In vitro antioxidant activity of Anisochilus carnosus leaf, stem and callus

Anisochilus carnosus (Lamiaceae) is an annual herb growing at high altitudes, which is used in traditional medicine. The present study was carried out to determine the total phenolic concentration, total flavonoid concentration and antioxidant activity of ethanolic extracts of leaf and stem, and their respective calli. For callus development, healthy leaf and stem explants of A. carnosus were inoculated in Murashige and Skoog medium with auxin-type plant growth regulators 2,4-dichlorophenoxy acetic acid (2,4-D), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and naphthalene acetic acid (NAA). Callus initiation was started within one week of inoculation and profound callusing was observed in presence of 2 mg L–1 2,4-D, IAA, and IBA. NAA alone did not induce any callus at lower doses, while combination of 2,4-D and 2,4-D + NAA produced callus at all tested concentrations. Maximum total phenolic concentration was found in the leaf callus, while the highest flavonoid concentration was found in the stem callus. The antioxidant activity of both leaf and stem calli extracts were consistent. In terms of antioxidant activity, callus extracts exceeded leaf and stem extracts. It can be concluded that the callus extract is an excellent source of phytotherapeutic antioxidants. Callus-derived secondary metabolites from A. carnosus have potential use in a variety of biological applications.