Inhibitory Effect and Mechanisms of an Anthocyanins- and Anthocyanidins-Rich Extract from Purple-Shoot Tea on Colorectal Carcinoma Cell Proliferation

• Published in: Journal of agricultural and food chemistry 2012-04, Vol.60 (14), p.3686-3692
• Main Authors: Hsu, Chih-Ping, Shih, Yi-Ting, Lin, Bor-Ru, Chiu, Chui-Feng, Lin, Chih-Cheng
• Format: Article
• Language: English
• Subjects: Animals; anthocyanidins; anthocyanins; Anthocyanins - administration & dosage; apoptosis; Apoptosis - drug effects; Biological and medical sciences; caspases; cell cycle; Cell Cycle - drug effects; Cell Line; Cell Line, Tumor; cell proliferation; Cell Proliferation - drug effects; chemoprevention; Coffee, tea and other stimulative beverage industries; colon; Colonic Neoplasms; colorectal neoplasms; Colorectal Neoplasms - pathology; cultivars; cyclin-dependent kinase; Epithelial Cells; flavanols; Flavonoids - analysis; Food industries; Fundamental and applied biological sciences. Psychology; HT29 Cells; Humans; inhibitory concentration 50; phytochemicals; Plant Extracts - administration & dosage; Plant Extracts - chemistry; Rats; tea; Tea - chemistry; Western blotting
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf204619n

One newly bred variety of tea cultivar, purple-shoot tea, was selected to evaluate its antiproliferative effects on colorectal carcinoma cells, as well as normal colon cells. The phytochemicals and identified catechins of purple-shoot tea extract (PTE) were significantly higher than that of ordinary tea, especially the anthocyanins (surpassed by 135-fold) and anthocyanidins (surpassed by 3.5-fold). PTE inhibited the proliferation of COLO 320DM (IC50 = 64.9 μg/mL) and HT-29 (IC50 = 55.2 μg/mL) by blocking cell cycle progression during the G0/G1 phase and inducing apoptotic death. Western blotting indicated that PTE induced cell cycle arrest by reducing the expression of cyclin E and cyclin D1 in COLO 320DM and the upregulation of p21 and p27 cyclin-dependent kinase inhibitors in HT-29. Two cells treated with PTE also indicated the cleavage of PARP, activation of caspase 3, and an increased Bax/Bcl-2 ratio. Our results showed that PTE is a potential novel dietary agent for colorectal cancer chemoprevention.