Phenolics and enzyme inhibitors from the Patagonian Empetrum rubrum berries

The small fruits from Empetrum rubrum were consumed by Native Americans in southern Patagonia. Two samples collected close to the Magellan Street and the Beagle channel in Tierra del Fuego were investigated. Three different extracts from the berries were analyzed, namely: methanol, phenolic-enriched (PEE) and ethyl acetate (EtOAc). The total phenolic, flavonoid, procyanidin and anthocyanin content of the extracts was determined. The effect of the extracts towards the metabolic syndrome-associated enzymes α-glucosidase, α-amylase and pancreatic lipase was assessed. In addition, the antioxidant capacity was measured using DPPH, FRAP, TEAC and ORAC assays. The composition of the extracts was determined by HPLC-MS/MS. Seventy-one compounds were identified for the first time in the berries, including 10 anthocyanins, 35 flavonoids, 11 phenylpropanoids and 13 procyanidins. The main compounds were quantified by HPLC-DAD. The extracts displayed strong activity as α-glucosidase inhibitors, with IC50 values ranging from 0.10 to 0.19 μg/mL for the PEE and 0.82–1.95 μg/mL for the EtOAc extracts, respectively. The results show high chemical diversity and differences with the boreal species E. nigrum.