Anticancer drug screening of natural products: In vitro cytotoxicity assays, techniques, and challenges

Natural products include several diverse compounds that have been found to be effective against cancer. Discovering anticancer compounds in nature is a multistep and complex process that requires pre-clinical and clinical studies. Only a few of the available natural products are used to treat cancer since most of them have very high complexity and low bioavailability. Therefore, the process of anticancer drug discovery requires a straightforward and effective method to assess anticancer activity using in vitro assays. This review summarizes various cell-based assays and techniques used to measure cell viability, migration, and apoptosis, focusing in particular on the principles, mechanisms, advantages, and disadvantages of each assay to provide a preliminary platform for cancer drug discovery.