Evaluation of free radical scavenging activity and total phenolic content in the petiole-derived callus cultures of Zingiber zerumbet Smith

This is the first report on the antioxidant activity of callus cultures of Zingiber zerumbet. Callus cultures were initiated from petiole explants of in vitro plantlets of Z. zerumbet on MS medium supplemented with 0.5 mg/L 2,4-D. Bright yellow and friable callus cultured on MS medium supplemented with 0.5 mg/L 2,4-D in combination with kinetin, picloram and 1-naphthaleneacetic acid (NAA) did not show any significant difference in biomass as compared to those cultured on MS medium supplemented with 0.5 mg/L 2,4-D. 30 g/L sucrose was found the best for callus growth and proliferation. Callus of Z. zerumbet proliferated better in the presence of light. Subculture frequency of Z. zerumbet callus culture showed consistency of callus biomass production. The anti oxidant activity of Z. zerumbet callus extract was evaluated by 2,2 diphenyl -1- picrylhydrazyl (DPPH) free Radical Scavenging Activity (RSA) and Total Phenolic Content (TPC) assay. The RSA of callus cultures of Z. zerumbet was concentration dependent with an EC 50 value of 254.55 mu g. At a concentration of 750 mu g/ml the callus extract was able to quench 93% of the DPPH free radical in 30 min. The TPC of the callus extract was estimated to be 9 mg GAE/g extract. There was a good correlation between DPPH free radical scavenging activity and TPC.