Phytochemicals are the chemical compounds naturally present in plants and haveprotective or disease-preventive properties. On account of their antioxidantproperties, some phytochemicals guard the cells against oxidative damage andreduce the risk of developing several cancer types, whereas others induce reactiveoxygen species (ROS) to increase ER stress level to an extent that it leads tocellular apoptosis. The intracellular concentration of ROS is generally raised in thetumour cells, exposing a key role of ROS in the course of carcinogenesis and canceradvancement. Raised levels of ROS induce mutations and thus promote cancer(Yang et al. 2013). Under mild oxidative stress environment, ER behaves as a cellularstress sensor, seeking to restore cellular homeostasis. If the stress-induceddamage is widespread, cellular apoptosis is initiated in ER by means of the unfoldedprotein response (Hetz 2012). Phytochemicals restrict DNA replication leading toinhibition of cancer cell proliferation.
