The low molecular fraction of Pyropia spp. improves hyperinsulinemia in KK-A^y mice

Abstract

Pyropia spp. (Nori) contain nutritional compounds and functional constituents. We previously reported the suppressive effect of the Nori fraction on blood glucose in normal rats. This fraction was 75 % ethanol soluble fraction (NS) and separated using an ultrafiltration membrane with a molecular weight of 1000 Da. The obtained fraction had a molecular weight of less than 1000 Da (NS ＜ 1000) and was used for administration. Patients with diabetes use subcutaneous injections of insulin; however, we would like to develop new orally available functional foods to relieve patients' pain and increase adherence. We assessed the antidiabetic effect of the NS ＜ 1000 fraction orally administered to diabetic/obese KK-A^y mice. The three animal groups (control, 0.5 g/kg B. W., and 2.0 g/kg B. W.) were orally administered the fraction once daily for 7 weeks. Although the NS＜ 1000 fraction had no significant effect on body and organ weight, the serum insulin levels in the NS ＜ 1000 groups were significantly lower than those in the control group after 4 weeks of administration and a glucose tolerance test. In conclusion, we discovered that the NS ＜ 1000 fraction has constituents that may improve glucose metabolism by saving insulin.