Anti-diarrhoeal effects of Garcinia kola (Heckel-Holl) seed methanolic extract and its fractions in animal models

Abstract

This study investigated the In vitro spasmolytic and In vivo anti-diarrhoeal effects of Garcinia kola seed extract/fractions. Extraction was done by maceration in 70% methanol, serially partitioned in ethyl acetate and n-hexane. Qualitative phytochemical screening was carried out on the crude extract/fractions. The In vitro spasmolytic effect of the extract and fractions at different concentrations (0.5×10³, 0.2×10³,0.1×10³, 0.6×10² mg/ml) were investigated against spontaneous and acetylcholine-induced contractions in isolated rabbit jejunum as well as histamine-induced contractions using isolated guinea pig ileum. The In vivo anti-diarrhoeal effect of the extract was evaluated using three diarrhoeal models: castor oil-induced diarrhoea, charcoal meal gastrointestinal transit time and castor oil-induced enteropooling. In each model, 25 mice were randomly divided into five groups of 5 mice each. Group I served as the untreated control, while group II was a positive control. Groups III-V were administered 125, 250 and 500 mg/kg of the crude methanol extract, respectively. The crude extract, ethyl acetate and aqueous fractions at 0.5×10³ mg/ml respectively exhibited 14.4%, 12.9% and 12.2% spasmolytic activities against acetylcholine-induced rabbit jejunum contractions. Histamine-induced guinea pig ileum contractions were inhibited by crude extract (6.2%), ethyl acetate (6.2%), aqueous fraction (7.2%) at 0.6×10² mg/ml. For castor oil-induced diarrhoea, the crude extract at 500 mg/kg produced a significant (p < 0.05) decrease in the diarrhoeal index and faecal weight with a percentage inhibition of 70.4% compared with controls. Similarly, the crude extract (500 mg/kg) significantly (p < 0.05) decreased the charcoal meal gastrointestinal transit time with a percentage inhibition of 33.9% and elicited significant (p < 0.05) intraluminal fluid reduction (9.1%) in castor oil-induced enter pooling test when compared with the untreated group. In conclusion, the anti-motility and anti-secretory activities of the crude extract were attributed to the phytochemical constituents present.