α‐Glucosidase Inhibitory Activity of Bromophenol Purified from the Red Alga Polyopes lancifolia

A bromophenol, bis(2,3‐dibromo‐4,5‐dihydroxybenzyl) ether, was purified from the red alga Polyopes lancifolia. Its IC 50 values were 0.098 and 0.120 μM against Saccharomyces cerevisiae and Bacillus stearothermophilus α‐glucosidases, respectively, and 1.00 and 1.20 mM against rat‐intestinal sucrase and maltase. This bromophenol competitively inhibited S. cerevisiae α‐glucosidase with a K I value of 0.068 μM and was very stable at pH 2 for 60 min at 37 °C. Therefore, this P. lancifolia bromophenol may have potential as natural nutraceutical for the management of type 2 diabetes. Practical Application: One therapeutic approach for preventing diabetes mellitus is to retard the absorption of glucose via inhibition of α‐glucosidase. In this study, one compound with strong α‐glucosidase‐inhibitory activity, bis(2,3‐dibromo‐4,5‐dihydroxybenzyl) ether, was purified and identified from the red alga P. lancifolia. Therefore, P. lancifolia bromophenol can potentially be developed as a novel natural nutraceutical for the management of type 2 diabetes.