Nutraceutical Activity of Anthocyanins from the Edible Berries of Rhamnus pompana

We present the inhibitory properties of the R. pompana anthocyanin fraction (RPAF) and its major constituents on alpha-glucosidase (AG), pancreatic lipase (PL), HMG-CoA reductase, and ornithine decarboxylase (ODC). The effect of RPAF was also evaluated in ICR male mice subjected to oral glucose tolerance test (OGTT) and hypercaloric/atherogenic diet for 30 days. RP-HPLC/MS profiling revealed that RPAF contained five major anthocyanins and induced slight inhibition on PL and HMG-CoA reductase (IC₅₀ , 245-338 μg mL^-1 ) whereas strong activity on AG and ODC (IC₅₀ , 130-133 μg mL^-1 ) was observed. Kinetic studies and molecular docking with pelargonidin-3-O-rutinoside (P3R) on ODC, revealed changes in K_m (0.9514-0.9746 mM) and V_max (1.96-2.32 μmol mg^-1  min^-1 ) suggesting mixed inhibition and molecular interaction with two active sites of ODC. P3R showed antiproliferative activity (IC_50, 46.5 μM) and decreased polyamine accumulation in DLD-1 cells. The results of OGTT confirmed that RPAF regulates postprandial glucose levels in diabetic animals which experienced a significant glucose depletion (30 %; p<0.001) from 30 to 120 min post-treatment. Prolonged supplementation of RPAF caused significant decrease (p<0.001) in plasma glucose, total cholesterol, LDL-c and triglycerides as well as significant increase (p<0.001) of HDL-c compared with normoglycemic untreated animals.