Synthesis, characterization, antimicrobial and cytotoxic activity of novel half-sandwich Ru(II) arene complexes with benzoylthiourea derivatives

Novel tetrahydronaphthalen-1-yl-phenethyl ureas: synthesis and dual antibacterial-anticancer activities

Cancer and antibiotic-resistant bacterial infections are significant global health challenges. The resistance developed in cancer treatments intensifies therapeutic difficulties. In addressing these challenges, this study synthesised a series of N,N'-dialkyl urea derivatives containing methoxy substituents on phenethylamines. Using isocyanate for the efficient synthesis yielded target products 14-18 in 73-76% returns. Subsequently, their antibacterial and anticancer potentials were assessed. Cytotoxicity tests on cancer cell lines, bacterial strains, and a healthy fibroblast line revealed promising outcomes. All derivatives demonstrated robust antibacterial activity, with MIC values ranging from 0.97 to 15.82 µM. Notably, compounds 14 and 16 were particularly effective against the HeLa cell line, while compounds 14, 15, and 17 showed significant activity against the SH-SY5Y cell line. Importantly, these compounds had reduced toxicity to healthy fibroblast cells than to cancer cells, suggesting their potential as dual-functioning agents targeting both cancer and bacterial infections.

Molecular insight into the structural and functional aspects of arene Ru(II) complexes bearing bulky thiourea ligands

Herein we report four new arene ruthenium(II) complexes [RuII(η6-p-cymene)(L1)к1(S)Cl2] (C1), [RuII(η6-benzene)(L1)к1(S)Cl2] (C2) where L1 is N-((2,6-dimethylphenyl)carbamothioyl)benzamide (L1), and [RuII(η6-p-cymene)(L2)к1(S)Cl2] (C3), [RuII(η6-benzene)(L2)к1(S)Cl2] (C4) where L2 is N-((2,6-diisopropylphenyl)carbamothioyl)benzamide (L2) which were synthesized and evaluated for biological activity. The monodentate coordination of thione sulphur (S) to ruthenium ion along with two terminal chloride was confirmed by X-Ray diffraction analysis thus revealing a typical "piano-stool" pseudo tetrahedral geometry. DPPH radical scavenging activity showed that ligands were less efficient however on complex formation it showed significant efficacy with C4 showing the highest activity. The ligands and ruthenium complexes exhibited minimal to no cytotoxic effects on HEK cells within the concentration range of 10-300 μM. Evaluating the cytotoxicity against prostate cancer cells (DU145) L1, L2 and C1 displayed more pronounced cytotoxic activity with C1 showing high cytotoxicity against the cancer cells, in comparison to cisplatin indicating its potential for further investigation and analysis. Considering this, compound C1 was used to further study its interaction with BSA using fluorescence spectroscopy and it was found to be 2.64 × 106 M-1. Findings from CD spectroscopy indicate the binding in the helix region which was further confirmed with the molecular docking studies.

Exploring the latest trends in chemistry, structure, coordination, and diverse applications of 1-acyl-3-substituted thioureas: a comprehensive review

Acyl thioureas represent a privileged moiety with vast potential applicability across diverse fields, making them the subject of extensive research efforts. The inherent flexibility of thiourea facilitates the synthesis of a wide range of core structures with diverse functionalities and properties. The distinctive presence of hard and soft donor sites renders acyl thioureas inclined to act as versatile ligands, thereby engendering a diverse array of metal complexes incorporating acyl thiourea as a pivotal ligand. Extensive investigations into the synthesized acyl thioureas and their derivatives have culminated in the elucidation of their substantial potential across a spectrum of applications, spanning biological activities, materials chemistry, catalysis, and beyond. This literature review represents a continuation of our ongoing endeavor to compile comprehensive data on research endeavors concerning acyl thioureas over the past two years.

Plight of CORMs: The unreliability of four commercially available CO-releasing molecules, CORM-2, CORM-3, CORM-A1, and CORM-401, in studying CO biology

Carbon monoxide (CO) is an endogenously produced gaseous signaling molecule with demonstrated pharmacological effects. In studying CO biology, three delivery forms have been used: CO gas, CO in solution, and CO donors of various types. Among the CO donors, four carbonyl complexes with either a transition metal ion or borane (BH3) (termed CO-releasing molecules or CORMs) have played the most prominent roles appearing in over 650 publications. These are CORM-2, CORM-3, CORM-A1, and CORM-401. Intriguingly, there have been unique biology findings that were only observed with these CORMs, but not CO gas; yet these properties were often attributed to CO, raising puzzling questions as to why CO source would make such a fundamental difference in terms of CO biology. Recent years have seen a large number of reports of chemical reactivity (e.g., catalase-like activity, reaction with thiol, and reduction of NAD(P)+) and demonstrated CO-independent biological activity for these four CORMs. Further, CORM-A1 releases CO in an idiosyncratic fashion; CO release from CORM-401 is strongly influenced or even dependent on reaction with an oxidant and/or a nucleophile; CORM-2 mostly releases CO2, not CO, after a water-gas shift reaction except in the presence of a strong nucleophile; and CORM-3 does not release CO except in the presence of a strong nucleophile. All these beg the question as to what constitutes an appropriate CO donor for studying CO biology. This review critically summarizes literature findings related to these aspects, with the aim of helping result interpretation when using these CORMs and development of essential criteria for an appropriate donor for studying CO biology.

Ru(II)-p-Cymene Complexes of Furoylthiourea Ligands for Anticancer Applications against Breast Cancer Cells

Half-sandwich Ru(II) complexes containing nitro-substituted furoylthiourea ligands, bearing the general formula [(η⁶-p-cymene)RuCl₂(L)] (1-6) and [(η⁶-p-cymene)RuCl(L)(PPh₃)]⁺ (7--12), have been synthesized and characterized. In contrast to the spectroscopic data which revealed monodentate coordination of the ligands to the Ru(II) ion via a "S" atom, single crystal X-ray structures revealed an unusual bidentate N, S coordination with the metal center forming a four-membered ring. Interaction studies by absorption, emission, and viscosity measurements revealed intercalation of the Ru(II) complexes with calf thymus (CT) DNA. The complexes showed good interactions with bovine serum albumin (BSA) as well. Further, their cytotoxicity was explored exclusively against breast cancer cells, namely, MCF-7, T47-D, and MDA-MB-231, wherein all of the complexes were found to display more pronounced activity than their ligand counterparts. Complexes 7-12 bearing triphenylphosphine displayed significant cytotoxicity, among which complex 12 showed IC₅₀ values of 0.6 ± 0.9, 0.1 ± 0.8, and 0.1 ± 0.2 μM against MCF-7, T47-D, and MDA-MB-231 cell lines, respectively. The most active complexes were tested for their mode of cell death through staining assays, which confirmed apoptosis. The upregulation of apoptotic inducing and downregulation of apoptotic suppressing proteins as inferred from the western blot analysis also corroborated the apoptotic mode of cell death. The active complexes effectively generated reactive oxygen species (ROS) in MDA-MB-231 cells as analyzed from the 2',7'-dichlorofluorescein diacetate (DCFH-DA) staining. Finally, in vivo studies of the highly active complexes (6 and 12) were performed on the mice model. Histological analyses revealed that treatment with these complexes at high doses of up to 8 mg/kg did not induce any visible damage to the tested organs.

Synthesis, Characterization, Cytotoxicity Analysis and Evaluation of Novel Heterocyclic Derivatives of Benzamidine against Periodontal Disease Triggering Bacteria

Periodontal disease (PD) is multifactorial oral disease that damages tooth-supporting tissue. PD treatment includes proper oral hygiene, deep cleaning, antibiotics therapy, and surgery. Despite the availability of basic treatments, some of these are rendered undesirable in PD treatment due to side effects and expense. Therefore, the aim of the present study is to develop novel molecules to combat the PD triggering pathogens. The study involved the synthesis of 4-((5-(substituted-phenyl)-1,3,4-oxadiazol-2-yl)methoxy)benzamidine (5a-e), by condensation of 2-(4-carbamimidoylphenoxy)acetohydrazide (3) with different aromatic acids; and synthesis of 4-((4-(substituted benzylideneamino)-4H-1,2,4-triazol-3-yl)methoxy)benzamidine (6a-b) by treatment of compound 3 with CS₂ followed by hydrazination and a Schiff reaction with different aromatic aldehydes. Synthesized compounds were characterized based on the NMR, FTIR, and mass spectrometric data. To assess the effectiveness of the newly synthesized compound in PD, new compounds were subjected to antimicrobial evaluation against P. gingivalis and E. coli using the micro-broth dilution method. Synthesized compounds were also subjected to cytotoxicity evaluation against HEK-293 cells using an MTT assay. The present study revealed the successful synthesis of heterocyclic derivatives of benzamidine with significant inhibitory potential against P. gingivalis and E. coli. Synthesized compounds exhibited minimal to the absence of cytotoxicity. Significant antimicrobial potential and least/no cytotoxicity of new heterocyclic analogs of benzamidine against PD-triggering bacteria supports their potential application in PD treatment.

Impact of aliphatic acyl and aromatic thioamide substituents on the anticancer activity of Ru(II)-p-cymene complexes with acylthiourea ligands-in vitro and in vivo studies

Six different acylthiourea ligands (L1-L6) and their corresponding Ru(II)-p-cymene complexes (P1-P6) were designed to explore the structure-activity relationship of the complexes upon aliphatic chain and aromatic conjugation on the C- and N-terminals, respectively. The compounds were synthesized and adequately characterized using various analytical and spectroscopic techniques. The structures of P2-P6, solved using single crystal X-ray diffraction (XRD), confirmed the neutral monodentate coordination of the S atoms of the acylthiourea ligands to Ru(II) ions. In silico studies showed an increase of lipophilicity for the ligands with an increase in alkyl chain length or aromatic conjugation at the C- or N-terminal, respectively. Subsequently, mitogen-activated protein kinases (MAPK) were predicted as one of the primary targets for the complexes, which showed good binding affinity towards extracellular signal-regulated kinases (ERK1, ERK2 and ERK5), c-Jun N-terminal kinase (JNK) and p38 of the MAPK pathway. Henceforth, the complexes were tested for their anticancer activity in lung carcinoma (A549) and cisplatin-resistant lung carcinoma (cisA549R) cells and human umbilical vein epithelial normal cells (HUVEC). Interestingly, an increase in chain length or aromatic conjugation led to an increase in the activity of the complexes, with P5 (7.73 and 13.04 μM) and P6 (6.52 and 14.45 μM) showing the highest activity in A549 and cisA549R cells, which is better than the positive control, cisplatin (8.72 and 44.28 μM). Remarkably, we report the highest activity yet observed for complexes of the type [(η6-p-cymene)RuIICl2(S-acylthiourea)] in the tested cell lines. Aqueous solution studies showed that complexes P5 and P6 are rapidly hydrolyzed to produce solely aquated species that remained stable for 24 h. Staining assays and flow cytometric analyses of P5 and P6 in A549 cells revealed that the complexes induced apoptosis and arrested the cell cycle predominantly in the S phase. In vivo studies demonstrated the higher toxicity of cisplatin and a comparatively higher survival rate of mice injected with the most active complex P6. Histological analyses revealed that treatment with P6 at high doses of up to 8 mg kg-1 did not cause any palpable damage to the tested organs.

Ruthenium(II) Diphosphine Complexes with Mercapto Ligands That Inhibit Topoisomerase IB and Suppress Tumor Growth In Vivo

Ruthenium(II) complexes (Ru1-Ru5), with the general formula [Ru(N-S)(dppe)₂]PF₆, bearing two 1,2-bis(diphenylphosphino)ethane (dppe) ligands and a series of mercapto ligands (N-S), have been developed. The combination of these ligands in the complexes endowed hydrophobic species with high cytotoxic activity against five cancer cell lines. For the A549 (lung) and MDA-MB-231 (breast) cancer cell lines, the IC₅₀ values of the complexes were 288- to 14-fold lower when compared to cisplatin. Furthermore, the complexes were selective for the A549 and MDA-MB-231 cancer cell lines compared to the MRC-5 nontumor cell line. The multitarget character of the complexes was investigated by using calf thymus DNA (CT DNA), human serum albumin, and human topoisomerase IB (hTopIB). The complexes potently inhibited hTopIB. In particular, complex [Ru(dmp)(dppe)₂]PF₆ (Ru3), bearing the 4,6-diamino-2-mercaptopyrimidine (dmp) ligand, effectively inhibited hTopIB by acting on both the cleavage and religation steps of the catalytic cycle of this enzyme. Molecular docking showed that the Ru1-Ru5 complexes have binding affinity by active sites on the hTopI and hTopI-DNA, mainly via π-alkyl and alkyl hydrophobic interactions, as well as through hydrogen bonds. Complex Ru3 displayed significant antitumor activity against murine melanoma in mouse xenograph models, but this complex did not damage DNA, as revealed by Ames and micronucleus tests.

Ruthenium Complexes in the Fight against Pathogenic Microorganisms. An Extensive Review

The widespread use of antibiotics has resulted in the emergence of drug-resistant populations of microorganisms. Clearly, one can see the need to develop new, more effective, antimicrobial agents that go beyond the explored 'chemical space'. In this regard, their unique modes of action (e.g., reactive oxygen species (ROS) generation, redox activation, ligand exchange, depletion of substrates involved in vital cellular processes) render metal complexes as promising drug candidates. Several Ru (II/III) complexes have been included in, or are currently undergoing, clinical trials as anticancer agents. Based on the in-depth knowledge of their chemical properties and biological behavior, the interest in developing new ruthenium compounds as antibiotic, antifungal, antiparasitic, or antiviral drugs has risen. This review will discuss the advantages and disadvantages of Ru (II/III) frameworks as antimicrobial agents. Some aspects regarding the relationship between their chemical structure and mechanism of action, cellular localization, and/or metabolism of the ruthenium complexes in bacterial and eukaryotic cells are discussed as well. Regarding the antiviral activity, in light of current events related to the Covid-19 pandemic, the Ru (II/III) compounds used against SARS-CoV-2 (e.g., BOLD-100) are also reviewed herein.

Design, synthesis, characterization, and biological evaluation of nicotinoyl thioureas as antimicrobial and antioxidant agents

Addressed herein a series of thioureas starting from various amines and nicotinic acid have been synthesized. Notably, thiourea based scaffolds are increasingly employed in medicinal chemistry owing to their tunable physicochemical and structural properties. As well-known from the literature, the pyridine ring contains various biological properties, especially antimicrobial activity. Therefore, we performed the synthesis of biologically important thiourea derivatives containing pyridine ring. The structures of the synthesized compounds were characterized by ¹H NMR, ¹³C NMR and FT-IR. In the second part of the study, newly synthesized compounds were also tested in order to demonstrate their antimicrobial and antioxidant properties. All compounds exhibited moderate activity against all tested bacteria known to cause nosocomial infections, which have acquired resistance to many antibiotics, as compared to the standard antibiotics and also strong antioxidant properties. Therefore, they can be evaluated as possible seeds of agents in the treatment of bacterial infections and many health problems related to aging such as cancer, and neurodegenerative diseases.