Pharmacology of natural compounds found in clinical trials used for ameliorating/preventing cancer

In the field of oncology, the use of herbal medicines as a supplemental or alternative treatment option has been generally accepted (Catharanthus roseus, Podophyllum peltatum L., Taxus brevifolia Nutt., Taxus baccata, etc.). As a result, several brand-new cytotoxic chemicals are discovered each year in plants, opening up fresh avenues for the treatment of cancer. The examination of naturally occurring molecular entities that could benefit the pharmaceutical business is a focus of many researchers. The search for clinical efficacy validation follows the discovery of drugs with anticancer activity in preclinical trials. Only 29 of the 240 anticancer medicines licensed in the previous 40 years are entirely synthetic, which could be attributed to the advantages of natural substances such as lower side effects and the ability to affect numerous Signaling pathways involved in the carcinogenesis process. In addition, synthetic compounds with natural pharmacophores that imitate the effects of natural products have been licensed as anticancer medications throughout the past ten years. Since the start of cancer research, phytochemicals have been a focal point because they were some of the first antineoplastic medicines found (e.g., leucovorin in 1950, carzinophilin in 1954, vincristine in 1963, actinomycin D in 1964, etc.). Additionally, their research is still ongoing today. It is crucial to note that natural substances are used both as adjuvants and chemotherapeutic agents in the treatment of cancer. By summarizing the three aspects of natural chemicals' anticancer action, this review offers a fresh viewpoint on their use in the field of oncology. Chemotherapeutic drugs because of their inherent antitumor effects, chemopreventive drugs, and sensitizers for multi-drug resistance are the first three categories.