Triangulating the pharmacological properties of thymoquinone in regulating reactive oxygen species, inflammation, and cancer: Therapeutic applications and mechanistic pathways

Cancer is a heterogeneous disease with high morbidity and mortality rate involving changes in redox balance and deregulation of redox signalling. For decades, studies have involved developing an effective cancer treatment to combat treatment resistance. As natural products such as thymoquinone have numerous health benefits, studies are also focusing on using them as a viable method for cancer treatment, as they have minimal toxic effects compared with standard cancer treatments. Thymoquinone studies have shown numerous mechanisms of action, such as regulation of reactive species interfering with DNA structure, modulating various potential targets and their signalling pathways as well as immunomodulatory effects in vitro and in vivo. Thymoquinone's anti-cancer effect is mainly due to the induction of apoptotic mechanisms, such as activation of caspases, downregulation of precancerous genes, inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), anti-tumour cell proliferation, ROS regulation, hypoxia and anti-metastasis. Insight into thymoquinone's potential as an alternative treatment for chemoprevention and inflammation can be accomplished via compiling these studies, to provide a better understanding on how and why it works, as well as its interactions with common chemotherapeutic treatments.