Human α-glucosidase inhibition and phytochemical profile of natural and shinzuke treated olives: implications from the processing method

Abstract

Abstract Olive (Olea europaea) phytochemicals are associated with a reduced risk of type 2 diabetes. Table olives typically have higher phytochemical concentrations than olive oil, but their impact on human intestinal α-glucosidase is largely unknown. Shinzuke, the most common trade preparation in Japan, are alkali-treated non-fermented green olives. In contrast, natural olives are debittered by brining, which may enhance phytochemical retention. We evaluated the α-glucosidase inhibitory effect of Shinzuke and natural green olives produced in-house and compared them with commercial table olives. Eight types of table olives were tested against human intestinal α-glucosidase. Shinzuke Mission was the least effective (IC50 0.710 ± 0.058 mg/mL), while Natural green olives showed double to triple activity, with a non-competitive mechanism. Natural table olives retained more phytochemicals than shinzuke and other treated olives, and are good inhibitors of human α-glucosidase in vitro, exhibiting potential as a functional food for the management of postprandial glycaemia. Graphical Abstract

Keywords

• Table olives
• Olea europaea
• α-Glucosidase inhibitor
• Debittering
• Secoiridoids
• Type-2 Diabetes