Adding Hydrogen Peroxide for Maximum Hypothiocyanite Production in Saliva

Objectives: Hydrogen peroxide (H₂O₂) is described as the limiting factor of the oxidation of thiocyanate to hypothiocyanite (OSCN⁻) by lactoperoxidase in saliva. However, the results of H₂O₂-based or dependent oral hygiene products are inconsistent. In this study, we determined the influence of hydrogen peroxide added to saliva samples on hypothiocyanite formation.
Methods: Saliva samples from 42 healthy volunteers (20f, 22m, 23.9±4.2 years) were collected using salivette^® cortisol. The collected saliva was divided into 0.2 ml portions to which increasing amounts of H₂O₂ were added. After a reaction time of 1min, the OSCN⁻, SCN⁻, nitrate and nitrite values were determined in all samples by ion chromatography. Initial values were determined in the original saliva sample.
The effect of H₂O₂ exposure on OSCN^- production was examined using the nlme package of R software (R Core Team, 2020). The exposure effect was finally adjusted for age, gender, baseline of SCN^-, and baseline of OSCN^-.
Results: Adding H₂O₂ (gradually from 28.7 to 1722µmol/L) to saliva samples resulted until 287.0μmol/L in a significant increase of OSCN^- production and in the greatest decrease of SCN^-. At this level, the OSCN^- concentration reached its maximum of 43.7±30.0μmol/L (mean value) / 36.8(20.3;52.4)μmol/L (median). Further addition of H₂O₂ led to the decrease of OSCN^- production.
The amount of added H₂O₂ was the main factor for OSCN^- formation, however, at a low-level range. Age, gender and baseline of SCN^- had no significant effect.
Conclusions: The results indicate that there is an optimum of hydrogen peroxide concentration in saliva to produce a maximum of OSCN^-, which is far below the 0.1% H₂O₂ concentration permitted for oral hygiene products.