Bioactivity Studies of Different Solvent Extracts of Defatted Residues From Terminalia catappa L. Seed Kernels

Abstract

Terminalia catappa Linn., also referred to as tropical almond or Indian almond, can play a significant role in improving food and nutritional security. The objective of this research was to assess the antioxidant, antihyperglycemic, and antiobesity potentials of the defatted residues from seed kernels of purple and yellow cultivars. The defatted residues obtained using a micro–screw-press oil extractor were subjected to sequential extraction using n-hexane, dichloromethane (DCM), and methanol (MeOH) as solvents. The crude extracts of both cultivars were subjected to the evaluation of total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities, namely, DPPH, ABTS⁺, and ferric reducing antioxidant power (FRAP). They were also subjected to enzyme inhibitory activities against α-amylase and lipase. Among the extracts, the MeOH extract of the yellow cultivar showed the highest TPC, superior antioxidant activities (DPPH and ABTS⁺), and strongest enzyme inhibitory activities. In contrast, the purple cultivar exhibited the highest FRAP activity. Gallic acid was the major phenolic constituent occurring in high concentrations in the defatted residues. These findings enlighten the potential uses of defatted residues of the T. catappa seed kernels, particularly those from the yellow cultivar as an ingredient for nutraceutical and functional food applications.