Valorization of Cashew Nut (Anacardium occidentale L.) Testa as a Source of Phenolic Compounds with α-Glucosidase and α-Amylase Inhibitory Properties

Purpose Cashew nut testa (CNT) is an underutilized cashew by-product. This agro-industrial by-product has the potential
for valorization. This study evaluates the novel potential of antioxidant, α-amylase, and α-glucosidase inhibitory activities of
cashew nut testa polyphenols through bioassay-guided fractionation.
Methods The antioxidant, α-glucosidase, and α-amylase enzyme inhibitory properties of crude and various phenolic frac-
tions of cashew nut testa were evaluated in this study. Chromatographic separation and in-vitro bioassays directed the iden-
tification of the most active fraction.
Results The crude ethanolic extract showed higher antioxidant activity from DPPH* (IC50 15.50 ± 0.67 µg mL− 1) and
ABTS* (IC50 40.20 ± 2.40 µg mL− 1) assays. Among the column fractions, fraction 7 is the most potent fraction with superior
antioxidant activity. Characterization was done by TLC, HPTLC, and HPLC, indicating the presence of flavonoids. Cashew
nut testa phenolics showed potential inhibition towards α-amylase and α-glucosidase.
Conclusion Polyphenols recovered from this agro-industrial by-product had antioxidant, α-amylase, and α-glucosidase
inhibitory properties. Flavonoids, especially (+)-catechin, (-)-epicatechin, epigallocatechin, and catechin gallate, are the
primary polyphenols responsible for the antioxidant, α-glucosidase and α-amylase inhibitory properties of cashew nut testa.
This study suggests the potential valorization of this agro-industrial by-product as a source of antioxidants and a natural
source of polyphenols to manage hyperglycaemia.