**2.5 Antioxidant and ROS cancer prevention**

 Antioxidant capacities describe the biological mechanism of bioactive compounds and how consequence prevents the oxidative stress in normal cell [11, 31, 35, 43]. But these compounds also can act as pro-oxidant agent and increase the ROS production in cancer cell [11, 31, 35, 43]. However, Gu et al. mentioned that those compounds are antioxidants in lower concentration and can be a pro-oxidant at a high level [31]. Also, the intake of polyphenols and phenolic compounds has multiple protective functions against inflammation and tumorigenesis. However, the success of the prevention and treatment also depends on the quality and quantity of bioactive compounds. But, more critical is the fact that the consumption and bioavailability of polyphenols are insufficiently studied to determine the efficacy for disease prevention or disease treatment [15, 35]. From this, derive the relationship among bioactive compounds and the induction of apoptosis, anti-proliferation, antimetastasis and anti-angiogenesis [12]. Further information notices the interaction of the phenolic compound is involved with receptor or enzymes in signal transduction [31]. This interaction may downregulate or upregulate essential proteins in signalling pathways that control the biological process [35].
