ANTIOXIDANT ACTIVITY OF LEVAN SYNTHESIZED BY LEVANSUCRASE FROM Bacillus subtilis natto

Levan is a fructose exopolysaccharide consisting of β-(2→6) bonds and branching points in β-(2→1), can be extracted from plants, produced by microorganisms such as bacteria, yeasts, and fungi, or can be synthesized by enzymes as levansucrase (β-2,6-fructan: d-glucose-fructosyl transferase, EC 2.4.1.10), by polymerization reaction in the presence of sucrose. Due to its biomedical properties as antioxidant, anti-inflammatory, anti-carcinogenic and hypoglycemic the levan has important features that allow its application in various areas of industry. Considering the beneficial properties of microbial exopolysaccharide this study aimed to produce levan by levansucrase from B. subtilis natto and investigate its antioxidant action in vitro by method of DPPH (2, 2-diphenyl-1-picryl-hydrazyl). For the synthesis of levan was used solution of sucrose 350 gL-1, 35 ° C for 36 h. The reaction was interrupted and the levan was obtained from the supernatant by precipitation with ethanol in the proportions 1:3 (high molecular mass levan) and 1:1.5 (mixtures of high and low mass levan), quantified and evaluated the antioxidant activity in different concentrations of levan (0.05, 0.25, 0.5, 1, 2, 3, 4 and 5 mg.mL-1). The result for production of levansucrase was 18 U/mL with 420.7 gL-1 sucrose, 37 °C, 150 rpm for 24 h. This enzyme was used in the synthesis of levan and reached 15.04 gL-1 with high molecular mass and 28.15 g.L-1 mixtures of levan. These values demonstrated that enzymatic synthesis may be a good strategy compared to fermentation microbial. The highest inhibition rates for antioxidant activity were 30.34 % high levan and 30.08 % mixtures of levan with 0.05 mg.mL-1 and 5 mg.mL-1, respectively. The high molecular mass levan showed a higher percentage of inhibition in the lowest concentration, therefore it is possible to use it in different applications, and antioxidant activity represents a desired property for the pharmaceutical and cosmetic industry.