GB7 acetate, a galbulimima alkaloid from Galbulimima belgraveana, possesses anticancer effects in colorectal cancer cells

Abstract GB7 acetate is a galbulimima alkaloid obtained from Galbulimima belgraveana. However, information regarding its structure, biological activities, and related mechanisms are not entirely available. A series of spectroscopic analyses, structural degradation, interconversion, and crystallography were performed to identify the structure of GB7 acetate. The MTT assay was applied to measure cell proliferation on HCT 116 cells. The expression of the related proteins was measured by western blotting. Transmission electron microscopy (TEM), acridine orange (AO) and monodansylcadaverine (MDC) staining were used to detect the presence of autophagic vesicles and autolysosomes. A transwell assay was performed to demonstrate metastatic capabilities. Oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) assays were performed to determine the mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis activity of HCT 116 cells. The data showed that GB7 acetate suppressed the proliferation and colony-forming ability of HCT 116 cells. Pretreatment with GB7 acetate significantly induced the formation of autophagic vesicles and autolysosomes. GB7 acetate upregulated the expression of LC3 and p-AMPKα, which are key elements of autophagy. In addition, GB7 acetate suppressed the metastatic capabilities of HCT 116 cells. Additionally, the production of MMP-2 and MMP-9 was reduced, whereas the expression of E-cadherin (E-cad) was upregulated. Furthermore, GB7 acetate significantly reduced mitochondrial OXPHOS and glycolysis. In conclusion, the structure of the novel Galbulimima alkaloid GB7 acetate was identified. GB7 acetate was shown to have anti-proliferative, pro-autophagic, anti-metastatic, and anti-metabolite capabilities in HCT 116 cells. This study might provide new insights into cancer treatment efficacy and cancer chemoprevention.