Fructooligosaccharides synthesized by fructosyltransferase from an indigenous coprophilous Aspergillus niger strain XOBP48 exhibits antioxidant activity

Abstract

Fructooligosaccharides (FOS) produced via sucrose biotransformation by partially purified Fructosyltransferase (Ftase) from an indigenous coprophilous Aspergillus niger strain XOBP48 (AnXOBP48) are reported to have antioxidant and nutraceutical properties in the present study. The Ftase activity on sucrose yielded FOS identified as monomeric glucose, 1- kestose (GF2), and 1,1– kestotetraose (GF3) which were further purified and quantified using HPLC-RI system. The antioxidant activities of purified FOS at concentrations of 1, 1.5, 3, 6, 12, 24 and 48 μg/ml were determined by applying three experimental models and comparing their properties with FOS standards and vitamin C. The free radical scavenging activity measured by 1,1 - diphenyl-2-picryl hydroxyl (DPPH) assay, ferric reducing antioxidant power (FRAP) assay and nitric oxide (NO) radical inhibition assay, yielded IC50 values of 2.6 μg/ml, 3.9 μg/ml and 3.4 μg/ml, 3.8 μg/ml and 0.69 μg/ml, 0.74 for purified GF2 and GF3, respectively. The free radical scavenging and inhibition activities showed a concentration dependent antioxidant activity of purified FOS with no significant differences as compared to the standards p < 0.01 and vitamin C. In conclusion, the results demonstrated that purified FOS could be exploited in biotechnological applications and/or as to be used as functional ingredients in commercial products such as the production of nutraceutical compounds due to their potential antioxidant properties.