EGCG makes up more than 40% of the total polyphenolic mixture and appears to be the polyphenols most responsible for green tea’s beneficial effects.
EGCG (epigallocatechin gallate) and EGC (epigallocatechin) competitively inhibit tyrosinase, the rate limiting enzyme in the synthesis of melanin-dihydroxyphenylalanine, norepinephrine, and epinephrine. EGCG is particularly abundant in green tea and biologically active.
EGCG and EGC competitively inhibit COMT (catechol-O-methyltransferase), one of the enzymes in the metabolism of catecholamines, which is associated with Parkinson’s disease.
These tea compounds have been shown to protect against iron-induced deficits in striatal neurotransmitter concentrations, as well as to decrease oxidative damage in the substatia nigra both of which are common etiological features associated with the disease.
A high activity of prolylendopeptidase is found in patients with Alzheimer’s disease and other neuropathologic disorders, and some studies have shown that this enzymes may be inhibited by EGCG.
Neurological effects of tea
