Phase IIa chemoprevention trial of green tea polyphenols in high-risk individuals of liver cancer: modulation of urinary excretion of green tea polyphenols and 8-hydroxydeoxyguanosine

Abstract

Modulation of urinary excretion of green tea polyphenols (GTPs) and oxidative DNA damage biomarker, 8-hydroxydeoxyguanosine (8-OHdG), were assessed in urine samples collected from a randomized, double-blinded and placebo-controlled phase IIa chemoprevention trial with GTP in 124 individuals. These individuals were sero-positive for both HBsAg and aflatoxin-albumin adducts, and took GTP capsules daily at doses of 500 mg, 1000 mg or a placebo for 3 months. Twenty-four hour urine samples were collected before the intervention and at the first and third month of the study. Urinary excretion of 8-OHdG and GTP components was measured by HPLC-CoulArray electrochemical detection. The baseline levels of 8-OHdG and GTP components among the three groups showed homogeneity (P > 0.70), and a non-significant fluctuation was observed in the placebo group over the 3 months (P > 0.30). In GTP-treated groups, epigallocatechin (EGC) and epicatechin (EC) levels displayed significant and dose-dependent increases in both the 500 mg group and 1000 mg group (P < 0.05). The 8-OHdG levels did not differ between the three groups at the 1 month collection, with medians of 1.83, 2.08 and 1.86 ng/mg-creatinine for placebo, 500 and 1000 mg group, respectively (P = 0.999). At the end of the 3 months' intervention, 8-OHdG levels decreased significantly in both GTP-treated groups, with medians of 2.02, 1.03 and 1.15 ng/mg-creatinine for placebo, 500 mg and 1000 mg group, respectively (P = 0.007). These results suggest that urinary excretions of EGC and EC can serve as practical biomarkers for green tea consumption in human populations. The results also suggest that chemoprevention with GTP is effective in diminishing oxidative DNA damage.

Cancer chemoprevention and chemotherapy: Dietary polyphenols and signalling pathways

“…In subsequent studies, Jatoi et al [177] and Luo et al [178] have described an antineoplastic activity in terms of biomarkers: diminished PSA levels [177] and decreased urinary 8-hydroxydeoxyguanosine [178] in patients with prostate and hepatic cancer, respectively. In these trials, patients with prostate cancer received 6 g of green tea per day in six divided doses [177], and four capsules daily containing either 500 or 1000 mg of green tea polyphenols were administrated to the patients with liver cancer [178].…”

Hepatitis B virus infection contributes to oxidative stress in a population exposed to aflatoxin B1 and high-risk for hepatocellular carcinoma

“…An antioxidant-based chemoprevention strategy might be appropriate for individuals presently at risk in this area [60]. In fact, chemoprevention trials conducted in this region have shown promising effects: Oltiplaz inhibited phase 1 activation while increasing phase 2 conjugation of aflatoxin [61], and an intervention by green tea polyphenols significantly decreased urinary 8-OHdG levels [62].…”

Limited Sampling Estimates of Epigallocatechin Gallate Exposures in Cirrhotic and Noncirrhotic Patients With Hepatitis C After Single Oral Doses of Green Tea Extract

“…[2][3][4][5][6] Preclinical data in cell culture and animal models suggest green tea may have a role as a chemopreventative agent for many types of cancer, including hepatocellular carcinoma (HCC). [7][8][9][10] After oral absorption, tea catechins undergo extensive methylation, glucuronidation, and sulfation. Rapid methylation of EGCG is catalyzed by liver cytosolic catechol-O-methyltransferase.…”