Synthesis And Activity Studies Of Metal Ruthenium/iridium Anticancer Complexes And Hydrogen Sulfide-triggered Activated Prodrugs

Platinum drugs are currently the most widely used metal drugs for the clinical treatment of cancer.However,they still have defects such as drug resistance and systemic toxicity.Therefore,ruthenium,iridium,and other transition metal anticancer drugs have received great attention.Among them,half-sandwich organometallic complexes not only have higher anticancer activity and lower side effects,but also have new sites and mechanisms of action that make them stand out in chemotherapy research.At the same time,theranostic prodrug with the dual-purpose of diagnosis and therapy is an emerging technology in biomedicine.They can be activated by the unique tumor microenvironment to release active species for improving specificity and pharmacological properties.First,we selected 9-aminoacridine（9AA）with anticancer effect to design and synthesize two arene metal complexes 9AA-Ru and 9AA-Ir.By utilization of modified9-aminoacridine with Ru-arene to enhance targeting and anticancer activity,Ru（II）-arene complex 9AA-Ru selectively inhibits the proliferation of leukemia cells and shows non-toxic to normal cells.The DNA was damaged and the cell cycle was arrested at the G0/G1 phase in acute myeloid leukemia cells.Meanwhile,mitochondrial function was affected by 9AA-Ru in many aspects,including ATP depletion,respiration inhibition,and metabolic disturbance,and the energy production was also restrained by inhibition of glycolysis.9AA-Ru not only reshaped transcriptome by altering genes for the cell cycle,down-regulating genes related to oxidative phosphorylation or glycolysis,but cell metabolic pathways were significantly affected as well.Therefore,9AA-Ru suppressed the energy metabolism of leukemia cells by inhibiting oxidative phosphorylation and glycolysis,leading to energy exhaustion and finally resulting in autophagy and mitophagy.This work provides an effective synergistic strategy and a novel approach to design multifunctional metallodrugs for chemotherapy of leukemia cells.Second,we successfully synthesized three metal complexes UA-Ru,UA-Ir and UA-bpy-Ru by chemical modification of the natural product ursolic acid（UA）with antitumor properties.The cytotoxicity of the metal-arene complexes UA-Ru and UA-Ir towards a variety of human tumor cell lines are comparable to cisplatin.Remarkably,their cytotoxicity to leukemia cells（NB-4,K562）and breast cancer cells（MCF-7）is better than that of cisplatin.Both of them can destroy mitochondrial morphology,change mitochondrial membrane potential,impair mitochondrial function,and cause cell death through mitochondrial-mediated apoptosis signaling pathways.The cyclometalated complex UA-bpy-Ru has good optical properties and phototoxicity.The phototoxicity index（PI）of cisplatin-resistant A549R cells reaches 14.6.UA-bpy-Ru is mainly distributed in the lysosomes.Upon the light,it can induce mitochondrial damage and produce a large amount of reactive oxygen species（ROS）,which in turn leads to DNA damage.Although UA-bpy-Ru has little effect on cell cycle arrest,it can inhibit the proliferation of cancer cells through apoptosis and autophagy.These complexes have been shown to overcome cisplatin resistance,which provides important reference values and application prospects for studying the anticancer mechanisms of metal complexes modified with ursolic acid and other natural products.In addition,we carried out different chemical modifications to the biologically active drug amonafide（ANF）to obtain two ligands AX（amonafide-amide ligand）and AS（amonafide-Schiff base ligand）,and coordinated the functionalized ligands with two dinuclear precursors to obtain four arene metal complexes AX-Ru,AX-Ir,AJ-Ru and AJ-Ir.The cytotoxicity of the amide metal-arene complexes AX-Ru and AX-Ir is less than that of the Schiff base metal-arene complexes AJ-Ru and AJ-Ir.In particular,AJ-Ir shows good anti-proliferative activity in vitro,which enters cells through endocytosis and is isolated in the lysosome.In an acidic environment,Schiff base metal-arene complex AJ-Ir is activated by hydrolysis,and releases ANF and transition metal Ir,then escapes from the lysosomes into the nucleus,mitochondria and other organelles to exert their respective effects.Further studies have shown that AJ-Ir arrests the cell cycle at the G2/M phase,damages DNA,changes mitochondrial membrane potential,induces ROS production,and up-regulates the expression of e IF-2αand CHOP proteins in the endoplasmic reticulum stress pathway.In addition,AJ-Ir can induce cells to produce autophagosomes and autophagy.This Schiff base mental-arene complex as a prodrug is triggered to release active species and play multiple functions in cancer cells,which opens up the boundaries for the research and development of new arene metal anticancer complexes for the integration of diagnosis and treatment.Based on the optical properties and anticancer activity of amonafide（ANF）,we have developed two prodrugs PNF and SNF with lysosomal targeting.Prodrugs PNF and SNF have high selectivity and sensitivity to H₂S,and excellent anti-interference performance.Both of them can be activated by intracellular H₂S to release ANF with anticancer activity and fluorescence.Activated PNF and SNF can escape from the lysosomes into the nucleus,induce DNA damage,block the G2/M phase,and destroy mitochondrial structure and function.PNF can down-regulate the expression of P-glycoprotein（multidrug resistance-related protein）and cause A549R autophagic cell death.SNF has better activity towards human glioblastoma-astrocytoma（U87MG）,and causes cell death by autophagy.PNF and SNF can be used as potential antitumor prodrugs,providing an overall strategy for the development of other prodrugs activated by H₂S.Finally,due to the excellent biological activity of amonafide（ANF）,we designed and synthesized small molecules numbered 3-21 by derivatizing ANF and its fluorophore 1,8-naphthalimide.Among them,3 and 9 have excellent antitumor activities,and can significantly inhibit the enzymatic activity of FTO and ALKBH5.This indicates that naphthalimide derivatives can be used as lead compounds targeting FTO and ALKBH5 for the treatment of many diseases such as tumors.In summary,comprehensively considering the current research status of metal complexes and theranostic methods,a series of novel metal-arene complexes,theranostic prodrugs and small molecule drugs with different bioactivity or targeting functions have been designed and synthesized based on the strategy of new arene metals and prodrugs and the platform of active compounds.The results of these studies provide new insight into the development of new metal drugs and other anticancer compounds through in-depth research on new structures,new pathways of action,and new targets.