IĸBζ as a Central Modulator of Inflammatory Arthritis Pathogenesis

OBJECTIVE

Current therapies targeting individual factors in inflammatory arthritis show variable efficacy, often requiring treatment with combinations of drugs, and are associated with undesirable side effects. NF-ĸB is critical for the production and function of most inflammatory cytokines. However, given its essential role in physiologic processes, targeting NF-ĸB is precarious. Hence, identifying pathways downstream of NF-ĸB that selectively govern the expression of inflammatory cytokines in inflammatory arthritis would be advantageous. We have previously identified IĸBζ as a unique inflammatory signature of NF-ĸB that controls the transcription of inflammatory cytokines only under pathologic conditions while sparing physiologic NF-ĸB signals.

METHODS

We generated mice harboring myeloid, lymphoid, and global deletion of Nfkbiz (the gene encoding IĸBζ). These models were subjected to serum transfer-induced arthritis. Additionally, pharmacologic inhibitors of IĸBζ were injected intraperitonially. Joint swelling, microcomputed tomography, immunohistochemistry, flow cytometry, and cytokine measurements were conducted using synovial tissue samples.

RESULTS

Global deletion of Nfkbiz or depletion of neutrophils (vastly IĸBζ+ cells) reduced inflammatory synovial cells and increased anti-inflammatory and regenerative synovial cells, plummeted expression of inflammatory factors and ameliorated experimental mouse inflammatory arthritis. Further, expression of immune responsive gene-1, the enzyme responsible for itaconate production, was increased in synovial cells. Accordingly, the itaconate derivative dimethyl itaconate (DI) inhibited IĸBζ-mediated inflammatory factors. Further, in silico screen identified 8-hydroxyquinoline (HQ) as a putative inhibitor of IĸBζ not affecting physiologic NF-ĸB activity. Congruently, systemic administration of either DI or HQ inhibited joint swelling and damage.

CONCLUSION

Our study positions IĸBζ as an inflammation-specific target for therapeutic consideration in rheumatoid arthritis because its inhibition spares the beneficial functions of NF-ĸB.

8-Hydroxyquinoline ruthenium(II) complexes induce ferroptosis in HeLa cells by down-regulating GPX4 and ferritin

Ruthenium complexes are one of the most promising anticancer drugs triggered extensive research. Here, the synthesis and characterization of two ruthenium(II) polypyridine complexes containing 8-hydroxylquinoline as ligand, [Ru(dip)2(8HQ)]PF6 (Ru1), [Ru(dpq)2(8HQ)]PF6 (Ru2) (8HQ = 8-hydroxylquinoline; dip = 4,7-diphenyl-1,10-phenanthroline; dpq = pyrazino[2,3-f][1,10]phenanthroline) were reported. On the basis of cytotoxicity tests, Ru1 (IC50 = 1.98 ± 0.02 μM) and Ru2 (IC50 = 10.02 ± 0.19 μM) both showed good anticancer activity in a panel of cell lines, especially in HeLa cells. Researches on mechanism indicated that Ru1 and Ru2 acted on mitochondria and nuclei and induced reactive oxygen species (ROS) accumulation, while the morphology of nuclei and cell cycle had no significant change. Western blot assay further proved that GPX4 and Ferritin were down-regulated, which eventually triggered ferroptosis in HeLa cells. In addition, the toxicity test of zebrafish embryos showed that the concentrations of Ru1 and Ru2 below 120 μM and 60 μM were safe and did not have obvious effect on the normal development of zebrafish embryos.

Low-dimensional compounds containing bioactive ligands. Part XVII: Synthesis, structural, spectral and biological properties of hybrid organic-inorganic complexes based on [PdCl4]2- with derivatives of 8-hydroxyquinolinium

In this study, four hybrid organic-inorganic compounds (8-H₂Q)₂[PdCl₄] (1), (H₂ClQ)₂[PdCl₄] (2), (H₂NQ)₂[PdCl₄] (3) and (H₂MeQ)₂[PdCl₄]·2H₂O (4) (where 8-H₂Q = 8-hydroxyquinolinium, H₂ClQ = 5-chloro-8-hydroxyquinolinium, H₂NQ = 5-nitro-8-hydroxyquinolinium and H₂MeQ = 2-methyl-8-hydroxyquinolinium) were synthesized through organic cation modulation. Single-crystal X-ray structure analysis of compounds 1 and 3 indicates that their structures are planar and consist of [PdCl₄]^2- anions and 8-H₂Q or H₂NQ cations, respectively. Both ionic components are held together through ionic interactions and hydrogen bonds forming infinite chains linked through π-π interactions to form 2D structures. Furthermore, NMR spectroscopy, UV-Vis spectroscopy, elemental analysis, and FT-IR spectroscopy were used to explore the synthesized compounds. The DNA interaction, antimicrobial activity, antiproliferative activity, and radical scavenging effect of the compounds were evaluated. The hybrid compounds and their free ligands can interact with the calf thymus DNA via an intercalation mode involving the insertion of the aromatic chromophore between the base pairs of DNA; compound 1 has the highest binding affinity. Moreover, they have high antimicrobial efficacy against the tested 14 strains of microorganisms with minimum inhibitory concentration values ranging from <1.95 to 250 μg/mL. The antiproliferative activity of the compounds was investigated against three different cancer cell lines, and their selectivity was verified on mesenchymal stem cells. Compounds 1 and 2 displayed selective and high cytotoxicity against human lung and breast cancer cells and showed moderate cytotoxicity against colon cancer cells. Accordingly, they might be auspicious candidates for future pharmacological investigations in lung and breast cancer research.

In silico and multi-spectroscopic analyses on the interaction of 5-amino-8-hydroxyquinoline and bovine serum albumin as a potential anticancer agent

5-Amino-8-hydroxyquinoline (5A8HQ), an amino derivative of 8-hydroxyquinoline, has become a potential anticancer candidate because of its promising proteasome inhibitory activity to overcome and yet synergize bortezomib for fighting cancers. Therefore, in this study, its physicochemical properties and interaction activities with serum protein have extensively been elucidated by both in vitro and in silico approaches to fulfill the pharmacokinetic and pharmacodynamic gaps. 5A8HQ exhibited the drug-likeness properties, where oral administration seems to be a route of choice owing to its high-water solubility and intestinal absorptivity. Multi-spectroscopic investigations suggested that 5A8HQ tended to associate with bovine serum albumin (BSA), a representative of serum protein, via the ground-state complexation. It apparently bound in a protein cleft between subdomains IIA and IIIA of BSA as suggested by the molecular docking and molecular dynamics simulations. The binding was mainly driven by hydrogen bonding and electrostatic interactions with a moderate binding constant at 10⁴ M⁻¹, conforming with the predicted free fraction in serum at 0.484. Therefore, 5A8HQ seems to display a good bioavailability in plasma to reach target sites and exerts its potent pharmacological activity. Likewise, serum albumin is a good candidate to be reservoir and transporter of 5A8HQ in the circulatory system.

Insights of 8-hydroxyquinolines: A novel target in medicinal chemistry

8-Hydroxyquinoline (8-HQ) is a significant heterocyclic scaffold in organic and analytical chemistry because of the properties of chromophore and is used to detect various metal ions and anions. But from the last 2 decades, this moiety has been drawn great attention of medicinal chemists due to its significant biological activities. Synthetic modification of 8-hydroxyquinoline is under exploration on large scale to develop more potent target-based broad spectrum drug molecules for the treatment of several life-threatening diseases such as anti-cancer, HIV, neurodegenerative disorders, etc. Metal chelation properties of 8-hydroxyquinoline and its derivatives also make these potent drug candidates for the treatment of various diseases. This review comprises 8-hydroxyquinoline derivatives reported in the literature in last five years (2016-2020) and we anticipate that it will assist medicinal chemists in the synthesis of novel and pharmacologically potent agents for various therapeutic targets, mainly anti-proliferative, anti-microbial, anti-fungal and anti-viral as well as for the treatment of neurodegenerative disorders.

Streptomyces sp. Strain MUSC 125 from Mangrove Soil in Malaysia with Anti-MRSA, Anti-Biofilm and Antioxidant Activities

There is an urgent need to search for new antibiotics to counter the growing number of antibiotic-resistant bacterial strains, one of which is methicillin-resistant Staphylococcus aureus (MRSA). Herein, we report a Streptomyces sp. strain MUSC 125 from mangrove soil in Malaysia which was identified using 16S rRNA phylogenetic and phenotypic analysis. The methanolic extract of strain MUSC 125 showed anti-MRSA, anti-biofilm and antioxidant activities. Strain MUSC 125 was further screened for the presence of secondary metabolite biosynthetic genes. Our results indicated that both polyketide synthase (pks) gene clusters, pksI and pksII, were detected in strain MUSC 125 by PCR amplification. In addition, gas chromatography-mass spectroscopy (GC-MS) detected the presence of different chemicals in the methanolic extract. Based on the GC-MS analysis, eight known compounds were detected suggesting their contribution towards the anti-MRSA and anti-biofilm activities observed. Overall, the study bolsters the potential of strain MUSC 125 as a promising source of anti-MRSA and antibiofilm compounds and warrants further investigation.

In vitro antimicrobial combinatory effect of Cinnamomum cassia essential oil with 8-hydroxyquinoline against Staphylococcus aureus in liquid and vapour phase

AIMS

The objective of the study was to evaluate the antimicrobial interactions between two volatile agents, Cinnamomum cassia essential oil (CCEO) and 8-hydroxyquinoline (8-HQ) against Staphylococcus aureus strains in liquid and vapour phases.

METHODS AND RESULTS

In vitro antimicrobial effect of CCEO in combination with 8-HQ was evaluated against 12 strains of S. aureus by broth volatilization chequerboard method. Results show additive effects against all S. aureus strains for both phases. In several cases, sums of fractional inhibitory concentration values of our test combinations were lower than 0·6, which can be considered as a strong additive interaction. Moreover, composition of CCEO was analysed by gas chromatography-mass spectrometry analysis. In the CCEO, 26 compounds in total were identified, where (E)-cinnamaldehyde was the predominant compound, followed by cinnamyl acetate, α-copaene, bornyl acetate and caryophyllene.

CONCLUSIONS

Results showed additive in vitro growth-inhibitory effect of CCEO and 8-HQ combination against various standard strains and clinical isolates of S. aureus.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report on antibacterial effect of 8-HQ and CCEO combination in liquid and vapour phases. Results of the study suggest these agents as potential candidates for development of new anti-staphylococcal applications that can be used in the inhalation therapy against respiratory infections.

Low-dimensional compounds containing bioactive ligands. Part XIV: High selective antiproliferative activity of tris(5-chloro-8-quinolinolato)gallium(III) complex against human cancer cell lines

Four gallium(III) complexes, [Ga(ClQ)₃]⋅MeOH (1 - MeOH), [Ga(ClQ)₃] (1), [Ga(BrQ)₃] (2), [Ga(dIQ)₃] (3) and [Ga(CQ)₃] (4), were prepared (H-ClQ = 5-chloro-8-quinolinol, H-BrQ = 7-bromo-8-quinolinol, H-dIQ = 5,7-diiodo-8-quinolinol, H-CQ = 5-chloro-7-iodo-8-quinolinol) and characterised by elemental analysis, IR and NMR spectroscopy. Single crystal structure analysis of 1 - MeOH confirmed that the complex has a molecular structure with gallium(III) metal ion coordinated in mer-fashion by N- and O-donor atoms of three ClQ ligands. Stability of all complexes in DMSO was proved by ¹H NMR spectroscopy. The in vitro antiproliferative activity of 1 was evaluated against the A2780, MBA-MB-231 and HCT116 cell lines. Complex 1 displays higher antiproliferative activity (IC₅₀ values in the range 2.1-6 μm) compared to the ClQ ligand and cisplatin; and a significant selective antiproliferative potency (IC₅₀ = 136 μm, for normal MRC5pd30 cell line). Radical scavenging experiments revealed that complex 1 exhibits the highest antioxidant activity of the prepared complexes as well as the ligands.

Insight into the Molecular Interaction of Cloxyquin (5-chloro-8-hydroxyquinoline) with Bovine Serum Albumin: Biophysical Analysis and Computational Simulation

Cloxyquin is a potential therapeutic compound possessing various bioactivities, especially antibacterial, antifungal, cardioprotective, and pain relief activities. Herein, the interaction mechanism between cloxyquin and bovine serum albumin (BSA) has been elucidated in order to fulfill its pharmacokinetic and pharmacodynamic gaps essential for further development as a therapeutic drug. Multi-spectroscopic and biophysical model analysis suggested that cloxyquin interacts with BSA via a static process by ground-state complex formation. Its binding behavior emerged as a biphasic fashion with a moderate binding constant at the level of 104 M-1. Thermodynamic analysis and molecular docking simulation concurrently revealed that hydrophobic interaction is a major driving force for BSA-cloxyquin complexation. Binding of cloxyquin tends to slightly enlarge the monomeric size of BSA without a significant increase of aggregate fraction. Cloxyquin preferentially binds into the fatty acid binding site 5 (FA5) of the BSA via hydrophobic interaction amongst its quinoline scaffold and Phe550, Leu531, and Leu574 residues of BSA. The quinoline ring and hydroxyl moiety of cloxyquin also form the π-π interaction and the hydrogen bond with Phe506. Our data indicate a potential function of serum albumin as a carrier of cloxyquin in blood circulation.