Isolation from Wen-Pi-Tang of the active principles possessing antioxidation and radical-scavenging activities.

The active principles of Wen-Pi-Tang possessing antioxidation and free radical-scavenging activities were isolated, and its properties were determined using the thiobarbituric acid-reactive substance (TBARS) procedure and a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical generating system. Significant inhibitory activities against both the formation of TBARS and generation of free radicals were shown by fractions 5, 6 and 7, which contained mainly polyphenolic compounds and phenolic glycosides as well as anthraquinone glycosides. The most active compounds were procyanidin B-2 3,3'-di-O-gallate, (-)-epicatechin 3-O-gallate, procyanidin B-2 and 1,2,6-tri-O-galloyl-β-glucose, the former two having been confirmed to be the most active principles of Wen-Pi-Tang in improving renal function. It is suggested that tannins make a prominent contribution to both the biological activity and pharmacological effects of Wen-Pi-Tang.