Main Article Content
Thunbergia laurifolia Lindl. is a medicinal plant which its flowers and leaves contain high antioxidants and use to detoxify poison from human body. Callus culture is one of plant tissue culture techniques that benefits to produce secondary metabolites of medicinal plants. Therefore, the objectives of this study were to investigate the effect of 2,4-D, NAA and BA at various concentrations for callus induction from in vitro leaf explants and antioxidant contents of T. luarifolia callus at different culture periods comparing to in vitro regenerated shoot and in vivo leaf. For callus induction, in vitro leaf explants were cultured on MS medium supplemented with 0.5-1.0 mg/L 2,4-D and NAA only or in combination with 0.5 mg/L BA comparing to MS medium without plant growth regulator (control treatment) for 6 weeks. The results showed that callus induction occurred on all test media except control treatment. MS medium supplemented with 0.5-1.0 mg/L NAA in combination with 0.5 mg/L BA, and MS medium supplemented with 0.5 mg/L 2,4-D in combination with 0.5 mg/L BA gave the highest callus fresh and dry weight. Antioxidant contents of 5, 6, and 7 week-old-calli cultured on MS medium supplemented with 0.5 mg/L NAA and 0.5 mg/L BA were investigated comparing to in vitro regenerated shoot and in vivo mature leaf. It was found that the four, five and six-week-old-calli and in vitro shoot exhibited greater total phenolic contents (64.41±1.29 - 67.29±3.17 mg GAE/g dry extract), flavonoid contents (44.38±11.61 - 54.60±9.22 mg CE/g dry extract), and DPPH radical scavenging activities (with the EC50 values in a range of 15.93±1.33 - 18.99±0.86 µg/mL), than those of in vivo mature leaf.
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