Accumulation of flavonoids and antioxidant activity of Stellera chamaejasme by an efficient callus culture

An efficient callus proliferation system of Stellera chamaejasme was developed. The calli were initially induced by cultivating the leaf explants on the MS medium containing 1.0 mg·L−1 2,4-dichlorophenoxy acetic acid (2,4-D). The culture had its fresh and dry weights increased by about 29 and 25 times, respectively, through further cultivation on the MS medium containing 0.5 mg·L−1-naphthalene acetic acid (NAA) and 1.0 mg·L−1 n-phenyl-n′ -1,2,3-thiadiazol-5-ylurea (TDZ). The concentrations of NAA and 6-benzylaminopurine (BA) for an efficient accumulation of the total flavonoids in the callus were found to be 1.0 mg·L−1 and 0.25 mg·L−1, respectively. With this combination, the content of the total flavonoids slightly increased to 10.8 mg·g−1 dry weight (DW) in comparison to 10.1 mg·g−1 DW obtained in the root of wild-type plant. The antioxidant activities of all flavonoid extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The flavonoid extracts from the callus as induced by 1.0 mg·L−1 NAA and 0.25 or 0.5 mg·L/t-1 BA was very active in radical scavenging, and their IC50 values were 11.94 and 19.17 g·mL−1, respectively. Compared to the ascorbic acid (IC50 21.21 g·mL−1), the antioxidant activity of callus from S. chamaejasme was even stronger, suggesting that be another potential source of new natural antioxidants.