The DNA binding properties of 9-aminoacridine carboxamide Pt complexes

Synthetic routes and chemical structural analysis for guiding the strategies on new Pt(II) metallodrug design

Metals in medicine is a distinct and mature field of investigation. Its progress in recent times cannot be denied, as it provides opportunities to advance our knowledge of the properties, speciation, reactivity and biological effects of metals in a medicinal context. The development of novel Pt(II) compounds to combat cancer continues to make valuable contributions but it has not yet achieved a complete cure. The chemistry of this field is basic for drug design improvements and our analysis of the chemical procedures is a practical tool for achieving effective Pt(II) anticancer drugs. We present chemical approaches in a manner that can be used to strategically plot new synthetic routes choosing right pathways. Clarifying the chemical challenge will help the scientific community to be aware of the ease and/or difficulty of the procedure before and after further studies, such as speciation, reactivity and biological action which are also very arduous and costly. The work provides information to tackle many challenges in chemistry, combining the knowledge on the Pt(II) reagent preparation together with the reactivity of the biological units used in the Pt(II) drug design. We discuss and include the description of the chemical reactions, the importance of multiple steps and the right order of such reactions to achieve the final drugs, analyzing the coordination principles as well as the organic and organometallic basis. This thorough study of the routes helps to detect the simpler or more complicated reactivity and will serve to improve the synthesis performance with possible post-modifications.

Developing novel antimicrobials by combining cancer chemotherapeutics with bacterial DNA repair inhibitors

Cancer chemotherapeutics kill rapidly dividing cells, which includes cells of the immune system. The resulting neutropenia predisposes patients to infection, which delays treatment and is a major cause of morbidity and mortality. To tackle this problem, we have isolated several compounds that inhibit bacterial DNA repair, alone they are non-toxic, however in combination with DNA damaging anti-cancer drugs, they prevent bacterial growth. These compounds were identified through screening of an FDA-approved drug library in the presence of the anti-cancer compound cisplatin. Using a series of triage tests, the screen was reduced to a handful of drugs that were tested for specific activity against bacterial nucleotide excision DNA repair (NER). Five compounds emerged, of which three possess promising antimicrobial properties including cell penetrance, and the ability to block replication in a multi-drug resistant clinically relevant E. coli strain. This study suggests that targeting NER could offer a new therapeutic approach tailor-made for infections in cancer patients, by combining cancer chemotherapy with an adjuvant that targets DNA repair.

Study on antitumor activity of three ruthenium arene complexes in vitro

Three ruthenium arene complexes, namely {[(η6-p-cymene)Ru(Cl)]2(dpb)}(PF6)2 (1), [(η6-p-cymene)Ru(dpb)Cl](PF6) (2) and [(η6-p-cymene) Ru(dpb)py](PF6) (3) (dpb = 2,3-bis(2-pyridyl)benzo-quinoxaline, py = pyridine), were synthesized and their antitumor properties were introduced. Complexes 1-3 were characterized by 1H NMR, MS, and elemental analysis. As a binuclear ruthenium structure, the absorption of metal ligand electron transfer (MLCT) of 1 extended to 700 nm. Complex 1 was significantly hydrolyzed under dark conditions. The cytotoxicity in vitro study showed that complexes 1 and 2 are more toxic to human lung cancer cells (A549) and human cervial cancer cells (Hela) than cisplatin. Moreover, there was almost no cross-resistance between complex 1-2 and cisplatin. Under the irradiation at 478 nm, complexes 1-3 all produced singlet oxygen (1O2), and the 1O2 quantum yield of complex 1 in PBS is the highest among complexes 1-3. Complex 1 also produced 1O2 under 600 nm light irradiation. DNA gel electrophoresis showed that 1 caused the photocleavage of plasmid DNA. The hydrolysis rate of complex 1 was accelerated under light (λ > 600 nm). And the phototoxicity of complex 1 to Hela cells under light (λ > 600 nm) was much greater than its dark toxicity, which may be due to its generation of 1O2 and the promotion of its hydrolysis under long-wave light irradiation.

Visible-light driven regioselective synthesis, characterization and binding studies of 2-aroyl-3-methyl-6,7-dihydro-5H-thiazolo[3,2-a]pyrimidines with DNA and BSA using biophysical and computational techniques

In recent times, fused azaheterocycles emerged as impressive therapeutic agents. Binding studies of such azaheterocycles with biomolecules is an important subject for pharmaceutical and biochemical studies aiming at the design and development of new drugs. Fused heterocyclic scaffolds, such as thiazolopyrmidines have long been used in the pharmaceutical industry for the treatment of various diseases. In this study, we have accomplished a regioselective synthesis of 2-aroyl-3-methyl-6,7-dihydro-5H-thiazolo[3,2-a]pyrimidines by the reaction of tetrahydropyrimidine-2(H)-thione with α-bromo-1,3-diketones, generated in situ from 1,3-diketones and NBS, using visible light as an inexpensive, green and renewable energy source under mild reaction conditions with wide-ranging substrate scope. The regioisomer was characterized unambiguously by 2D-NMR [1H-13C] HMBC and [1H-13C] HMQC spectroscopy. In silico toxicity data analysis showed the low toxicity risks of the synthesized compounds. Computational molecular docking studies were carried out to examine the interaction of thiazolo[3,2-a]pyrimidines with calf-thymus DNA (ct-DNA) and Bovine Serum Albumin (BSA). Moreover, different spectroscopic approaches viz. steady-state fluorescence, competitive displacement assay, UV-visible and circular dichroism (CD) along with viscosity measurements were employed to investigate the binding mechanisms of thiazolo[3,2-a]pyrimidines with DNA and BSA. The results thus obtained revealed that thiazolo[3,2-a]pyrimidines offer groove bindings with DNA and showed moderate bindings with BSA.