Arene Substitutions in Orchid Bibenzyls: Mechanistic Insights into Glucose Uptake and Lipid Metabolism for Targeting Metabolic Disorders

Abstract

Background: Phytochemicals possess diverse therapeutic potential; however, the impact of arene substitutions on the pharmacological properties of the bibenzyl compounds batatasin III and gigantol, derived from Dendrobium venustum, remains unexplored. Objectives: This study examines how structural differences between these compounds affect cellular glucose uptake and lipid metabolism during adipocyte differentiation. Methods: The effects of both bibenzyl compounds on cytotoxicity and glucose uptake were assessed in mouse and human pre-adipocytes and rat skeletal muscle myoblasts using colorimetric assays. Lipid metabolism was evaluated through Oil Red O staining and quantification of triglyceride and glycerol levels, while protein and gene expression during adipocyte differentiation were analyzed via western blotting and RT-qPCR. Results: At the highest non-cytotoxic concentration (25 µM), gigantol significantly enhanced glucose uptake (up to 2-fold) under both basal and insulin-stimulated conditions, whereas batatasin III showed a similar effect only under basal conditions. Gigantol upregulated GLUT1 and GLUT4 in myotubes but downregulated them in adipocytes, whereas batatasin III had minimal impact on these transporters. Both compounds suppressed lipid accumulation in mouse and human adipocytes by decreasing intracellular triglyceride content and promoting extracellular glycerol release. However, batatasin III did not affect extracellular glycerol release during early adipocyte differentiation, as evidenced by the marked downregulation of key lipogenic proteins (PLIN1, LPL, FABP4) observed only with gigantol. Molecular docking analyses suggest that gigantol’s greater bioactivity may result from its higher number of arene substitutions. Conclusions: This study provides the first evidence that differences in arene substitutions among orchid-derived bibenzyls influence their pharmacological properties. Our findings support the strategic modification of natural products as a potential approach for managing metabolic disorders.