Figure 2.
Effect of quercetin on Arg-gingipain (Rgp) and Lys-gingipain (Kgp) activity. P. gingivalis culture was harvested and suspended in PBS to OD660nm of 2 for Rgp activity and of 1 for Kgp activity. The P. gingivalis cells were incubated in PBS with or without quercetin at 37 °C in the dark for 3 h. Activity of Rgp (a,b) and Kgp (c,d) indicated as the hydrolysis of the specific chromogenic substrates (BAPNA and ALNA) was detected at every 2 min for 1 h by measuring the absorbance at 405 nm. The inhibition of substrate degradation was also measured as a function of time (b,d). Bars denoted by (****) indicate significant difference at p < 0.0001 by one-way analysis of variance (ANOVA) with Dunnett’s post hoc test.