FREE RADICAL SCAVENGING ACTIVITY OF ZIZIPHUS MUCRONATA BARK EXTRACTS

摘要

Generation of free radicals because of oxidation processes is a natural phenomenon in all living entities including plants. Natural anti-oxidants are the good source for scavenging and reducing free radicals generated in the body after multifold oxidative stress. The present study was aimed to evaluate in vitro anti-oxidant properties of different types of bark extracts of Ziziphus mucronata, a tree found in Botswana. Gallic acid was used a reference control for all experiments. Different types of extracts were prepared with 100% hexane; 50% hexane/chloroform; 100% chloroform; 50% methanol/chloroform; 100% methanol and 70% methanol/water solvent system. The anti-oxidant studies included DPPH-TLC-Semi quantitative assay and ABTS free radical scavenging. Total phenol content was also determined. ABTS scavenging activity noted in this study was 70.3 mug/ml (IC_(50) (mug/ml) with 100 % methanol extract. The total phenol content was seen to increase from the less polar solvent to the more polar solventand the maximum was shown in 70% methanol extract (21 mgGAE/g). It is concluded that different extracts of bark had free radical scavenging activities and extent of scavenging increased from extract obtained from low polarity solvent to the extract obtained from high polarity solvent. Maximum activity was observed with 100 methanol extract and least activity was observed with hexane extract.