- Characterization of a novel thermostable glucose-tolerant GH1 β-glucosidase from the hyperthermophile Ignisphaera aggregans and its application in the efficient production of baohuoside I from icariin and total epimedium flavonoids
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The minor flavonoid baohuoside I from Herba epimedii has better bioactivities than its precursor compounds icariin and other major epimedium flavonoids. In this study, a novel β-glucosidase gene (Igag_0940) was cloned and expressed to improve the conversion efficiency in the process of baohuoside I production. For the first time, the recombinant IagBgl1 was purified and then identified uniquely as a trimer in GH 1 family protein from Archaea. The maximum activity of recombinant IagBgl1 was exhibited at 95 °C, pH 6.5, and it retained more than 70% after incubation at 90 °C for 4 h. IagBgl1 had a high catalytic activity towards icariin with a Kcat/Km ratio of 488.19 mM?1·s?1. Under optimized conditions (65 °C, pH 6.5, 0.8 U/mL enzyme, and 90 min), 10 g/L icariin was transformed into 7.564 g/L baohuoside I with a molar conversion of 99.48%. Meanwhile, 2.434 g/L baohuoside I was obtained from 10 g/L total epimedium flavonoids by a two-step conversion system built with IagBgl1 and two other thermostable enzymes. This is the first report of enzymatic conversion for producing baohuoside I by thermostable enzymes.
- Jiang, Jianchun,Wei, Min,Xie, Jingcong,Xu, Hao,Yang, Jing,Zhang, Ning,Zhao, Jian
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- Biotransformation of major flavonoid glycosides in herb epimedii by the fungus Cunninghamella blakesleana
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Biotransformation of icariin (1), epimedin C (2), epimedoside A (3), epimedin A (4) and epimidin B (5), five major components of E. koreanum, were performed by using Cunninghamella blakesleana. And they could be metabolized efficiently to icariside II (1a), 2″-O-rhamnosylikarisoside II (2a), epimedoside b (3a), baohuoside VII (4a) and sagittatoside B (5a) with high yields of 95.1%, 97.7%, 93.7%, 95.8% and 96.4%, respectively. And these transformed products as major forms of herb epimedii in vivo exhibited the more significant anti-osteoporosis activities. Our method could be applied for enriching these rare flavonoids in herb epimedii, for further development of anti-osteoporosis medicines or functional foods.
- Xin, XiuLan,Fan, Guang-Jun,Sun, Zheng,Zhang, Ning,Li, Ye,Lan, Rong,Chen, Liang,Dong, PeiPei
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p. 141 - 146
(2015/10/12)
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