title: Improving Free Radical Scavenging Activity of Soy Isoflavone Glycosides Daidzin and Genistin by 3'-Hydroxylation Using Recombinant Escherichia coli.
abstract: The present study describes the biotransformation of a commercially available crude extract of soy isoflavones, which contained significant amounts of the soy isoflavone glycosides daidzin and genistin, by recombinantEscherichia coliexpressing tyrosinase fromBacillus megaterium. Two major products were isolated from the biotransformation and identified as 3'-hydroxydaidzin and 3'-hydroxygenistin, respectively, based on their mass and nuclear magnetic resonance spectral data. The two 3'-hydroxyisoflavone glycosides showed potent 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity with IC50values of 7.4 and 9.8 μM for 3'-hydroxydaidzin and 3'-hydroxygenistin, respectively. The free radical scavenging activities of the two 3'-hydroxyisoflavone glycosides were, respectively, 120 and 72 times higher than the activity of their precursors, daidzin and genistin, and were also stronger than the activity of ascorbic acid, which showed an IC50value of 15.1 μM. This is the first report of the bio-production and potential antioxidant applications of both 3'-hydroxydaidzin and 3'-hydroxygenistin.
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy and Science, No. 60, Sec. 1, Erh-Jen Rd., Jen-Te District, Tainan 71710, Taiwan. cmchiang@mail.cnu.edu.tw.
authors.forename: Chien-Min
authors.initials: CM
authors.lastname: Chiang
authors.affiliation: Department of Biological Sciences and Technology, National University of Tainan, Tainan 70005, Taiwan. afg459326@yahoo.com.tw.
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Wang
authors.affiliation: Department of Biological Sciences and Technology, National University of Tainan, Tainan 70005, Taiwan. mozyme2001@gmail.com.
authors.forename: Te-Sheng
authors.initials: TS
authors.lastname: Chang
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000378:metabolism; D001410:Bacillus megaterium / Q000201:enzymology; D001711:Biotransformation / Q000502:physiology; D001713:Biphenyl Compounds / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism; D007529:Isoflavones / Q000737:chemistry* / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010851:Picrates / Q000737:chemistry; D013025:Glycine max / Q000378:metabolism
chemical_list: C538958:3'-hydroxydaidzein; C000617873:3'-hydroxygenistin; D000975:Antioxidants; D001713:Biphenyl Compounds; D006027:Glycosides; D007529:Isoflavones; D010851:Picrates; C040641:genistin; C013908:daidzin; C004931:1,1-diphenyl-2-picrylhydrazyl; D014442:Monophenol Monooxygenase
keywords: antioxidant; biotransformation; daidzin; genistin; hydroxylation