Adjuvant Anti-tumor Therapy with Polyphenolic Compounds: A Review

The search for effective methods of treatment and prevention of oncological diseases, despite the successes achieved in recent decades, remains one of the most urgent issues in modern medicine. It is known that chemotherapy and radiation therapy are based on the induction of cell death by increasing the intracellular concentration of reactive oxygen species (ROS). To increase the effectiveness of chemo- and radiotherapy, inducing and increasing oxidative stress in tumor cells has been proposed. A new class of promising adjuvants in combination with anticancer therapy, which has already been shown to be effective in preclinical and clinical studies, includes natural and synthetic polyphenols. Polyphenolic compounds not only exhibit antitumor activity but also significantly reduce the resistance of tumor cells to chemo- and radiotherapy. However, almost all chemotherapeutic drugs and regimens of radiation treatment have a damaging toxic effect on normal tissues, which significantly affects the quality of life of patients, and treatment options for managing these side effects are limited. In this regard, some of the most promising agents for the management of toxic side effects are natural polyphenols. This study discusses the possible molecular mechanisms and prospects for the clinical use of natural and synthetic polyphenolic compounds in chemo- and radiotherapy. In addition, the protective role/effect of polyphenols on the effects of chemo- and radiotherapy in tumor patients is discussed.