Ginsenoside compound K-loaded gold nanoparticles synthesized from Curtobacterium proimmune K3 exerts anti-gastric cancer effect via promoting PI3K/Akt-mediated apoptosis

Background Compound K (CK) is the minor ginsenoside present in fermented Panax ginseng extract. Despite the pharmacological efficacy of CK, its industrial use has been restricted due to its low water solubility and poor permeability. To overcome this defect, our study was to synthesize gold nanoparticles from CK (CK-AuNPs) to investigate their potential as anticancer candidates. Methods To biologically synthesize CK-AuNPs, a novel strain, Curtobacterium proimmune K3, was isolated from fermented ginseng beverage, then combined with CK and gold salts to biosynthesize gold nanoparticles (CurtoCK-AuNPs). Their physicochemical characteristics were evaluated using UV-Vis spectrometry, FE-TEM, EDX, elemental mapping, XRD, SAED, DLS and TGA. Results CurtoCK-AuNPs exerted significant selective cytotoxic effects on AGS human gastric cancer cells. Fluorescence staining with Hoechst, propidium iodide, and MitoTracker demonstrated that CurtoCK-AuNPs induce apoptosis and mitochondrial damage, respectively. Quantitative real-time PCR and western blotting analyses showed that cytotoxic effect of CurtoCK-AuNPs were involved in apoptosis, based on their activation of Bax/Bcl-2, cytochrome c, caspase 9, and caspase 3, as well as their suppression of PI3K-Akt signaling. Conclusion Our findings provide data for understanding the molecular mechanisms of nanoparticles; thus, providing insight into the development of alternative medications based on gold nanoparticles of ginseng-derived CK.