Structural optimization of adaptaquin, a HIF prolyl hydroxylase inhibitor

Designing, synthesis and evaluation of derived analogues of selected small molecule non-peptidic inhibitors against serotype BoNT/ F

Botulinum neurotoxins are lethal Biowarfare categorized in group A of selected agents, by CDC USA. The unavailability of counter-measures against these neurotoxins has been a matter of extensive research. The 8-hydroxyquinoline (8-HQ) scaffold is established privileged compound and its potential as drug candidate against BoNTs is recently being explored. We have reported 8-HQ compounds NSC1014 and NSC1011 as potential small molecule inhibitors against BoNT/F. In the present study, analogues of NSC84087 and NSC1014 were designed, synthesized and studied for their inhibitory role against BoNT/F intoxication through in silico study, in vitro and in-vivo assays. ∼25 in-house synthesized small molecule inhibitors were evaluated against rBoNT/F light chain through fluorescence thermal shift (FTS) assay and then further assessed through endopeptidase assay. The binding affinity analysis was done through surface plasmon resonance (SPR) based Proteon™ XPR 36 system. Finally, the in-vivo efficacy of these compounds was evaluated in mice model. Analogues C87.9, C87.10 and C87.12 of compound NSC84087 and C14.10, C14.11 and C14.13 of NSC1014 showed promising results through FTS assay and endopeptidase assay. SPR based protein-small molecule interaction studies showed KD values in sub-micromolar range signifying high affinity interaction. The IC₅₀ of C14.10 was found to be the lowest of 3.016 ± 0.798 μM as determined through endopeptidase assay. Finally, efficacy of selected molecules was evaluated in mice, C14.10 and C14.13 protected 40% animals against 4X LD₅₀ and extended survival time up to 200% at 10X LD₅₀. The present study thus proposes the emergence of NSC84087 and NSC1014 analogues as lead compound against BoNT/F.

Chemical Induction of Trophoblast Hypoxia by Cobalt Chloride Leads to Increased Expression of DDIT3

Choriocarcinoma cells BeWo b30 are used to model human placental trophoblast hypoxia using cobalt (II) chloride and hydroxyquinoline derivative (HD) as chemical inducers of hypoxia-inducible factor (HIF). In this study, it was shown that both substances activate the hypoxic pathway and the epithelial-mesenchymal transition and inhibit the pathways of cell proliferation. However, CoCl2 caused activation of the apoptosis pathway, increased the activity of effector caspases 3 and 7, and increased the expression of the unfolded protein response target DDIT3. The mTORC1 pathway was activated upon exposition to CoCl2, while HD suppressed this pathway, as it happens during real trophoblast hypoxia. Thus, effect of CoCl2 on BeWo cells can be a model of severe hypoxia with activation of apoptosis, while HD mimics moderate hypoxia.

Levels of miR-374 increase in BeWo b30 cells exposed to hypoxia

In humans, trophoblast hypoxia during placental development can be a cause of serious pregnancy complications, such as preeclampsia and fetal growth restriction. The pathogenesis of these conditions is not fully clear and may be associated with changed expression of some genes and regulatory molecules, including miRNA, in trophoblast cells. The aim of this study was to analyze miRNA profiles and measure the expression of their target genes in a model of trophoblast hypoxia. Human choriocarcinoma BeWo b30 cells were used as a trophoblast model. Hypoxia was induced by cobalt chloride (CoCl2) and an oxyquinoline derivative. MRNA and miRNA expression profiles were evaluated by means of next generation sequencing (NGS); the expression of individual genes was analyzed by PCR. We studied the secondary structure of mRNAs of target genes for those miRNAs whose expression had changed significantly and analyzed potential competition between these miRNAs for the binding site. The observed changes in the expression of the key genes involved in the response to hypoxia confirmed the feasibility of using CoCl2 and the oxyquinoline derivative as hypoxia inducers. The analysis revealed an increase in miR-374 levels following the activation of the hypoxia pathway in our trophoblast model. The changes were accompanied by a reduction in FOXM1 mRNA expression; this mRNA is a target for hsa-miR-374a-5p and hsa-miR374b-5p, which can compete with hsa-miR-21-5p for the binding sites on FOXM1 mRNA. The involvement of FOXM1 in the regulation of the invasive cell potential suggests the role of miR-374 and FOXM1 in the pathogenesis of disrupted trophoblast invasion during placental development as predisposing for fetal growth restriction and preeclampsia.

HIF Prolyl Hydroxylase Inhibitors for COVID-19 Treatment: Pros and Cons

The review analyzes the potential advantages and problems associated with using HIF prolyl hydroxylase inhibitors as a treatment for COVID-19. HIF prolyl hydroxylase inhibitors are known to boost endogenous erythropoietin (Epo) and activate erythropoiesis by stabilizing and activating the hypoxia inducible factor (HIF). Recombinant Epo treatment has anti-inflammatory and healing properties, and thus, very likely, will be beneficial for moderate to severe cases of COVID-19. However, HIF PHD inhibition may have a significantly broader effect, in addition to stimulating the endogenous Epo production. The analysis of HIF target genes reveals that some HIF-targets, such as furin, could play a negative role with respect to viral entry. On the other hand, HIF prolyl hydroxylase inhibitors counteract ferroptosis, the process recently implicated in vessel damage during the later stages of COVID-19. Therefore, HIF prolyl hydroxylase inhibitors may serve as a promising treatment of COVID-19 complications, but they are unlikely to aid in the prevention of the initial stages of infection.

Neuroprotective Effect of HIF Prolyl Hydroxylase Inhibition in an In Vitro Hypoxia Model

A novel potent analog of the branched tail oxyquinoline group of hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitors, neuradapt, has been studied in two treatment regimes in an in vitro hypoxia model on murine primary hippocampal cultures. Neuradapt activates the expression of HIF1 and HIF2 target genes and shows no toxicity up to 20 μM, which is more than an order of magnitude higher than its biologically active concentration. Cell viability, functional activity, and network connectivity between the elements of neuronal networks have been studied using a pairwise correlation analysis of the intracellular calcium fluctuations in the individual cells. An immediate treatment with 1 μМ and 15 μМ neuradapt right at the onset of hypoxia not only protects from the death, but also maintains the spontaneous calcium activity in nervous cells at the level of the intact cultures. A similar neuroprotective effect in the post-treatment scenario is observed for 15 μМ, but not for 1 μМ neuradapt. Network connectivity is better preserved with immediate treatment using 1 μМ neuradapt than with 15 μМ, which is still beneficial. Post-treatment with neuradapt did not restore the network connectivity despite the observation that neuradapt significantly increased cell viability at 1 μМ and functional activity at 15 μМ. The preservation of cell viability and functional activity makes neuradapt promising for further studies in a post-treatment scenario, since it can be combined with other drugs and treatments restoring the network connectivity of functionally competent cells.

Enantioselective Synthesis of 8-Hydroxyquinoline Derivative, Q134 as a Hypoxic Adaptation Inducing Agent

Hypoxia is a common feature of neurodegenerative diseases, including Alzheimer’s disease that may be responsible for disease pathogenesis and progression. Therefore, the hypoxia-inducible factor (HIF)1 system, responsible for hypoxic adaptation, is a potential therapeutic target to combat these diseases by activators of cytoprotective protein induction. We have selected a candidate molecule from our cytoprotective hydroxyquinoline library and developed a novel enantioselective synthesis for the production of its enantiomers. The use of quinidine or quinine as a catalyst enabled the preparation of enantiomer-pure products. We have utilized in vitro assays to evaluate cytoprotective activity, a fluorescence-activated cell sorting (FACS) based assay measuring mitochondrial membrane potential changes, and gene and protein expression analysis. Our data showed that the enantiomers of Q134 showed potent and similar activity in all tested assays. We have concluded that the enantiomers exert their cytoprotective activity via the HIF1 system through HIF1A protein stabilization.