Structural characterization and antioxidant activity of a polysaccharide produced by <i>Chaetomium globosum</i> CGMCC 6882 from waste tobacco leaves

Due to the restricts of treatment methods and high costs, waste tobacco materials are usually discarded, which leads to resources waste and environmental pollution. Present work used waste tobacco leaves as carbon source to produce polysaccharide (CGP-TL) by <i>Chaetomium globosum</i> CGMCC 6882 via submerged fermentation. CGP-TL yield was 1.62 ± 0.35 g/L, and the contents of carbohydrate and protein in which were 91.73% ± 6.49% and 5.51% ± 0.84%. Structural characterization showed CGP-TL was composed of rhamnose, arabinose, galactose, glucose, mannose and xylose in a molar ratio of 9.9688: 6.8482: 19.6045: 29.4448: 0.8033: 0.5874. Meanwhile, its weight-average molecular weight, number-average molecular weight and polydispersity were 286.035 kDa, 118.146 kDa and 2.421, respectively. In vitro antioxidant analysis showed CGP-TL scavenged DPPH, ABTS, hydroxyl and superoxide radicals positively correlated to its concentration, and the corresponding scavenging effects at 2.5 mg/mL were 75.53% ± 1.89%, 96.24% ± 2.32%, 52.91% ± 2.28% and 65.26% ± 2.47%. Furthermore, CGP-TL not only improved the antioxidative status of RAW 264.7 cells, but also exerted oxidative repairing effects on H₂O₂-damaged RAW 264.7 cells via increasing the levels of SOD, CAT and GSH-Px, and reducing MDA level. Overall, this work will provide references for green and efficient utilization of waste tobacco materials and cellulose resources.