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Bioconversion of Flavonoid Glycosides from Hippophae rhamnoides Leaves into Flavonoid Aglycones by Eurotium amstelodami

The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
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Microorganisms 2019, 7(5), 122; https://doi.org/10.3390/microorganisms7050122
Received: 29 March 2019 / Revised: 30 April 2019 / Accepted: 30 April 2019 / Published: 5 May 2019
(This article belongs to the Special Issue The Mechanisms and Applications of Microbial Electrocatalysis)
The flowering process has been reported to play crucial roles in improving the flavor and efficacy of fermented tea. Hippophae rhamnoides leaves containing many beneficial ingredients are a suitable plant source for tea processing. In this study, we isolated a β-glucosidase-producing fungus Eurotium amstelodami BSX001 from the fermented tea and used Hippophae rhamnoides leaves (HRL) as a substrate to explore the detailed process of bioconversion of some important functional factors. The results show that the contents of total phenolic compounds and flavonoids increased significantly after seven days, especially flavonoid aglycones (e.g., quercetin, kaempferol, and isorhamnetin). Such compounds greatly enhance the antioxidative activity of fermented products. Metabolic analysis of the standard compounds (rutin, quercetin-3-glucoside, kaempferol-3-glucoside, quercetin, isorhamnetin-3-glucoside, isorhamnetin, and kaempferol) further confirmed the effective biotransformation by E. amstelodami. Mechanisms of the bioconversion could be involved in deglycosylation, dihydroxylation, and O-methylation. Our findings expand the understanding of tea fermentation process and provide further guidance for the fermented tea industry. View Full-Text
Keywords: Eurotium amstelodami; Hippophae rhamnoides leaves; bioconversion; flavonoid glycosides; flavonoid aglycones; antioxidative activity Eurotium amstelodami; Hippophae rhamnoides leaves; bioconversion; flavonoid glycosides; flavonoid aglycones; antioxidative activity
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MDPI and ACS Style

Gu, Q.; Duan, G.; Yu, X. Bioconversion of Flavonoid Glycosides from Hippophae rhamnoides Leaves into Flavonoid Aglycones by Eurotium amstelodami. Microorganisms 2019, 7, 122.

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