抄録
Inhibitory potencies against α-glucosidase activities were compared among bromophenols obtained from extracts of three Rhodomelaceae red algae, Symphyocladia latiuscula, Odonthalia corymbifera, and Polysiphonia morrowii. The bromophenols from these species are characterized by a number of Br atoms per benzene ring: S. latiuscula, three Br atoms (1 and 2); O. corymbifera, two Br atoms (3-7); and P. morrowii, one Br atom (8 and 9). The bromophenols exhibited mixed inhibition against yeast α-glucosidase reaction. In particular, symmetric dibenzyl ethers, bis(2, 3, 6-tribromo-4, 5-dihydrox-ybenzyl) ether (2) and bis(2, 3-dibromo-4, 5-dihydroxybenzyl) ether (5), exhibited about 103 fold smaller Ki values than the other bromophenols. Their inhibition modes are disclosed to be mixed inhibition closed to competitive inhibition. Inhibitory potencies of the bromophenols increased with the increasing degree of bromo-substitution per benzene ring and the decreasing degree of methyl-substitution. In contrast to the strong inhibitory activity against yeast α-glucosidase activity, the bromophenols moderately inhibited rat-intestinal sucrase and maltase activity. The inhibitory potencies were all comparative among the bromophenols examined.
