牛至精油对体外变形链球菌的抑菌活性及活性成分分析。
Antibacterial activity of oregano essential oils against Streptococcus mutans in vitro and analysis of active components.
机构信息
Beijing Technology and Business University, Beijing, 100048, China.
Department of Stomatology, Sixth Medical Center of PLA General Hospital, Beijing, 100048, China.
出版信息
BMC Complement Med Ther. 2023 Feb 21;23(1):61. doi: 10.1186/s12906-023-03890-4.
BACKGROUND
Streptococcus mutans (S. mutans) is considered the most relevant bacteria during the transition of the non-pathogenic commensal oral microbial community to plaque biofilms that promote the development of dental caries. Oregano (Origanum vulgare L.), is a universally natural flavoring and its essential oil has been demonstrated to have good antibacterial effects. However, the specific antibacterial mechanism of oregano essential oil (OEO) against S. mutans is still not completely understood.
METHODS
In this work, the composition of two different OEOs was determined by GC‒MS. Disk-diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined to assess their antimicrobial effect on S. mutans. The inhibition of acid production, hydrophobicity, biofilm formation and real-time PCR for gtfB/C/D, spaP, gbpB, vicR, relA and brpA mRNA expression by S. mutans were assessed to preliminarily investigate the mechanisms of action. Molecular docking was performed to simulate the interactions with the virulence proteins and active constituents. MTT test using immortalized human keratinocytes cells was also performed to investigate cytotoxicity.
RESULTS
Compared with the positive drug Penicillin /streptomycin 100X (DIZ: 34.13 ± 0.85 mm, MIC: 0.78125 μL/mL, MBC: 6.25 μL/mL), the essential oils of Origanum vulgare L. (DIZ: 80 mm, MIC: 0.625μL/mL, MBC:2.5μL/mL) and Origanum heracleoticum L. (DIZ: 39.67 ± 0.81 mm, MIC: 0.625μL/mL, MBC: 1.25μL/mL) could also exhibit similar effects to inhibit the acid production and reduce the hydrophobicity and biofilm formation of S. mutans at 1/2-1MIC concentration. And gene expression of gtfB/C/D, spaP, gbpB, vicR and relA were found to be downregulated. Due to the composition of essential oils from different sources being highly variable, through effective network pharmacology analysis, we found that OEOs contained many effective compounds, like carvacrol and its biosynthetic precursors γ-terpinene and p-cymene, which may directly target several virulence proteins of S. mutans. Besides, no toxic effect was instigated by OEOs at 0.1 μL/mL in the immortalized human keratinocytes cells.
CONCLUSION
The integrated analysis in the present study suggested that OEO might be a potential antibacterial agent for the prevention of dental caries.
背景
变形链球菌（S. mutans）被认为是从非致病性共生口腔微生物群落过渡到促进龋齿发展的菌斑生物膜过程中最相关的细菌。牛至（Origanum vulgare L.）是一种普遍的天然调味料，其精油已被证明具有良好的抗菌作用。然而，牛至精油（OEO）对 S. mutans 的具体抗菌机制仍不完全清楚。
方法
本研究采用 GC-MS 法测定两种不同 OEO 的组成。采用圆盘扩散法、最小抑菌浓度（MIC）和最小杀菌浓度（MBC）评估其对 S. mutans 的抗菌作用。通过测定 S. mutans 的产酸抑制、疏水性、生物膜形成和实时 PCR 检测 gtfB/C/D、spaP、gbpB、vicR、relA 和 brpA mRNA 表达，初步探讨其作用机制。采用分子对接模拟其与毒力蛋白和活性成分的相互作用。采用永生化人角质形成细胞 MTT 试验检测细胞毒性。
结果
与阳性药物青霉素/链霉素 100X（DIZ：34.13±0.85 mm，MIC：0.78125 μL/mL，MBC：6.25 μL/mL）相比，牛至精油（DIZ：80 mm，MIC：0.625 μL/mL，MBC：2.5 μL/mL）和奥勒冈精油（DIZ：39.67±0.81 mm，MIC：0.625 μL/mL，MBC：1.25 μL/mL）也能在 1/2-1MIC 浓度下抑制产酸，降低 S. mutans 的疏水性和生物膜形成。并且发现 gtfB/C/D、spaP、gbpB、vicR 和 relA 的基因表达下调。由于不同来源的精油组成差异很大，通过有效的网络药理学分析，我们发现 OEO 含有许多有效化合物，如香芹酚及其生物合成前体γ-萜品烯和对伞花烃，这些化合物可能直接针对 S. mutans 的几种毒力蛋白。此外，OEO 在 0.1 μL/mL 浓度下对永生化人角质形成细胞没有引发毒性作用。
结论
本研究的综合分析表明，OEO 可能是预防龋齿的一种潜在抗菌剂。
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