Williamson MP, McCormick TG, Nance CL, Shearer WT: Epigallocatechin Gallate, the Main Polyphenol in Green Tea, Binds to the T-cell Receptor, CD4: potential for HIV-1 therapy. J Allergy Clin Immunol. 2006;188:1369-1374.
Background. The polyphenol compound epigallocatechin gallate (EGCG), found in green tea, has been reported to have antitumor, anti-inflammatory, antioxidative, antiproliferative, antibacterial, and antiviral effects. It has recently been suggested that EGCG may also have an anti–HIV-1 effect in preventing binding of HIV-1 glycoprotein (gp) 120 to the CD4 molecule on T cells. A series of experiments were performed to evaluate the potential therapeutic value of EGCG for HIV-1 infection.
Methods. The experiments were designed to determine whether EGCG binds to CD4 at the gp120 attachment site, thus resulting in physiologically relevant inhibition of gp10 binding. Binding of CGCG to the CD4-IgG2 fusion protein was assessed by nuclear magnetic resonance spectroscopy, compared with that of (-)-catechin—a control polyphenol that does not bind to CD4. Flow cytometry was used to assess gp120 binding to human CD4_ T cells.
Results. Addition of CD4 to EGCG was associated with a consistent decline in nuclear magnetic resonance signal intensity, compared to no change with (-)-catechin. Saturation transfer difference experiments showed strong saturation at the aromatic rings of EGCG after CD4 was added, whereas identical concentrations of (-)-catechin produced substantially lesser effects. Thus EGCG/CD4 binding was strong enough to lead to a significant reduction in gp120/CD4 binding. The binding site for EGCG appeared to be located in the D1 domain of CD4, which is also the site of gp120 binding. Flow cytometry showed that a physiologically relevant 0.2 _mol/L concentration of EGCG inhibited binding of gp120 to isolated human CD4_ T cells.
Conclusion. The green tea polyphenol EGCG binds with high affinity to the CD4 molecule, thus inhibiting binding between gp120 and human CD4_ T cells. These experimental findings support the suggestion that ECGG might have therapeutic value against HIV-1 infection.
Commentary: Evidence for the potential health benefits of green tea or substances that are in green tea continues to mount. Epigallocatechin gallate, a component of green tea, has been demonstrated to block HIV entry into the cell through binding to certain receptor sites.
Copyright 2007, EXPLORE: The Journal of Science and Healing
Reprinted with permission.