Metal complexes of β-carboline: Advances in anticancer therapeutics

Abstract

The platinum-based complexes were the first anticancer metallotherapeutics to emerge and since their discovery several other coordination compounds consisting of transition metal ions of variable oxidation states in complex with various ligands have been developed. However, indiscriminative cytotoxicity, unbearable side effects and incessant drug-resistance mainly limit their clinical application, hence, create a strong impetus for alternative chemotherapeutic designs. Consequently, the broad pharmacological spectrum of b-Carboline (bC) ligands against tumour growths prompted the synthesis and probe of their corresponding metal complexes for improved efficacy as multi-mechanistic anticancer agents. However, to our knowledge, the overview of these interesting innovations needed to advance the knowledge-based cancer therapeutic modelling remains sparse. This review is aimed at comprehensive highlights of the scientific up-to-date development towards effective anticancer therapeutic designs through various metal ion complexes of bC derivatives reported in the last decade. The basic synthetic procedures, anti cancer activity and systemic toxicity towards healthy cells were focused. This review reveals that the complexes possess interesting efficacy against malignant transformations through various chemothera peutic, photodynamic therapeutic and combined photothermal-chemotherapeutic mechanisms in vitro and in vivo. They mostly demonstrate stronger cytotoxicity against several cancer cells including the cisplatin-resistant types than cisplatin and tolerable toxicity to normal cells including the human hepatic cells, breast epithelial cells and lung fibroblasts. Especially, complexes 4, 9, 11–13, 15, 30, 35, 36, 44, 45, 48, 56–59 and the nanoparticle composite of 60 deserve further attention. This review presents funda mental updates for further studies on anticancer therapeutic designs through metal complexes of bCs.