Isolation and identification of Garciyunnanensisin A-O from Garcinia yunnanensis: a study on its antibacterial activity and mechanism against Staphylococcus aureus.

Abstract

Staphylococcus aureus has a strong biofilm-forming ability that protects it from the external environment, making it difficult to remove during food processing and storage, thereby increasing the incidence of foodborne illness. In order to improve food safety and protect human health, it is important to find safe and effective antimicrobial agents. In this study, a total of 20 compounds (1-20), including 15 new compounds (1-15), were isolated from Garcinia yunnanensis and elucidated by Nuclear Magnetic Resonance (NMR) data analysis, calculation of optical rotation values, and Electronic Circular Dichroism (ECD) spectra. Compound 1, a rare caged polycyclic polyprenylated acylphloroglucinol, demonstrated significant antibacterial activity against S. aureus with a minimum inhibitory concentration (MIC) of 6.25 μg/mL and showed rapid bactericidal effects at high concentrations. In addition, 1 inhibited S. aureus biofilm formation by reducing bacterial metabolism, decreasing bacterial viability, inhibiting bacterial surface hydrophobicity and adhesion, and modulating the synthesis and secretion of extracellular polysaccharides, DNA, and proteins. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) also further confirmed that 1 significantly inhibited biofilm formation. In conclusion, 1 not only has excellent antibacterial and biofilm inhibitory properties, but also exhibits low toxicity, making it a promising candidate for development as a food-grade bacterial biofilm inhibitor.