Isolation and identification of antioxidant constituents from the flowers of Salvia miltiorrhiza

A new salvianolic acid derivative, (7′E)-(7S, 8S)-salvianolic acid V (1), together with four previously described compounds (2-5) were obtained from the n-butanol fraction of Salvia miltiorrhiza flowers. Their structures were established by a series of spectroscopic methods, and the absolute configuration of 1 was determined by electronic circular dichroism (ECD) calculation. Salvianolic acids (1) and phenolic acids (2-4) showed stronger DPPH free radical scavenging abilities and certain protective effects against H2O2-induced human skin fibroblast (HSF) cells oxidative damage, in which compound 1 (IC50 7.12 μM) possessed more noticeable free radical scavenging activity than the positive control vitamin C (IC50 14.98 μM).