Phosphodiesterase Inhibitor Research Articles

Discovery of Selective PDE1 Inhibitors with Anti-pulmonary Fibrosis Effects by Targeting the Metal Pocket.

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with no ideal drugs. Our previous research demonstrated that phosphodiesterase 1 (PDE1) could be a promising target for the treatment of IPF. However, only a few selective PDE1 inhibitors are available, and the mechanism of recognition between inhibitors and the PDE1 protein is not fully understood. This study carried out a step-by-step optimization of a dihydropyrimidine hit Z94555858. By targeting the metal pocket of PDE1, a lead compound 3f was obtained, exhibiting an IC50 value of 11 nM against PDE1, moderate selectivity over other PDEs, and significant anti-fibrotic effects in bleomycin-induced pulmonary fibrosis rats. The structure-activity relationship study aided by molecular docking revealed that forming halogen bonds with water in the metal pocket greatly enhanced the PDE1 inhibition, providing a novel strategy for further rational design of PDE1 inhibitors.

Closed-perfusion transretinal ERG setup for preclinical drug and nanostructure testing.

The isolated mammalian retina may serve as a sensitive biosensor for preclinical drug testing, including eye drugs and a broader range of pharmaceuticals. To facilitate testing with minimal amounts of drug molecules or nanostructures, we developed a closed-perfusion transretinal electroretinography (tERG) setup. The major challenge with small amounts of circulating perfusate was maintaining retinal viability and stability during long experiments. We conducted ex vivo tERG using WT C57BL/6J and Gnat1-/- mice to assess rod- and cone-mediated light signals. The dark-adapted retina was stimulated with full-field light flashes while perfused at 5-6 ml/min. The minimum perfusate needed in our closed-circulation was around 50 ml. Penicillin-Streptomycin (Pen-Strep) was indispensable for long recordings. Rod responses remained stable for at least 42 hours, the longest recording we conducted, with the retina still responsive, and rod and cone bipolar cell responses for up to 12 hours. IBMX (3-isobutyl-1-methylxanthine), a non-specific phosphodiesterase (PDE) inhibitor with reversible effects, validated our setup. We used our setup to test the zwitterionic polymer poly(sulfobetaine methacrylate) (PSMBA), serving as a promising material for thermoresponsive nanostructures, and the corresponding monomer SBMA for possible harmful effects on mouse rod and bipolar cell functioning. Our closed-perfusion tERG setup enables long experiments with small amounts of perfusate. PSMBA or SBMA had no effect on rod and bipolar cell responses. This method is applicable for assessing drug functionality, as well as conducting preliminary biocompatibility and toxicity testing using small amounts of molecules or nanostructures that could impact neuronal or synaptic function.

Real-time imaging of cGMP signaling shows pronounced differences between glomerular endothelial cells and podocytes.

Recent clinical trials of drugs enhancing cyclic guanosine monophosphate (cGMP) signaling for cardiovascular diseases have renewed interest in cGMP biology within the kidney. However, the role of cGMP signaling in glomerular endothelial cells (GECs) and podocytes remains largely unexplored. Using acute kidney slices from mice expressing the FRET-based cGMP biosensor cGi500 in endothelial cells or podocytes enabled real-time visualization of cGMP. Stimulation with atrial natriuretic peptide (ANP) or SNAP (NO donor) and various phosphodiesterase (PDE) inhibitors elevated intracellular cGMP in both cell types. GECs showed a transient cGMP response upon particulate or soluble guanylyl cyclase activation, while the cGMP response in podocytes reached a plateau following ANP administration. Co-stimulation (ANP + SNAP) led to an additive response in GECs. The administration of PDE inhibitors revealed a broader basal PDE activity in GECs dominated by PDE2a. In podocytes, basal PDE activity was mainly restricted to PDE3 and PDE5 activity. Our data demonstrate the existence of both guanylyl cyclase pathways in GECs and podocytes with cell-specific differences in cGMP synthesis and degradation, potentially suggesting new therapeutic options for kidney diseases.

Phosphodiesterase inhibitors and testicular torsion: A systematic review and meta-analysis of animal studies.

Testicular torsion is a common urological emergency in children and teenagers that, in most cases, requires surgical exploration and detorsion. However, even after a successful intervention, a high number of patients still develop irreversible damage. To investigate whether the administration of phosphodiesterase inhibitors (PDE) in animal models of testicular torsion can reduce damages caused by the ischemia-reperfusion syndrome. A systematic search of the Medline, Web of Science, Embase, and Ovid databases for studies up to December 2023 was performed using PRISMA guidelines. A detailed search was conducted using the following key terms: "testicles," "ischemia," "reperfusion," and "phosphodiesterase inhibitors." There was no restriction regarding language or year of publication. We investigated spermatogenesis by the Johnsen's biopsy score (JTBS) and histological damage by the Cosentino's biopsy score (CBS). Malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and glutathione peroxidase (GPx) testicular levels were also analyzed. Initially, 296 articles were identified. However, only 20 studies met the inclusion criteria. PDE inhibitors improved JTBS (MD=2.53, CI=1.94 to 3.13), CBS (MD=-1.11, CI=-1.25 to -0.97) and SOD (SMD=3.27, CI=1.59 to 4.95) outcomes. PDE did not improve MDA (SMD=-0.93, CI=-2.19 to 0.34), NO (SMD=-0.54, CI=-1.56 to 0.48), and GPx (SMD=0.77, CI=-0.38 to 1.92) outcomes. A higher dose of PDE inhibitors only improved CBS outcome. This review indicates that the administration of PDE inhibitors in rats ameliorated the outcomes, representing a promising complementary strategy for spermatogenesis recovery following testicular torsion. Our review suggests that JTBS and CBS could be translated into future human studies, validating and extending these findings within the context of human physiopathology, while providing applicability of interventions in real clinical practice.

Phosphodiesterase inhibition and Gucy2C activation enhance tyrosine hydroxylase Ser40 phosphorylation and improve 6-hydroxydopamine-induced motor deficits

BackgroundParkinson’s disease is characterized by a progressive loss of dopaminergic neurons in the nigrostriatal pathway, leading to dopamine deficiency and motor impairments. Current treatments, such as L-DOPA, provide symptomatic relief but result in off-target effects and diminished efficacy over time. This study explores an alternative approach by investigating the activation of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis. Specifically, we explore the effects of phosphodiesterase (PDE) inhibition and guanylate cyclase-C (GUCY2C) activation on tyrosine hydroxylase Ser40 phosphorylation and their impact on motor behavior in a 6-hydroxydopamine (6-OHDA) Parkinson's disease model.ResultsOur findings demonstrate that increasing cyclic nucleotide levels through PDE inhibition and GUCY2C activation significantly enhances tyrosine hydroxylase Ser40 phosphorylation. In a Pitx3-deficient mouse model, which mimics the loss of dopaminergic neurons seen in Parkinson’s disease, Ser40 phosphorylation remained manipulable despite reduced tyrosine hydroxylase protein levels. Moreover, we observed no evidence of tyrosine hydroxylase degradation due to Ser40 phosphorylation, challenging previous reports. Furthermore, both PDE inhibition and GUCY2C activation resulted in improved motor behavior in the 6-OHDA Parkinson’s disease mouse model, highlighting the potential therapeutic benefits of these approaches.ConclusionsThis study underscores the therapeutic potential of enhancing tyrosine hydroxylase Ser40 phosphorylation to improve motor function in Parkinson’s disease. Both PDE inhibition and GUCY2C activation represent promising non-invasive strategies to modulate endogenous dopamine biosynthesis and address motor deficits. These findings suggest that targeting cyclic nucleotide pathways could lead to novel therapeutic approaches, either as standalone treatments or in combination with existing therapies like L-DOPA, aiming to provide more durable symptom relief and potentially mitigate neurodegeneration in Parkinson's disease.

Dual Inhibition of Phosphodiesterase 3 and 4 Enzymes by Ensifentrine Protects against MRSA-Induced Lung Endothelial and Epithelial Dysfunction.

Acute Respiratory Distress Syndrome (ARDS) is a severe lung condition with a high mortality rate for which there are no effective therapeutics. The failure of the alveolar-capillary barrier, composed of lung endothelial (EC) and alveolar epithelial (AEC) cells, is a critical factor leading to excessive inflammation and edema characteristic of acute lung injury (ALI) pathophysiology. Phosphodiesterases (PDE) are enzymes well-recognized for their roles in regulating endothelial permeability and inflammation. Although PDE inhibitors are used as therapeutics for inflammatory diseases like COPD (chronic obstructive pulmonary disease), their efficacy in treating ARDS has not yet been established. In this study, we investigated the effects of ensifentrine, an FDA-approved novel dual PDE 3/4 inhibitor, on lung endothelial and epithelial dysfunction caused by methicillin-resistant S. aureus (MRSA), a pathogen involved in bacterial ARDS. Human primary lung endothelial cells and alveolar epithelial cell lines (A549 and immortalized AEC) were treated with heat-killed MRSA, and their responses were assessed in the presence or absence of ensifentrine. Ensifentrine given either pre- or post-exposure attenuated MRSA-induced increased lung endothelial permeability. VE-cadherin junctions, which serve to stabilize the EC barrier, were disrupted by MRSA; however, ensifentrine effectively prevented this disruption. Pre-treatment with ensifentrine protected against MRSA-induced EC pro-inflammatory signaling by inhibiting the expression of VCAM-1, ICAM-1, and by reducing the IL-6 and IL-8 release. In AEC, MRSA caused the upregulation of ICAM-1, the activation of NF-kB, and the production of IL-8, all of which were inhibited by ensifentrine. These results indicate that the dual inhibition of phosphodiesterases 3 and 4 by ensifentrine is barrier protective and attenuates MRSA-induced inflammation in both lung endothelial and epithelial cells. The PDE3/4 inhibitor ensifentrine may represent a promising novel strategy for the treatment of MRSA-induced ARDS.

Nerandomilast Improves Bleomycin-Induced Systemic Sclerosis-Associated Interstitial Lung Disease in Mice by Regulating the TGF-β1 Pathway.

Systemic sclerosis (SSc) is a rare connective tissue disease with a heterogeneous clinical course. Interstitial lung disease (ILD) is a common complication of SSc and a major contributor to SSc-related deaths. Besides nintedanib and tocilizumab, there are currently no clinically approved drugs for SSc-ILD, highlighting the urgent need for new treatment strategies. Previous studies have shown that cyclic adenosine monophosphate (cAMP) plays a crucial role in the pathogenesis of SSc and lung fibrosis. Phosphodiesterases (PDEs) are enzymes that specifically hydrolyze cAMP, making PDE inhibitors promising candidates for SSc-ILD treatment. Nerandomilast, a preferential phosphodiesterase 4B (PDE4B) inhibitor currently undergoing phase III clinical trials for idiopathic pulmonary fibrosis and progressive fibrosing interstitial lung diseases (PF-ILD), has good preference for PDE4B but lacks studies for SSc-ILD. Our research demonstrates that nerandomilast effectively inhibits skin and lung fibrosis in a bleomycin-induced mouse model of SSc-ILD. For lung fibrosis, we found that nerandomilast could improve bleomycin-induced SSc-ILD through inhibiting PDE4B and the TGF-β1-Smads/non-Smads signaling pathways, which provides a theoretical basis for potential therapeutic drug development for SSc-ILD.

Phosphodiesterase 5 and its inhibitors with ischemic heart disease: a Mendelian randomization analysis and a real-world study.

Accumulating studies reported that several phosphodiesterases (PDEs) inhibitors might have cardiovascular benefits. This study aimed to explore the relationship between genetically-predicted PDEs and ischemia heart disease via drug target Mendelian randomization (MR) approach, and then examine the effect of inhibitors of identified target on the outcomes by using real-world data. In the two-sample MR study, the expression of genes encoding PDEs was used to proxy the level of PDEs and available expression quantitative trait loci (eQTLs) for each target gene were identified as the genetic instruments. The outcomes included coronary heart disease (CHD) and myocardial infarction (MI). In the real-world study, a retrospective cohort was conducted to compare the incidence of outcomes between PDE5 inhibitors and alprostadil use by linking Swedish nationwide registers. MR analyses identified two types of PDEs, PDE5 and PDE8, genetically-predicted expression in blood of the encoded genes was significantly associated with the risk of CHD (ORPDE5A=1.22,95% CI=1.06-1.40; ORPDE8A=1.26,95% CI=1.07-1.49) and MI (ORPDE5A=1.27,95% CI=1.09-1.48; ORPDE8A=1.24,95% CI=1.04-1.48). Notably, the highest expression of PDE5A was observed in artery aorta, which was also positively related to CHD (OR=1.17,95% CI=1.05-1.32) and MI (OR=1.15,95% CI=1.02-1.30). Real-world study provided supportive evidence that as compared to alprostadil use, PDE5 inhibitors use significantly reduced the incidence of CHD (adjusted HR=0.70,95% CI=0.66-0.73) and MI (adjusted HR=0.79,95% CI=0.73-0.84). This study provided observational and genetic evidence about the protective role of PDE5 inhibition against ischemic heart disease, indicating the potential of these drugs to be repurposed for ischemia heart disease prevention and treatment.

Mediation of mammalian olfactory response by presence of odor-evoked potassium current.

It is well understood that odorants interact with specialized G-protein coupled receptors embedded in the ciliary membrane of olfactory sensory neurons (OSN) which initiates a voltage-generating intracellular cascade of signal transduction events that can be recorded at the epithelial level as an electroolfactogram (EOG). While the depolarizing excitatory pathway in vertebrates involving cyclic adenosine monophosphate (cAMP)-induced Na+/Ca2+ influx and calcium-induced Cl- efflux is well established, there is evidence of potassium-associated inhibitory currents that correspond with cellular activation. While several Ca2+-dependent feedback mechanisms contribute to cellular deactivation which have been commonly attributed to these inhibitory currents, the frequently observed positive ionic conductance prior to excitatory depolarization have led many to suggest an additional earlier inhibitory mechanism at the receptor level that may be independent of downstream calcium influx. Due to conflicting conclusions, the role and mechanism behind Ca2+-independent inhibitory currents in olfactory cells is not fully understood. We investigated the functional and temporal involvement of potassium channels in odor transduction by comparing electroolfactogram (EOG) recordings in rat olfactory epithelia following ion channel inhibition and targeted activation of downstream components with or without potassium-blocking. Several K+-channel blocking agents (4-Aminopyridine, charybdotoxin, & iberiotoxin) demonstrated a diminished pre-action potential positive current that corresponded with reduced excitatory response to odor stimulation that was recovered when blockers were removed. We further assessed EOG responses in the absence of odor or with odor response enhancing zinc nanoparticles. Chemically eliciting membrane excitation in the absence of odor stimulation with a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX), in combination with K+-channel inhibition, further indicated potassium channel activation precedes excitatory events and is independent of cAMP-induced calcium influx. These results support previous findings of odor-activated inhibitory potassium currents that may play a functional role in subsequent G-protein activity.

Phosphodiesterase Inhibitors in Fetal Growth Restriction: Do Not Forget to Consider Fetal Sex and Subcellular Compartmentation.

Fetal growth restriction (FGR) is a common complication of pregnancy, associated with major perinatal mortality and morbidity, and with an increased risk to develop cardiometabolic diseases later in life. There is currently no effective approach to prevent or treat FGR, despite numerous animal and human studies assessing substances likely to improve fetal growth. Phosphodiesterase (PDE) inhibitors appeared as promising drugs to improve FGR management. However, to date, studies have led to somewhat disappointing or controversial results. In this Opinion article, we would like to draw attention to the need to consider the biological sex and the relative reactivity of human umbilical vein and arteries when developing therapeutic interventions to improve human umbilical circulation using PDE inhibitors. Indeed, we suspect that fetal sex, vessel type and the presence of FGR may influence subcellular compartmentation, which could jeopardize beneficial effects of PDE inhibitors.

Drug Repurposing for Effective Alzheimer's Disease Medicines: Existing Methods and Novel Pharmacoepidemiological Approaches.

Drug repurposing is a methodology used to identify new clinical indications for existing drugs developed for other indications and has been successfully applied in the treatment of numerous conditions. Alzheimer's disease (AD) may be particularly well-suited to the application of drug repurposing methods given the absence of effective therapies and abundance of multi-omic data that has been generated in AD patients recently that may facilitate discovery of candidate AD drugs. A recent focus of drug repurposing has been in the application of pharmacoepidemiologic approaches to drug evaluation. Here, real-world clinical datasets with large numbers of patients are leveraged to establish observational efficacy of candidate drugs for further evaluation in disease models and clinical trials. In this review, we provide a selected overview of methods for drug repurposing, including signature matching, network analysis, molecular docking, phenotypic screening, semantic network, and pharmacoepidemiological analyses. Numerous methods have also been applied specifically to AD with the aim of nominating novel drug candidates for evaluation. These approaches, however, are prone to numerous limitations and potential biases that we have sought to address in the Drug Repurposing for Effective Alzheimer's Medicines (DREAM) study, a multi-step framework for selection and validation of potential drug candidates that has demonstrated the promise of STAT3 inhibitors and re-evaluated evidence for other drug candidates, such as phosphodiesterase inhibitors. Taken together, drug repurposing holds significant promise for development of novel AD therapeutics, particularly as the pace of data generation and development of analytical methods continue to accelerate.

Development of selective heterocyclic PDE4 inhibitors for treatment of psoriasis

Psoriasis is a chronic autoimmune disease that badly affects the life quality of patients and their families. Inadequate efficacy, safety risks, high cost and low compliance of current psoriasis drugs urge development of novel small molecular drugs. In this study, two series of 37 novel compounds were designed and synthesized as inhibitors of phosphodiesterase 4 (PDE4) that specifically hydrolyzes second messenger cAMP and is an effective target for treatment of inflammatory diseases. Comprehensive structural-activity optimization led to finding of inhibitor 2e with IC50 = 2.4 nM for PDE4D and >4100-fold selectivity over other PDE families. Compound 2e inhibited the release of TNF-α (IC50 = 21.36 μM) and IL-6 (IC50 = 29.22 μM) in the LPS-stimulated Raw264.7 cells. Topical application of 2e exhibited remarkable therapeutic efficacy in imiquimod-induced psoriasis mice model, suggesting that 2e is a strong drug candidate for treatment of psoriasis.

Unbiased high-throughput screening of drug-repurposing libraries identifies small-molecule inhibitors of clot retraction

AbstractPlatelet clot retraction, the ultimate phase of platelet thrombus formation, is critical for clot stabilization. It requires functional αIIbβ3 receptors, fibrin, and the integrated actions of the actin-myosin contractile and cytoskeletal systems. Disturbances in clot retraction have been associated with both bleeding and thrombosis. We recently demonstrated that platelets treated with the αIIbβ3 antagonist peptide RGDW, which eliminates fibrinogen-mediated platelet aggregation, are still able to retract clots. We have exploited this observation to develop an unbiased, functional high-throughput assay to identify small-molecule inhibitors of fibrin-mediated clot retraction adapted for a 384-well plate format. We tested 9710 compounds from drug-repurposing libraries (DRLs). These libraries contain compounds that are either US Food and Drug Administration approved or have undergone preclinical/clinical development. We identified 27 compounds from the Library of Pharmacologically Active Compounds library as inhibitors of clot retraction, of which 14 are known inhibitors of platelet function. From the DRLs, we identified 135 compounds (1.6% hit rate). After extensive curation, these compounds were categorized based on the activity of their reported target. Multiple kinase and phosphodiesterase inhibitors with known antiplatelet effects were identified, along with multiple deubiquitination and receptor inhibitors, as well as compounds that have not previously been reported to have antiplatelet activity. Studies of 1 of the deubiquitination inhibitors (degrasyn) suggest that its effects are downstream of thrombin-induced platelet-fibrinogen interactions and thus may permit the separation of platelet thrombin-induced aggregation-mediated events from clot retraction. Additional studies of the identified compounds may lead to novel mechanisms of inhibiting thrombosis.

Phosphodiesterase Inhibitor ‘Rolipram’ Alleviates Sleep-Deprivation-Mediated Appetitive-Delay-Conditioned Memory in the Rat

Phosphodiesterase Inhibitor ‘Rolipram’ Alleviates Sleep-Deprivation-Mediated Appetitive-Delay-Conditioned Memory in the Rat

A Brief Overview of Cholinergic and Phosphodiesterase-5 Inhibitors in Diabetic Bladder Dysfunction.

Diabetic bladder dysfunction (DBD) comprises a wide spectrum of lower urinary tract symptoms that impact diabetic patients' lives, including urinary frequency, urgency, incontinence, and incomplete bladder emptying. To relieve symptoms, anticholinergics have been widely prescribed and are considered an effective treatment. There is increasing evidence that diabetic patients may benefit from the use of phosphodiesterase 5 (PDE5) inhibitors. This narrative review aims to provide a brief overview of the pathophysiology of DBD along with a focus on cholinergic and phosphodiesterase inhibitors as therapies that benefit DBD. An examination of the literature suggests compelling avenues of research and underscores critical gaps in understanding the mechanisms underlying DBD. New tools and models, especially rodent models, are required to further elucidate the mechanisms of action of current therapies in the treatment of DBS.

GPR35 agonists inhibit TRPA1-mediated colonic nociception through suppression of substance P release.

The development of nonopioid analgesics for the treatment of abdominal pain is a pressing clinical problem. To address this, we examined the expression of Gi/o-coupled receptors, which typically inhibit nociceptor activation, in colonic sensory neurons. This led to the identification of the orphan receptor GPR35 as a visceral analgesic drug target because of its marked coexpression with transient receptor potential ankyrin 1 (TRPA1), a mediator of noxious mechanotransduction in the bowel. Building on in silico docking simulations, we confirmed that the mast cell stabiliser, cromolyn (CS), and phosphodiesterase inhibitor, zaprinast, are agonists at mouse GPR35, promoting the activation of different Gi/o subunits. Pretreatment with either CS or zaprinast significantly attenuated TRPA1-mediated colonic nociceptor activation and prevented TRPA1-mediated mechanosensitisation. These effects were lost in tissue from GPR35-/- mice and were shown to be mediated by inhibition of TRPA1-evoked substance P (SP) release. This observation highlights the pronociceptive effect of SP and its contribution to TRPA1-mediated colonic nociceptor activation and sensitisation. Consistent with this mechanism of action, we confirmed that TRPA1-mediated colonic contractions evoked by SP release were abolished by CS pretreatment in a GPR35-dependent manner. Our data demonstrate that GPR35 agonists prevent the activation and sensitisation of colonic nociceptors through the inhibition of TRPA1-mediated SP release. These findings highlight the potential of GPR35 agonists to deliver nonopioid analgesia for the treatment of abdominal pain.

Control of nerve-mediated and urothelial ATP release by a protein kinase G-dependent pathway in the mouse bladder

Aim:ATP signalling is involved in urinary bladder motor and sensory pathways, including stimulation-mediated release from parasympathetic varicosities to detrusor muscle and from urothelial cells when mechanically stressed. Both modalities are present in humans and other mammals but are especially prominent in overactive bladder syndromes. There is therefore an unmet need to understand how to regulate such release. This study tested the hypothesis that the nitric oxide (NO•)/ soluble guanylate cyclase (sGC)/ cyclic GMP/ protein kinase-G (PKG) pathway has a central role. Methods:In vitro nerve-mediated contractions and ATP/acetylcholine (ACh) release were measured from bladder wall strips, as was ATP release from urothelial cell suspensions subject to mechanical stresses. Enhanced spontaneous contractile activity was also measured in bladder wall preparations of spinal cord-injured mice. Interventions were designed to increase cellular cGMP levels (a cell-permeable cGMP analogue, a NO•donor, a phosphodiesterase inhibitor (PDEI), a sGC activator), or agents to reduce activity of pathway enzymes (sCG or PKG). Results:ATP-dependent contractions were reduced by the above interventions, as was ATP release; but ACh-dependent contractions and ACh release were unaffected. Spontaneous contractile activity was also reduced by the cGMP analogue and by a PDEI. ATP release from urothelial cell suspensions was also reduced by similar interventions. Conclusions:ATP release from efferent nerves and from urothelial cells were selectively reduced by upregulating the NO•/sGC/cGMP/PKG pathway. Translational aspects are discussed with respect to purinergic pathways and overactive bladder pathologies.

Review on Therapeutic Diversity of Oxazole Scaffold: An Update

AbstractOxazole, a five‐membered cyclic ring containing oxygen and nitrogen, displays diverse interactions and structural variations, enhancing its potential applications across various domains. Oxazole derivatives exhibit diverse pharmacological activities, including antidiabetic, anticonvulsant, anticancer, phosphodiesterase inhibition, antiprotozoal, and antibacterial effects, making them appealing to medicinal chemists. Their presence in naturally occurring pharmacologically active substances as well as synthetic medicines underscores their therapeutic potential. This review encompasses recent advancements in the biological activities of oxazole derivatives during the period of 2018–2023. The discussed activities include antitumor, central nervous system (CNS) modulation, antidiabetic, anti‐Alzheimer, antibacterial, and enzyme inhibitory effects. The review highlights the mechanisms of action of these compounds in various diseases, the most potent compounds along with their respective IC50/MIC (inhibitory concentration/minimum inhibitory concentration) values, and discusses the models utilized for quantifying their activity. Currently, there are eight FDA‐approved drugs bearing oxazole scaffolds available in the market. Analysis of the literature reveals that the antitumor activity of oxazole derivatives is particularly noteworthy among their various activities. The incorporation of phenyl, methoxyphenyl, or halogen‐substituted phenyl moieties significantly enhances therapeutic activities compared to reference drugs. The substitution flexibility at three positions of oxazole derivatives contributes to their spectrum of pharmacological activities.

Non-arteritic anterior ischemic optic neuropathy in Black patients

Prior studies have shown that non-arteritic anterior ischemic optic neuropathy (NAION) is uncommon in persons of Black race compared to those of White race, but the reasons behind this discrepancy remain unknown. Our goal was to analyze the systemic and ocular features of Black NAION patients compared to White patients. Retrospective cross-sectional study METHODS: Self-reported race was collected from all NAION patients seen between 2014-2022 from a single US neuro-ophthalmology service. All Black NAION patients and a randomly selected sample of White NAION patients were included. We collected information on hypertension, hyperlipidemia, diabetes mellitus, hypothyroidism, obesity, ischemic heart disease, atrial fibrillation, pacemaker insertion, chronic kidney disease, dialysis, anemia, obstructive sleep apnea, deep vein thrombosis, stroke, use of phosphodiesterase inhibitors, and smoking status. We reviewed color fundus photographs and optic nerve OCT images to assess cup-to-disc ratio and document the presence of optic disc drusen. Counterfactual random forest was used to estimate associations for each characteristic of interest by race controlling for the other exposures. We included 32 Black NAION patients (mean age 57 ± 11 years, 38% men) and 69 of 432 White patients (mean age 57 ± 15 years, 59% men). Time between NAION onset and neuro-ophthalmic examination was significantly longer in Black patients (1.5 to <3 months: OR 4.07, P = 0.03; 6 to <12 months: OR 6.05, P = 0.007). Chronic kidney disease (OR 7.53, P = 0.003) and hemodialysis (OR 13.69, P = 0.02) were significantly more frequent in Black patients. No significant differences in cup-to-disc ratio were present (0.15 to <0.25: OR 2.83, P = 0.09; 0.25 to <0.35: OR 0.56, P = 0.46; ≥0.35: OR 0.66, P = 0.44). Referral delay occurs in Black patients with NAION, likely due to its relative rarity and concern for alternate diagnoses. Black NAION patients were substantially more likely to have chronic kidney disease and be on dialysis than White patients. Despite known racial differences in cup-to-disc ratio, we found no difference between Black and White NAION patients, suggesting that the underlying proposed compartment mechanism is the same between races.

Identification of potent and orally efficacious phosphodiesterase inhibitors in Cryptosporidium parvum-infected immunocompromised male mice

Cryptosporidium parvum and C. hominis are parasites that cause life-threatening diarrhea in children and immunocompromised people. There is only one approved treatment that is modestly effective for children and ineffective for AIDS patients. Here, screening 278 compounds from the Merck KGaA, Darmstadt, Germany collection and accelerated follow-up enabled by prior investigation of the compounds identifies a series of pyrazolopyrimidine human phosphodiesterase (PDE)-V (hPDE-V) inhibitors with potent anticryptosporidial activity and efficacy following oral administration in C. parvum-infected male mice. The lead compounds affect parasite host cell egress, inhibit both C. parvum and C. hominis, work rapidly, and have minimal off-target effects in a safety screening panel. Interestingly, the hPDE-V inhibitors sildenafil and the 4-aminoquinoline compound 7a do not affect Cryptosporidium. C. parvum expresses one PDE (CpPDE1) continuously during asexual growth, the inhibited life stage. According to homology modeling and docking, the lead compounds interact with CpPDE1. Bulkier amino acids (Val900 and His884) in the CpPDE1 active site replace alanines in hPDE-V and block sildenafil binding. Supporting this, sildenafil kills a CRISPR-engineered Cryptosporidium CpPDE1 V900A mutant. The CpPDE1 mutation also alters parasite susceptibility to pyrazolopyrimidines. CpPDE1 is therefore a validated pyrazolopyrimidine molecular target to exploit for target-based optimization for improved anticryptosporidial development.