Overview of the New Bioactive Heterocycles as Targeting Topoisomerase Inhibitors Useful Against Colon Cancer.

Colorectal cancer (CRC) is the third most common worldwide cancer with high mortality. Factors such as more effective screening programs and improvements in treatment modalities have favored a decrease in the incidence and mortality rate of colorectal cancer in the last three decades. Metastatic CRC is incurable in most cases, and therapy using multiple drugs can increase patients' life expectancy by 2 to 3 years. Chemotherapy is the primary treatment, and fluoropyrimidines correspond to the first treatment line. They can be used in monotherapy or therapeutic schemes of oxaliplatin, FOLFOX (intravenous fluorouracil, leucovorin, and oxaliplatin), and CAPOX (oral capecitabine and oxaliplatin) or regimens based on Irinotecan, such FOLFIRI (fluorouracil, leucovorin, and Irinotecan) and CAPIRI (capecitabine and Irinotecan). Like Camptothecin, irinotecan and other analogs have a mechanism of action based on forming a ternary complex with Topoisomerase I and DNA by reversibly binding, providing DNA damage and consequent cell death. This way, topoisomerases are vital enzymes for DNA maintenance and cell viability. Thus, here we will review the main works demonstrating the correlation between the inhibition of different isoforms of topoisomerases and the in vitro cytotoxic activity in colon cancer. The findings revealed that natural compounds, semi-synthetic and synthetic analogs showed potential cytotoxicity against several colon cancer cell lines in vitro and that this activity was often accompanied by the ability to inhibit type I and II topoisomerases, demonstrating that these enzymes can be promising drug targets for the development of new chemotherapeutics against colon cancer.