Antibacterial, anti-inflammatory, and anti-osteoclastogenesis roles of allicin in periodontitis

Periodontitis is an infectious inflammatory immune disease. Allicin, because of its antibacterial, antiinflammatory and immunomodulation properties, appears to be a promising drug for treating periodontitis. In this study, the antimicrobial activity of allicin against Porphyromonas gingivalis (P. gingivalis) and its effects on inflammatory cytokine expression in experimental periodontitis and osteoclast activity in vitro were investigated. Allicin inhibited P. gingivalis growth, with a minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of 4 mg/I and 8 mg/I, respectively. Allicin showed inhibitory effects on P.gingivalis biofilm formation, with a minimum biofilm inhibition concentration (MBIC50/MBIC90) of 4 mg/I and 16 mg/I, respectively, and affected the viability of 1-day-old biofilms with a minimum biofilm reduction concentration (MBRC50) of 32 mg/I. Confocal laser scanning microscopy (CSLM) revealed that treatment with 32 mg/I allicin resulted in a lower bacteria number, fewer live bacteria, and a thinner biofilm. In gingivomucosal tissues around first right molar teeth undergoing ligatureinduced periodontitis, allicin substantially inhibited periodontal destructive cytokines, including TNF-alpha, IL-1 beta, IL-6, INF-gamma, and IL-12, but promoted protective cytokines such as IL-4 and IL-10. By affecting the cytokine framework and the secretion of M-CSF and RNAKL from osteoblasts, allicin suppressed osteoclastogenesis by modulating the RANK-RANKL system, as demonstrated by a decrease in NF-kB p65 levels. These results suggested that allicin is a potential natural product for treating periodontitis.