Anti-iflammatory and Analgesic effects of methanol fractions of cola hispida leaf in male albino rats

Abstract

The study is aimed at evaluating the anti-inflammatory and analgesic effects of methanol fraction of Cola hispida leaves on male albino rats. Cola hispida is a medicinal plant believed to contain many secondary metabolites that may be effective in the treatment of inflammation and pain. This study investigated the qualitative and quantitative phytochemical constituents, acute toxicity, in vitro percentage inhibition of protein denaturation, the analgesic and anti-inflammatory effects of the plant fraction. The extract did not produce mortality up to 1000 mg/kg b. w. The phytochemal analysis showed the presence of flavonoids (4.28 ± 0.28 mg/g), phenolic compounds (4.03 ± 0.03 mg/g), taninns (1.27 ± 0.04 mg/g), alkaloids (1.68 ± 0.02 mg/g), glycosides (0.84 ± 0.02 mg/g) and saponins (0.74 ± 0.06 mg/g). However terpenoid was not detected. The methanol extract of Cola hispida was fractionated using solvent-solvent partitioning. The three (3) solvents used for the partitioning were n hexane, ethylacetate and 20% methanol based on increasing polarity. The in vitro anti-inflammatory effect of Cola hispida was determined through the ability of the plant fractions to inhibit protein denaturation. As part of the investigation on the mechanism of the anti-inflammation activity, ability of the plant fractions to inhibit heat induced albumin denaturation was studied. The reaction mixture (5 mL) consisted of 0.2 mL of egg albumin (from fresh hen’s egg), 2.8 mL of phosphate buffered saline (PBS, pH 6.4) and 2 mL of varying concentrations of the methanol fraction so that concentrations become 100, 200, 300, 400, 500 μg/ml. The fraction that contains 20% methanol was the most effective in inhibiting heat induced albumin denaturation, maximum inhibition of 61.15% was observed at 500 μg/ml. A total of Eighty (80) male albino rats were used. The animals were randomly divided into four (4), for the main experimental models, each experimental models was further divided into five (5) groups containing four (4) animals each. The egg albumin-induced paw oedema and agar-induced leukocyte mobilization to the peritoneal cavity methods were used to evaluate the anti-inflammatory effect of the 20% methanol fraction at 100, 200, and 400 mg/kg dose levels, the plant fraction was administered orally 1 hour before injecting the philogistic agent; whereas central and peripheral analgesic effect was evaluated using formalin-induced paw licking and acetic acid induced writhing rats models, of the plant fraction at the same dose levels. Data were analyzed using one-way ANOVA followed by Duncan’s post hoc test. All tested doses of the plant fraction showed significant (p < 0.05) analgesic effect with maximum result of 54.83% and 71.42% inhibition of acetic acid induced writhing and formalin-induced paw licking respectively. Maximum anti-inflammatory effect was recorded at 4 hours after induction, with 50.00% reduction in egg albumin-induced paw oedema. Moreover, all tested doses of the plant fraction significantly (p < 0.05) inhibited leukocyte mobilization to the intraperitoneal cavity. The control had the highest total leukocyte count (9626.02) and the highest percentage of neutrophils that migrated (65.18%). They all had their maximum inhibitory effect at the highest dose (400 mg/kg) and these compared well with that of indomethacin (standard drug), which implies that the effect is dose dependent. The present study indicated that the plant fraction had both analgesic and anti-inflammatory activity, which probably depended on their ability to prevent the production of some pro-inflammatory mediators and cytokinesfinal.