Lactobacillus paracasei M11-4 isolated from fermented rice demonstrates good antioxidant properties in vitro and in vivo.

Background Probiotics are defined as microorganisms that can exert health benefits for the host. Among the recognized probiotics, Lactobacillus paracasei are one of the most frequently used probiotics in humans. The L. paracasei strain M11-4, isolated from fermented rice, which could ferment soymilk within a short curd time, and fermented soymilk presented high viability, acceptable flavor and antioxidant activity, which revealed that the strain maybe have a potential antioxidant value. Therefore, it is necessary to further explore the antioxidant activity of L. paracasei strain M11-4. Results The radical scavenging activities, lipid peroxidation inhibition, and reducing power of L. paracasei M11-4 were the highest in the fermentation culture without cells, while the activities of other antioxidant enzymes of L. paracasei M11-4 were high in the cell-free extract and bacterial suspension. Moreover, L. paracasei M11-4 exerted its antioxidant effect by upregulating the gene expression of its antioxidant enzymes, thioredoxin (Trx) and glutathione (GSH) systems when hydrogen peroxide (H2 O2 ) existed. Supplementation of rats with L. paracasei M11-4 effectively alleviated D-galactose-induced oxidative damage in the liver and serum and prevented D-galactose-induced changes to intestinal microbiota. Supplementation with L. paracasei M11-4 also reduced the elevated expression of Trx and GSH system genes induced by D-galactose. Conclusion L. paracasei M11-4 has good antioxidant properties both in vitro and in vivo and the antioxidant mechanism of it was studied at the molecular level. This article is protected by copyright. All rights reserved.