When concentrations of morin exceeded 225 μM, biofilm biomass was reduced by over 50%,

compared to the untreated control (Fig. 1) which was found to be statistically significant (P < 0.001). The reduction in biofilm biomass corresponded to a reduction in viable biofilm cells, from 3.2 × 107 CFU mL−1 (0 μM morin) to between 1.2 and 1.6 × 107 CFU mL−1 (225–300 μM morin). The effect of morin on aggregation of S. pyogenes was investigated using 0, 200, 225, 250, 275 and 300 μM morin. Aggregation was monitored over a period of 120 min; optical density was recorded at 30-min intervals (A650 nm). Morin facilitated bacterial aggregation, and the amount of aggregation was dose dependent (Fig. 2). Table 1 shows the percentage difference in aggregation between treated and untreated

samples. The extent of bacterial aggregation is demonstrated in Fig. 3, where a dense aggregate of cells was deposited Selleck Ibrutinib in the cuvette following treatment with 275 and 300 μM morin for 120 min (Fig. 3b and c, respectively). The TVC of these aggregated cells was determined, and treated cells showed a 14.6- and 18.3-fold decrease (275 and 300 μM morin, respectively) from 2.2 × 108 CFU mL−1 (0 μM morin) to 1.5 × 107 CFU mL−1 (275 μM morin) and 1.2 × 107 CFU mL−1 (300 μM morin). Statistical analysis (anova, minitab v14) demonstrated that following 10-min incubation of the test organism with 250, 275 and 300 μM morin, and aggregation was significantly higher (P < 0.05) than PRKD3 in the untreated culture. Cells treated with 200 and 225 μM did not show a significant increase (P > 0.05) PLX4032 datasheet over the same period of time, but after 20-min incubation at all concentrations, aggregation was significantly increased when compared to the untreated control. Streptoccocal biofilms are associated with persistant infections (Costerton et al., 1999; Donlan, 2001) and are known to exhibit antibiotic resistance (Baldassarri et al., 2006). Flavonols inhibit bacterial growth and have been demonstrated to possess an ‘anti-plaque’ activity, disrupting both the growth and adhesion of Streptococcus mutans (Duarte et al.,

2006; Prabu et al., 2006; Shure et al., 2006; Gregoire et al., 2007; Escaich, 2010). This study demonstrated that the flavonol morin significantly decreased biofilm biomass (P < 0.001) at concentrations of 225 μM and above resulting in up to 65% reductions. The data presented here also demonstrated that morin facilitated rapid, statistically significant (P < 0.05) aggregation of planktonic S. pyogenes in a dose-dependent manner. Streptococcus pyogenes are known to form cellular aggregates ordinarily over time; however, morin appeared to enhance this process (Frick et al., 2000; Collado et al., 2008; Maddocks et al., 2011). Numerous host proteins, including the salivary glycoprotein gp340, are known to facilitate the rapid aggregation of streptococci and as such these are regarded as being components of the innate immune response (Golub et al.