Antimicrobial, Antioxidant and Protective Effect of Methanol Extract of Trichilia emetica (Meliaceae) Stem and Root Bark against Free Radical-induced Oxidative Haemolysis

Background: The objectives of this study are to investigate the antimicrobial, antioxidant and antiradical properties of methanol extract of the stem and root bark of Trichilia emetica on a model of free radical-induced membrane damage.

Methodology: p-Iodonitrotetrazolium chloride colorometric assay was used to determined bacterial and yeast susceptibility to plant samples. The antioxidant activity was evaluated using DPPH radical, hydroxyl radical, nitric oxide scavenging and reducing power assays. The cellular oxidative stress was evaluated through haematolysis and haematoprotective assays.

Results: The stem bark extract revealed a great antibacterial activity against 62.5% of bacteria strains tested with minimal inhibitory concentrations ranging from 32 to 64 µg/ml. The IC₅₀ value the stem and root bark extracts were 9.68 ± 0.75 and 10.05 ± 0.86 μg/ml, 9.98 ± 0.52 and 200.49 ± 3.40 μg/ml, 45.92 ± 2.45 and 4081 ± 212 μg/ml, respectively for DPPH radical, hydroxyl radical and reducing ability assays. Both extracts exhibited concentration dependent haemolysis of sheep red blood cells (RBCs). Stem and root bark extracts (25 µg/ml) diminish respectively by 95.9 and 85.68% hydrogen peroxide-mediated cytotoxicity.

Conclusion: Our data reveals that antibacterial and antioxidant activities of the methanol extract of Trichilia emetica stem bark were better than that of root bark.