Show of the Week June-8-2012

 

Epigallocatechin-3-gallate is a new inhibitor of hepatitis C virus entry.

 

Antiviral effects of ascorbic and dehydroascorbic acids in vitro

 

The effect of black tea on risk factors of cardiovascular disease in a normal population

 

Black tea reduces uric acid and C-reactive protein levels in humans susceptible to cardiovascular diseases

 

Black tea polyphenols inhibit tumor proteasome activity

 

Black tea polyphenol theaflavins inhibit aromatase activity

 

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(-)-Epigallocatechin-3-gallate is a new inhibitor of hepatitis C virus entry.

Hepatology. 2012 Mar;55(3):720-9

Authors: Calland N, Albecka A, Belouzard S, Wychowski C, Duverlie G, Descamps V, Hober D, Dubuisson J, Rouillé Y, Séron K

Here, we identify (-)-epigallocatechin-3-gallate (EGCG) as a new inhibitor of hepatitis C virus (HCV) entry. EGCG is a flavonoid present in green tea extract belonging to the subclass of catechins, which has many properties. Particularly, EGCG possesses antiviral activity and impairs cellular lipid metabolism. Because of close links between HCV life cycle and lipid metabolism, we postulated that EGCG may interfere with HCV infection. We demonstrate that a concentration of 50 μM of EGCG inhibits HCV infectivity by more than 90% at an early step of the viral life cycle, most likely the entry step. This inhibition was not observed with other members of the Flaviviridae family tested. The antiviral activity of EGCG on HCV entry was confirmed with pseudoparticles expressing HCV envelope glycoproteins E1 and E2 from six different genotypes. In addition, using binding assays at 4°C, we demonstrate that EGCG prevents attachment of the virus to the cell surface, probably by acting directly on the particle. We also show that EGCG has no effect on viral replication and virion secretion. By inhibiting cell-free virus transmission using agarose or neutralizing antibodies, we show that EGCG inhibits HCV cell-to-cell spread. Finally, by successive inoculation of naïve cells with supernatant of HCV-infected cells in the presence of EGCG, we observed that EGCG leads to undetectable levels of infection after four passages. CONCLUSION: EGCG is a new, interesting anti-HCV molecule that could be used in combination with other direct-acting antivirals. Furthermore, it is a novel tool to further dissect the mechanisms of HCV entry into the hepatocyte.—PMID: 22105803 [PubMed – indexed for MEDLINE]

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Antiviral effects of ascorbic and dehydroascorbic acids in vitro.

Furuya A, Uozaki M, Yamasaki H, Arakawa T, Arita M, Koyama AH.

Source–Department of Cellular and Molecular Medicine, Wakayama Medical University Graduate School of Medicine, Wakayama 641-8509, Japan.

In the present study, ascorbic acid weakly inhibited the multiplication of viruses of three different families: herpes simplex virus type 1 (HSV-1), influenza virus type A and poliovirus type 1[U1] . Dehydroascorbic acid, an oxidized form of ascorbic acid and hence without reducing ability, showed much stronger antiviral activity than ascorbic acid, indicating that the antiviral activity of ascorbic acid is due to factors other than an antioxidant mechanism. Moreover, addition of 1 mM Fe3+, which oxidizes ascorbic acid to dehydroascorbic acid and also enhances the formation of hydroxyl radicals by ascorbic acid in the culture media, strongly enhanced the antiviral activity of ascorbic acid to a level significantly stronger than that of dehydroascorbic acid. Although both ascorbic acid and dehydroascorbic acid showed some cytotoxicity, the degree of cytotoxicity of the former was 10-fold higher than the latter, suggesting that the observed antiviral activity of ascorbic acid with and without ferric ion is, at least in part, a secondary result of the cytotoxic effect of the reagent, most likely due to the free radicals. However, the possibility that oxidation of ascorbic acid also contributed to the antiviral effects of ascorbic acid exists, in particular in the presence of ferric ion, since dehydroascorbic acid exhibited a very strong antiviral activity. Characterization of the mode of antiviral action of dehydroascorbic acid revealed that the addition of the reagent even at 11 h post infection almost completely inhibited the formation of progeny infectious virus in the infected cells, indicating that the reagent inhibits HSV-1 multiplication probably at the assembly process of progeny virus particles after the completion of viral DNA replication.

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Benefits of Black Tea

 

The effect of black tea on risk factors of cardiovascular disease in a normal population.

Bahorun T, Luximon-Ramma A, Neergheen-Bhujun VS, Gunness TK, Googoolye K, Auger C, Crozier A, Aruoma OI.

Source-ANDI Centre of Excellence for Biomedical and Biomaterials Research, CBBR Building, MSIRI, University of Mauritius, Réduit, Republic of Mauritius.

OBJECTIVES-A prospective randomized controlled clinical trial determined the effect of Mauritian black tea consumption on fasting blood plasma levels of glucose, lipid profiles and antioxidant status in a normal population.

METHODS-The study group (71%) consumed 3 x 200ml of black tea infusate/day for 12weeks without additives followed by a 3week wash-out. The control group (29%) consumed equivalent volume of hot water for same intervention period.

RESULTS–The tea used had high levels of gallic acid derivatives (50±0.4mg/L), flavan-3-ols (42±2mg/L), flavonols (32±1mg/L) and theaflavins (90±1mg/L). Daily 9g supplementation of black tea infusate induced, in a normal population, a highly significant decrease of fasting serum glucose (18.4%; p<0.001) and triglyceride levels (35.8%; p<0.01), a significant decrease in LDL/HDL plasma cholesterol ratio (16.6%; p<0.05) and a non significant increase in HDL plasma cholesterol levels (20.3%), while a highly significant rise in plasma antioxidant propensity (FRAP: 418%; p<0.001) was noted .

CONCLUSION-Black tea consumed within a normal diet contributes to a decrease of independent cardiovascular risk factors and improves the overall antioxidant status in humans.

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Black tea reduces uric acid and C-reactive protein levels in humans susceptible to cardiovascular diseases.

Bahorun T, Luximon-Ramma A, Gunness TK, Sookar D, Bhoyroo S, Jugessur R, Reebye D, Googoolye K, Crozier A, Aruoma OI.

Source–Department of Biosciences, Faculty of Science, University of Mauritius, Réduit, Mauritius. tbahorun@uom.ac.mu

The effect of black tea on the level of uric acid (UA) and C-reactive proteins (CRP) in humans susceptible to ischemic heart diseases was assessed in a prospective randomized controlled study. The study group consumed 9 g of black tea (equivalent to three cups of tea) daily for 12 weeks without additives followed by a 3-week wash-out (with control group consuming equivalent volume of hot water). Black tea consumption induced a highly significant decrease in the high uric acid baseline groups > 6 mg/dL by 8.5%; p < 0.05. For men and women in the base line group > 7 mg/dL, the decrease was 9.4% and 7.1%, respectively. In the low baseline serum uric acid levels there was a non-significant increase of 3.7% and 15% in men and women, respectively. C-reactive protein in the high risk group > 3mg/L was significantly decreased by 53.4% and 41.1% in men and women, respectively. For the non-supplemented group in this range the changes were 3.7% decrease for men and 2.9% increase for women. Tea supplementation-associated decrease in plasma uric acid and C-reactive protein levels may benefit humans at high risk of cardiovascular events and may augment drug therapy.–

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Black tea polyphenols inhibit tumor proteasome activity.

Mujtaba T, Dou QP.

Source

The Developmental Therapeutics Program, Barbara Ann Karmanos Cancer Institute and Department of Oncology, School of Medicine, Wayne State University, Detroit, MI 48201-2013, USA.

Abstract

Tea is a widely consumed beverage and its constituent polyphenols have been associated with potential health benefits. Although black tea polyphenols have been reported to possess potent anticancer activities, the effect of its polyphenols, theaflavins on the tumor’s cellular proteasome function, an important biological target in cancer prevention, has not been carefully studied. Here black tea extract (T5550) enriched in theaflavins inhibited the chymotrypsin-like (CT) activity of the proteasome and proliferation of human multiple myeloma cells in a dose-dependent manner. Also an isolated theaflavin (TF-1) can bind to, and inhibit the purified 20S proteasome, accompanied by suppression of tumor cell proliferation, suggesting that the tumor proteasome is an important target whose inhibition is at least partially responsible for the anticancer effects of black tea.

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Black tea polyphenol theaflavins inhibit aromatase activity and attenuate tamoxifen resistance in HER2/neu-transfected human breast cancer cells through tyrosine kinase suppression.

Way TD, Lee HH, Kao MC, Lin JK.

Source

Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, No. 1, Section. 1, Jen-Ai Road, Taipei 10018.

Abstract

The aromatase enzyme, which converts androstenedione to oestrone, regulates the availability of oestrogen to support the growth of hormone-dependent breast tumours. In this study, we investigated the inhibitory effects of black tea polyphenols on aromatase activities. We found that black tea polyphenols, TF-1, TF-2 and TF-3, significantly inhibited rat ovarian and human placental aromatase activities. In addition, using an in vivo model, these black tea polyphenols also inhibited the proliferation induced by 100 nM dehydroepiandrosterone (DHEA) in MCF-7 cells. Transfection of HER2/neu in MCF-7 breast cancer cells appeared to be associated with an increased resistance of the cells to hormonal therapy. Interestingly, unlike the selective oestrogen receptor modulator (SERM) tamoxifen, black tea polyphenols had antiproliferation effects in breast cancer cells with hormonal resistance. The inhibitory effect of black tea polyphenols on hormone-resistant breast cancer cells suppressed the basal receptor tyrosine phosphorylation in HER2/neu-overexpressing MCF-7 cells. These findings suggest the use of black tea polyphenols may be beneficial in the chemoprevention of hormone-dependent breast tumours and represent a possible remedy to overcome hormonal resistance of hormone-independent breast tumours.

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TOP B


[U1]This would be dose dependent the stronger the dose the higher the success

 

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