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The Aim: Evaluation of some antioxidants on human colon cancer cells viability and proliferation at various oxygen levels., Material and Methods: Human primary (SW480) and metastatic (SW620) colon cancer cells were cultured at hypoxia (1% oxygen), tissues (10% oxygen) and atmospheric (21% oxygen) normoxia with quercetin, epigallocatechin gallate, lipoic acid, hydroxycitric acid, their mixture, and without studied compounds (control). Antioxidants were used at physiological concentrations. The cell viability was determined by trypan blue dye exclusion and proliferation by MTT assay., Results: The viability of each line ranged from 80% to 97%, and it was independent on the compound and oxygen availability. At hypoxia the cell count of both lines was lower than for the controls in the presence of each studied compound. At tissue normoxia the cell count of primary cancer cells was decreased only with epigallocatechin gallate, whereas metastatic cells were sensitive for each antioxidant., Conclusions: Our results indicated, that the studied antioxidants were not cytotoxic at physiological levels for both pirmary and metastatic colon cancer. Their cytostatic effect depend on the type of cell, oxygen availability and antioxidant concentration.

Numerous in vivo and in vitro studies point to the possibility of using green tea's catechins in chemoprevention of cancer. Recent studies show the inhibitory effects of epigallocatechin gallate on the growth of existing tumors including breast cancer, skin cancer and gastrointestinal tract cancers. Another mode of action of biologically active compounds in green tea involves inhibiting the neoplastic process. All these mechanisms may be useful in prevention and inhibition of the cancer processes (initiation, promotion and progress) by the consumption of green tea. However, clinical studies show contradictory results. Several independent factors, such as the temperature of the beverage, the duration of consumption, the amount of consumed tea and the diet used by the analyzed group, have a decisive effect on the final effect of plant polyphenols on the process of carcinogenesis.

Unlabelled: Obese people are at high risk for developing diabetes, dyslipidemia, hypertension, and cardiovascular diseases, which lead to an increased risk of mortality. Evidence for the potential role of oxidative stress in various diseases and pathophysiological processes suggests that the dietary intake and the therapeutic use of antioxidants may have positive health effects. The aim of the study was: 1) to investigate the ability of the major tea polyphenols: (-)-epigallocatechin gallate (EGCG), theaflavins (TF) and gallic acid (GA) to protect in vitro human neutrophils from oxidative damage induced by phorbol myristate acetate (PMA), 2) estimation the level of reactive oxygen species (ROS) production in obese patient depending on the red tea Pu-Erh drinking, 3) estimation inflammatory marker: CRP., Material and Methods: We tested 14 obese patients (aged 45+/-12 years, women, BMI=34+/-5.1 kg/m2). The inclusion criteria were based on physical examination, BMI, WHR, and the body composition examination based on bioimpedance method. PMA were isolated and oxidant production, in response to 1 microg/ml PMA, was characterized by the production of hydrogen peroxide, nitric oxide and chemiluminescence intensity. CRP level was assayed by the immunoturbidimetric test in serum. Control group consisted of healthy blood donors., Results: Women consuming red tea revealed alteration in reactive oxygen species generation; the relative decrease of RFT was greater after 5 months than that after 1 month of treatment. A decrease in ROS generation after red tea consumption was accompanied by the decrease of ROS in response to tested compounds in normal cells. EGCG and TF showed similar potency in antioxidative activities. Tea polyphenols were not found to modulate CRP level in obese women., Conclusions: Tea may thus represent an important source of dietary antioxidants; there is need for more detailed studies to improve our understanding of the role of tea in reducing risk of major disease states.