Evaluation of free radical scavenging activity of an ayurvedic formulation, panchvalkala.

We report the free radical scavenging activity of an Ayurvedic preparation Panchvalkala and its individual components (stem bark of Ficus benghalensis, F. glomerata, F. religiosa, F. virens and Thespesia populnea). Being stem barks, these samples contain phenolics (ranging from 3.5% to 10.8% w/w) and tannins (1.6% to 7.0% w/w). This prompted us to study the free radical scavenging activity of Panchvalkala and its components which was evaluated in three in vitro models viz. 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, superoxide radical scavenging activity and reducing power assay. Panchvalkala and its individual components showed significant antiradical activity by bleaching 1,1-diphenyl-2-picrylhydrazyl radical (EC(50) ranging from 7.27 to 12.08 microg) which was comparable to pyrogallol (EC(50) 4.85 microg). Thin layer chromatography of the methanol extracts when sprayed with 0.2% 1,1-diphenyl-2-picrylhydrazyl in methanol revealed several bands with antiradical activity as seen by bleaching of 1,1-diphenyl-2-picrylhydrazyl. All the samples showed good superoxide scavenging potential (EC(50) ranging from 41.55 to 73.56 microg) comparable to ascorbic acid (EC(50) 45.39 microg) in a dose-dependent manner. The reduction ability, Fe(3+) to Fe(2+) transformation was found to increase with increasing concentrations of all the sample extracts.