title: Effects of Withania somnifera on the growth and virulence properties of Streptococcus mutans and Streptococcus sobrinus at sub-MIC levels.
abstract: The aim of this study was to evaluate the effect of the methanol extract of Withania somnifera (MEW) on the growth and virulence properties of Streptococcus mutans and Streptococcus sobrinus at sub-minimum inhibitory concentration (MIC) levels and to identify the main components of MEW. First, antibacterial activity of MEW against oral bacteria was determined using a micro-dilution method. Then, the effect of MEW on the growth of S. mutans and S. sobrinus was investigated at sub-MIC levels. To test the effect of MEW on the virulence properties of S. mutans and S. sobrinus, assays for acid production, acid tolerance, and biofilm formation were performed at sub-MIC levels. A GC-MS analysis for the main components of MEW was also carried out. MEW showed a broad antibacterial range against oral bacteria (MIC: 0.125-2 mg/mL). At sub-MIC levels, MEW dose-dependently increased doubling times of S. mutans and S. sobrinus up to 258% and 400%, respectively. Furthermore, MEW inhibited acid production, acid tolerance, and biofilm formation of S. mutans and S. sobrinus at sub-MIC levels. The GC-MS analysis revealed the presence of mono- and disaccharides, sugar alcohols, and organic acids as main components. These data suggest that MEW might be useful for restraining physiological activities of cariogenic bacteria.
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Institute of Oral Bioscience and BK 21 Program, Chonbuk National University, 664-14 DuckJin Dong, Jeonju 561-756, Republic of Korea.
authors.forename: Santosh
authors.initials: S
authors.lastname: Pandit
authors.forename: Kee-Wan
authors.initials: KW
authors.lastname: Chang
authors.forename: Jae-Gyu
authors.initials: JG
authors.lastname: Jeon
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018441:Biofilms / Q000254:growth & development; D008401:Gas Chromatography-Mass Spectrometry; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology; D016986:Streptococcus sobrinus / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology; D014774:Virulence / Q000187:drug effects; D032341:Withania / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts