Phenolic compounds and antioxidant activities of edible flowers from Thailand

We investigated the phenolic compounds and antioxidant capacities of free and bound phenolics from 12 available Thai edible flowers which have long been consumed as vegetable and used as ingredients in cooking. Cassia siamea showed the highest value of total phenolic content (TPC) (88 mg gallic acid equivalents (GAE)/g dry weight). Tagetes erecta had the highest total flavonoid content (TFC) (68.9 mg RE/g dry weight). Antigonon leptopus and T. erecta had the highest ferric reducing antioxidant power (FRAP) value (62.0 and 60 mmolFeSO4/g 100 dry weight). Major phenolic acids identified in these analyses were gallic acid, ferulic acid and sinapic acid, while predominant flavonoids were quercetin and rutin. The results of this study showed that soluble as well as bound fractions of edible flowers are rich sources of phenolic compounds with antioxidant, DPPH radical-scavenging activity and reducing power. This study has provided useful information for screening edible flowers as potential sources of bioactive components with high antioxidant properties that may be of interest to consumers and public health workers.

► Major flavonoids in edible flowers were quercetin and rutin.
► Antigonon leptopus and Tagetes erecta showed the highest antioxidant activity.
► Major bound phenolic acids in edible flowers were sinapic acid and ferulic acid.
► The highest total bound phenolics were found in Bougainvillea hybrida and Nelumbo nucifera.