Analgesic and Anti-Inflammatory constituents of annickia polycarpa stem and root barks and clausena anisata root.
Clausena anisata and Annickia polycarpa are medicinal plants used to treat various painful and inflammatory disorders among other ailments in traditional medicine. The aim of this study was to investigate the analgesic/antinociceptive and anti-inflammatory activities of the ethanol extracts of C. anisata root (CRE), A. polycarpa stem (ASE) and root barks (AR) in order to provide scientific justification for their use as anti-inflammatory and analgesic agents. Analgesic activity was evaluated using the hot plate and the acetic acid induced writhing assays. The mechanism of antinociception was evaluated by employing pharmacological antagonism assays at the opioid and cholinergic receptors in the hot plate and the writhing assays. Anti-inflammatory activity was also evaluated by carrageenan induced edema in rats’ paw assay. The compounds were isolated using bioassay-guided fractionation and their structures identified by spectroscopic methods. CRE at 1000 mg/kg p.o. produce significant (p < 0.001) analgesic activity of 72.15 and 48.05 % in the hot plate and writhing assays respectively and significant (p < 0.01) anti-inflammatory activity of 27.53 %. ASE also produced significant (p < 0.001) analgesic activity of 82.54 and 44.03 % in the hot plate and writhing assays respectively and significant anti-inflammatory activity of 69.64 %. Furthermore, the results also showed that the petroleum ether (pet ether) fraction (PEF) of C. anisata root extract and the chloroform fraction (AC) of A. polycarpa stem bark extract were the most active fractions among the petroleum ether, chloroform and aqueous fractions of these extracts. A total of seven (7) compounds were isolated. Four (4) coumarins, namely, anisocoumarin B, osthol, imperatorin and xanthotoxol in addition to a carbazole alkaloid, heptaphyline were isolated from PEF. Two (2) protoberberine alkaloids namely jatrorrhizine and palmatine were also isolated from AC. Palmatine was further isolated from the chloroform fraction of A. polycarpa root bark. The seven isolated compounds were tested for analgesic activity in the writhing test. Six of them at 6 mg/kg p.o., produced significant analgesic activity of 38.13 to 47.28 %. One of the isolates (xantothoxol) was inactive. Analgesic activity of diclofenac in the writhing test was 32.92 % at 6 mg/kg p.o. Four of the isolates were also tested for analgesic activity in the hot plate assay. These isolates at 9 mg/kg p.o. produced immence analgesic effect of 30.13 to 93.87 %. The analgesic effect of tramadol 9 mg/kg p.o. was 27.13 % in the hot plate test.
A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Department of Pharmacognosy faculty of Pharmacy and Pharmaceutical Sciences College of Health Sciences, 2016.