Physico Chemical Properties and Antioxidant Activity of Roselle Seed Extracts

The aim of this research was to extract phenolic compounds from defatted Roselle (Hibiscus sabdariffa L.) seed and assess their antioxidant potential. Water, ethanol (30%), methanol (30%) and acetone (30%) were used as solvent for extraction. The proximate composition, total phenolic content and extraction yield were analyzed. Antioxidant efficacies of Roselle seed extract were tested by using 1, 1-Diphenyl-2-Picrylhydrazyl (DPPH), hydroxyl, 2, 2’-azinobis-3-ethylbenzothiaz oline-6-sulfonic acid (ABTS) radicals scavenging capacities and reducing power analysis. Roselle seeds were found to be rich in protein (27.745%), carbohydrates (40.45%) and oil (20.83%). The total phenolic content ranged from 1.66±0.03 to 1.99±0.01 (GAE) mg/g using water and 30% acetone respectively. The highest inhibitory capacity on DPPH and ABTS radicals was observed in 30% acetone extract and was at 3 mg/mL for DPPH and 6 mg/mL for ABTS respectively. Ethanol extract showed the highest hydroxyl radical scavenging ability value of 66.36 at 20 mg/mL, followed by methanol (57.27), acetone (56.36) and water (30). The reducing potential of the different extracts was concentration dependent and increased with increase in concentration. These results indicate that substantial antioxidant activity can be obtained from Roselle seed phenolic compounds extract by using 30% acetone.