In vitro and in vivo antidiabetic and anti-obesity activities of two methanolic pulp extracts of Malus domestica Borkh

Apples are fruits of great agricultural and economic interest in Europe, being also highly appreciated for its nutritional value and its association with several health benefits. The largest amount of apple consumed in Spain corresponds to commercial and imported varieties, losing some autochthonous genotypes well adapted to our climate and geography. Some studies suggest that its consumption produces a decrease in the risk of suffering cardiovascular diseases and diabetes, which could be related to the presence of polyphenols.

The aim of this project is to evaluate the antioxidant, antidiabetic, and anti-obesity effects of pulp apple extracts through in vitro and in vivo assays. The fruits tested come from two commercial apple varieties, Pinova and Verde Doncella. The extraction of bioactive compounds was achieved by using methanol as solvent and ultrasonication.

Total quantity of polyphenols was determined using the Folin method. To determine the antioxidative properties, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay and the inhibition of xanthine oxidase were performed. To evaluate the antidiabetic and anti-obesity potential, we analyzed the production of advanced glycation end products and the inhibition of the enzymes α-glucosidase and pancreatic lipase. Additionally, Caenorhabditis elegans was used to assess the extracts toxicity and their abilities to interfere with the accumulation of lipid droplets.

The results of Verde Doncella are slightly better than Pinova variety. Verde Doncella shows better antioxidant, antidiabetic, and anti-obesity properties than the Pinova pulp extract, spite of having almost the same total polyphenol content.