- 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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- Molecular Mechanism by Which Tea Catechins Decrease the Micellar Solubility of Cholesterol
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Tea polyphenols lower the levels of cholesterol in the blood by decreasing the cholesterol micellar solubility. To clarify this mechanism, the interactions between taurocholic acid and (-)-epigallocatechin gallate (EGCg) and its derivatives were investigated. 13C NMR studies revealed remarkable chemical-shift changes for the carbonyl carbon atom and the 1″- and 4″-positions in the galloyl moiety. Furthermore, 1H NMR studies using (-)-EGCg derivatives showed that the number of hydroxyl groups on the B ring did not affect these interactions, whereas the carbonyl carbon atom and the aromatic ring of the galloyl moiety had remarkable effects. The configuration at the 2- and 3-positions of the catechin also influenced these interactions, with the trans-configuration resulting in stronger inhibition activity than the cis-configuration. Additionally, a 1:1 component ratio for the catechin-taurocholic acid complex was determined by electrospray ionization-mass spectrometry. These molecular mechanisms contribute to the development of cholesterol-absorption inhibitors.
- Sakakibara, Takumi,Sawada, Yoshiharu,Wang, Jilite,Nagaoka, Satoshi,Yanase, Emiko
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- METHODS OF TREATING COGNITIVE AND BEHAVIORAL IMPAIRMENT IN DOWN SYNDROME AND ALZHEIMERS DISEASE PATIENTS
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The present invention relates to methods of treating cognitive and behavioral impairment in Down syndrome and/or Alzheimer's disease patients, Alzheimer's disease, neurodegenerative disease, cancer, DYRK1A-mediated disorders and methods of modulating and inhibiting DYRK1-A comprising use of catechins.
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- Potential O-acyl-substituted (-)-epicatechin gallate prodrugs as inhibitors of DMBA/TPA-induced squamous cell carcinoma of skin in swiss albino mice
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(-)-Epicatechin-3-gallate (1) is one of the principal catechins of green tea and exhibits cancer-preventive activities in various animal models. However, this compound is unstable in neutral or alkaline medium and, therefore, has a poor bioavailability. To improve its stability, O-acyl derivatives of 1 were prepared by isolating the partially purified tea catechin fraction from green tea extract and treating it with a variety of acylating agents. The resulting derivatives, compounds 2-6, were screened for their antitumor potential against 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced squamous cell carcinogenesis of skin in mice. The results showed that the antitumor activity decreased with the increase in size of the chain length of the acyl groups, i.e., from compound 2, derivative with an Ac group, to compound 6, possessing a valeryl group. Moreover, the C4 derivative with a branched acyl chain, 5, had a lower activity than the linear C4 derivative 4. This reduction in the inhibitory activity may be due to the steric hindrance by the two Me groups. Moreover, significant increases in the protein levels analyzed by ELISA of c-Jun, p65, and p53 were observed in the skin of DMBA/TPA treated mice, whereas mice treated with 2 and DMBA/TPA had a similar expression of these transcription factors than the control mice. The prodrug potential of the O-acyl derivatives 2-6 showed that they were adequately stable to be absorbed intact from the intestine, more stable at gastric pH, and suitable for oral administration. Copyright
- Vyas, Sandeep,Manon, Benu,Vir Singh, Tej,Dev Sharma, Pritam,Sharma, Manu
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experimental part
p. 599 - 613
(2011/11/12)
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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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- New oligomeric proanthocyanidin glycosides platanoside-A and platanoside-B from Platanus orientalis trunk bark
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Two new oligomeric proanthocyanidin glycosides were isolated from trunk bark of Platanus orientalis. Their structures and relative configurations were found to be 7-O-β-D-Glcp-(-)-epicatechin-(4β-8)-(-)- epicatechin(4β-8)-(-)-epicatechin-3-O-gallate (plat
- Nishanbaev,Khidyrova,Vdovin,Abdullaev,Shakhidoyatov,Aripov
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experimental part
p. 357 - 362
(2010/10/03)
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- Epimerization of tea catechins under weakly acidic and alkaline conditions
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Tea catechins in a buffer at pH 7 with N2 replacing O 2 epimerized rapidly at 80 °C with less than 10% of oxidative side reactions and gave catechin epimers in a 50-63% yield. The epimerization of catechins with three hydroxyl groups was faster than with two groups, and of galloyl-free catechins was faster than catechins with a galloyl ester.
- Ishino, Nobuyoshi,Yanase, Emiko,Nakatsuka, Shin-Ichi
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scheme or table
p. 875 - 877
(2011/07/30)
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- Study of the green tea polyphenols catechin-3-gallate (CG) and epicatechin-3-gallate (ECG) as proteasome inhibitors
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The green tea polyphenol catechin-3-gallate (CG) and epicatechin-3-gallate (ECG) were synthesized enantioselectively via a Sharpless hydroxylation reaction followed by a diastereoselective cyclization. Their potencies to inhibit the proteasome activity were measured. The unnatural enantiomers were found to be equally potent to the natural compounds.
- Wan, Sheng Biao,Chen, Di,Dou, Q. Ping,Chan, Tak Hang
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p. 3521 - 3527
(2007/10/03)
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- Stereoselective synthesis of procyanidin B3-3-O-gallate and 3,3″-di-O-gallate, and their abilities as antioxidant and DNA polymerase inhibitor
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A simple method for the synthesis of procyanidin B3 substituted with a galloyl group at the 3 and 3″ position is described. Condensation of a benzylated catechin-3-O-gallate electrophile with a nucleophile, catechin and catechin-3-O-gallate, proceeded smoothly and stereoselectively to afford the corresponding dimer gallates, procyanidin B3-3-O-gallate and procyanidin B3-3,3″-di-O-gallate, in good yields. Further, their antioxidant activities on UV-induced lipid peroxide formation, DPPH radical scavenging activity and inhibitory activity of DNA polymerase were also investigated. Among three procyanidin B3 congeners (procyanidin B3, 3-O-gallate and 3,3″-di-O-gallate), the 3,3″-di-O-gallate derivative showed the strongest antioxidant and radical scavenging activity. Interestingly, the 3-O-gallate derivative was the strongest inhibitor of mammalian DNA polymerase α with IC50 value of 0.26 μM, although it showed the weakest antioxidant and radical scavenging activity. It became apparent that the presence of a galloyl group at the C-3 position in the proanthocyanidin oligomer was very important for biological activity, however, the antioxidant activity of these compounds was not parallel to the DNA polymerase inhibitory activity. Graphical Abstract
- Saito, Akiko,Emoto, Mana,Tanaka, Akira,Doi, Yuki,Shoji, Kazuaki,Mizushina, Yoshiyuki,Ikawa, Hiroshi,Yoshida, Hiromi,Matsuura, Nobuyasu,Nakajima, Noriyuki
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p. 12043 - 12049
(2007/10/03)
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- Cysteinyl-flavan-3-ol conjugates from grape procyanidins. Antioxidant and antiproliferative properties.
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New bio-based antioxidant compounds have been obtained by depolymerisation of grape polymeric flavanols in the presence of cysteine. Their preparation and purification, as well as their antiradical/antioxidant and antiproliferative properties are reported
- Torres,Lozano,Julia,Sanchez-Baeza,Anglada,Centelles,Cascante
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p. 2497 - 2509
(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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- HYDROLYSABLE TANNINS AND PROANTHOCYANIDINS FROM GREEN TEA
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Two hydrolysable tannins were isolated from green tea, and their structures were characterized by chemical and spectral means as 1,4,6-tri-O-galloyl-β-D-glucose and 1-O-galloyl-4,6-(-)-hexahydroxydiphenoyl-β-D-glucose.In addition, a new proanthocyanidin gallate was isolated, together with the known procyanidins B-2, B-4 and C-1.The structure of the proanthocyanidin was established as epigallocatechin-(4β -> 8)-3-O-galloylepicatechin.Key Word Index - Thea sinensis; Theaceae; green tea; ellagitannin; gallotannin; proanthocyanidin; polyphenol.
- Nonaka, Gen-Ichiro,Sakai, Ryo,Nishioka, Itsuo
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p. 1753 - 1756
(2007/10/02)
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- DIMERIC PROANTHOCYANIDINS OF Hibiscus cannabinus
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Two dimeric proanthocyanidins have been isolated from the bark and roots of kenaf of variety Uzbekskii 1574.On the basis of chemical transformations and NMR and mass-spectral analyses it has been established that the proanthocyanidins have the structure of a dehydro dimer of 3,3',4',5,7-pentahydroxyflavan and that of 8-(3-galloyloxy-3',4',5,7-tetrahydroxyflavan-4-yl)-3,3',4',5,7-pentahydroxyflavan, respectively, with a C4-C8 (or C6) bond between the flavan moieties.
- Fam Van Tkhin',Makhsudova, B.,Otroshchenko, O. S.
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p. 310 - 314
(2007/10/02)
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- Tannins and Related Compounds. I. Rhubarb (1)
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Three new tannin-related compounds (I, II and III), along with lindleyin (IV), (+)-catechin, 3-O-galloyl-(-)-epicatechin, gallic acid, 3,5,4'-trihydroxystilbene 4'-O-β-D-(6''-O-galloyl)-glucopyranoside, 3,5,4'-trihydroxystilbene 4'-O-β-D-glucopyranoside and 4-(4'-hydroxyphenyl)-2-butanone 4'-O-β-D-glucopyranoside, have been isolated from commercial rhubarb (Rhei Rhizoma).On the basis of spectral and chemical evidence, I, II and III were characterized as 3,3'-di-O-galloylprocyanidin B-2, 3-O-galloylprocyanidin B-1 and 1,2,6-tri-O-galloylglucose, respectively.The occurence of IV in rhubarb is of great significance, since IV has been reported to have analgesic and anti-inflammatory activities almost equal to those of aspirin and phenylbutanone.Tannins in rhubarb have been partially purified (designated as rhatannin (V)).Thiolysis degradation and enzymatic hydrolysis have shown that V is mainly composed of C4 to C8 linked 3-O-galloyl-(-)-epicatechin units in the extension part (upper part) with either 3-O-galloyl-(-)-epicatechin or (+)-catechin unit in the lower terminal part.Keywords. rhubarb; polygonaceae; 3,3'-di-O-galloylprocyanidin B-2; 3-O-galloylprocyanidin B-1; 1,2,6-tri-O-galloylglucose; lindleyin; rhatannin
- Nonaka, Gen-Ichiro,Nishioka, Itsuo,Nagasawa, Tetsuro,Oura, Hikokichi
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p. 2862 - 2870
(2007/10/02)
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