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

Abstract

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.