Progresses in TCM Metal-Based Antitumour Agents

Traditional Chinese medicines (TCM) have recently been recognized as a new source of anticancer drugs and new chemotherapy adjuvant to enhance the efficacy of chemotherapy and to diminish side effects and resistance of cancer chemotherapies. At the same time, cisplatin, one of the most widely used anticancer drugs, is effective in treating a variety of cancers, especially testicular cancer for which it has a greater than 90% cure rate, but its clinical efficacy is limited by significant side effects and acquired or intrinsic resistance. Therefore, many efforts have been devoted to designing new platinum compounds with improved pharmacological properties and a broader range of antitumour activity. New strategies have been applied in the designs of antitumour coordination compounds as drugs, such as synthesizing new ligands or metal complexes with different reaction mechanisms. Among them, new coordination compounds based on traditional Chinese medicines (TCMs) provide a novel approach to potential (pro-)drugs. This review mainly focuses on the synthesis, structure, antitumour activity and interactions with molecular targets of TCM based metal complexes. TCM alkaloids, flavonoids, cantharidin, coumarins, plumbagin, curcumin and camphoric acid metal-based antitumour agents are covered. The future development of hybrid TCM-metal complexes as antitumour drugs is discussed. The pursuit of new TCM metal-based anticancer drugs and enhancement of modern TCM holds promise for overcoming multidrug resistance (MDR).