Visible-Light-Mediated Oxidative Cyclization of 2-Aminobenzyl Alcohols and Secondary Alcohols Enabled by an Organic Photocatalyst.

This paper describes a visible-light-mediated oxidative cyclization of 2-aminobenzyl alcohols and secondary alcohols to produce quinolines at room temperature. This photocatalytic method employed anthraquinone as an organic small-molecule catalyst and DMSO as an oxidant. According to this present procedure, a series of quinolines were prepared in satisfactory yields.

Mitochondria-targeted Re(I) complexes bearing guanidinium as ligands and their anticancer activity.

As the "powerhouse" of a cell, mitochondria maintain energy homeostasis, synthesize ATP via oxidative phosphorylation, generate ROS signaling molecules, and modulate cell apoptosis. Herein, three Re(I) complexes bearing guanidinium derivatives have been synthesized and characterized. All of these complexes exhibit moderate anticancer activity in HepG2, HeLa, MCF-7, and A549 cancer cells. Mechanism studies indicate that complex 3, [Re(CO)3(L)(Im)](PF6)2, can selectively localize in the mitochondria and induce cancer cell death through mitochondria-associated pathways. In addition, complex 3 can effectively depress the ability of cell migration, cell invasion, and colony formation.

Lysosome-targeted ruthenium(II) complexes induce both apoptosis and autophagy in HeLa cells.

Ruthenium complexes with good biological properties have attracted increasing attention in recent decades. In this work, three ruthenium polypyridine complexes containing 5-fluorouracil derivatives as ligands, [Ru(bpy)2(L)]2+ (Ru1), [Ru(phen)2(L)]2+ (Ru2), [Ru(dip)2(L)]2+ (Ru3) (L = 1-((1,10-phenanthroline-5-amino) pentyl)-5-fluorouracil; bpy = 2,2'-bipyridine; phen =1,10-phenanthroline; dip = 4,7-diphenyl-1,10-phenanthroline), were synthesized and characterized. Based on in vitro cytotoxicity tests, Ru3 (IC50 = 7.35 ± 0.39 µM) showed the best anticancer activity among three compounds in the selected cell lines. It is worth noting that Ru3 also exerts less cytotoxicity on LO2 cell lines, with an IC50 value 5 times higher than that on HeLa cells, indicating its selective activity. Mechanism studies revealed that Ru3 can specifically target lysosomes and induce cell apoptosis in a caspase-dependent manner. Specifically, Ru3 can arrest cell cycle at the G0/G1 phase, increase the intracellular reactive oxygen species (ROS) level, and then damage DNA. In short, Ru3 can eventually cause cell death through the synergy of inducing apoptosis and autophagy, which was further proven by western blot assay results.

Cyclometalated iridium(III) complexes as mitochondria-targeted anticancer and antibacterial agents to induce both autophagy and apoptosis.

Mitochondrial damage will hinder the energy production of cells and produce excessive ROS (reactive oxygen species), resulting in cell death through autophagy or apoptosis. In this paper, four cyclometalated iridium(III) complexes (Ir1: [Ir(piq)2L]PF6; Ir2: [Ir(bzq)2L]PF6; Ir3: [Ir(dfppy)2L]PF6; Ir4: [Ir(thpy)2L]PF6; piq = 1-phenylisoquinoline; bzq = benzo[h]quinoline; dfppy = 2-(2,4-difluorophenyl)pyridine;thpy = 2-(2-thienyl)pyridine; L = 1,10-phenanthroline-5-amine) were synthesized and characterized. Cytotoxicity tests show that these complexes have excellent cytotoxicity to cancer cells, and mechanism studies indicatethat these complexes can specifically target mitochondria. Complexes Ir1 and Ir2 can damage the function of mitochondria, subsequently increasing intracellular levels of ROS, decreasing MMP (mitochondrial membrane potential), and interfering with ATP energy production, which leads to autophagy and apoptosis. Furthermore, autophagy induced by Ir1 and Ir2 can promote cell death in coordination with apoptosis. Surprisingly, these four complexes also showed moderate antibacterial activity to S. aureusand P. aeruginosa.

Guanidine-modified cyclometalated iridium(III) complexes for mitochondria-targeted imaging and photodynamic therapy.

PDT is a well-established therapeutic modality for many types of cancer. Photoluminescent cyclometalated iridium(III) complexes are one of the most commonly used classes of organometallic compounds with potential beneficial applications in bioimaging and as promising anticancer agents. In the present study, three new cyclometalated iridium(III) complexes (Ir1-Ir3) containing guanidinium ligands were found to exert excellent cytotoxic effects on different types of cancer cells upon light irradiation at 425 nm. Notably, Ir1 conferred almost no dark toxicity (IC50 > 100 µM) to HepG2 cells, but the value decreased by 387-fold to 0.36 µM following 10 min of light irradiation (425 nm). Further mechanistic investigation revealed that complex Ir1 could induce apoptosis via the activation of reactive oxygen species (ROS)-mediated mitochondrial signaling pathways in the presence or absence of light irradiation. In vivo studies demonstrated that Ir1 significantly inhibited tumor growth in HepG2 xenograft-bearing mice under light irradiation at 425 nm. Taken together, these findings indicate that designing PDT-based Ir(III) complexes may hold a great deal of promise for anticancer drug development.