In vitro callus induction and antioxidant activity of Rauwolfia vomitoria Afzel. (Apocynaceae)

Background: Rauwolfia vomitoria Afzel. (Apocynaceae) is a medicinal plant valued for its antipsychotic effect and used in various herbal preparations.Objectives: This study was designed to develop a protocol for callus initiation in Rauvolfia vomitoria and to investigate the antioxidant activity of the wild plant and the leaf-derived callus of the plant.Materials and methods: Callus initiation of the leaf explants was achieved on Murashige and Skoog’s medium fortified with α-naphthaleneacetic acid (NAA), 2, 4-dichlorophenoxyacetic acid (2,4- D) and 6-benzylamino purine (BAP). Methanol extracts of leaf and root of the wild plant and callus were analyzed for their antioxidant activity using 2, 2, diphenyl-1-picryl hydrazyl (DPPH) for the radical scavenging activity (RSA) and Folin Ciocalteau spectrophotometric method for the total phenolic content (TPC).Results: Of the various plant growth hormones employed in this study for callus establishment, 1.0 mg/L NAA + 4.0 mg/L BAP induced maximum callus formation of 83.0%, while 1.0 mg/L 2,4-D gave 20.0% formation. Leaf explants placed in the dark phase produced whitish, friable calli. The highest antioxidant activity was obtained from the root extract of the wild plant with IC50 values of 3.56±1.67 and 429.72±19.83 μgGAE/g for RSA and TPC, respectively. Leaf-derived callus had the least antioxidant effect. Ascorbic and Gallic acid included in the study as standards had IC50 values of 6.9±0.18 and 8.6±0.65 μg/mL, respectively.Conclusion: An efficient protocol has been established for the induction and proliferation of callus of Rauwolfia vomitoria, justifying the use of tissue culture technique for the conservation of this important medicinal plant.Keywords: Rauwolfia vomitoria, In vitro callus induction, Antioxidant, Plant tissue culture, Conservation