Tea and Its Components Prevent Cancer: A Review of the Redox-Related Mechanism

Abstract

Cancer is a worldwide epidemic and represents a major threat to human health and survival. Reactive oxygen species (ROS) play a dual role in cancer cells, which includes both promoting and inhibiting carcinogenesis. Tea remains one of the most prevalent beverages consumed due in part to its anti- or pro-oxidative properties. The active compounds in tea, particularly tea polyphenols, can directly or indirectly scavenge ROS to reduce oncogenesis and cancerometastasis. Interestingly, the excessive levels of ROS induced by consuming tea could induce programmed cell death (PCD) or non-PCD of cancer cells. On the basis of illustrating the relationship between ROS and cancer, the current review discusses the composition and efficacy of tea including the redox-relative (including anti-oxidative and pro-oxidative activity) mechanisms and their role along with other components in preventing and treating cancer. This information will highlight the basis for the clinical utilization of tea extracts in the prevention or treatment of cancer in the future.

Oxidation of Hydrogen Sulfide by Quinones: How Polyphenols Initiate Their Cytoprotective Effects

“…There is increasing interest in the health benefits of a variety of teas [ 1 ]. Green tea and its polyphenolic catechins are especially noteworthy for their anticancer properties [ 2 , 3 , 4 , 5 ], protection of the cardiovascular system and associated metabolic diseases [ 6 , 7 , 8 ] and protection against neurodegenerative diseases [ 9 , 10 ]. The presumed biological efficacy of these polyphenols is attributed to their antioxidant properties and ability to serve as free radical scavengers and quench reactive oxygen species (ROS) [ 11 , 12 ], although they may also form covalent adducts with protein and non-protein thiols [ 13 , 14 ] and may bind to, or sterically interfere with, enzymes or other regulatory proteins [ 15 ].…”

Green tea polyphenolic antioxidants oxidize hydrogen sulfide to thiosulfate and polysulfides: A possible new mechanism underpinning their biological action

“…Today, tea is the second most consumed beverage after water [ 2 ]. Numerous health benefits have been attributed to the ingestion of tea and its bioactive constituents including anticancer effects [ [3] , [4] , [5] , [6] , [7] , [8] , [9] ], protection against cardiovascular diseases [ 10 , 11 ] and metabolic syndrome [ [12] , [13] , [14] , [15] , [16] ], protectant activity against Alzheimer's, Parkinson's and other neurodegenerative diseases [ [17] , [18] , [19] , [20] , [21] ] as well as affecting mood and alleviating stress [ 22 , 23 ], antiviral activity [ 24 ], protection against infectious diseases [ 25 ] and perturbation of the gut microflora [ 26 ] and against gastrointestinal inflammatory diseases [ 27 ], while also improving fertility [ 28 ]. Most of these benefits are attributed specifically to green tea, which comprises twenty percent of total tea consumption.…”

Novel N,N′-Disubstituted Acylselenoureas as Potential Antioxidant and Cytotoxic Agents

“…Although the connection among reactive oxygen species (ROS) and cancer was suggested in the 1980s [1], in the last years, the scientific community has driven their attention to cellular oxidative stress for treating cancer [2][3][4]. ROS homeostasis is required for normal cell survival and proper cell 2 of 16 signaling, and the excessive production of ROS is considered as an important molecular hallmark for carcinogenesis [5][6][7]. Typically, endogenous radicals usually arise from certain ROS, such as the hydroxyl radical ( − OH), hydrogen peroxide (H 2 O 2 ), the superoxide anion ( • O 2 − ), and singlet oxygen ( 1 O 2 ).…”