- Study on in Vitro Preparation and Taste Properties of N-Ethyl-2-Pyrrolidinone-Substituted Flavan-3-Ols
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N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs) were prepared by an in vitro model reaction, and the taste thresholds of EPSFs and their dose-over-threshold factors in large-leaf yellow tea (LYT) were investigated. The effects of initial reactant
- Han, Zisheng,Ho, Chi-Tang,Jiang, Zongde,Lai, Guoping,Qin, Chunyin,Wan, Xiaochun,Wen, Mingchun,Zhai, Xiaoting,Zhang, Hui,Zhang, Liang
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- Mechanism of oolongtheanin formation via three intermediates
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To clarify the mechanism of oolongtheanin formation, the oxidations of (?)-epigallocatechin and (?)-epigallocatechin gallate were investigated, and key intermediates were isolated. These intermediates were determined to be dehydrotheasinensins and pro-oolongtheanins, which we have reported previously, and one novel intermediate. Based on the chemical structures of these intermediates, a mechanism was proposed for oolongtheanin formation from catechins, and confirmed by NMR and GC–MS analysis.
- Hirose, Sayumi,Kamatari, Yuji O.,Yanase, Emiko
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supporting information
(2020/01/24)
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- Metabolic characterization of the anthocyanidin reductase pathway involved in the biosynthesis of flavan-3-ols in elite Shuchazao tea (Camellia sinensis) cultivar in the field
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Anthocyanidin reductase (ANR) is a key enzyme in the ANR biosynthetic pathway of flavan-3-ols and proanthocyanidins (PAs) in plants. Herein, we report characterization of the ANR pathway of flavan-3-ols in Shuchazao tea (Camellia sinesis), which is an elite and widely grown cultivar in China and is rich in flavan-3-ols providing with high nutritional value to human health. In our study, metabolic profiling was preformed to identify two conjugates and four aglycones of flavan-3-ols: (-)-epigallocatechin-gallate [(-)-EGCG], (-)-epicatechin-gallate [(-)-ECG], (-)-epigallocatechin [(-)-EGC], (-)-epicatechin [(-)-EC], (+)-catechin [(+)-Ca], and (+)-gallocatechin [(+)-GC], of which (-)-EGCG, (-)-ECG, (-)-EGC, and (-)-EC accounted for 70-85% of total flavan-3-ols in different tissues. Crude ANR enzyme was extracted from young leaves. Enzymatic assays showed that crude ANR extracts catalyzed cyanidin and delphinidin to (-)-EC and (-)-Ca and (-)-EGC and (-)-GC, respectively, in which (-)-EC and (-)-EGC were major products. Moreover, two ANR cDNAs were cloned from leaves, namely CssANRa and CssANRb. His-Tag fused recombinant CssANRa and CssANRb converted cyanidin and delphinidin to (-)-EC and (-)-Ca and (-)-EGC and (-)-GC, respectively. In addition, (+)-EC was observed from the catalysis of recombinant CssANRa and CssANRb. Further overexpression of the two genes in tobacco led to the formation of PAs in flowers and the reduction of anthocyanins. Taken together, these data indicate that the majority of leaf flavan-3-ols in Shuchazao's leaves were produced from the ANR pathway.
- Zhao, Lei,Jiang, Xiao-Lan,Qian, Yu-Mei,Wang, Pei-Qiang,Xie, De-Yu,Gao, Li-Ping,Xia, Tao
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- Enantioselective total syntheses of (+)-gallocatechin, (-)- epigallocatechin, and 8-C-ascorbyl-(-)-epigallocatechin
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Reading the tea leaves: The enatioselective total syntheses of 8-C-ascorbyl-(-)-epigallocatechin was accomplished by CuII-mediated oxidative coupling of ascorbic acid and (-)-epigallocatechin as a key step. Also, the asymmetric total syntheses of tea-leaf extracts (+)-gallocatechin and (-)-epigallocatechin were achieved by Au-catalyzed intramolecular cycliarylation of the precursor epoxide and Sharpless dihydroxylation. Copyright
- Lin, Guang,Chang, Le,Liu, Yongxiang,Xiang, Zheng,Chen, Jiahua,Yang, Zhen
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supporting information
p. 700 - 704
(2013/05/09)
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- Isolation of two new bioactive proanthocyanidins from Cistus salvifolius herb extract
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Two new proanthocyanidins, epigallocatechin-3-O-p-hydroxybenzoate- (4β→8)-epigallocatechin (1) and epigallocatechin-3-O-p- hydroxybenzoate-(4β→8)-epigallocatechin-3-O-gallate (2) in addition to the known compound epigallocatechin-(4β→6)-epigallocatechin-3-O- gallate (3), were isolated from the air-dried herb of Cistus salvifolius. The chemical structures were determined on the basis of 1D-and 2D-NMR-spectra (HSQC, HMBC) of their peracetylated derivatives, MALDI-TOF-mass spectra, and by acid-catalysed degradation with phloroglucinol. The isolated compounds 1-3 and the water extract of C. salvifolius herb were tested for their inhibitory activities against COX-1 and COX-2. Compound 2 showed the strongest inhibitory effect on COX-2 followed by compound 3, compound 1 and the water extract, while compounds 1-3 exhibited moderate in vitro inhibition against COX-1.
- Qa'dan, Fadi,Nahrstedt,Schmidt
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experimental part
p. 454 - 457
(2012/01/12)
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- New oligomeric proanthocyanidins from Alhagi pseudalhagi
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Two new oligomeric proanthocyanidin glucosides were isolated from the aerial part and roots of Alhagi pseudalhagi. Their structures and relative configurations were elucidated as 7-O-β-D-Glc p→6 galloyl-(+)catechin-(4α-8)-(+)-catechin-(4α-8)-(-
- Alimova,Nishanbaev,Vdovin,Abdullaev,Aripova
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experimental part
p. 352 - 356
(2010/10/03)
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- General synthesis of epi-series catechins and their 3-gallates: Reverse polarity strategy
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A general synthetic route to the epi-series catechins was developed based on the reverse polarity strategy. Aromatic nucleophilic substitution reaction followed by the sulfinyl-metal exchange and cyclization enabled stereo-controlled access to various members of epi-series catechins and their 3-gallates.
- Ohmori, Ken,Yano, Takahisa,Suzuki, Keisuke
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supporting information; experimental part
p. 2693 - 2696
(2010/08/21)
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- Metabolism of (-)-epigallocatechin gallate by rat intestinal flora
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Anaerobic metabolism of ( - )-epigallocatechin gallate (EGCg) by rat intestinal bacteria was investigated in vitro. First, intestinal bacteria which are capable of hydrolyzing EGCg to ( - )epigallocatechin (EGC) and gallic acid (2) were screened with 169 strains of enteric bacteria. As a result, Enterobacter aerogenes, Raoultella planticola, Klebsiella pneumoniae susp. pneumoniae, and Bifidobacterium longum subsp. infantis were found to hydrolyze EGCg. Subsequent steps of EGCg metabolism are degradation of EGC (1) by intestinal bacteria. Then, EGC was incubated with rat intestinal bacteria in 0.1 M phosphate buffer (pH 7.1) and the degradation products were analyzed with time by HPLC or LC-MS. Further, the products formed from EGC were isolated and identified by LC-MS and NMR analyses. The results revealed that EGC was converted first to 1-(3', 4', 5'-trihydroxyphenyl)-3-(2 , 4 , 6 -trihydroxyphenyl)propan-2-ol (3) by reductive cleavage between 1 and 2 positions of EGC, and subsequently metabolite 3 was converted to 1-(3', 5'-dihydroxyphenyl)-3-(2 , 4 , 6 -trihydroxyphenyl)propan-2-ol (4) followed by the conversion to 5-(3, 5-dihydroxyphenyl)-4-hydroxyvaleric acid (5) by decomposition of the phloroglucinol ring in metabolite 4. This degradation pathway was considered to be the major route of EGCg metabolism in the in vitro study, but two minor routes were also found. In addition to the in vitro experiments, metabolites 3, 4, 5, and 6 were detected as the metabolites after direct injection of EGC into rat cecum. When EGCg was administered orally to the rats, metabolites 4, 5, 6, 11, and 12 were found in the feces. Among the metabolites detected, metabolite 5 was dominant both in the cecal contents and feces. These findings suggested that the metabolic pathway of EGCg found in the in vitro study may be regarded as reflecting its metabolism in vivo.
- Takagaki, Akiko,Nanjo, Fumio
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experimental part
p. 1313 - 1321
(2010/09/04)
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- Dimeric prodelphinidins from Limonium gmelinii roots. III
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Two dimeric proanthocyanidines identified as 2R,3R,4R-(-)-epigallocatechin- (4β→ 8)-2R,3R-(-)-epigallocatechin-3-O-gallate and 2R,3R,4R-(-)-epigallocatechin-(4β→8)-(-)-2R,3R,3,5,7,3′, 4′,6′-hexahydroxyflavan were isolated by adsorption chromatography over polyamide of the ethylacetate fraction of the aqueous alcohol extract of Limonium gmelinii roots. The former proanthocyanidine was isolated for the first time from sea lavender whereas the latter is new. 2006 Springer Science+Business Media, Inc.
- Zhusupova,Abil'kaeva
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p. 164 - 168
(2008/02/01)
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- Stereoselective oxidation at C-4 of flavans by the endophytic fungus Diaporthe sp. isolated from a tea plant
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The microbial transformation of five flavans (1-5) by endophytic fungi isolated from the tea plant Camellia sinensis was investigated. It was found that the endophytic filamentous fungus Diaporthe sp. oxidized stereoselectively at C-4 position of (+)-catechin (1) and (-)-epicatechin (2) to give the correspondent 3,4-cis-dihydroxyflavan derivatives (6, 10), respectively. (-)-Epicatechin 3-O-gallate (3) and (-)-epigallocatechin 3-O-gallate (4) were also oxidized by the fungus into 3,4-dihydroxyflavan derivatives (10, 12) via (-)-epicatechin (2) and (-)-epigallocatechin (11), respectively. Meanwhile, (-)-gallocatechin 3-O-gallate (5), (-)-catechin (ent-1) and (+)-epicatechin (ent-2), which possess a 2S-phenyl substitution, resisted the biotransformation.
- Agusta, Andria,Maehara, Shoji,Ohashi, Kazuyoshi,Simanjuntak, Partomuan,Shibuya, Hirotaka
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p. 1565 - 1569
(2007/10/03)
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- New oligomeric proanthocyanidine from Ziziphus jujuba
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Chemical and spectral data establish the structure of an oligomeric proanthocyanidine PZ-5 isolated from Ziziphus jujuba.
- Malik, Aibek,Kuliev,Akhmedov,Vdovin,Abdullaev
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- Determination of condensed Tannin Monomers in environmental samples by capillary gas chromatography of acid depolymerization extracts
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A method for molecular-level quantification of condensed tannin is described that uses acid depolymerization and carbocation capture by phloroglucinol. Resulting monomers and phloroglucinol adducts are trimethylsilyl derivatized, separated by capillary gas chromatography, detected by flame ionization, and quantified relative to standards. Optimal depolymerization conditions were determined for acid strength, phloroglucinol concentration, time, and temperature. The method gives reproducible results in leaf litter that are linear over 2 orders of magnitude with detection limits down to ～100 ng condensed tannin. In addition to tannin, triterpenoids were also identified and can be quantified with this method. Analyses of soils and sediments indicate that mineral interactions with condensed tannin are important both analytically and environmentally.
- Hemes, Peter J.,Hedges, John I.
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p. 5115 - 5124
(2007/10/03)
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- Oligomeric proanthocyanidin glycosides of Clementsia semenovii and their biological activity. III
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The structures of two oligomeric proanthocyanidins isolated from roots of Clementsia semenovii have been established using chemical and spectral data. Animal studies showed that these compounds possess hypocholesterinemic, hypolipidemic, and anti-inflammatory activities.
- Kuliev,Kim,Vdovin,Abdullaev,Khushbaktova,Syrov
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- Novel norsesquiterpenoids from the roots of Phyllanthus emblica
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Three ester glycosides, named phyllaemblicins A (3), B (4), and C (5), and a methyl ester (2), of a highly oxygenated norbisabolane, phyllaemblic acid (1), were isolated from the roots of Phyllanthus emblica, along with 15 tannins and related compounds. The structures of 2-5 were established by spectral and chemical methods.
- Zhang, Ying-Jun,Tanaka, Takashi,Iwamoto, Yoko,Yang, Chong-Ren,Kouno, Isao
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p. 1507 - 1510
(2007/10/03)
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- Oligomeric proanthocyanidin glycosides of Clementsia semenovii
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Five new proanthocyanidins have been isolated from the roots of Clementsia semenovii A. Bor. The structures of two of these compounds have been established by various chemical and physical methods: 7-0-[6-0-galloyl-β-D-Glcp →6 O-βD-Glcp →6O-β-D-Glcp → 6O-β-D-Glcp]-(+)-gallocatechin-(4α-8)-(+)-gallocatechin- (4α-8)-(-)-epigallocatechin-(4β-8)-(-)-epigallocatechin-(4β-8)- (-) -epigallocatechin-(4β-8)-(+)-catechin - CS-1 and 3-O-galloyl-7-O-(β-D-Glcp → 6O-β-D-Glcp)-(-)-epigallocatechin-(4β-8)-[3-O-galloyl-(-)- epigallocatechin]-(4β-8)-[3-O-galloyl-(-)-epigallocatechin]-(4β-8)-[3- O-galloyl-5-O-(6-O-galloyl-O-β-D-Glcp)]-(-)-epicatechin - CS-2.
- Matamarova,Kuliev,Vdovin,Abdullaev,Murzubraimov
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p. 676 - 682
(2007/10/03)
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- Reduction potentials of flavonoid and model phenoxyl radicals. Which ring in flavonoids is responsible for antioxidant activity?
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Model phenoxyl and more complex flavonoid radicals were generated by azide radical induced one-electron oxidation in aqueous solutions. Spectral, acid-base and redox properties of the radicals were investigated by the pulse radiolysis technique. The physicochemical characteristics of the flavonoid radicals closely match those of the ring with the lower reduction potential. In flavonoids which have a 3,5-dihydroxyanisole (catechins), or a 2,4-dihydroxyacetophenone (hesperidin, rutin, quercetin)-like A ring and a catechol- or 2-methoxyphenol-like B ring, the antioxidant active moiety is clearly the B ring [reduction potential difference between the model phenoxyls is ΔE(A-B ring models) > 0.1 V]. In galangin, where the B ring is unsubstituted phenyl, the antioxidant active moiety is the A ring. Even though the A ring is not a good electron donor, E7, > 0.8/NHE V, it can still scavenge alkyl peroxyl radicals, E7, = 1.06 V, and the Superoxide radical, E7 > 1.06 V. Quercetin is the best electron donor of all investigated flavonoids (measured E10.8 = 0.09 V, and calculated E7 = 0.33 V). The favourable electron-donating properties originate from the electron donating O-3 hydroxy group in the C ring, which is conjugated to the catechol (B ring) radical through the 2,3-double bond. The conjugation of the A and B rings is apparently minimal, amounting to less than 2.5% of the substituent effect in either direction. Thus, neglecting the acid-base equilibria of the A ring, and using those of the B ring and the measured values of the reduction potentials at pH 3,7 and 13.5, the pH dependence of the reduction potentials of the flavonoid radicals can be calculated. In neutral and slightly alkaline media (pH 7-9), all investigated flavonoids are inferior electron donors to ascorbate. Quercetin, E7 = 0.33 V, and gallocatechins, E7 = 0.43 V, can reduce vitamin E radicals (assuming the same reduction potential as Trolox C radicals, E7 = 0.48 V). Since all investigated flavonoid radicals have reduction potentials lower than E7 = 1.06 V of alkyl peroxyl radicals, the parent flavonoids qualify as chain-breaking antioxidants in any oxidation process mediated by these radicals.
- Jovanovic, Slobodan V.,Steenken, Steen,Hara, Yukihiko,Simic, Michael G.
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p. 2497 - 2504
(2007/10/03)
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- POLYPHENOLIC COMPOUNDS FROM CROTON LECHLERI
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The blood-red sap of Croton lechleri was found to contain proanthocyanidins as major constituents which accounted for up to 90percent of the dried weight.In addition to (+)-catechin, (-)-epicatechin, (+)-gallocatechin, (-)-epigallocatechin and dimeric procyanidins B-1 and B-4, five novel dimers and trimers were isolated and characterized as catechin-(4α->8-epigallocatechin, gallocatechin-(4α->8)-epicatechin, gallocatechin-(4α->6)-epigallocatechin, catechin-(4α->8)-gallocatechin-(4α->8)-gallocatechin and gallocatechin-(4α->8)-gallocatechin-(4α->8)-epigallocatechin.Higher oligomers were also obtained.A new procedure combining chemical degradation with 1H NMR spectroscopy has been developed for determination of the composition and molecular size of oligomeric/polymeric proanthocyanidins.The oligomers of the sap were shown to have the mean degree of polymerization of 4,5-6 and 6-7, respectively, and Mr up to 2130.The heterogeneity of the oligomers was clearly indicated by the presence of a variety of flavan-3-ols as extension and terminal units.An exceptionally high content of gallocatechin and epigallocatechin in the oligomers was observed.Key Word Index: Croton lechleri; Euphorbiaceae; Sangre de Grado; Dragon's blood; polyphenol; proanthocyanidins; flavan-3-ols; procyanidins; prodelphinidins.
- Cai, Y.,Evans, F. J.,Roberts, M. F.,Phillipson, J. D.,Zenk, M. H.,Gleba, Y. Y.
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p. 2033 - 2040
(2007/10/02)
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- Tannins and Related Compounds. LXXVII. Novel Chalcan-flavan Dimers, Assamicains A, B and C, and a New Flavan-3-ol and Proanthocyanidins from the Fresh Leaves of Camellia sinensis L. var. assamica KITAMURA
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Three novel chalcan-flavan dimers, assamicains A (1), B (2) and C (3), and a new flavan-3-ol (14) and proanthocyanidins (19,20) have been isolated, together with the known flavan-3-ols (4-13), proanthocyanidins (15-18,21), theasinensins (22-24) and hydrolyzable tannins (25,26), from the fresh leaves of Camellia sinensis var. assamica (Camelliaceae), and their structures have been established on the basis of spectroscopic evidence in conjunction with thiolytic degradation and enzymatic hydrolysis. - Keywords: Camellia sinensis var. assamica; Camelliaceae; polyphenol; assamicain; chalcan-flavan dimer; proanthocyanidin; theasinensin; flavan-3-ol; hydrolyzable tannin; black tea
- Hashimoto, Fumio,Nonaka, Gen-ichiro,Nishioka, Itsuo
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- Tannins and Related Compounds. XV. A New Class of Dimeric Flavan-3-ol Gallates, Theasinensins A and B, and Proanthocyanidin Gallates from Green Tea Leaf. (1)
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Along with four dimeric proanthocyanidin gallates, viz. prodelphinidin B-2 3'-O-gallate (IV) and procyanidins B-2 3,3'-di-O-gallate (V), B-2 3'-O-gallate (VI) and B-4 3'-O-gallate (VII), two novel dimeric flavan-3-ol gallates (VIII and IX) named theasinensins A and B, in which two flavan units are linked at the B-ring, have been isolated from fresh green tea leaves, and their structures have been established on the basis of spectroscopic evidence in conjunction with enzymatic hydrolyses with tannase.Three new monomeric acylated flavan-3-ols have also been isolated, and their structures were similarly characterized as (-)-epigallocatechin 3-O-p-coumaroate (I), (-)-epigallocatechin 3,3'-di-O-gallate (II) and (-)-epigallocatechin 3,4'-di-O-gallate (III).In addition, the occurrence of the know (-)-epicatechin 3-O-gallate (X), (-)-epigallocatechin 3-O-gallate (XI), (+)-catechin (XII), (-)-epicatechin (XIII), (-)-epigallocatechin (XIV) and (-)-epicatechin 3-O-(3-O-methyl)-gallate (XV) in green tea leaves was confirmed.Keywords - green tea leaf; Thea sinensis; Theaceae; tannin; theasinensin; proanthocyanidin gallate; flavan-3-ol p-coumaroate; flavan-3-ol gallate
- Nonaka, Gen-Ichiro,Kawahara, Osamu,Nishioka, Itsuo
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p. 3906 - 3914
(2007/10/02)
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