Development and future prospects of selective organometallic compounds as anticancer drug candidates exhibiting novel modes of action.

Organometallic complexes have widely been used for the treatment of various diseases viz., malaria, arthritis, syphilis, pernicious anemia, tuberculosis and particular in cancers. Recent decades have witnessed an upsurging interest in the application of organometallic compounds to treat various phenotypes of cancers with multiple etiologies. The unique and exceptional properties of organometallic compounds, intermediate between classical inorganic and organic materials provide new insight in the progress of inorganic medicinal chemistry. Herein, we have selectively focused on various organometallic sandwich and half-sandwich complexes of ruthenium (Ru), titanium (Ti), gold (Au) and iron (Fe) exhibiting promising activity towards a panel of cancer cell lines and resistant cancer cell lines. These complexes exhibit novel mechanisms of drug action through incorporation of outer-sphere recognition of molecular targets and controlled activation features based on ligand substitution along with monometallic and heterometallic redox processes. Furthermore, they are usually found to be uncharged or neutral possessing metals in a low oxidation state, exhibit kinetic stability, relative lipophilicity and are amenable to a host of various chemical transformations. This review mainly sheds light on the successful advancement of organometallic complexes as anticancer drug aspirants in relation to their versatile structural chemistry and innovative mechanisms of action targeting nucleic acids, several enzymes viz; thioredoxin reductases (Thrx), EGFR, transferrin, cathepsin B, topoisomerases etc.