Anticancer Potential of Quercetin, Epigallocatechin Gallate, Kaempferol, Apigenin, and Curcumin against Several Human Carcinomas

Cancer remains a global health problem that requires constant research for the development of new treatment strategies. Flavonoids, a diverse group of naturally occurring polyphenolic compounds abundant in fruits, vegetables, and other plant sources, have received considerable attention for their potential anticancer properties. This review aimed to provide a comprehensive overview of the current scientific literature on five specific natural flavonoids, namely quercetin, Epigallocatechin Gallate (EGCG), kaempferol, apigenin, and curcumin that have been widely reported in numerous carcinomas and evaluate their effectiveness and mechanisms in fighting different types of cancer. Known for its antioxidant and anti-inflammatory properties, quercetin has shown promise in inhibiting cancer cells and modulating key signaling pathways. EGCG, a prominent catechin found in green tea, has been extensively studied for its ability to induce apoptosis and inhibit angiogenesis, highlighting its potential as an anticancer agent. Kaempferol has antioxidant and anti-inflammatory effects and has shown anticancer potential by modulating cellular processes involved in tumor development. Apigenin, abundant in parsley and chamomile, has been shown to exert anticancer properties by interrupting the cell cycle and inducing apoptosis in cancer cells. Curcumin has shown several anticancer effects, including inhibiting cell proliferation, inducing apoptosis, and modulating inflammatory pathways. Despite these promising findings, it is essential to recognize the complexity of cancer biology and the need for further research to clarify the precise mechanisms of action of these natural flavonoids and optimize their therapeutic applications. Furthermore, understanding flavonoids' potential synergy and interactions with traditional cancer therapies is paramount for developing effective combinatorial strategies. This review thus aimed to summarize the current knowledge on these natural flavonoids and provide insight into their potential role as an adjunctive or stand-alone therapy in the fight against breast, prostate, colon, lung, skin, ovarian, liver, and pancreatic cancer.