Mechanism Study On 4NQO Degenotoxic Activity Of Lactobacillus. Salivarius Ren

Lactobacillus salivarius REN was recently isolated from Bama centenarians in our previous stduies.It exhi-bited effective prevention of oral cancer induced by 4-NQO?4-nitroquinoline-N-oxide?.In this study,by HPLC analysis we illuminated the process of the degradation of 4-NQO by L salivarius REN and identified the bioactive components responsible for the 4NQO degrading.Based on low concentration Fenton reagent,we analyzed the mechanism of the degradation of 4HAQO?4-hydroxyaminoquinoline-1-oxide?.This study made revolutionary progress in the interpretation of degradation of aromatic compounds by probiotics and provided new evidence for the cancer prevention by probiotics.L.salivarus REN has been demonstrated to be able to degrade 4NQO in vitro.In our study,by HPLC analysis,we found that 4NQO was transformed to 4HAQO by L.salivarus REN,and then 4HAQO was degraded to no-toxic products.Most interesting,we found that the degradation of HAQO was the critical step in this progress.By chysical and chemical properties analysis,we found that Fenton reagent composed of H₂O₂ and transition metal ions such as ferric and manganium was the bioactive reagents during this process.After a survey,we found that many probiotic strains with the ability to produce H₂O₂,such as Lplantarum and Lcasei,had the same property to degrade 4HAQO as L.salivarius REN.To give further explanation,we assayed the decoloration of Rhodamine B by L.salivarius REN secretion and the oxidation of Lsalivarius REN secretion on cultured cells.Nether L.salivarius REN secretion nor Fenton reagent with equal concentration was not of strong oxidizing property,indicating some special mechanisms of the degrading of 4HAQO.Mechanism study suggested that the rapid degradation of 4HNQO was a result of Fenton reaction accelerated by 4HAQO itself.4HAQO accelerates the reduction of Fe???to Fe???,which triggers Fenton action.During this process,4HAQO was not only the substrate but also one of the key factors triggering the actions.The H₂O₂ secreted by Lsalivarius REN was the key component during the degradation of 4NQO.During the production of secretion,the preserved lactic acid inside L.salivarius Ren would be converted to acetone acid and NADH,which were further converted to H₂O₂ by Pox and Nox-1.And during our analysis,we found that the production of H₂O₂ was regulated by glucose metabolism during the culture.