Organoplatinum(II) Complexes Self-Assemble and Recognize AT-Rich Duplex DNA Sequences

Kinetically Inert Platinum (II) Complexes for Improving Anticancer Therapy: Recent Developments and Road Ahead

The search for better chemotherapeutic drugs to alleviate the deficiencies of existing platinum (Pt) drugs has picked up the pace in the millennium. There has been a disparate effort to design better and safer Pt drugs to deal with the problems of deactivation, Pt resistance and toxic side effects of clinical Pt drugs. In this review, we have discussed the potential of kinetically inert Pt complexes as an emerging class of next-generation Pt drugs. The introduction gives an overview about the development, use, mechanism of action and side effects of clinical Pt drugs as well as the various approaches to improve some of their pharmacological properties. We then describe the impact of kinetic lability on the pharmacology of functional Pt drugs including deactivation, antitumor efficacy, toxicity and resistance. Following a brief overview of numerous pharmacological advantages that a non-functional kinetically inert Pt complex can offer; we discussed structurally different classes of kinetically inert Pt (II) complexes highlighting their unique pharmacological features.

Structure-based drug design of DNA minor groove binders and evaluation of their antibacterial and anticancer properties

Antimicrobial and chemotherapy resistance are escalating medical problem of paramount importance. Yet, research for novel antimicrobial and anticancer agents remains lagging behind. With their reported medical applications, DNA minor groove binders (MGBs) are worthy of exploration. In this study, the approach of structure-based drug design was implemented to generate 11 MGB compounds including a novel class of bioactive alkyne-linked MGBs. The NCI screening protocol was utilized to evaluate the antitumor activity of the target MGBs. Furthermore, a variety of bactericidal, cytopathogenicity, MIC90, and cytotoxicity assays were carried out using these MGBs against 6 medically relevant bacteria: Salmonella enterica, Escherichia coli, Serratia marcescens, Bacillus cereus, Streptococcus pneumoniae and Streptococcus pyogenes. Moreover, molecular docking, molecular dynamic simulations, DNA melting, and isothermal titration calorimetry (ITC) analyses were utilized to explore the binding mode and interactions between the most potent MGBs and the DNA duplex d(CGACTAGTCG)2. NCI results showed that alkyne-linked MGBs (26 & 28) displayed the most significant growth inhibition among the NCI-60 panel. In addition, compounds MGB3, MGB4, MGB28, and MGB32 showed significant bactericidal effects, inhibited B. cereus and S. enterica-mediated cytopathogenicity, and exhibited low cytotoxicity. MGB28 and MGB32 demonstrated significant inhibition of S. pyogenes, whereas MGB28 notably inhibited S. marcescens and all four minor groove binders significantly inhibited B. cereus. The ability of these compounds to bind with DNA and distort its groove dimensions provides the molecular basis for the allosteric perturbation of proteins-DNA interactions by MGBs. This study shed light on the mechanism of action of MGBs and revealed the important structural features for their antitumor and antibacterial activities, which are important to guide future development of MGB derivatives as novel antibacterial and anticancer agents.

Synthesis, Structure and Anticancer Activity of a Dinuclear Organoplatinum(IV) Complex Stabilized by Adenine

The dinuclear organoplatinum(IV) compound {Pt(CH3)3}2(μ-I)2(μ-adenine) (abbreviated Pt2ad), obtained by treating cubic [Pt(CH3)3(μ3-I)]4 with two equivalents of adenine, was isolated and structurally characterized by single crystal X-ray diffraction. The National Cancer Institute Developmental Therapeutics Program's in vitro sulforhodamine B assays showed Pt2ad to be particularly cytotoxic against central nervous system cancer cell line SF-539, and human renal carcinoma cell line RXF-393. Furthermore, Pt2ad displayed some degree of cytotoxicity against non-small cell lung cancer (NCI-H522), colon cancer (HCC-2998, HCT-116, HT29, and SW-620), melanoma (LOX-IMVI, MALME-3M, M14, MDA-MB-435, SK-MEL-28, and UACC-62), ovarian cancer (OVCAR-5), renal carcinoma (A498), breast cancer (BT-549 and MDA-MB-468), and triple-negative breast cancer (MDA-MB-231).

The Power of Kinetic Inertness in Improving Platinum Anticancer Therapy by Circumventing Resistance and Ameliorating Nephrotoxicity

Even in the modern era of precision medicine and immunotherapy, chemotherapy with platinum (Pt) drugs remains among the most commonly prescribed medications against a variety of cancers. Unfortunately, the broad applicability of these blockbuster Pt drugs is severely limited by intrinsic and/or acquired resistance, and high systemic toxicity. Considering the strong interconnection between kinetic lability and undesired shortcomings of clinical Pt drugs, we rationally designed kinetically inert organometallic Pt based anticancer agents with a novel mechanism of action. Using a combination of in vitro and in vivo assays, we demonstrated that the development of a remarkably efficacious but kinetically inert Pt anticancer agent is feasible. Along with exerting promising antitumor efficacy in Pt-sensitive as well as Pt-resistant tumors in vivo, our best candidate has the ability to mitigate the nephrotoxicity issue associated with cisplatin. In addition to demonstrating, for the first time, the power of kinetic inertness in improving the therapeutic benefits of Pt based anticancer therapy, we describe the detailed mechanism of action of our best kinetically inert antitumor agent. This study will certainly pave the way for designing the next generation of anticancer drugs for effective treatment of various cancers.

Anticancer Activity of Nonpolar Pt(CH3)2I2{bipy} is Found to be Superior among Four Similar Organoplatinum(IV) Complexes

The anticancer properties of well-defined molecules serve to bolster the field of metals in medicine. Such compounds, particularly those of platinum and their closely related structural analogs, continue to be potentially highly interesting to researchers and clinicians alike. The four octahedral organoplatinum(IV) compounds [Pt(CH3)2X2{bipy-R 2 }] (X = Br, I; bipy-R 2 = 2,2'-bipyridine, 2,2'-bipyridine-4,4'-dicarboxylic acid) have been isolated and structurally characterized by single-crystal X-ray diffraction. Nuclear magnetic resonance and infrared spectroscopic data are also tabulated as useful reference values. The anticancer potential of each compound was assessed via in vitro MTT assays, using human breast cancer cells (cell line ZR-75-1). EC50 values were determined as 11.5 μM for Pt(CH3)2Br2{bipy}; 3020 μM, for Pt(CH3)2Br2{bipy-(CO 2 H) 2 }; 6.1 μM, for Pt(CH3)2I2{bipy}; and 86.0 μM, for Pt(CH3)2I2{bipy-(CO 2 H) 2 }; for comparison, the EC50 value for cisplatin against the ZR-75-1 cells was 16.4 μM. The most cytotoxic of the four compounds Pt(CH3)2I2{bipy} undergoes reaction with glutathione in a THF/water mixture at 68°C very slowly.

Terpyridine copper(II) complexes as potential anticancer agents by inhibiting cell proliferation, blocking the cell cycle and inducing apoptosis in BEL-7402 cells

Four mononuclear terpyridine complexes [Cu(H-L^a)Cl₂]·CH₃OH (1), [Cu(H-L^a)Cl]ClO₄ (2), [Cu(H-L^b)Cl₂]·CH₃OH (3), and [Cu(H-L^b)(CH₃OH)(DMSO)](ClO₄)₂ (4) were prepared and fully characterized. Complexes 1-4 exhibited higher cytotoxic activity against several tested cancer cell lines especially BEL-7402 cells compared to cisplatin, and they showed low toxicity towards normal human liver cells. ICP-MS detection indicated that the copper complexes were accumulated in mitochondria. Mechanistic studies demonstrated that the copper complexes induced G0/G1 arrest and altered the expression of the related proteins of the cell cycle. All copper complexes reduced the mitochondrial membrane potential while increasing the intracellular ROS levels and the release of Ca²⁺. They also up-regulated Bax and down-regulated Bcl-2 expression levels, caused cytochrome c release and the activation of the caspase cascade, and induced mitochondrion-mediated apoptosis. Animal studies demonstrated that complex 1 suppressed tumor growth in a mouse xenograft model bearing BEL-7402 tumor cells.

A 2-(benzothiazol-2-yl)-phenolato platinum(II) complex as potential photosensitizer for combating bacterial infections in lung cancer chemotherapy†

Cancer and antibiotic resistance are two global health threats that usually hamper clinical chemotherapeutic efficacy. Particularly for lung cancer, bacterial infections frequently arise thereby complicating the course of cancer treatment. In this sense, three new neutral luminescent cycloplatinated(II) photosensitizers of the type [Pt(dmba)(L)] (dmba = N,N-dimethylbenzylamine-κN,κC; L = 2-(benzo[d]oxazol-2-yl)-phenolato-κN,κO1, 2-(benzo[d]thiazol-2-yl)-phenolato-κN,κO2, and 2-(1-methyl-1H-benzo[d]imidazole-2-yl)phenolato-κN,κO3) have been characterized and developed to potentially eliminate both resistant bacteria and lung cancer cells. The phototherapeutic effects of complex 2 have been evaluated using low doses of blue light irradiation. Complex 2 exerted promising photoactivity against pathogenic Gram-positive bacteria strains of clinical interest, displaying a phototoxic index (PI) of 15 for methicillin-resistant Staphylococcus aureus, one of the major microorganisms predominating lung infections. Likewise, the anticancer activity of 2 was also increased upon light irradiation in human lung A549 cancer cells (PI = 36). Further in vitro experiments with this platinum(II) complex suggest that ROS-generating photodynamic reactions were involved upon light irradiation, thus providing a reasonable mechanism for its dual anticancer and antibacterial activities.

Luminescent cyclometalated platinum(ii) complexes with acyclic diaminocarbene ligands: structural, photophysical and biological properties

Four new cyclometalated Pt(ii) complexes bearing acyclic diaminocarbene (ADC) ligands, [Pt(C^N)Cl{C(NHXyl)(NHR)}] [C^N = 2,6-difluorophenylpyridine (dfppy), phenylquinoline (pq); R = Pr 3a, 4a, CH₂Ph 3b, 4b], were prepared by the nucleophilic attack on the isocyanide [Pt(C^N)Cl(CNXyl)] (C^N = dfppy 1, pq 2) by the corresponding amine RNH₂ (R = Pr, CH₂Ph). Complexes 3 show in their ¹H NMR spectra in CDCl₃ a notable concentration dependence, with a clear variation of the δ_H (NHXyl) signal, suggesting an assembling process implying donor-acceptor NH_XylCl bonding, also supported by 1D-PGSE (Pulse Field Gradient Spin Echo) and 2D-DOSY (Diffusion Ordered Spectroscopy) NMR experiments in solution and X-ray diffraction studies. The intermolecular interactions in compounds 3a and 3b were studied by using Hirshfeld surface analysis and Non-Covalent Interaction (NCI) methods on their X-ray structures. Their photophysical properties were investigated by absorption and emission spectroscopies and also by TD-DFT calculations performed on 3a and 4b. These complexes show green (3) or orange (4) phosphorescence, attributed to a mixed ³IL/³MLCT excited state. The carbene ligand does not affect the emission maxima but it produces an increase of the quantum yields in relation to the isocyanide in the precursors. In fluid solutions, the emission is not concentration-dependent, but the complexes may show aggregation induced emission as detailed for complexes 3a and 4a. In addition, cytotoxicity studies in the human cell lines A549 (lung carcinoma) and HeLa (cervix carcinoma) showed good activity for these complexes and 3a, 3b and 4a exhibit a strong effect on DNA electrophoretic mobility. To the best of our knowledge, compounds 3 and 4 represent the first examples of cycloplatinated complexes bearing acyclic diamino carbenes with antiproliferative properties.