Effect of Rhoicissus digitata extracts on acetylcholine-mediated contraction in rat uterus

Rhoicissus digitata (L.f.) Gilg & M. Brandt (Vitaceae) is used in traditional medicine in Southern Africa to tone the uterus during pregnancy and to facilitate delivery. Aqueous and methanolic extracts were prepared from powdered dry leaves and roots of R. digitata. The uterine horns were surgically removed from female Sprague Dawley rats in estrous, placed in de Jalon solution (NaCl: 9g/l, KCl: 0,42g/l, NaHCO3: 1,50g/l, Glucose: 0,5g/l, CaCl2: 0,12g/l) and hung in the experimental setup in the uterus contraction assay. After mounting, the uterine horns were allowed to equilibrate in the organ bath for 30min, renewing the solution every 10min by flushing. The organ strips were incubated with extract in a concentration of 1.3mg/ml for 5min before starting cumulative addition of acetylcholine. The water extract of the root and the methanol extract of the leaves increased the response significantly (p<0.0001 for both (two-way ANOVA)), and the methanol extract of the root inhibited the response significantly (p<0.0001). The results suggests that the use of water extracts (decoctions) of R. digitata roots in South African traditional medicine as pregnancy related medicine can be justified, as they increase the acetylcholine-mediated uterine contractions in rats. The uterus contracting effect of the methanol extract of the leaves of R. digitata suggests that alcoholic leaf extracts could be used as substitutes for root extracts, which as a renewable source could help with sustainable usage of these species.