Functions of polyphenols and its anticancer properties in biomedical research: a narrative review

Cancer is a major health concern as the incidence is growing worldwide and still lacks successful therapies. Plant-derived functional foods are getting considerable attention, primarily due to their safety and therapeutic potential. Polyphenols are a group of mostly natural, water-soluble organic compounds. Here, we review the functions of selected polyphenols and their anticancer properties on numerous cancer cell lines and their mechanisms. The literature search was performed using the electronic database PubMed, Google scholar up to June 2020, with the following keywords-polyphenol, polyphenol anticancer, quercetin anticancer, resveratrol anticancer, curcumin anticancer, and kaempferol anticancer. Chemical structures of the selected polyphenols were obtained using the ChemDraw program. The initial search identified 40,554 polyphenols papers and among that, 2,559 were limited to polyphenol and cancer, 987 quercetin and cancer, 2,174 curcumin and cancer, 1,079 resveratrol and cancer, and 226 were limited to kaempferol and cancer. A total of 84 papers are included in this review paper. Most studies report the multiple anticarcinogenic properties of plant-derived polyphenols, including its inhibitory effects on the proliferation of cancer cells, tumor expansion, angiogenesis, inflammation, and metastasis. Besides, some studies shows potential synergistic effects when polyphenol treatment combined with chemotherapeutic agents. Anticancer effects of polyphenolic compounds like quercetin, curcumin, resveratrol, and kaempferol are investigated on numerous cancer cell lines and have shown prominent results. The present review provides a direction to determine the anticarcinogenic ability of the selected polyphenols in vitro and in vivo. Consequently, the use of polyphenols in cancer treatment should be investigated in-depth in the future.