University of Maiduguri, Nigeria.
This study was aimed at evaluation of phytochemical constituents and the effect of ethanol leaf extract of Piliostigma thonningii on the central and peripheral nervous systems in laboratory animals. Fresh leaves of Piliostigma thonningii were air-dried, pulverized extracted using soxhlet extraction technique with ethanol 148.24% w/w after being concentrated. The extract was screened for phytochemicals using standard methods. 20 g of the ethanol extract was subjected to column chromatographic (CC) analysis using ethyl acetate and n-butanol as mobile phase at different ratios and silica gel of 60-120 mesh as the stationary phase. Fractions obtained with similar retention factor (Rf) using thin layer chromatography (TLC) were combined, coded and subsequently screened for phytochemicals. Subsequent purification of fraction PTE3 was carried out using CC (ethylacetate and methanol were used as mobile phase at different ratios) and TLC until a sub-fraction PTE34 amongst other fractions gave a single spot on TLC and had a melting point of 102-103 oC. The phytochemical studies of the ethanol leaf extract of Piliostigma thonningii revealed the presence of some useful chemical compounds such as flavonoids, cardiac glycosides, tannins, saponins, and terpenoids. The pharmacological effects of Piliostigma thonningii was determined by examining the effects of the leaf extract on phenobarbitone sleeping time, analgesic and muscle relaxant activities using experimental animals. The analgesic effect of the leaf extract was evaluated with acetic acid induced writhing and thermally induced Nociception for pain. It was observed that the extract conferred 48.00 and 57.20% protection from writhes induced by acetic acid on mice when extract doses of 200 and 400 mg/Kg were administered. Similarly, there was a significant (p<0.5) dose dependent effect conferred on mice when pain was induced by heat. The extract also had a muscle relaxant effect as 20%, 60% and 80% were observed to slide down an inclined board in a dose dependent manner. The extract also significantly potentiated sleeping time of phenobarbitone dose dependently in rats of which the mean time duration of (72.0±04.64) min, (83.40±02.11) min, and (123.60±11.57) min were observed when rats were administered extract doses of 200, 400 and 600 mg/Kg b wt. Thus the ethanol leaf extract of Piliostigma thonningii was able to provide depressant effects which were shown in its ability to potentiate barbiturate sleeping, analgesia and muscle relaxant effect.