IN VITRO ANTIOXIDANT AND FREE RADICAL SCAVENGING EFFECTS OF EXTRACTS AND FRACTIONS, ACUTE AND SUB-ACUTE TOXIXITY OF AQUEOUS EXTRACT FROM IPOMOEA BATATAS (L.) LAM. (CONVOLVULACEAE) LEAVES FROM CENTRAL KASAI IN DEMOCRATIC REPUBLIC OF CONGO

Dr. Cimanga Kanyanga R., Ndala Kasanda N., Mutambele Hity D., Vlietinck A. J. and Pieters L.

ABSTRACT

The potential antioxidant and free radical scavenging activities of aqueous extract and its soluble fractions, and 80% methanol extract from Ipomoea batatas leaves was measured using various in vitro assays. The acute and sub-acute toxicity aqueous was also evaluated. In antioxidant assays, among these tested samples, 80% methanol extract showed greater antioxidant activity measured as scavenging effects on DPPH, ABTS, superoxide anions O2●-, hydroxyl HO● and hydrogen peroxide H2O2 radicals with IC50 values of 2.3±0.03, 3.62±0.06, 6.52±0.10, 5.06±0.11 and 8.63±0.01 μg/ml. respectively, It was followed by aqueous extract showing IC50 values of 3.56±0.02, 5.62±0.03, 8.56±0.03, 9.63±0.02 and 14.63±0.01 μg/ml respectively against the same order of selected ROS. Choroform, ethylacetate, n-butanol and residual aqueous soluble fractions from the partition of the aqueous extract exerted also scavenging activity against these ROS with IC50 values ranging from 13.25±0.08 to 23.02±0.06 μg/ml as their antioxidant activity. Total polyphenols and flavonoids inhibited the activities of these selected ROS with IC50 values from 1.75±0.02 to 7.65±0.02 μg/ml, showing thus their antioxidant activity. In acute and subacute toxicity, aqueous extract of Ipomea batatas leaves did not induced mortality of treated rats and its lethal dose 50 (LD50) was estimated to be > 5000 mg/kb body weight. It had no influence on haematological, biochemical and organ weights of treated rats. The extract was considered non-toxic per oral route, safe and well tolerated. Data from the present results revealed that samples form Ipomoea batatas acted as antioxidant agents due to its free radical scavenging activities and the plant can be considered as new source of antioxidant constituents which remained to be isolated in future.

Keywords: Ipomoea batatas, Convolvulaceae, leaves, extracts, fractions, total phenols and flavonoids, free scavenging and antioxidant activities.