Inactivating effects of the lactoperoxidase system on bacterial lyases involved in oral malodour production

Abstract

The main components of oral malodour have been identified as volatile sulfur compounds (VSCs), including hydrogen sulfide (H 2 S) and methyl mercaptan (CH 3 SH). The lactoperoxidase (LPO) system (consisting of LPO, glucose oxidase, glucose and thiocyanate) was previously shown to exhibit antimicrobial activities against some oral bacteria in vitro and suppressive effects on VSCs in mouth air in a clinical trial. Here, we examined the in vitro effects of the LPO system on the activities of the bacterial lyases involved in the production of VSCs by oral anaerobes. The exposure of crude bacterial extracts of Fusobacterium nucleatum and Porphyromonas gingivalis or purified methionine c-lyase to the LPO system resulted in the inactivation of their lyase activities through L-cysteine and L-methionine, which was linked to the production of H 2 S and CH 3 SH, respectively. The exposure of living F. nucleatum and P. gingivalis cells to the LPO system resulted in the suppression of cell numbers and lyase activities. The inactivation of the crude bacterial extracts of F. nucleatum and purified methionine c-lyase by the LPO system was partly recovered by the addition of DTT. Therefore, the LPO system may inactivate bacterial lyases including methionine c-lyase by reacting with the free cysteine residues of lyases. These results suggested that the LPO system suppresses the production of VSCs not only through its antimicrobial effects, but also by its inactivating effects on the bacterial lyases of F. nucleatum and P. gingivalis.

Effects of lactoferrin and lactoperoxidase‐containing food on the oral hygiene status of older individuals: A randomized, double blinded, placebo‐controlled clinical trial

“…28 LF + LPO tablets had an inhibitory effect on halitosis within a short period of time in healthy adults, 11 with the LPO system suppressing the production of VSC using its antimicrobial effects and inactivation of the bacterial lyases of F. nucleatum and P. gingivalis. 29 As we were unable to control the food and drinks consumed by the participants of the present study, the VSC component gas concentration at baseline was low and did not allow evaluation of the influence of the intervention on oral malodor.…”

Effect of tablets containing lactoferrin and lactoperoxidase on gingival health in adults: A randomized, double‐blind, placebo‐controlled clinical trial

“…Lactoferrin has antibacterial, anti‐biofilm, and anti‐inflammatory activity . The LPO system exhibits a bactericidal effect against pathogens, and LPO itself shows an anti‐inflammatory effect . During the dissolution of LF and LPO‐containing tablets in the mouth, the salivary concentrations of LF and LPO increase about 100‐ and 30‐fold compared with the basal state, respectively.…”

A randomized, double-blind, crossover, placebo-controlled clinical trial to assess effects of the single ingestion of a tablet containing lactoferrin, lactoperoxidase, and glucose oxidase on oral malodor

“…In spite of this moderate antibacterial effect, the suppressive effects of the active ingredients on VSCs were demonstrated in the present and previous studies. A recent in vitro study reported that the LPO system exhibited inactivation activity against the bacterial lyases related to the production of VSCs [ 21 ]. Inactivation activity may be the main contributor to suppressive effects on VSCs.…”

“…In a previous clinical trial that enrolled 15 healthy volunteers aged 26–54 years, sucking a trial tablet containing 100 mg of LF, 1.8 mg of LPO, and 24 mg of Sumizyme PGO which was composed of dextrin and GO, had short-term suppressive effects on the concentrations of VSCs in mouth air [ 20 ]. The underlying mechanisms of action reducing VSCs were suggested to involve the antimicrobial effects of LF and the LPO system [ 20 ] in addition to the inactivating effects of the LPO system on bacterial lyases involved in the production of VSCs [ 21 ]. Based on these findings, a powder composition including 20 mg of LF, 2.6 mg of LPO, and 2.6 mg of GO was developed for functional food products [ 22 ].…”