Analysis of accumulation patterns and preliminary study on the condensation mechanism of proanthocyanidins in the tea plant [Camellia sinensis].
In the present study, proanthocyanidins were qualitatively and quantitatively identified using hydrolysis and thiolysis assays, NP-HPLC, HPLC-ESI-MS, MALDI-TOF-MS, (1)H-NMR, and (13)C-NMR techniques in different organs of tea plants. The results showed that in leaves, the tri-hydroxyl, cis- and galloylated flavan-3-ols were the main monomeric catechins units, and (epi)catechin was found to be the major unit of polymeric flavan-3-ols when the degree of polymerization was greater than five. In roots, the PAs were found to be abundant, and epicatechin formed the predominant extension unit of oligomeric and polymeric PAs. In order to understand the mechanism of proanthocyanidins polymerization, auto-condensation of the flavan-3-ols was investigated. The results showed that the same trimers (m/z 865) were detected in the extracts of tea plants and in the non-enzymatic in vitro assay, in weak acid as well as weak alkaline solutions at room temperature, when the substrates used were either procyanidin B2 and monomeric flavan-3-ols (epicatechin or catechin), or only procyanidin B2. This suggested that procyanidin B2 not only released carbocation as electrophilic upper units, but also could be used as nucleophilic lower units directly itself, to form the procyanidin trimer in vitro or in vivo.
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China.
Xiaolan
X
Jiang
School of Life Science, Anhui Agricultural University, Hefei, Anhui, China.
Yajun
Y
Liu
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China.
Yahui
Y
Wu
Biotechnology Center, Anhui Agricultural University, Hefei, Anhui, China.
Huarong
H
Tan
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China.
Fei
F
Meng
School of Life Science, Anhui Agricultural University, Hefei, Anhui, China.
Yun Sheng
YS
Wang
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China.
Mingzhuo
M
Li
College of Horticulture, Qingdao Agricultural University, Qingdao, Shandong, China.
Lei
L
Zhao
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China.
Li
L
Liu
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China.
Yumei
Y
Qian
School of Life Science, Anhui Agricultural University, Hefei, Anhui, China.
Liping
L
Gao
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China.
Tao
T
Xia
D044946:Biflavonoids / Q000032:analysis / Q000737:chemistry; D053898:Biosynthetic Pathways; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry*; D058105:Polymerization; D044945:Proanthocyanidins / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D044946:Biflavonoids; D044945:Proanthocyanidins; C479580:procyanidin B2; D002392:Catechin