Antioxidant activity and cytotoxicity of the leaf and bark extracts of Tarchonanthus camphorates

Abstract

Purpose: To investigate the antioxidant potential and cytotoxicity of the leaf and bark extracts of Tarchonanathus campharatus. Methods: The antioxidant activity of the aqueous leaf extract (Aq LF), methanol leaf extract (MET LF), dichloromethane leaf extract (DCM LF), methanol bark extract (MET BK), dichloromethane bark extract (DCM BK), and ethyl acetate bark extract (Et Ac BK) were examined by 1,1-Diphenyl-2-picryl-hydrazil (DPPH), 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS.+), nitric oxide radical scavenging, reducing power and iron chelating activity methods. Brine shrimp lethality and MTT cytotoxicity tests were used to investigate the cytotoxicity of the extracts. Results: The Aq LF, DCM LF, MET LF and MET BK showed good DPPH, ABTS radical scavenging and total reducing power activities. Total reducing power was high and in the rank order of DCM LF > Aq LF > MET LF > MET BK. All the extracts, however, showed weak nitric oxide scavenging activity as well as weak iron chelating ability. Flavonoids, phenols, tannins and saponins were present in some of the extracts, but alkaloids, terpenoids, cardenolides and cardiac glycosides were absent in all the extracts. All the extracts did not show significant cytotoxic properties (p ≥ 0.05) with 50% inhibitory concentration IC50 values > 30 μg/ml in both cytotoxicity assays. Conclusion: The antioxidant activity and low cytotoxicity of Tarchonanthus camphoratus probably justify its use in folk medicine. © Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria. All rights reserved.