Identification of anti-biofilm components in Withania somnifera and their effect on virulence of Streptococcus mutans biofilms.

AIMS: The aim of this study was to identify components of the Withania somnifera that could show anti-virulence activity against Streptococcus mutans biofilms. METHODS AND RESULTS: The anti-acidogenic activity of fractions separated from W. somnifera was compared, and then the most active anti-acidogenic fraction was chemically characterized using gas chromatography-mass spectroscopy. The effect of the identified components on the acidogenicity, aciduricity and extracellular polymeric substances (EPS) formation of S. mutans UA159 biofilms was evaluated. The change in accumulation and acidogenicity of S. mutans UA159 biofilms by periodic treatments (10 min per treatment) with the identified components was also investigated. Of the fractions, n-hexane fraction showed the strongest anti-acidogenic activity and was mainly composed of palmitic, linoleic and oleic acids. Of the identified components, linoleic and oleic acids strongly affected the acid production rate, F-ATPase activity and EPS formation of the biofilms. Periodic treatment with linoleic and oleic acids during biofilm formation also inhibited the biofilm accumulation and acid production rate of the biofilms without killing the biofilm bacteria. CONCLUSIONS: These results suggest that linoleic and oleic acids may be effective agents for restraining virulence of S. mutans biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: Linoleic and oleic acids may be promising agents for controlling virulence of cariogenic biofilms and subsequent dental caries formation.

Effect of brief cetylpyridinium chloride treatments during early and mature cariogenic biofilm formation.

OBJECTIVES: The aim of this study was to investigate the antibiofilm activity of brief cetylpyridinium chloride (CPC) treatments during early and mature Streptococcus mutans biofilm formation. METHODS: Streptococcus mutans biofilms were formed on saliva-coated hydroxyapatite disks. The biofilms were treated with CPC twice daily (1 min/treatment) from 0 to 50 h or from 48 to 98 h. Acidogenicity, dry weight, viability, and water-insoluble extracellular polysaccharides of the biofilms were analyzed. Confocal laser scanning microscopy (CLSM) images were obtained to confirm the antibiofilm activity during mature biofilm formation and to evaluate the relationship between treatment time and the antibiofilm activity. RESULTS: CPC showed complete antibiofilm activity during early biofilm formation at 0.025% to 0.1%. During mature biofilm formation, CPC inhibited dry weight, viability, and acidogenicity at 0.075% and 0.1%. CLSM images showed an increase in dead cells at 0.075% and 0.1% CPC. The antibiofilm activity during mature biofilm formation increased as the concentration of CPC increased. Images from the CLSM study also showed that antibiofilm activity increased as treatment time increased. CONCLUSION: Our findings suggest that brief CPC treatments have strong anti-S. mutans biofilm activity. The antibiofilm activity was dependent on the stage of biofilm formation, CPC concentration, and treatment time.

Coumarins from the fruits of Cnidium monnieri.

Two novel biscoumarins, cnidimonal (1) and cnidimarin (2), and two new coumarin derivatives, 5-formylxanthotoxol (3) and 2'-deoxymeranzin hydrate (4), were isolated from a traditional Chinese crude drug, the fruits of Cnidium monnieri, together with 15 known compounds. Among the known compounds, five of the minor compounds were isolated for the first time from this plant. The structures of 1-4 were determined with the use of spectroscopic methods.

Examination of coumarins, flavonoids and polysaccharopeptide for antibacterial activity.

1. Coumarins, flavonoids and polysaccharopeptide were tested for antibacterial activity. 2. The bacteria used for this study included clinical isolates of Staphylococcus aureus, Shigella flexneri, Salmonella typhi, Escherichia coli and Pseudomonas aeruginosa. 3. Most of the coumarins tested failed to inhibit the bacteria at 25 mg/l. Edultin at 128 mg/l inhibited 4 of the 8 P. aeruginosa strains and 1 of the S. aureus strains tested. O-acetylcolumbianetin and imperatorin did not inhibit any isolate, even at 128 mg/l. 4. When tested at the dose of 128 mg/l, the flavonoids (rutin, naringin and baicalin) inhibited 25% or less of P. aeruginosa and only baicalin was active against S. aureus. 5. Arbutin and 4-(beta-D-glucopyranosyloxyl)-benzaldehyde inhibited 3 of the 8 P. aeruginosa strains when tested at 128 mg/l. 6. Polysaccharopeptide from the fungus Coriolus versicolor failed to inhibit any P. aeruginosa or S. aureus strain at 128 mg/l.