Phytochemical Analysis and Biological Evaluation of Muntingia calabura Leaf Extracts

The crude extract of Muntingia calabura (M. calabura) was subjected to preliminary phytochemical screening, which confirmed the presence of various bioactive constituents, including steroids, flavonoids, saponins, tannins, and carbohydrates. Among the different extracts, the aqueous extract exhibited the highest concentration of these phytoconstituents. High-Performance Liquid Chromatography (HPLC) analysis revealed that β-sitosterol (46.33%) and stigmasterol (53.67%) were the predominant phytosterols present in the extract. Further investigation focused on the effect of β-sitosterol on GLUT-4 expression and glucose uptake in C2C12 myotube cells. The findings demonstrated a significant upregulation of GLUT-4 expression, which enhanced glucose uptake and indicated its potential role in maintaining glucose homeostasis. In addition, β-sitosterol was also found to influence GLUT-6 expression, suggesting a non-specific modulatory effect of the plant-derived compound. These results indicate that M. calabura exhibits notable antidiabetic activity, primarily attributed to its phytosterol content. The phytosterols were found to stimulate GLUT-4 translocation to the cell membrane and may act either independently or synergistically to enhance its epigenetic expression. The improved GLUT-4 translocation suggests the potential of M. calabura in correcting defects associated with insulin-mediated glucose transport, thereby highlighting its promise as a therapeutic agent in diabetes management. Moreover, the ability of β-sitosterol and structurally related compounds such as stigmasterol to modulate GLUT protein expression at the genetic level indicates a broader regulatory influence on glucose metabolism. Overall, the study underscores the therapeutic potential of M. calabura in the management of both insulin-dependent and insulin-independent diabetes mellitus.