EFFECTS OF TEA POLYPHENOL COMPONENTS ON REVERSION OF TUMOR MULTIDRUG RESISTANCE

The effects of tea polyphenol (TP) and its main components,(-)epicatechin (EC), (-)epicatechin gallate(ECG), epigallocatechin (EGC) and (-)epigallocatechin gallate (EGCG) with caffeine on reversion of tumor multidrug resistance (MDR) are investigated by using MCF7/Adr cell line and 99TcmMIBI as a substrate of Pglucoprotein(Pgp). MCF7/Adr cells are incubated with 99TcmMIBI in the presence or absence of TP or its main components (separate or mixed). The cell uptake of 99TcmMIBI is measured and compared with a contrast to estimate the MDR reversion effect.The experimental results indicate that the native tea polyphenol exhibits a moderate MDR reversion effect. The MDR reversion efficacies of the four main components of TP are found in the sequence ECG>EGC>EC>EGCG. Caffeine as well as the mixture of EGCGECGEGCEC in the mass ratio 10∶3∶2∶1 shows practically no MDR reversion effect.