Progress of Metal‐Based Anticancer Chemotherapeutic Agents in Last two Decades and their Comprehensive Biological (DNA/RNA Binding, Cleavage and Cytotoxicity Activity) Studies

During last two decades, there has been an enormous growth in the discovery of innovative active inorganic anticancer complexes (exerting remarkable cytotoxicity at sub micro‐molar levels) derived from myriad ligand scaffolds, mainly acting on cancerous vs healthy cells by either halting or inhibiting their uncontrolled growth. The phenomenal success of cisplatin to treat numerous forms of solid malignancies has placed metal‐based drugs to the forefront of treatment strategies against cancers. More than 10,000 platinum anticancer complexes have been developed during the past 40 years, but only five drugs have been approved for usage in humans while ten more complexes are currently undergoing clinical trials. Most of the compounds have failed either at R&D stages or in preclinical trails. This has led to extensive investigations by researchers of medicinal chemistry, including our group to design and prepare tailored 3d‐metallo‐drugs and organotin(IV) compounds from some naturally occurring bioactive compounds, such as amino‐acids, peptides, chromone derivatives and NSAID's etc. that were used either alone or in cocktail combination, capable of specifically targeting DNA, lnc RNAs and proteins. Furthermore, 3d‐metal ions such as copper, cobalt and zinc etc. incorporated in these ligand framework are biocompatible and induce a unique multi‐modal mechanism of cytotoxic action involving angiogenesis, ROS‐induced DNA damage, apoptosis by p53 mitochondrial genes and caspases etc. The results observed a positive correlation between the binding affinity of complexes with DNA (as quantified by intrinsic binding constant values) and their cytotoxic behavior. Complexes with high DNA binding propensity were typically lethal against a diverse panel of malignant cell types compared to normal cells. This review focuses on the design, synthesis and validation of new metal‐based chemotherapeutic agents embedded in bioactive ligand scaffolds like (i) amino acid & peptide ligands (ii) chromone derivatives (iii) Schiff base ligands (iv) NSAIDs etc. The choice of the ligands was found to be crucial in influencing the cytotoxic potency that could arise due to multimodal action towards specific targets ct‐DNA/tRNA.