Antioxidant and Immunomodulatory Properties of Partially purified Exopolysaccharide from Lactobacillus Casei Isolated from Chinese Northeast Sauerkraut

Abstract

ABSTRACT Background Exopolysaccharides (EPS) from Lactobacillus spp. have been found to have biological activities. Our previous work demonstrated the antibiofilm activity of EPS from Lactobacillus casei NA-2 (L.casei NA-2) isolated from northeast Chinese sauerkraut (Suan Cai). The present study has focussed on the antioxidant and immunomodulatory activities of the EPS in vitro. Methods Antioxidant properties of the EPS were evaluated by the radical-scavenging activities in vitro. The immunomodulatory effects of EPS were assayed by measuring nitric oxide (NO), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and reactive oxygen species (ROS) in RAW 264.7 macrophages, and the mechanism was investigated through NF-κB and JNK. Result EPS contains 88% total sugar, with the molecular weights (Mw) of 1.3 × 106 Da, 6.4 × 105 Da, 2.0 × 105 Da, and 1.4 × 104 Da. EPS showed antioxidant activity by scavenging hydroxyl radicals (42% at 1.2 mg/mL), superoxide radicals (76% at 100 µg/mL), and DPPH (80% at 10 mg/mL); and did not affect the proliferation of unstimulated or lipopolysaccharide (LPS)-induced RAW 264.7 cells at the concentrations ranging from 31.25 to 500 µg/mL. Results showed EPS promoted the production of ROS and TNF-α involved in NF-κB p65 and JNK signaling pathways in unstimulated RAW 264.7 cells. On the other hand, the levels of NO and iNOS were reduced after EPS treatment in LPS-induced RAW 264.7 cells. Conclusion Our results showed the protective effect against oxidative damage and potential immunomodulatory and anti-inflammatory properties of EPS from Lactobacillus casei NA-2.