Preparation of Bioactive Oligosaccharides from Mallow Residues by Enzymes Mixture of Isolated Aspergillus flavus B2 and Evaluation of their Biological Activities

Abstract

The preparation of biologically active oligosaccharides from the stem residues of the mallow plant (Corchorus olitorius) was evaluated by the enzymatic hydrolysis method. The isolated strain Aspergillus flavus B2 (accession number OL655454) was selected as a potential producer of the enzymes mixture. The factors affecting the hydrolysis of Mallow stems (MS) by enzyme mixture were tested using Plackett-Burman and Central Composite statistical designs. Different production conditions yielded 13 bioactive oligosaccharides (MSOS) that differed in their yield, components, monosaccharides constitution, percentage, and degree of polymerization. The optimized conditions yielded 525 milligrams of oligosaccharide per gram of dry MS using enzymes-mixture containing cellulase 4.9 U/mL, xylanase 6.8 U/mL, and pectinase 12.9 U/mL. Oligosaccharide no. 4 showed higher fibrinolytic activity than Hemoclar. All tested oligosaccharides (1 %) improved the growth of both the probiotics Bifidobacterium lactis and Lactobacillus plantarum. The antioxidant activity of the produced oligosaccharides varies depending on their characteristics and method of evaluation. Of all the samples tested, MSOS no. 11 showed the highest level of DPPH, reducing power, ABTS, and FRAP activity. Moreover, the highest reduction in tumor cell viability and the inhibited ascites were obtained by MSOS no. 11 (37.24±0.31 %).