Antimetastatic Properties of Tea Polyphenols

Metastasis of cells from primary site to distant organs involves a series of sequential steps, and molecules responsible for all these events are understandably considered as potential targets for metastasis management. Tea polyphenols, the secondary metabolites of the tea leaf Camellia sinensis, are increasingly being studied for their antimetastatic properties. In this article, effects of green tea polyphenols (GTP) and black tea polyphenols (BTP) on the molecules and events involved in metastasis are discussed in detail. As tea is a very popular beverage, tea polyphenols are expected to be potential chemopreventive agents that can be taken with normal diet and can be nontoxic due to their natural origin. However, individual variations in metabolic pathways, bioavailability, dose, and toxicity are some important factors that can modify the effectiveness of tea polyphenols within the human system.

In Vitro and In Silico Studies of the Molecular Interactions of Epigallocatechin-3-O-gallate (EGCG) with Proteins That Explain the Health Benefits of Green Tea

Green tea has been shown to have beneficial effects on many diseases such as cancer, obesity, inflammatory diseases, and neurodegenerative disorders. The major green tea component, epigallocatechin-3-O-gallate (EGCG), has been demonstrated to contribute to these effects through its anti-oxidative and pro-oxidative properties. Furthermore, several lines of evidence have indicated that the binding affinity of EGCG to specific proteins may explain its mechanism of action. This review article aims to reveal how EGCG-protein interactions can explain the mechanism by which green tea/EGCG can exhibit health beneficial effects. We conducted a literature search, using mainly the PubMed database. The results showed that several methods such as dot assays, affinity gel chromatography, surface plasmon resonance, computational docking analyses, and X-ray crystallography have been used for this purpose. These studies have provided evidence to show how EGCG can fit or occupy the position in or near functional sites and induce a conformational change, including a quaternary conformational change in some cases. Active site blocking, steric hindrance by binding of EGCG near an active site or induced conformational change appeared to cause inhibition of enzymatic activity and other biological activities of proteins, which are related to EGCG’s biological oligomer and formation of their toxic aggregates, leading to the prevention of neurodegenerative diseases and amyloidosis. In conclusion, these studies have provided useful information on the action of green tea/catechins and would lead to future studies that will provide further evidence for rational EGCG therapy and use EGCG as a lead compound for drug design.

Inhibition of attachment of oral bacteria to immortalized human gingival fibroblasts (HGF-1) by tea extracts and tea components

Background

Tea has been suggested to promote oral health by inhibiting bacterial attachment to the oral cavity. Most studies have focused on prevention of bacterial attachment to hard surfaces such as enamel.

Findings

This study investigated the effect of five commercial tea (green, oolong, black, pu-erh and chrysanthemum) extracts and tea components (epigallocatechin gallate and gallic acid) on the attachment of five oral pathogens (Streptococcus mutans ATCC 25175, Streptococcus mutans ATCC 35668, Streptococcus mitis ATCC 49456, Streptococcus salivarius ATCC 13419 and Actinomyces naeslundii ATCC 51655) to the HGF-1 gingival cell line. Extracts of two of the teas (pu-erh and chrysanthemum) significantly (p < 0.05) reduced attachment of all the Streptococcus strains by up to 4 log CFU/well but effects of other teas and components were small.

Conclusions

Pu-erh and chrysanthemum tea may have the potential to reduce attachment of oral pathogens to gingival tissue and improve the health of oral soft tissues.

Health-promoting effects of green tea

Green tea is manufactured from the leaves of the plant Camellia sinensis Theaceae and has been regarded to possess anti-cancer, anti-obesity, anti-atherosclerotic, anti-diabetic, anti-bacterial, and anti-viral effects. Many of the beneficial effects of green tea are related to the activities of (-)-epigallocatechin gallate (EGCG), a major component of green tea catechins. For about 20 years, we have engaged in studies to reveal the biological activities and action mechanisms of green tea and EGCG. This review summarizes several lines of evidence to indicate the health-promoting properties of green tea mainly based on our own experimental findings.

Epigallocatechin-3-gallate (EGCG) downregulates gelatinase-B (MMP-9) by involvement of FAK/ERK/NFkappaB and AP-1 in the human breast cancer cell line MDA-MB-231

Epigallocatechin-3-gallate (EGCG) is effective against the initiation, progression, and invasion of carcinogenesis.Matrix-metalloproteinases (MMPs) are a family of endopeptidases that hydrolyze the majority of extracellular proteins. MMP-9 is one of the most important members of the family and we observed the effect of EGCG on MMP-9 in the human breast cancer cell line, MDA-MB-231.The effect of EGCG on MMP-9 was studied by gelatin zymography, western blot, quantitative and semiquantitative real-time RT-PCR, immunoflourescence, cell adhesion assay, enzyme-linked immunosorbent assay,and electrophoretic mobility shift assay. EGCG treatment reduced the activity, protein, and mRNA expression ofMMP-9 and enhanced the expression of the tissue inhibitor of MMP 1 (TIMP-1). EGCG downregulated the activation of focal adhesion kinase (FAK) and extracellular regulated kinase (ERK), reduced the adhesion of MDA-MB-231 cells to fibronectin and vitronectin, and reduced the mRNA expression of the integrin receptors alpha5beta1 and alphavbeta3. The expression of the nuclear factor kappa B (NFjB), and the DNA binding activity of NFjB and activator protein 1 (AP1)to MMP-9 promoter were noticeably reduced on EGCG treatment. Upregulation of TIMP-1 and disruption of the functional status of integrin receptors may indicate decreased MMP-9 activation; inhibition of FAK andERK activation might indicate disruption in the FAK/ERK-induced MMP-9 secretion and induction. Decreased DNA binding activity of NFjB and AP1 to MMP-9 promoter might indicate transcriptional deregulation of MMP-9 gene on EGCG treatment. We propose EGCG as a potential inhibitor of the expression and activity of MMP-9 by a process involving FAK/ERK and transcription factorsin MDA-MB-231.