Assessment of the Anti-inflammatory and Anti-oxidant Activities of Flavonoid-rich Fraction of <i>Pleiocarpa mutica </i>Leaves

Abstract

<i>Pleiocarpa mutica</i> is a medicinal plant that is native to large areas of tropical Africa and belongs to the family of <i>Apocynaceae</i>. It is a medicinal herb used in traditional Nigerian medicine to treat a variety of diseases, including inflammatory disorders. The present study investigated the anti-inflammatory and anti-oxidant effects of flavonoid-rich fraction of <i>Pleiocarpa mutica</i> leaves (FRFPML) using both <i>in-vivo </i>and <i>in-vitro </i>based assays. A total of thirty (30) adult male albino rats (110-150g) were divided into five (5) groups of six (6) rats each for the <i>in-vivo</i> anti-inflammatory assay. Group 1 untreated; Group 2 was given 10 mg/kg body weight of Indomethacin and Groups 3, 4 and 5 were given 200, 400 and 600 mg/kg body weight of FRFPML respectively. Tannins, phenols, flavonoids, alkaloids, steroids, terpenoids and saponins were found in varied amounts in the plant secondary metabolites according to quantitative analysis. The extract demonstrated no harm in an acute toxicity assay when dosed up to 5000 mg/kg b.w. Scalar dosages of the FRFPML significantly (p<0.05) suppressed the development of paw oedema induced by egg albumin in the systemic rat paw oedema model. This compares favorably to the standard anti–inflammatory drug indomethacin (10 mg/kg b.w) which at 24 hours inhibited egg albumin-induced rat paw oedema (11.82%). Varying doses of the extract significantly (p<0.05) inhibited egg albumin denaturation, hypotonicity-induced membrane stabilization, protease inhibition and phospholipase A₂ in a concentration-dependent manner, causing inhibition comparable to that of the standard anti-inflammatory drug used. The extract at different concentrations (0.2-0.8 mg/ml), significantly (p<0.05) exhibited DPPH (1-1diphenyl-2-picrylhydrazyl) and H₂O₂ (hydrogen peroxide) radical scavenging activities in a concentration-dependent manner similar to the standard antioxidant ascorbic acid used. Results from the study revealed that the FRFPML exhibited remarkable anti-inflammatory and anti-oxidant activity.