Two Unsaturated Fatty Acids with Potent α-Glucosidase Inhibitory Activity Purified from the Body Wall of Sea Cucumber (Stichopus japonicus)

One therapeutic approach for preventing diabetes mellitus and obesity is to retard the absorption of glucose via inhibition of a-glucosidase. Two unsaturated fatty acids with strong a-glucosidase inhibitory activity, 7(Z)-octadecenoic acid (1) and 7(Z),10(Z)-octadecadienoic acid (2), were purified from the body wall of Stichopus japonicus. IC50 values of compounds 1 and 2 were 0.51 and 0.67 mu g/mL against Saccharomyces cerevisiae a-glucosidase and 0.49 and 0.60 mu g/mL against Bacillus stearothermophilus a-glucosidase, respectively. These compounds mildly inhibited rat-intestinal sucrase and maltase. In addition, both compounds showed a mixed type of inhibition against S. cerevisiae a-glucosidase and were very stable under thermal and acidic conditions up to 60 min. The KI and KIS values of compounds 1 and 2 were 0.44 and 0.22 mu g/mL, and 0.39 and 0.13 mu g/mL, respectively.