BIOASSAY-GUIDED FRACTIONATION, MECHANISM OF ACTION AND TOXICOLOGICAL EVALUATION OF ANTI-NOCICEPTIVE PRINCIPLES OBTAINED FROM ERYTHROPHLEUM IVORENSE
Wakeel O. K., Elusiyan C. A., Adewole T. A. and Adeyeba A. O.
ABSTRACT
The present study describes the bioactivity guided identification of anti-nociceptive compounds found in stem bark extract of Erythrophleum ivorense. The stem bark of the plant was air-dried, grounded and macerated using absolute methanol which was then filtered. The filtrate was evaporated using rotary evaporator and Crude Methanol Extract (CME) was obtained. Bioactivity-guided fractionations of CME was performed using partitioning, thin layer, and open column chromatography. Partitioned fractions (20 mg/kg), E. ivorense-fractions (EiF-1 to EiF-6) (20 mg/kg), EiF-1 (5, 10, 20 mg/kg), fractions (F1 to F8) (20 mg/kg), and semi-purified fractions (50 mg/kg) were screened for anti-nociceptive and anti-inflammatory
activities. Animals in each group were administered with extract or fractions intraperitoneally. The mechanism of action and toxicological evaluation of semi-purified fraction were also studied. Data were analyzed using One-Way Analysis of Variance (ANOVA) and the level of significance of the data were taken at p<0.05. Partitioned CME yielded butanol (34.7 g), ethyl-acetate (27.0 g), dichloromethane (17.2 g), and n-hexane (6.1 g) extracts. Chromatographic fractionation of ethyl acetate yielded six fractions (EiF-1 to EiF-6). Purified fraction (EiF-1), the only fraction with anti-nociceptive activity yielded sub-fractions (F1 to F8). Screened fractions (F1 to F8) produced F3 as the fraction with highest activities. Further purification of F3 yielded semi-purified fractions coded as F3C1, F3C2, F3C3, F3C4, F3C5-mother liquor (F3C5-MQ) and F3C5-crystal. F3C5-MQ produced a central anti-nociceptive effect while F3C2 indicated peripheral effect. Atropine significantly reversed the anti-nociceptive effect of F3C5-crystal in both phases of formalin test. At the doses studied, the fraction was fairly non-toxic. In conclusion, the semi-purified fractions exhibited peripheral and central anti-nociceptive activities. The central anti-nociceptive effect of F3C5-MQ may be mediated via muscarinic receptor.
Keywords: Erythrophleum ivorense, Anti-nociceptive, chromatography, partition.
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