Antioxidant activities and heat stability of edible flowers of Telosma minor and Sesbania javanica

Abstract

Aqueous and ethanolic extracts from the edible flowers of Telosma minor (cowslip creeper), and Sesbania javanica (sesbania) were assessed for their their total phenolics, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, and anti-lipid peroxidation ability. Aqueous extracts of cowslip creeper had the highest activities as a DPPH radical scavenger and as an inhibitor of lipid peroxidation. The value of the half-maximal effective concentration (EC50) for DPPH radical-scavenging of the aqueous cowslip creeper extract was 252.5 mg L−1, compared to the EC50 values for the standards, ascorbic acid, and butylated hydroxytoluene (BHT), which were 2.26 and 21.80 mg L−1, respectively. For anti-lipid peroxidation, the IC50 (the half-maximal inhibition concentration) value of the aqueous cowslip creeper extract was 1539.93 mg L−1 while the IC50 value of BHT was 683.5 mg L−1. The aqueous extract of cowslip creeper had the highest total phenolic concentration (991.3 mg gallic acid equivalents 100 g−1 DW). The total phenolic content in cowslip creeper and sesbania flowers had high positive correlation with their antioxidant activities and anti-lipid peroxidation. The aqueous extract of sesbania flowers was the most heat stable antioxidant (100°C for 15 or 30 min), decreasing in total phenolic content but no changes in DPPH scavenging or in anti-lipid peroxidation activity.