MILWAUKEE -- The major component of green tea prevents the binding of HIV to human T cells, the first step in HIV infection, according to a study and an accompanying editorial published in the November 2003 issue of the Journal of Allergy and Clinical Immunology (JACI). The JACI is the peer- reviewed journal of the American Academy of Allergy, Asthma & Immunology (AAAAI).
Green tea is the nonoxidized, unfermented product of the leaves from the evergreen plant, Camellia sinensis. It is made up of catechins, the most abundant of which is Epigallocatechin Gallate (EGCG). It is believed that EGCG is responsible for the vast array of presumed health benefits green tea possesses, such as the prevention of cancer and cardiovascular disease. Several studies have reported that EGCG may also have a protective effect against HIV infection.
Kuzushige Kawai, MD, and colleagues from the University of Tokyo demonstrated in laboratory studies that EGCG blocked the binding of HIV envelope glycoprotein to human CD4 molecules on human T cells. The CD4 molecule acts as a binding target for HIV vesicles and plays an important role in the aggressive infection process.
Researchers found that EGCG showed a strong affinity for the CD4 molecule, and by binding them, could effectively prevent the binding of the HIV glycoprotein envelope. These findings open new doors for the clinical application of EGCG as a new anti-HIV drug.
Further research into the potential preventive effects of the green tea catechin EGCG on HIV infection is being conducted by researchers at the National Center for Macromolecular Imaging at Baylor College of Medicine in Houston, Texas, and the Department of Molecular Biology and Biotechnology at the University of Sheffield in Sheffield, England. In an editorial accompanying the Kawai study, William T. Shearer, MD, PhD, FAAAAI, and colleagues from Baylor report on the use of advanced computer programs to better define the nature and power of the binding effects of EGCG to the CD4 molecule.
"It might be possible to locate the precise EGCG binding spot on the CD4 molecule and compare that spot to where the HIV glycoprotein normally binds, in an attempt to explain the exciting discovery of Dr. Kawai," said Shearer. "Molecular modeling of a drug form of EGCG for HIV infection might be a further development of these investigations."
The study and the accompanying editorial are the first to describe the inhibitory effect of green tea catechin in the attachment of HIV to human T cells and offer a new perspective for the treatment of the life-threatening disease.
Researchers do not suggest the use of green tea to counter HIV infection or as an alternative therapy to current anti-viral agents now used. The concentrations of EGCG used to demonstrate these inhibitory effects in laboratory studies are many times over the blood concentration that could be achieved by normal green tea consumption. However, the current findings call for additional research into the clinical application of green tea catechin as an anti-HIV drug.
Source: American Academy of Allergy, Asthma and Immunology