3 mM (10.2 mg/l) H2O2 caused complete inhibition that lasted for nearly 16 h, whereas 0.3 mM (10.2 mg/l) H2O2 alone had no effect. However, if no more H2O2 was added, the concentration of the inhibitor OSCN- Entospletinib mouse fell because of slow decomposition of OSCN-, and, when OSCN- fell below 0.01 mM (0.74 mg/l), the bacteria resumed metabolism and growth. The loss of OSCN- over time is based
on decomposition, not on the reaction with bacteria [29]. The typical concentration of peroxidases in whole saliva is roughly 5 μg/ml, whereas the MPO concentration (3.6 μg/ml) is approximately twice the amount of SPO (1.9 μg/ml) [30]. Therefore, even if SPO is deficient, MPO activity would probably be adequate for SCN- oxidation in mixed saliva [30]. The study by Adolphe et al. [31] showed that the lactoperoxidase system’s antimicrobial efficiency can be enhanced by better concentration ratios of the LPO system components. However, this finding was
postulated for only near physiological conditions and did not consider a concentration of thiocyanate R406 clinical trial and H2O2 higher than the physiological one. Rosin et al. [32] showed that, in the saliva peroxidase system, increasing SCN-/H2O2 above its physiologic saliva level reduced plaque and gingivitis significantly compared to baseline values and a placebo. A new dentifrice formulated on these results showed the same effects regarding plaque and gingivitis prevention in comparison to a benchmark product containing DUB inhibitor triclosan [33]. However, the effects were not sufficient to recommend using the SPO system to effectively prevent oral diseases in the long run. Thus, the question arose, Is it possible to increase antimicrobial effectiveness by adding not just Nutlin3 thiocyanate and hydrogen peroxide but also LPO to oxidize as much the SCN- anions as possible to become an effective antimicrobial agent? Therefore, we conducted a standardized quantitative suspension test at a fixed concentration level of all three components above the physiological one to evaluate the influence of LPO on the lactoperoxidase-thiocyanate-hydrogen peroxide system relative to its bactericidal and fungicidal effectiveness against Streptococcus mutans and sanguinis and Candida albicans. Results
The reduction factors (RF) of the test suspensions without and with LPO on the viability of Streptococcus mutans, Streptococcus sanguinis, and Candida albicans at different time points (1, 3, 5, and 15 min) are shown in tables 1, 2 &3. Table 1 Reduction factors of the test thiocyanate hydrogen peroxide microbial suspension without and with LPO to Streptococcus mutans at different time points. Group A Group B A vs. B2 Without LPO With LPO Time Reduction factor Comparisons within A1 Reduction Factor Comparisons within B1 1 vs. 3 3 vs. 5 5 vs. 15 1 vs. 3 3 vs. 5 5 vs. 15 [min] Mean ± SD p p p Mean ± SD p p p p 1 0.23 ± 0.26 0.03 ± 0.17 0.128 0.844 0.016 3 0.21 ± 0.36 0.53 ± 0.22 0.026 0.375 0.