In Vitro and In Vivo Antidiabetic Effects of Acidic Polysaccharides Extracted from Seaweeds

We evaluated the α-glucosidase inhibitory activity of acidic polysaccharides (APs) extracted from seaweeds in vitro and their antidiabetic effects in KK-A^y mice. The α-glucosidase inhibitory activity of APs was differed among various seaweed species. Some APs showed higher inhibitory activity in the high-molecular-weight range, whereas others showed higher inhibitory activity in the low-molecular-weight range. Mice were fed low-molecular-weight APs from hijiki (LMWAPsH), which showed higher α-glucosidase inhibitory activity. Fasting blood glucose and HbA1c levels were significantly lower in the LMWAPsH group than in the control group (p<0.01). The calculated homeostasis model assessment-insulin resistance in the LMWAPsH group was significantly lower than that in the control group (p<0.05). These results suggest that α-glucosidase inhibitory activity differ among APs from different seaweed species, and each have an optimum molecular-weight range, and that LMWAPsH prevents the hyperglycemia in KK-A^y mice.