PHYTOCHEMISTRY, ANTI-INFLAMMATORY AND ANTIOXIDANT ACTIVITIES OF THE ROOT BARK OF ANTHOSTEMA AUBRYANUM (BAILL)

ABSTRACT The work presented in this thesis involves the scientific investigation into the traditional uses of the root bark of Anthostema aubryanum (Baill., family, Euphorbiaceae) as an anti-inflammatory and antioxidant agent. It also describes the isolation and characterization of two compounds from the alkaloid extract of the root bark of Anthostema aubryanum Baill. The anti-inflammatory activity was investigated using the acute carrageenan – induced foot pad edema model in six weeks old rats. The extracts were given orally to the rats at 30, 100 and 300 mg/kg body weight, 1 hour after induction of oedema with carrageenan using diclofenac as the reference drug. All extracts of the root bark were demonstrated to display a time-and dose-dependent anti-inflammatory effects in rats with methanolic extract showing the highest activity (ED50 = 5.29± 0.02 BDW) compared to the standard drug, diclofenac (ED50 = 1.99± 0.01). The antioxidant properties of the extracts were investigated using three assays; total antioxidant capacity, total phenolic content and DPPH scavenging activity. The antioxidant activity of the methanolic crude extract (IC50=8.84±0.02 µg/ml) was equivalent to the standard vitamin E (IC50=8.61±0.01 µg/ml) with total phenolic content of 74.53±0.004. Comprehensive chromatographic and spectroscopic analyses of the alkaloid extract led to the isolation and characterization of two major anti-inflammatory and antioxidant agent as 5-methoxycanthin-6-one and canthin-6-one with the former showing the highest pharmacological activity (ED50=60.84±0.01, IC50=27.62±0.010 and ED50=96.64±0.01, IC50=33.60±0.01 respectively). This is the first report of the isolation of these compounds from the family Euphorbiacea