Free radical scavenging activity and chemical constituents of Urvillea ulmaceae

The methanol extract of Urvillea ulmaceae Kunth (Sapindaceae) aerial parts and the hexane, ethyl acetate, and hydromethanol fractions were evaluated for their free radical scavenging activity with the DPPH assay. Among all the tested fractions, the ethyl acetate fraction was the most active, exhibiting an IC₅₀ of 16.33?μg/mL, comparable to that of the commercial antioxidant BHT. Fractionation of the ethyl acetate fraction through chromatographic methods afforded trans-N-methyl-5-hydroxypipecolic acid, epicatechin, and proanthocyanidin A2 as the main constituents. Epicatechin and proanthocyanidin A2 showed potent DPPH radical scavenging activity, with IC₅₀ values of 18.34 and 11.45?μg/mL, respectively. A new compound, trans-N-methyl-5-hydroxypipecolic acid, did not show any antioxidant effect (IC₅₀?>?500?μg/mL).