Tamarind flower as an unexplored functional food: Nutritional composition, phenolic characterization, and bioactive properties

Tamarind flowers represent an underutilized component of Tamarindus indica L., despite their traditional consumption as vegetables in Thai cuisine. Due to limited recognition of their edible applications, comprehensive data regarding their nutrients, phytochemicals, and health benefits remain scarce. This study therefore aimed to characterize the nutritional profile, phenolic composition, and in vitro bioactivities of tamarind flowers. Nutritional analysis revealed that per 100 g fresh weight, tamarind flowers constituted an excellent source of dietary fiber and copper, providing 45% and 41% of the Thai Reference Daily Intakes (RDIs), respectively. The aqueous ethanolic extract exhibited a total phenolic content (TPC) of 193.95 mg gallic acid equivalent (GAE)/g dry weight (DW) and total flavonoid content (TFC) of 475.73 mg quercetin equivalent (QE)/g DW. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis identified gallic acid and 4-hydroxybenzoic acid as the predominant compounds, with 3,4-dihydroxybenzoic acid, p -coumaric acid, and caffeic acid present at lower concentrations. Bioactivity assessment demonstrated potent antioxidant capacity, as evidenced by ORAC, DPPH radical scavenging, and FRAP assays, along with significant inhibitory activity against enzymes implicated in type 2 diabetes mellitus (α-glucosidase, α-amylase, and dipeptidyl peptidase-IV) and Alzheimer's disease (cholinesterases). Notably, the extract exhibited exceptionally high α-glucosidase inhibitory potency, exceeding that of acarbose, a standard pharmaceutical agent employed in type 2 diabetic management. Furthermore, combination treatment with the tamarind flower extract demonstrated synergistic effects at low acarbose concentrations. These findings provide scientific evidence supporting the nutritional and potential bioactive properties of tamarind flowers, suggesting their valorization as a functional food ingredient.