Evaluation of In-vivo and In-vitro Antioxidant Activities of Methanol Extract of Salacia lehmbachii Loes Leaf

Aims: This study was carried out to evaluate the in-vitro and in-vivo antioxidant activities of methanol extract of Salacia lehmbachii leaf (SLLE).

Place and Duration of Study: Department of Pharmacology, University of Calabar, NIGERIA, between October, 2014 and December, 2014.

Methodology: Ability to scavenge 2,2–diphenylpicryl hydrazyl (DPPH) radicals as well as chelate divalent ferrous ions served as paradigms for in-vitro methods. On the other hand, cross-clamping of both hepatic artery and hepatic portal veins for 60 min and reperfusion for the next 60 min in rats produces oxidative stress with consequent lipid peroxidation against which the activity of the extract was tested.

Results: SLLE showed considerable potency in-vitro in the brine shrimp assay with an IC50 of 4.66 µg/ml. At very low concentrations (<10 µg/ml), SLLE showed superior activity over that of Vitamin C in the DPPH assay with IC50 of 4.9 µg/ml and 9.6 µg/ml for SLLE and Vit C respectively. At higher concentrations (10-1000 µg/ml), the antioxidant activity was found to be very weak indeed. The FIC assay showed a dose-dependent and significant (P<.01) response for both the SLLE (2.199±19.29) and the standard ethylenediaminetetraacetic acid (EDTA) (81.94±5.022); while EDTA showed ability to prevent Fenton-type reaction, SLLE showed a lack of this ability and even a possible enhancement of Fenton-type reactivity. When given at a dose of 100 mg/kg, SLLE also produced significant (P<.05) protective activity against hepatic lipid peroxidation in ischaemic / reperfussion injury in rats.

Conclusion: The antioxidant activity of the extract was found to be superior to that of Vit C at low concentrations in the DPPH while not so remarkable at higher concentration and FIC ability. Significant activity in lowering MDA in ischemic-reperfusion model in rats seen at the highest dose (100 mg/kg) (P<.05) demonstrated its tissue protective potential.