Green tea extracts are abundant in a number of different polyphenols including catechins, which specifically, are derived from the plant Camellia sinensis. Catechins are believed to be stronger antioxidants than Vitamin C. The four main derivatives of catechins present in green tea are epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG). EGCG is the most abundant of them all, and also acts as a potent antioxidant that can be used for many therapeutic purposes. Research has shown that EGCG may be effective in treating HIV infection, specifically, reducing plaques related to AIDS dementia. This breakthrough suggests that EGCG may be capable of regulating viral load, but it would be an over-reach to think drinking green tea could cure or prevent HIV infection.
Flavnoids, inclulding kaempferol, quercetin, and myricetin can also be found in abundance in green tea. Myricetin in particular, is detected in much higher concentration than in extracts of other plants. These substances, together with polyphenols, give green tea its strong antioxidant activity. The polyphenols in green tea extract are capable of eliminating free radicals at a noticeably faster rate. Consuming green tea also boosts levels of superoxide dismultase (SOD) and glutathione dismultase (GSHP) which promote rancidification, the breakdown of fats, oils and lipids by hydrolysis or oxidation.
Moreover, many studies show green tea exatract exihibits inhibitory effects in many cancer cells. Catechins appears to interrupt cell cycles and hence, inducing apoptosis, programmed cell death. In addition to anti-carcinogenic properties, green tea extract also shows anti-inflammatory characteristics. Japanese material is proven to have bactericidal activity against Streptococcus mutans, which are Gram-positive, faculatively anaerobic bacteria that inhabit in the oral cavity. Maltose levels are also found to be significantly reduced in the mouth after tea consumption. Another interesting property grean tea extract possesses is anti-radiation effect on white rats in radioactive isotope experiments. More on-going research is currently being conducted on the benefits of green tea extracts.
References: (1) http://en.wikipedia.org/wiki/Green_tea_extract (2) http://en.wikipedia.org/wiki/Polyphenol (3) http://en.wikipedia.org/wiki/Catechins (4) http://en.wikipedia.org/wiki/Epigallocatechin_gallate