Antibacterial efficacy of a polysaccharide from Mangosteen Scarfskin (MSP) against Streptococcus mutans and Streptococcus salivarius: experimental and molecular dynamics validation

Abstract Streptococcus mutans mediates enamel demineralization through acid production via glycolysis, while Streptococcus salivarius, as a commensal bacterium, promotes caries progression by enhancing biofilm formation. Their synergistic interaction amplifies cariogenicity. Therefore, developing strategies to inhibit both bacterial species is imperative. This study investigated the extraction and characterization of a polysaccharide from mangosteen scarfskin (MSP) and its antimicrobial potential against cariogenic bacteria. Using ultrasonic-assisted extraction, MSP was obtained with a yield of (9.93 ± 0.5696)%, presenting light brown coloration. Antimicrobial assays demonstrated strong anti-efficacy activity against Streptococcus mutans and Streptococcus salivarius, showing a MIC of 1 mg/mL and significant bactericidal effects at 1×MIC and 2×MIC concentrations. Biofilm metabolism analysis showed that MSP caused dose-dependent suppression of bacterial metabolism, while its inhibitory effect on EPS production increased proportionally with concentration. Molecular docking identified specific hydrogen-bond interactions between arabinose (the primary component of MSP) and key residues (THR-315, SER-10, and SER-247) of glucosyltransferase-C (GTF-C), while molecular dynamics simulations demonstrated that arabinose disrupted the structural stability of GTF-C. These findings collectively suggest MSP’s promising application as a novel food additive for caries prevention through oral streptococcal control. Graphical abstract