Antioxidant activity of phenolic compounds extracted from Jatropha curcas L. stem bark

Phenolic compounds were extracted from Jatropha curcas L. stem bark, a residue from tree pruning. In the extraction process, the sample was refluxed with three different solvents by a Soxhlet extractor to evaluate the suitable extraction solvent. The results revealed that the sample refluxed with water gave the highest total phenolic content (13.41 µg GAE/g dry weight of sample). The antioxidant activity of the crude extract was further investigated by comparing the two radical scavenging assays; namely, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). The results showed that the crude extract exhibited antioxidant activity with IC₅₀ values of 155.96 µg/ml by DPPH, and 24.58 mg/ml by ABTS methods, respectively.