Differences in cytotoxicity and apparent extracellular glucose utilisation among sequentially prepared Cinnamomum cassia stem-bark extracts in basal and palmitate-associated C2C12 myotubes

Background Cinnamomum cassia bark has a documented history of use in traditional medicine and food-medicine practices associated with diabetes and metabolic disorders. This study compared preliminary phytochemical fingerprints, MTT metabolic-viability responses and apparent extracellular glucose utilisation among sequentially prepared stem-bark extracts. Methods Authenticated, vouchered stem bark was extracted sequentially with n-hexane, ethyl acetate, ethanol and water. Extracts were examined by thin-layer chromatography and qualitative phytochemical screening. MTT reduction was assessed after 72 h. Residual extracellular glucose was measured after 180 min, and apparent extracellular glucose utilisation was calculated as 15 mmol/L minus the residual concentration. This endpoint does not directly measure membrane glucose transport or intracellular utilisation. Three independent experiments were conducted in technical triplicate, with technical wells averaged within experiments. The retained non-insulin basal well-level values were reconstructed from reported summary statistics and were therefore treated descriptively; the palmitate-associated dataset was analysed using independent-experiment means. Results The sequential fractions showed different preliminary fingerprints and concentration-related MTT profiles. Within each palmitate-associated extract series, one or more concentrations showed greater apparent extracellular glucose utilisation than the concurrent palmitate-only control; no formal comparison among extracts was performed. Conclusion Sequential fractions showed different MTT and apparent extracellular glucose-utilisation profiles. The endpoint is indirect, was not normalised to concurrent viability or cell number, and may be affected by vehicle or assay interference. Quantitative cinnamaldehyde and coumarin characterisation was not performed. The findings are hypothesis-generating and do not establish glucose uptake, GLUT4 activation, insulin sensitisation, extract superiority, therapeutic efficacy or in vivo safety.