Investigation of the antioxidant properties and the effect on pancreatic lipase inhibition of Isabella grape (Vitis labrusca L.) grown in Rize province

In this study, the antioxidant properties and inhibitory effects on pancreatic lipase of Isabella grape (Vitis labrusca L.) grown in Rize province were investigated. According to the literature, grapes are rich in phenolic compounds and exhibit strong antioxidant and antiinflammatory effects, while also playing an important role in the prevention of obesity, diabetes, and cardiovascular diseases. In particular, the inhibition of pancreatic lipase is considered one of the major enzymatic mechanisms targeted in obesity treatment by reducing dietary fat absorption. Within this context, grape samples collected from Köprülü village in Rize were analyzed for total phenolic and flavonoid contents, while antioxidant capacity was evaluated using DPPH radical scavenging activity, cupric ion reducing antioxidant capacity (CUPRAC) method, and ferric reducing antioxidant power (FRAP) method assays. Phenolic compounds were further identified by high-performance liquid chromatography–diode array detector (HPLC-DAD) analysis, which revealed gallic acid, protocatechuic acid, and catechin as the major constituents. Pancreatic lipase inhibition was assessed using a modified Kurihara method, and the results were compared with orlistat, a potent enzyme inhibitor used in the treatment of obesity. The findings demonstrated that Isabella grapes possess high antioxidant capacity and exert significant, dose-dependent inhibition of pancreatic lipase. Although the inhibitory effect was not as strong as that of orlistat, Isabella grapes showed notable bioactivity and may serve as a promising supportive option in anti-obesity therapy.