A novel series of organometallic antitumour agents based on Ru II and Os II complexes containing N-substituted 2-pyridinecarbothioamides (PCAs) has been synthesized and characterized. To the best of our knowledge, this is the first report of organometallic anticancer compounds with an S,N-bidentate ligand system. While the ligands showed activity as gastric mucosal protectants and low acute toxicity in vivo (J. Med. Chem., 1990, 33, 327-336), coordination leads to highly antiproliferative metallodrugs, depending on lipophilicity and steric demand, in colon carcinoma and non-small lung cancer cell lines with intrinsic chemoresistances. The most lipophilic and smallest congeners are the most effective with IC 50 values in the low micromolar range. This new family of potential metallodrugs features exceptional stability in hydrochloric acid (60 mM), characterized by complete suppression of hydrolysis and low reactivity towards biological nucleophiles. Therefore, their unexpected aqueous chemistry renders this family of antiproliferative agents suitable for oral administration. An unprecedented feature is their ability to form transient thioketone-bridged dimers in aqueous solution upon hydrolysis, which is believed to minimize deactivation by biological nucleophiles. However, the biological effect seems to be caused by the monomer as observed with crystallographic studies of the nucleosome core particle (NCP), which revealed that [chlorido(h 6 -p-cymene)(N-phenyl-2-pyridinecarbothioamide)osmium(II)] chloride and [chlorido(h 6 -p-cymene)(N-fluorophenyl-2-pyridinecarbothioamide)osmium(II)] chloride react at two types of binding sites on the histone proteins. The adducts form at histidine side chains located on the nucleosome surface and the inner cleft of the nucleosome in the midst of an extensive histonehistone interface, suggesting interference with chromatin activity as a possible mode of action of these compounds. Additionally, ligand-based S / O exchange allows for a potential dual-mode of action by targeting DNA (J. Med. Chem., 2009, 52, 7753-7764). The quantitative estimates of drug-likeness (QED) for this family of compounds revealed a similar drug-likeness compared to erlotinib, tamoxifen, imatinib and sorafenib.

Aim of the Review. To grasp the fragmented information available on the botany, traditional uses, phytochemistry, pharmacology, and toxicology of Olea europaea to explore its therapeutic potential and future research opportunities. Material and Methods. All the available information on O. europaea was collected via electronic search (using Pubmed, Scirus, Google Scholar, and Web of Science) and a library search. Results. Ethnomedical uses of O. europaea are recorded throughout the world where it has been used to treat various ailments. Phytochemical research had led to the isolation of flavonoids, secoiridoids, iridoids, flavanones, biophenols, triterpenes, benzoic acid derivatives, isochromans, and other classes of secondary metabolites from O. europaea. The plant materials and isolated components have shown a wide spectrum of in vitro and in vivo pharmacological activities like antidiabetic, anticonvulsant, antioxidant, anti-inflammatory, immunomodulatory, analgesic, antimicrobial, antiviral, antihypertensive, anticancer, antihyperglycemic, antinociceptive, gastroprotective, and wound healing activities. Conclusions. O. europaea emerged as a good source of traditional medicine for the treatment of various ailments. The outcomes of phytochemical and pharmacological studies reported in this review will further expand its existing therapeutic potential and provide a convincing support to its future clinical use in modern medicine.

The synthesis and in vitro anticancer activity of dihalogenido(eta6-p-cymene)(3,5,6-bicyclophosphite-alpha-D-glucofuranoside)ruthenium(II) complexes are described. The compounds were characterized by NMR spectroscopy and ESI mass spectrometry, and the molecular structures of dichlorido-, dibromido- and diiodido(eta6-p-cymene)(3,5,6-bicyclophosphite-1,2-O-isopropylidene-alpha-D-glucofuranoside)ruthenium(II) were determined by X-ray diffraction analysis. The complexes were shown to undergo aquation of the first halido ligand in aqueous solution, followed by hydrolysis of a P--O bond of the phosphite ligand, and finally formation of dinuclear species. The hydrolysis mechanism was confirmed by DFT calculations. The aquation of the complexes was markedly suppressed in 100 mM NaCl solution, and notably only very slow hydrolysis of the P--O bond was observed. The complexes showed affinity towards albumin and transferrin and monoadduct formation with 9-ethylguanine. In vitro studies revealed that the 3,5,6-bicyclophosphite-1,2-O-cyclohexylidene-alpha-D-glucofuranoside complex is the most cytotoxic compound in human cancer cell lines (IC50 values from 30 to 300 microM depending on the cell line).

Despite the severe side effects and the emergence of drug resistance, the use of DNA-targeting platinum drugs remains strong either alone or in a combination chemotherapy regimen. New strategies and formulations are being explored in the design of anticancer metal complexes that exhibit nonclassical modes of action, selectively hit precise biomolecular targets or are even able to induce immunogenic anticancer activity. These developments will ameliorate the systemic toxicity of metal-based drugs and widen the range of treatable cancers.

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Hydroxypyr(id)ones are versatile ligands for the synthesis of organometallic anticancer agents, equipping them with fine-tunable pharmacological properties. Herein, we report on the preparation, mode of action, and in vitro anticancer activity of Ru(II)- and Os(II)-arene complexes with alkoxycarbonylmethyl-3-hydroxy-2-pyridone ligands. The hydrolysis and binding to amino acids proceed quickly, as characterized by NMR spectroscopy and ESI mass spectrometry. However, the reaction with amino acids causes cleavage of the pyridone ligands from the metal center because the amino acids act as multidentate ligands. A similar behavior was also observed during the reactions with the model proteins ubiquitin and cytochrome c, yielding mainly [protein + M(eta(6)-p-cymene)] adducts (M = Ru, Os). Notably the ligand cleavage of the Os derivative was significantly slower than of its Ru analogue, which could explain its higher activity in in vitro anticancer assays. Furthermore, the reaction of the compounds to 5'-GMP was characterized and coordination to the N7 of the guanine moiety was demonstrated by (1)H NMR spectroscopy and X-ray diffraction analysis. CDK2/Cyclin A protein kinase inhibition studies revealed potent activity of the Ru and Os complexes.

Excessive oxidative stress in cancer cells can induce cancer cell death. Anticancer activity and drug resistance of chemotherapy are closely related to the redox state of tumor cells. Herein, five lipophilic Pt(IV) prodrugs were synthesized on the basis of the most widely used anticancer drug cisplatin, whose anticancer efficacy and drug resistance are closely related to the intracellular redox state. Subsequently, a series of cisplatin-sensitive and drug-resistant cell lines as well as three patient-derived primary ovarian cancer cells have been selected to screen those prodrugs. To verify if the disruption of redox balance can be combined with these Pt(IV) prodrugs, we then synthesized a polymer with a diselenium bond in the main chain for encapsulating the most effective prodrug to form nanoparticles (NP(Se)s). NP(Se)s can efficiently break the redox balance via simultaneously depleting GSH and augmenting ROS, thereby achieving a synergistic effect with cisplatin. In addition, genome-wide analysis via RNA-seq was employed to provide a comprehensive understanding of the changes in transcriptome and the alterations in redox-related pathways in cells treated with NP(Se)s and cisplatin. Thereafter, patient-derived xenograft models of hepatic carcinoma (PDX HCC ) and multidrugresistant lung cancer (PDX MDR ) were established to evaluate the therapeutic effect of NP(Se)s, and a significant antitumor effect was achieved on both models with NP(Se)s. Overall, this study provides a promising strategy to break the redox balance for maximizing the efficacy of platinum-based cancer therapy.

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