substrates, yielding yellow oxidation products, but the
long alkyl (>C10) chain esters inhibited the enzyme without
producing the pigmented products, indicating that
the carbon chain length was related to their tyrosinase
inhibitory activity(64,66-68). The most abundant hydroxyflavanols
in green tea included ECG [(-)epicatechin-3-
O-gallate], GCG [(-)gallocatechin-3-O-gallate], EGCG
[(-)epigallocatechin-3-O-gallate], and EGC [(-)epigallocatechin].
It was reported that EGCG and hinokitiol
(structurally not related to hydroxyflavanols) were not
only tyrosinase inhibitors, but also agents that decreased
MITF production in cells(69).
(IV) Procyanidins
Procyanidins, polymers of catechins found in tea and
fruits such as apples and grapes had been recently introduced
as inhibitors of melanogenesis(70,71). Procyanidinrich
extract would reduce DOPA-postive melanocytes and
8-hydroxy-2Œ-deoxyguanosine positive melanin containing
cells, and this effect may related to inhibition of tyrosinase
and ROS-induced melanocytes proliferation(70).