Determination of phenolic contents and antioxidant activities of extracts of Jatropha curcas L. seed shell, a by-product, a new source of natural antioxidant

Due to severe energy crisis, Jatropha curcas L. has been heavily cultivated in many countries. Seed shell will may be generated in huge quantities as a by-product in the biodiesel production. However, the bioactivity of seed shell has not been cleared. So, the present study was designed to investigate the phenolic content and in vitro antioxidant activity of J. curcas seed shell. Three extracts, ethyl acetate extract, ethanol extract and water extract, were tested using Folin-Ciocaltus method and seven different methods (DPPH, ABTS and OH radicals scavenging, ORAC, reducing power, metal chelating and β-carotene bleaching assays) for phenolic content and antioxidant measurement, respectively. The results showed that all of three extracts contained high contents of phenolic compounds and exhibited relatively strong antioxidant activities. There is no regular difference between each other with respects to various antioxidant evaluation methods. The results indicated that phenolic compounds of seed shell deserve more attention. The present study demonstrated that J. curcas seed shell is a new source of natural antioxidant, and could be used for industrial, and which would strongly enhance the utilization of J. curcas.