Phytochemical Analysis and Anti-diabetic Activity of Leaf extract of Psydrax horizontalis Schum and Thonn (Rubiaceae)

Introduction: Rubiacaeae is a large family of flowering plants of 630 genera with over 13000 species widely distributed in the tropical and warm regions of the world. The Psydrax genus has been reported to have various pharmacological activities. Based on ethno-pharmacological information, Psydrax horizontalis Schum. and Thonn. (Bridson) locally known as “Akata-ike” in Nsukka is used in the management of diabetes in South-eastern Nigeria. However as at the time of this research, no previous work has been done to investigate its phytochemical constituents and anti-diabetic activity. Methods: The methanol extract (ME) obtained by maceration was analysed for phytochemicals present using standard procedures. Alloxan monohydrate at 150 mg/Kg was used to induce diabetes. Acute toxicity test was done using the Lorke’s method. The normoglycemic and alloxan-induced groups of twenty animals each were treated orally with 100, 200 and 400 mg/Kg of ME; 5 mg/Kg of glibenclamide and 2 mL/kg of 3% Tween 80 as the controls. The fasting blood glucose concentrations were monitored at 0, 1, 3 and 6 h, as well as 1^st, 3^rd and 5^th day. Results: Phytochemical screening revealed the presence of glycosides, alkaloids, tannins, flavonoids, steroids, saponins and terpenoids. Median lethal dose was greater than 5000 mg/kg. In the alloxan-induced diabetic rats, significant activity at p<0.01 on the 6th hour was recorded at doses 100, 200 and 400 mg/Kg ME on day 3. Conclusion: The ME of Psydrax horizontalis possesses significant anti-diabetic activity in the alloxan-induced diabetic rats. The results obtained validate its traditional use in management of diabetes.