Comparative Free Radical Scavenging Activity of Seed Coat Extracts from Caesalpinia pulcherrima and Delonix regia

摘要

Caesalpinia pulcherrima and Delonix regia are generally grown in Thailand and used in traditional medicine having medicinal therapeutic effects. The antioxidant ability of seed extract has been presented by few investigators whereas no data has been reported the different antioxidant activity between embryo, endosperm and seed coat extracts from both species. Difference types of tissues and varieties may cause a difference seed contents and antioxidant characters. Hence, the main aim of this study is to compare the free radical scavenging activity of embryo, endosperm and seed coat extracts between C. pulcherrima and D. regia. It was found that the phenolic compounds found in embryo extract (100, 200, 400 and 1,000 μg/ml) of C. pulcherrima (16 to 238 μg gallic acid equivalents) and D. regia (33 to 379 μg gallic acid equivalents) were significantly higher than those of endosperm and seed coat extracts. The percentage of DPPH scavenging activity of seed coat extracts of C. pulcherrima (8.68 to 76.16) and D. Regia (2.69 to 9.63) were higher than those of endosperm and embryo extracts. In addition, the percentage of DPPH scavenging activity of seed coat extracts of C. pulcherrima was statistically significant higher than D. regia. Finally, we can conclude that (1) the highest phenolic contents were found in embryo extract, (2) the seed coat extract of C. pulcherrima had the highest antioxidant activity (3) phenolic contents and antioxidant activity of seed coat extracts of C. pulcherrima were significantly higher than D. regia, and (4) the total contents of phenolic compounds and the percent DPPH scavenging activity were depended on types of tissues and species.