Antioxidant Effects of Alperujo Extract (Arbequina and Frantoio Varieties) on MIN6 <i>β</i>-Cells Subjected to Stress with Glucose or H₂O₂

Abstract

Alperujo, an antioxidant-rich by-product of olive oil extraction, could protect β -cells against oxidative damage. Our goal was to study the antioxidant effects of an alperujo extract (AE) on MIN6 β -cells challenged with glucose or hydrogen peroxide. MIN6 β -cells were challenged with glucose (100 mM) or H 2 O 2 (0.15 mM), with or without AE (20 μM phenol). Reactive oxygen species, intracellular iron (Fe), insulin, glucose uptake, and mRNA gene expression of Uncoupling Protein-2 (UCP-2), Thioredoxin (TRDX), p47phox, and the ratio Bax/Bcl-2 were measured. ROS increased when the stressors were incubated with AE (p < 0.05 and p < 0.01, respectively). Intracellular Fe increased in glucose presence (100 mM p < 0.001). Insulin secretion improved when cells were pre-incubated with AE (p < 0.001) and glucose uptake increased when cells were pre-incubated with AE for 3 days and then further treated with glucose (p < 0.001). After 3 days of AE alone, mRNA relative expression of UCP-2 and TRDX increased (p < 0.001) and after 5 days p47phox, also increased. The Bax/Bcl-2 ratio tended to decrease in the samples pre-incubated with AE. The Alperujo extract,in vitro, had a pro-oxidant behavior, however pre-incubating MIN6 β -cells with AE tended to protect them against apoptosis, thereby enhancing insulin secretion.