Studies on the effects of oral administration of nutrient mixture, quercetin and red onions on the bioavailability of epigallocatechin gallate from green tea extract

Abstract

Epigallocatechin gallate (EGCG), a main anticancer component in green tea, has a poor bioavailability in rats and humans due to oxidation, metabolism and its efflux. It was hypothesized that nutrients that address these problems might result in increased bioavailability. Plasma concentrations of EGCG at various time intervals were determined to calculate and compare the pharmacokinetic parameters after oral administration of green tea extract (GTE) or GTE as a nutrient mixture (E) or E + quercetin (Q)/red onions. In rat studies, supplementation of GTE with other nutrients (E) or E + Q raised the plasma C(max) from 55.29 +/- 1.70 to 61.94 +/- 1.70 ng/mL and 94.44 +/- 1.59 ng/mL, respectively. The corresponding t((1/2)) elimination was 2.04 +/- 0.2 h, 3.63 +/- 0.66 h and 2.28 +/- 0.049 h. The AUC(0-24h) were 510.16 +/- 9.88 for GTE, 601.72 +/- 19.10 ng.h/mL for E and 794.08 +/- 15.27 ng x h/mL (p < or = 0.05) for E + Q. In human studies when GTE was fed as GTE or E or E + red onions, the C(max) values were 348.4 +/- 76.6, 384.0 +/- 78.5 ng/mL and 468.4 +/- 131.4. AUC(0-8h) was 1784.1 +/- 56.06 (GTE), 1971.5 +/- 566.5 ng x h/mL (E) and 2490 +/- 878.1 (E + Q), but the change in t((1/2)) elimination was not significant.In conclusion, it is possible to increase the bioavailability of EGCG by supplementing it with nutrients and quercetin.

Preparation of catechin extracts and nanoemulsions from green tea leaf waste and their inhibition effect on prostate cancer cell PC-3

“…However, because of instability, the bioavailability of catechins in vivo remained low. [15][16][17] Thus, through preparation of microemulsion or nanoemulsion for encapsulation of bioactive compounds such as catechin, it is possible to enhance stability so that both bioavailability and biological activity of catechins can be greatly enhanced. More importantly, the efficiency dose of catechins can be reduced substantially to minimize side effects.…”

Gold-conjugated green tea nanoparticles for enhanced anti-tumor activities and hepatoprotection — synthesis, characterization and in vitro evaluation

“…Not surprisingly, EGCG has become one of the most popular phytochemicals in the study of cancer treatment. However, poor bio-availability, susceptibility to oxidation, first-pass metabolism and rapid efflux has been the major hurdles in drug development [18][19][20]. Investigators have shown that the absolute bio-availability of EGCG, EGC and EC after intra-gastric administration of decaffeinated green tea is 0.1%, 14% and 31% [21].…”

Epicatechin acts synergistically with curcumin-induced cytogenotoxic effect in acute promyelocytic leukemia HL-60 cell line

“…The effectiveness of curcumin, however, can be potentiated simply by using a combination of the compound and other polyphenols. This constitutes one of the most natural ways to improve the efficiency of curcumin action, and effectively increase its bioavailability [24,25] .…”