In Vitro Inhibitory Effects of Viburnum opulus Bark and Flower Extracts on Digestion of Potato Starch and Carbohydrate Hydrolases Activity

One of the effective treatments for diabetes is to reduce and delay the absorption of glucose by inhibition of alpha-amylase and alpha-glucosidase in the digestive tract. Currently, there is a great interest in natural inhibitors from various part of plants. In the present study, the phenolic compounds composition of V opulus bark and flower, and their inhibitory effects on in vitro potato starch digestion as well as on alpha-amylase and alpha-glucosidase, have been studied. Bark and flower phenolic extracts reduced the amount of glucose released from potato starch during tree-stage simulated digestion, with IC50 value equal to 87.77 mu g/mL and 148.87 mu g/mL, respectively. Phenolic bark extract showed 34.9% and 38.4% more potent inhibitory activity against alpha-amylase and alpha-glucosidase, respectively, but the activity of plant extracts was lower than that of acarbose. Chlorogenic acid (27.26% of total phenolics) and (+)-catechin (30.48% of total phenolics) were the most prominent phenolics in the flower and bark extracts, respectively. Procyanidins may be responsible for the strongest V opulus bark inhibitory activity against alpha-amylase, while (+)-catechin relative to alpha-glucosidase. This preliminary study provides the basis of further examination of the suitability of V opulus bark compounds as components of nutraceuticals and functional foods with antidiabetic activity.