Phenolic linked anti-hyperglycemic bioactives of barley (Hordeum vulgare L.) cultivars as nutraceuticals targeting type 2 diabetes

Barley (Hordeum vulgare L.) is an important commercial and industrial crop rich in phenolic bioactives and dietary antioxidants and can be targeted for developing non-food nutraceuticals and functional ingredients to counteract diet-linked chronic diseases such as type 2 diabetes (T2D). In this study 13 barley cultivars were screened for phenolic-linked functionalities targeting antioxidant and anti-hyperglycemic properties using in vitro assay models. Total soluble phenolics (TSP) content, individual phenolic acid profile, and antioxidant activity of barley extracts (hot water, cold water, and 12% ethanol) were evaluated. The α-amylase and α-glucosidase inhibitory activities of barley extracts were also evaluated using in vitro assays. The TSP content of barley varied between 0.44 and 0.63 mg/g gallic acid equivalent (GAE) on a dry weight basis across cultivars and extraction types, with hot water extracts having highest TSP content. Across barley cultivars, cv. Pinnacle had the highest antioxidant activity, while among extraction types ethanol extracts had highest antioxidant activity. Cold water and ethanol extracts of most barley cultivars had significantly high α-amylase inhibitory activity; however, significant differences were not observed among most cultivars. The black barley cultivar had the highest α-glucosidase inhibitory activity (34%) across all extraction types, and a dose-dependent pattern was observed in all barley cultivars. Therefore, barley cultivars with significant potential to modulate the activity of key enzymes that regulate carbohydrate metabolism were screened and identified in this in vitro study. Consequently, grains of such cultivars may be utilized for further clinical and animal studies to develop phenolic bioactive-rich non-food type nutraceuticals and bioactive functional ingredients that can be used to complement current drug design strategies to offset hyperglycemia and oxidative stress associated with early stages of T2D.