Evaluation of Antiradical and Antioxidant Activities of Lipopeptides Produced by Bacillus subtilis Strains

Abstract

This study investigated the antiradical and antioxidant potential of the three families of lipopeptides (i.e., surfactin, mycosubtilin, and plipastatin/fengycin) produced by Bacillus subtilis strains. The antiradical/antioxidant activities of highly purified lipopeptides were studied in acellular models using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, superoxide anion ( ${\text{O}}_2^{.-}$ ), hydrogen peroxide, (H₂O₂) and hydroxyl radical (HO^.). At a lipopeptide concentration of 500 mg.L^-1, the maximum inhibition of DPPH reached 22.88% (obtained for plipastatin). Moreover, the scavenging effects of ${\text{O}}_2^{.-}$ , H₂O₂, and HO^. at the highest concentration tested (250 mg.L^-1) were found to be 6, 21, and 3% for surfactin, 19, 9, and 15% for mycosubtilin, 21, 18, and 59% for plipastatin, 21, 31, and 61% for the mixture of surfactin/plipastatin, and 13, 16, and 15% for the mixture of surfactin/mycosubtilin, respectively. These results showed that plipastatin was the best candidate due to its antioxidant activities.

Keywords: Bacillus subtilis; antioxidant; antiradical; lipopeptides; reactive oxygen species.