Methyl 4-O-Demethylbarbatate Destabilises HIF-1α and Enhances Temozolomide Sensitivity in Glioma Cells

Gliomas remain among the most lethal brain tumours, driven by aggressive invasion, stem-like properties, metabolic plasticity, and frequent resistance to temozolomide (TMZ). Hypoxia-inducible factor-1α (HIF-1α) is a central regulator of these malignant traits. In this study, we identify methyl 4-O-demethylbarbatate (Me-4-O-DBA), a biosynthetically produced lichen-derived metabolite, as a potential modulator of HIF-1α signaling. Molecular docking analysis suggested a possible interaction between Me-4-O-DBA and HIF-1α near the Lys304 ubiquitination site, which may contribute to reduced HIF-1α stability and suppression of downstream EMT and stemness signaling. This inhibition simultaneously attenuated both glycolytic activity and mitochondrial respiration, indicating a broad suppression of metabolic reprogramming. Network pharmacology and molecular docking further indicated HIF-1α-associated signaling as a potential regulatory hub, while in vitro assays demonstrated marked reductions in glioma cell viability, invasion, migration, and clonogenicity. Notably, Me-4-O-DBA synergised with TMZ to enhance suppression of motility, stemness, and metabolic activity, resulting in profound impairment of tumourigenic potential. In vivo zebrafish assays also indicated a favourable safety profile at the tested concentrations. Together, these findings suggest that Me-4-O-DBA suppresses HIF-1α-associated malignant phenotypes and enhances TMZ responsiveness in glioma cells, highlighting its potential as a natural product-derived modulator of glioma progression.