Synthesis and anticancer evaluation of copper(II)- and manganese(II)- theophylline mixed ligand complexes

Copper complexes induce haem oxygenase-1 (HMOX1) and cause apoptotic cell death in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic malignancy, has a dismal 5-year survival rate, making palliative chemotherapy the only treatment option. Targeted therapy has limited efficacy in PDAC, underscoring the need for novel therapeutic approaches. The inducible stress-response protein, haem oxygenase-1 (HMOX1), has been implicated in treatment failure in PDAC. Copper coordination complexes have shown promise as anticancer agents against various cancers, and are associated with apoptotic cell death. The different ligands to which copper is complexed, determine the specificity and efficacy of each complex. Three different classes of copper complexes were evaluated for anti-cancer activity against AsPC-1 and MIA PaCa-2 pancreatic cancer cell lines. A copper-phenanthroline-theophylline complex (CuPhTh2), a copper-8-aminoquinoline-naphthyl complex (Cu8AqN), and two copper-aromatic-isoindoline complexes (CuAIsI) were effective inhibitors of cell proliferation with clinically relevant IC50 values below 5 μM. The copper complexes caused reactive oxygen species (ROS) formation, promoted annexin-V binding, disrupted the mitochondrial membrane potential (MMP) and activated caspase-9 and caspase-3/7, confirming apoptotic cell death. Expression of nuclear HMOX1 was increased in both cell lines, with the CuPhTh2 complex being the most active. Inhibition of HMOX1 activity significantly decreased the IC50 values of these copper complexes suggesting that HMOX1 inhibition may alter treatment outcomes in PDAC.

Unveiling the antifungal mechanisms of CTP, a new copper(II)-theophylline/1,10-phenanthroline complex, on drug-resistant non-albicans Candida species

Candida species undeniably rank as the most prevalent opportunistic human fungal pathogens worldwide, with Candida albicans as the predominant representative. However, the emergence of non-albicans Candida species (NACs) has marked a significant shift, accompanied by rising incidence rates and concerning trends of antifungal resistance. The search for new strategies to combat antifungal-resistant Candida strains is of paramount importance. Recently, our research group reported the anti-Candida activity of a coordination compound containing copper(II) complexed with theophylline (theo) and 1,10-phenanthroline (phen), known as "CTP" - Cu(theo)2phen(H2O).5H2O. In the present work, we investigated the mechanisms of action of CTP against six medically relevant, antifungal-resistant NACs, including C. auris, C. glabrata, C. haemulonii, C. krusei, C. parapsilosis and C. tropicalis. CTP demonstrated significant efficacy in inhibiting mitochondrial dehydrogenases, leading to heightened intracellular reactive oxygen species production. CTP treatment resulted in substantial damage to the plasma membrane, as evidenced by the passive incorporation of propidium iodide, and induced DNA fragmentation as revealed by the TUNEL assay. Scanning electron microscopy images of post-CTP treatment NACs further illustrated profound alterations in the fungal surface morphology, including invaginations, cavitations and lysis. These surface modifications significantly impacted the ability of Candida cells to adhere to a polystyrene surface and to form robust biofilm structures. Moreover, CTP was effective in disassembling mature biofilms formed by these NACs. In conclusion, CTP represents a promising avenue for the development of novel antifungals with innovative mechanisms of action against clinically relevant NACs that are resistant to antifungals commonly used in clinical settings.

An 8-aminoquinoline-naphthyl copper complex causes apoptotic cell death by modulating the expression of apoptotic regulatory proteins in breast cancer cells

Breast cancer is one of the most common cancers globally and a leading cause of cancer-related deaths among women. Despite the combination of chemotherapy with targeted therapy, including monoclonal antibodies and kinase inhibitors, drug resistance and treatment failure remain a common occurrence. Copper, complexed to various organic ligands, has gained attention as potential chemotherapeutic agents due to its perceived decreased toxicity to normal cells. The cytotoxic efficacy and the mechanism of cell death of an 8-aminoquinoline-naphthyl copper complex (Cu8AqN) in MCF-7 and MDA-MB-231 breast cancer cell lines was investigated. The complex inhibited the growth of MCF-7 and MDA-MB-231 cells with IC50 values of 2.54 ± 0.69 μM and 3.31 ± 0.06 μM, respectively. Nuclear fragmentation, annexin V binding, and increased caspase-3/7 activity indicated apoptotic cell death. The loss of mitochondrial membrane potential, an increase in caspase-9 activity, the absence of active caspase-8 and a decrease of tumour necrosis factor receptor 1(TNFR1) expression supported activation of the intrinsic apoptotic pathway. Increased ROS formation and increased expression of haem oxygenase-1 (HMOX-1) indicated activation of cellular stress pathways. Expression of p21 protein in the nuclei was increased indicating cell cycle arrest, whilst the expression of inhibitor of apoptosis proteins (IAPs); cIAP1, XIAP and survivin were decreased, creating a pro-apoptotic environment. Phosphorylated p53 species; phospho-p53(S15), phospho-p53(S46), and phospho-p53(S392) accumulated in MCF-7 cells indicating the potential of Cu8AqN to restore p53 function in the cells. In combination, the data indicates that Cu8AqN is a useful lead molecule worthy of further exploration as a potential anti-cancer drug.

Copper(II)-photocatalyzed Hydrocarboxylation of Schiff bases with CO2: antimicrobial evaluation and in silico studies of Schiff bases and unnatural α-amino acids

We synthesized and characterized two copper(II) complexes: [CuL2Cl]Cl and [CuL'2Cl]Cl, where L = 2,2'-bipyridine and L' = 4,4'-dimethyl-2,2'-bipyridine. We evaluated their photocatalytic hydrocarboxylation properties on a series of synthesized Schiff bases (SBs): (E)-1-(4-((5-bromo-2-hydroxybenzylidene)amino)phenyl)ethanone (SB1), (E)-N-(4-(dimethylamino)benzylidene)benzo[d]thiazol-2-amine (SB2), (E)-4-Bromo-2-((thiazol-2-ylimino)methyl)phenol (SB3), and (E)-4-((5-bromo-2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (SB4). Under mild photocatalytic reaction conditions (room temperature, 1 atm CO2, 30-watt Blue LED light), the derivatives of α-amino acids UAA1-4 were obtained with yields ranging from 5% to 44%. Experimental results demonstrated that [CuL2Cl]Cl exhibited superior photocatalytic efficiency compared to [CuL'2Cl]Cl, attributed to favourable electronic properties. In silico studies revealed strong binding strengths with E. faecalis DHFR (4M7U) for docked Schiff bases (SB) and unnatural α-amino acids (UAAs). In vitro studies further demonstrated significant antimicrobial and antifungal activity for SB2, SB3, and SB4, while none of the synthesized UAAs exhibited such properties, primarily due to the electronic and binding properties of these molecules.Communicated by Ramaswamy H. Sarma.

Study on Computer Screening and Drug Properties of Herbs Intervening in Copper Death

Objective

The objective of this study was to explore the medicinal properties of herbal medicines that can interfere with the copper death pathway.

Methods

The Human Gene Database, Chemical Interactions in Comparative Toxicogenomics Database, Encyclopedia of Traditional Chinese Medicine, China Medical Information Platform, and Cytoscape software were used to find target and chemicals that interfere with copper death targets, as well as herbal medicines containing these chemicals and their four natures and five flavors (basic properties of herbal medicines).

Results

27 copper death-related targets were finally retrieved, as well as 2143 chemicals that could interfere with them, including 180 herbal compounds. The compounds with the highest degree values (number of nodes connected to this node) were folic acid, resveratrol, and quercetin. The 180 compounds were related to 278 herbs; those with the highest degree values (number of nodes connected to this node) were Jujubae Fructus, Ginkgo biloba L, and Acanthopanax senticosus. The 27 copper death targets were indirectly associated with 278 herbs; those with the highest degree values (number of nodes connected to this node) were Achyranthis Bidentatae Radix, Polygonum cuspidatum Sieb. et Zucc, and Mori Folium. Among the 278 herbs, 6 had incomplete information. A pharmacological analysis showed that among the 272 Chinese herbs, the most frequent meridians were the liver (133), lung (104), and spleen (91). Of the four natures, the most frequent were cold (73), warm (68), and flat (45). Of the five flavors, the most frequent were bitter (165), pungent (116), and sweet (99).

Conclusion

This study preliminarily discussed the material basis and medicinal properties of herbs that can intervene in copper death, which can provide reference for the theoretical discussion, drug development, and clinical research of Chinese medicine regulating copper death.

Cu(II)-Catalysed Hydrocarboxylation of Imines Utilizing CO2 to Synthesize α-Unsaturated Aminocarboxylic Acids

Here, we report the Cu(II)-photocatalysed hydrocarboxylation of imines (C=N) from a series of synthesized Schiff Base derivatives, namely (E)-1-(4-((4-methylbenzylidene)amino)phenyl)ethanone, (E)-1-(3-((5-bromo-2-hydroxybenzylidene)amino)phenyl)ethanone, (E)-4-((5-bromo-2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one, and (E)-1,5-dimethyl-4-((4-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-one, with carbon dioxide (CO₂) to generate disubstituted amino acids. Under mild conditions (atmospheric pressure of CO₂, room temperature, and 30 W Blue LED light), good to excellent yields confirming the formation of substituted amino acid unsaturated acid derivatives were obtained. Single crystal X-ray diffraction (SC-XRD) and UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS) confirmed the square pyramidal geometry of the Cu(II) photocatalyst. Docking and DFT calculations of the substituted amino acid unsaturated acid derivatives showed their potential as antimicrobial molecules.