A new 3-arylcoumarin, 7-hydroxy-6-(1,1-dimethylallyl)-2',5'-dihydroxy-4'-(3,3dimethylprenyl)-3-arylcoumarin (desmoarylcoumarin) 1, a previously unreported oleanane-type triterpenoid, 3β,22β,23-trihydroxyolean-12-en (episoyasapogenol B) 2, together with five known flavonoids including darbergioidin (3), isoferreirin (4), quercetin (5), vitexin (6), swertizin (7), and one carbohydrate, sucrose (8) were isolated from the methanolic extract of the roots of Desmodium salicifolium. Their structures were elucidated mainly by extensive spectroscopic analysis (1D and 2D) and mass spectrometric (HRFAB-MS) data. The methanolic extract, EtOAc and n-BuOH fractions as well as some isolated compounds were assessed for their antibacterial and antioxidant activities. The EtOAc fraction exhibited moderate activity against Enterococcus faecalis with MIC value of 128 µg/mL. The methanolic extract and the EtOAc fraction displayed DPPH scavenging activity with EC50 values of 5.99 and 2.06 μg/mL, respectively. Compound 1 showed a moderate antibacterial activity against Enterococcus faecalis with a MIC of 16 µg/mL. It also showed moderate DPPH scavenging activity.
Keywords: 3-arylcoumarin; Desmodium salicifolium; antibacterial activity; antioxidant activity; triterpenoid.