Ligustrum robustum (Roxb.) Blume is utilized as a traditional Chinese herbal tea with various health benefits and protective effects. Streptococcus mutans is an important cariogenic oral bacteria species. The present study aimed to assess the influence of Ligustrum robustum extract (LRE) on the biofilm formation of S. mutans and the mechanism of its action, as well as to identify its chemical components. For chemical identification, HPLC‐MS and nuclear magnetic resonance were applied and four identified phytochemicals were reported (Ligurobustoside B, Ligurobustoside N, Ligurobustoside J, and Ligurobustoside C). The dose‐dependent (0.5 to 2.0 μg/μL) antimicrobial toxicity of LRE against S. mutans biofilm formation and exopolysaccharide (EPS) synthesis was evaluated by confocal laser scanning microscopy (CLSM), Crystal violet stain, and CFU counting. The microstructure of S. mutans biofilm treated with LRE was investigated both on glass coverslips and ex vivo bovine dental enamel by scanning electron microscopy (SEM). Moreover, LRE downregulated the expression of S. mutans glucosyltransferase‐encoding genes gtfB, gtfC, and gtfD, and the quorum sensing (QS) factors comD and comE, suggesting its toxic mechanism. In addition, the result of CCK‐8 test on human oral cells revealed an acceptable biocompatibility of LRE. These findings indicated the possible application of this daily consumed herbal tea for caries prevention.

中文翻译：

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女贞（Roxb。）Blume提取物对变形链球菌的生物膜形成和胞外多糖合成的活性

女贞（Roxb。）Blume被用作具有多种健康益处和保护作用的传统中草药茶。变形链球菌是一种重要的龋齿口腔细菌。本研究旨在评估女贞子提取物（LRE）对S的生物膜形成的影响。变形菌及其作用机理，以及鉴定其化学成分。为了进行化学鉴定，应用了HPLC-MS和核磁共振技术，并报告了四种已鉴定的植物化学物质（Ligurobustoside B，Ligurobustoside N，Ligurobustoside J和Ligurobustoside C）。LRE对变形链球菌的剂量依赖性（0.5至2.0μg/μL）抗菌毒性通过共聚焦激光扫描显微镜（CLSM），结晶紫染色和CFU计数评估生物膜的形成和胞外多糖（EPS）的合成。LRE处理的变形链球菌生物膜的微观结构在玻璃盖玻片和离体牛牙釉质上均通过扫描电子显微镜（SEM）进行了研究。此外，LRE下调的表达变异链球菌葡糖基转移酶编码基因GTFB，GTFC，和gtfD，和群体感应（QS）因子的comD和来，提示其毒性机制。此外，对人口腔细胞进行CCK-8测试的结果表明，LRE具有可接受的生物相容性。这些发现表明这种日常食用的凉茶可以预防龋齿。