Flexion of Nrf2 by tea phytochemicals: A review on the chemopreventive and chemotherapeutic implications

Nuclear factor erythroid 2 [NF-E2]-related factor 2 (Nrf2), the redox-sensitive transcription factor, plays a key role in stress-defense and detoxification. Nrf2 is tightly controlled by its negative regulator cum sensor Kelch-[ECH]-associated protein 1 (Keap1). Nrf2 is well known for its dual nature owing to its cancer preventive and cancer promoting abilities. Modulation of this biphasic nature of Nrf2 signaling by phytochemicals may be a potential cancer preventive and anticancer therapeutic strategy. Phytocompounds may either act as Nrf2-activator or Nrf2-inhibitor depending on their differential concentration and varied cellular environment. Tea is not just the most popular global beverage with innumerable health-benefits but has well-established chemo-preventive and chemotherapeutic effects. Various types of tea infusions contain a wide range of bioactive compounds, such as polyphenolic catechins and flavonols, which are endowed with potent antioxidant prop-erties. Despite of their rapid biotransformation and poor bioavailability, regular tea consumption is risk -reductive for several cancer forms. Tea catechins show their dual Nrf2-modulatory effect by directly acting on Nrf2-Keap1 or their upstream regulators and downstream effectors in a highly case-specific manner. In this re-view, we have tried to present a comprehensive evaluation of the Nrf2-mediated chemopreventive and chemotherapeutic applications of tea in various preclinical cancer models, the Nrf2-modulatory mechanisms, and the limitations which need to be addressed in future research.

Automated summary

Nuclear factor erythroid 2 [NF-E2]-related factor 2 (Nrf2) is a redox-sensitive transcription factor that plays a key role in stress-defense and detoxification. Tea, with its bioactive compounds, has the potential to modulate the Nrf2 signaling and may be used as a preventive and therapeutic strategy for cancer. However, the rapid biotransformation and low bioavailability of tea compounds need further investigation.