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.