New hopane triterpenes and antioxidant constituents from Potentilla fulgens.

Phytochemical investigation of the aerial parts of Potentilla fulgens L. led to the isolation of two new triterpenes, potentene A (1) and potentene B (2). In addition, three known compounds afzelchin-4alpha --> 8"-catechin (3), epiafzelchin (4) and rutin (5) were isolated. The structures of all these compounds were elucidated by extensive spectroscopic and chemical evidence. Compounds 3, 4, and 5 exhibited significant 1,1,diphenyl-2-picrylhydrazyl radical scavenging activity, with IC50 values of 1.21, 2.88 and 5.20 mg/mL, respectively; the known standard antioxidant, vitamin C, had a value of 0.44 mg/mL.