title: Analysis of stereochemistry and biosynthesis of epicatechin in tea plants by chiral phase high performance liquid chromatography.
abstract: Tea (Camellia sinensis) is rich in flavan-3-ols (catechins), especially epicatechin (EC), which is the predominant extension unit of polymeric proanthocyanidins (PAs). However, studies assessing EC's stereochemistry are scarce. Here, a high performance liquid chromatography column using amylose tris-(3, 5-dimethylphenylcarbamate) immobilized on silica-gel as chiral stationary phases (CSPs) was applied to explore its stereochemistry and biosynthetic pathway in tea plants. The results revealed (-)-epicatechin [(-)-EC] was the predominant di-hyroxy-non-galloylated-catechins, while (+)-epicatechin [(+)-EC] was not detected. Interestingly, (-)-EC was the only product obtained from cyanidin using the partially purified native C. sinensis anthocyanidin reductase (CsANR) in the presence of reduction nicotinamide adenine dinucleotide phosphate (NADPH); meanwhile, (+)-EC was the main product using recombinant CsANR in the same conditions. In addition, (-)-EC could be obtained from (+)-catechin [(+)-C] using recombinant CsANR, which displayed C3-epimerase activity in the presence of oxidation nicotinamide adenine dinucleotide phosphate (NADP(+)). But the partially purified native CsANR did not possess this function. Finally, (-)-EC could result from the de-gallate acid reaction of epicatechin gallate (ECG) catalyzed by a novel partially purified native galloylated catechins hydrolase (GCH) from tea leaves. In summary, (-)-EC is likely the product of native protein from the tea plants, and (+)-EC is only produced in a reaction catalyzed by recombinant CsANR in vitro.
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China; School of Biological and Food Engineering, Suzhou University, 49 Middle Bianhe Rd., Suzhou 234000 Anhui, China.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Qian
authors.affiliation: School of Life Science, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China.
authors.forename: Xianqian
authors.initials: X
authors.lastname: Zhao
authors.affiliation: College of Horticulture, Qingdao Key Laboratory of Genetic Improvement and Breeding in Horticultural Plants, Qingdao Agricultural University, 700Changcheng Rd., Qingdao 266109 Shandong, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China.
authors.forename: Lilan
authors.initials: L
authors.lastname: Cui
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China.
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Jiang
authors.affiliation: School of Life Science, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Life Science, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China. Electronic address: gaolp62@126.com.
authors.forename: Liping
authors.initials: L
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130 West Changjiang Rd., Hefei 230036 Anhui, China. Electronic address: xiatao62@126.com.
authors.forename: Tao
authors.initials: T
authors.lastname: Xia
mesh_terms: D002392:Catechin / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D053858:Metabolic Networks and Pathways; D013237:Stereoisomerism; D013662:Tea / Q000378:metabolism*
chemical_list: D013662:Tea; D002392:Catechin
keywords: Biosynthesis; Chiral phase; Epicatechin; High performance liquid chromatography; Stereochemistry; Tea