Antioxidative, hypoglycaemic and hepatoprotective properties of five Vaccinium spp. berry pomace extracts

BACKGROUND: Berry pomaces contain biologically active substances and therefore may have considerable potential applications in food and pharmaceutical industries. However, there is a lack of studies on extracting these valuable products from berry pomaces. OBJECTIVE: This study aims to evaluate major constituents of five Vaccinium spp. berry pomace extracts and investigate their antioxidant, hypoglycaemic and hepatoprotective properties. METHODS: Total anthocyanin, procyanidin and polyphenol contents in berry residues were measured by spectrophotometric pH-differential, 4-dimethylaminocinnamaldehyde and Folin-Ciocalteu method, respectively. Identification and quantification of separate compounds were assessed by ultra-performance liquid chromatography and liquid chromatography-time-of-flight-masspectroscopy. Anti-hyperglycaemic properties of pomace extracts were evaluated based on inhibition of alpha-amylase and alpha-glucosidase activity. Extract hepatoprotective effects were estimated based on increased human hepatic cell line HepG2 viability in oxidative stress conditions. RESULTS: The extracts possessed strong antioxidant effects and efficacy for inhibiting the activities of enzymes involved in carbohydrate digestion and for protecting hepatic cells from oxidative damage. CONCLUSIONS: Hepatoprotective and hypoglycaemic properties of berry pomace extracts may be due to the presence of active polyphenols and their synergistic effects. Our results support the use of berry pomaces for designing standardised formulations for the prevention of chronic diseases associated with oxidative stress.