In Vitro and In Vivo Antidiabetic Effects of Cratoxylum formosum Leaf Extract in Low-Dose Streptozotocin- and High-Fat Diet-Induced Diabetic Mice

Cratoxylum formosum (CF) is a phenolic-rich plant and exhibits in vitro antioxidant properties, yet its in vivo therapeutic potential remains uncharacterized. This study evaluated the antidiabetic efficacy of an ethanolic CF leaf extract using high-fat diet/streptozotocin-induced diabetic mice, complemented by enzymatic and INS-1 rat insulinoma cell line assays. This study found that 5-O-caffeoylquinic acid (5-CQA) was identified as the major phenolic compound in the CF leaf extract. In vitro, CF extract inhibited α-amylase and α-glucosidase activities and protected INS-1 cells from high-glucose-induced cytotoxicity. In diabetic mice, CF extract administration attenuated hyperglycemia, partially preserved serum insulin and C-peptide levels, and suppressed serum neuropeptide Y (NPY) concentrations. Histological analysis confirmed the preservation of pancreatic islet architecture and pancreatic β-cell mass. These findings indicate that CF extract supports glycemic regulation and pancreatic β-cell preservation, warranting further exploration as a candidate for diabetes management.