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Application of immobilized enzymes to accelerate the conversion of genistin to genistein in pigeon pea root extracts and the evaluation their antioxidant activity

Zhang, Dong-Yang, Zu, Yuan-Gang, Fu, Yu-Jie, Luo, Meng, Wang, Wei, Gu, Cheng-Bo, Yao, Xiao-Hui
Industrial crops and products 2013 v.42 pp. 409-415
antioxidant activity, beta-glucosidase, genistein, genistin, immobilized enzymes, pigeon peas
The effect of incubation of pigeon pea root extracts with immobilized β-glucosidase on the conversion of genistin to genistein was investigated. β-Glucosidase was effectively immobilized on alginate by the method of crosslinking–entrapment. After optimization, the incubation conditions were as follow, amounts of immobilized β-glucosidase 30U, temperature 30°C, pH=4 and incubation time 2h. On the optimal conditions, about 94.9% of genistin was conversed to genistein, and the content of genistein was 0.689mg/mL, which increased 63.7% after incubation. Immobilized β-glucosidase possessed extended stability and higher reusability. Furthermore, the antioxidant activity of genistein, genistin and the extracts with and without incubation were assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. The IC50 value of extracts after incubation with immobilized β-glucosidase reached 726.21±11.25μg/mL, which was higher than that of the extract (932.76±13.75μg/mL) without incubation.