The effect of cytokinins on shoot proliferation, secondary metabolite production and antioxidant potential in shoot cultures of Scutellaria alpina

Abstract

The present study evaluates the effects of various cytokinins on Scutellaria alpina shoot proliferation and production of polyphenolic metabolites (baicalin, wogonoside, luteolin, luteolin 7-O-glucoside, verbascoside). The shoots were induced from shoot tips on MS medium supplemented with IAA (indole-3-acetic acid, 0.57 µM) and various concentrations of 6-benzylaminopurine (BAP), kinetin, zeatin (1, 2, 4, 8 µM) or tidiazuron (TDZ) (0.2, 0.5, 1 µM). Among the cytokinins tested, BAP was the most effective for shoot induction, and the highest number of shoots (25 per explant) was achieved with 2 and 4 µM BAP. Maximum biomass production was also achieved on these media. Significantly higher baicalin, wogonoside and verbascoside contents were recorded in treatments containing cytokinins combined with 0.57 µM IAA, when compared to cytokinin-free medium. TDZ at a concentration of 0.5 µM was the most effective for polyphenol production. However, supplementation with cytokinins often results in the reduction of luteolin and its 7-O-glucoside production in the shoot culture of S. alpina. ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)] and ferric reducing antioxidant power assays were used to identify the antioxidant potential of methanolic extracts from shoots cultured in the presence of different types and concentrations of cytokinins. In both tests, the shoots from medium supplemented with 0.5 µM TDZ demonstrated the strongest antioxidant activity. The results indicate that higher polyphenolic content correlated with greater reducing power and antiradical efficiency.