The antihyperglycemic potential of Saccharina japonica: a comparative study of water and ethanol extracts through chemical profiling and in vitro and in vivo studies

Type 2 diabetes mellitus (T2DM) is a global health concern due to postprandial hyperglycemia, complications, and mortality. Synthetic drugs, despite efficacy, cause side effects like hypoglycemia, driving demand for alternatives. This study evaluated Saccharina japonica (SJ) extracts’ effects on postprandial glucose control. Chemical profiling determined the compound compositions of both water and ethanol extracts. In vitro, water and ethanol extracts inhibited α-glucosidase and glucose uptake, significantly reducing sodium/glucose cotransporter 1 (SGLT1) and glucose transporter 2 (GLUT2) expression (P < 0.05) compared to the glucose-treated group. In vivo, SJ extracts lowered blood glucose in C57BL/6 mice given maltose or sucrose (P < 0.05) versus controls, with reduced area under the curve (AUC) for glucose and sucrose. These findings suggest SJ extracts could mitigate postprandial hyperglycemia, offering a promising natural alternative to synthetic drugs.