyl-(1→2)- β - D -glucuronopyranoside ( 2 )) together with nine known secondary metabolites including kaikasaponin III ( 3 ), spinosin ( 4 ), isovitexin ( 5 ), β -sitosterol 3- O - β - D -glucopyranoside ( 6 ), neorautenol ( 7 ), kaempferol ( 8 ), oleanolic acid ( 9 ), betulinic acid ( 10 ), and lupeol ( 11 ). The structures of these compounds were elucidated mainly by extensive spectroscopic analysis, particularly 1D and 2D NMR spectroscopy, electrospray ionization-mass spectrometry and by comparison of their spectroscopic data with those of related compounds reported in the literature. The methanolic extract, EtOAc and n -BuOH fractions as well as some isolated compounds were assessed for their antifungal activities against two fungi using microdilution method. The methanolic extract displayed weak activity against Candida albicans (MIC = 512 µg/mL). The EtOAc fraction also exhibited weak inhibitory effect with MIC of 256 µg/mL against Candida albicans and Candida glabrata . Compound 3 showed moderate effect against Candida glabrata with MIC value of 16 µg/mL while 1 was inactive against both fungi. • This is the first phytochemical study on Desmodium salicifolium (Poir.) DC. • A new isoflavanone and a new saponin were isolated together with nine known secondary metabolites. • The major isolated compounds were tested for their antifungal activity.