Hypoglycemic, anti-glycation and antioxidant in vitro properties of two Vaccinium species from Macaronesia: A relation to their phenolic composition

Vaccinium cylindraceaeum (Azores blueberry) and V. padifolium (Madeira blueberry) are two Portuguese endemic species, which phytochemical composition and beneficial properties lack scientific validation. In this work, their potential in vitro inhibitory effects against key enzymes linked to type 2 diabetes and obesity and glycation of proteins were evaluated. Anthocyanins were predominant in fruits, while hydroxycinnamic acids (in particular 5-O-caffeoylquinic acid) and fiavonoids were the main compounds in leaves. Vaccinium extracts showed effective inhibitions of glucosidases and glycation of proteins and mild activity towards alpha-amylase and pancreatic lipase (by comparison with reference compounds). Phenolic composition was strongly correlated with reported bioactivities. In fact, 5-O-caffeoylquinic can be considered one of the main hypoglycemic and anti-glycation agents of analysed extracts. Consumption of both Vaccinium species should be encouraged since berries could offer a dietary option in the prevention and control of diabetes and obesity, while leaves are good candidates for development of nutraceuticals.