New salicylic acid derivatives, double inhibitors of glycolate oxidase and lactate dehydrogenase, as effective agents decreasing oxalate production

Discovery of first-in-class human glycolate oxidase near infrared molecular rotor inhibitors (NIRGOi)

Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder that affects the metabolism of oxalate leading to formation of renal calculi and end stage kidney failure. Currently, no specific drug exists for PH1 treatment, while human glycolate oxidase (hGO), which influences endogenous oxalate synthesis, is a clinically validated target for PH1 treatment. We envisioned the possibility of exploiting the reported salicylate scaffold as an hGO interactor to develop the first in their class Near Infrared hGO inhibitors, that we termed NIRGOi. These could enable the simultaneous tracking and inhibition of hGO in a single moiety. We encompassed different electron acceptors (A) and 5-formylsalicylic acid, the electron donor (D), as a two in one moiety, to develop three D-A-type NIRGOi, new compounds capable of enhancing their photophysical properties upon interaction with the target protein, hGO. Their photophysical properties verified that the D-A interactions successfully redshifted the emission maxima to wavelengths ranging from 550 nm to 690 nm. Their interaction with hGO was first modelled in silico and then an array of in vitro assays were used to verify their low micromolar efficacy along with the alteration of their photophysical properties upon binding. This study provides new tools, the NIRGOi, that are promising starting points for the development of NIR reporting probes to explore and potentially treat Primary Hyperoxaluria type 1.

Early Detection and Monitoring of Nephrolithiasis: The Potential of Electrochemical Sensors

Nephrolithiasis (kidney stone disease) continues to pose a significant global health challenge, affecting millions of individuals and placing substantial economic pressures on healthcare systems. Traditional diagnostic methods-such as computed tomography (CT), ultrasound, and basic urinalysis-are often limited by issues including radiation exposure, lower sensitivity in detecting small stones, operator dependency, and the inability to provide real-time analysis. In response, electrochemical sensors have emerged as innovative and powerful tools capable of the rapid, sensitive, and specific detection of key biomarkers associated with nephrolithiasis. This review highlights the advances in electrochemical approaches for monitoring oxalate and uric acid, the two primary metabolites implicated in kidney stone formation. We discuss the principles of electrode design and fabrication, including nanomaterial integration, 3D printing, and molecular imprinting, which have markedly improved detection limits and selectivity. Furthermore, we critically evaluate the practical challenges-such as sensor fouling, reproducibility, and stability in complex biological matrices-that currently impede widespread clinical implementation. The potentials for miniaturization and point-of-care integration are emphasized, with an eye toward continuous or home-based monitoring systems that can offer personalized insights into risk of stone formation and progression. By consolidating recent findings and exploring future trends in multi-analyte detection and wearable diagnostics, this review provides a roadmap for translating electrochemical sensors from research laboratories to routine clinical practice, ultimately aiming to enhance early intervention and improve patient outcomes in nephrolithiasis.

Synthesis and hLDHA Inhibitory Activity of New Stiripentol-Related Compounds of Potential Use in Primary Hyperoxaluria

Human lactate dehydrogenase A (hLDHA) is a homotetrameric isozyme involved in the conversion of glyoxylate into oxalate in the cytosol of liver cells (hepatocytes) and partially responsible for the overproduction of oxalate in patients with the rare disease called primary hyperoxaluria (PH). Recently, hLDHA inhibition has been validated as a safe therapeutic method to try to control the PH disease. Stiripentol (STP) is an approved drug used in the treatment of seizures associated with Dravet's syndrome (a severe form of epilepsy in infancy) which, in addition, has been drawing interest in recent years also for potentially treating PH, due to its hLDHA inhibitory activity. In this work, several new STP-related compounds have been synthesized and their hLDHA inhibitory activity has been compared to that of STP. The synthesis of these analogues to STP was accomplished using crossed-aldol condensation guided by lithium enolate chemistry and a successive regioselective reduction of the resulting α,β-unsaturated ketones. The target molecules were obtained as racemates, which were separated into their enantiomers by chiral HPLC. The absolute configurations of pure enantiomers were determined by the modified Mosher's method and electronic circular dichroism (ECD) spectroscopy. For the inhibitory effect over the hLDHA catalytic activity, a kinetic spectrofluorometric assay was used. All the new synthesized compounds turned out to be more active at 500 μM (46-72% of inhibition percentage) than STP (10%), which opens a new line of study on the possible capacity of these analogues to reduce urinary oxalate levels in vivo more efficiently.

Inhibition of hepatic oxalate overproduction ameliorates metabolic dysfunction-associated steatohepatitis

The incidence of metabolic dysfunction-associated steatohepatitis (MASH) is on the rise, and with limited pharmacological therapy available, identification of new metabolic targets is urgently needed. Oxalate is a terminal metabolite produced from glyoxylate by hepatic lactate dehydrogenase (LDHA). The liver-specific alanine-glyoxylate aminotransferase (AGXT) detoxifies glyoxylate, preventing oxalate accumulation. Here we show that AGXT is suppressed and LDHA is activated in livers from patients and mice with MASH, leading to oxalate overproduction. In turn, oxalate promotes steatosis in hepatocytes by inhibiting peroxisome proliferator-activated receptor-α (PPARα) transcription and fatty acid β-oxidation and induces monocyte chemotaxis via C-C motif chemokine ligand 2. In male mice with diet-induced MASH, targeting oxalate overproduction through hepatocyte-specific AGXT overexpression or pharmacological inhibition of LDHA potently lowers steatohepatitis and fibrosis by inducing PPARα-driven fatty acid β-oxidation and suppressing monocyte chemotaxis, nuclear factor-κB and transforming growth factor-β targets. These findings highlight hepatic oxalate overproduction as a target for the treatment of MASH.

Tracking Selective Internalization and Intracellular Dynamics of Modified Chitosan Polymeric Micelles of Interest in Primary Hyperoxaluria Diseases

Primary hyperoxalurias (PHs) represent rare diseases associated with disruptions in glyoxylate metabolism within hepatocytes. Impaired glyoxylate detoxification in PH patients results in its accumulation and subsequent conversion into oxalate, a process catalyzed by the hepatic lactate dehydrogenase A enzyme (hLDHA). Targeting this enzyme selectively in the liver using small organic molecules emerges as a potential therapeutic strategy for PH. However, achieving selective hepatic inhibition of hLDHA poses challenges, requiring precise delivery of potential inhibitors into hepatocytes to mitigate adverse effects in other tissues. Our recent efforts focused on the design of polymeric micelle nanocarriers tailored for the selective transport and release of hLDHA inhibitors into liver tissues. In this study, we synthesized and assessed the internalization and disaggregation dynamics of chitosan-based polymeric micelles in both hepatic and nonhepatic cell models using live-cell imaging. Our findings indicate that lactonolactone residues confer internalization capacity to the micelles upon exposure to cells. Moreover, we demonstrated the intracellular disaggregation capacity of these nanocarriers facilitated by the cystamine redox-sensitive linker attached to the polymer. Importantly, no cytotoxic effects were observed throughout the experimental time frame. Finally, our results underscore the higher selectivity of these nanocarriers for hepatic HepG2 cells compared to other nonhepatic cell models.

A molecular journey on the pathogenesis of primary hyperoxaluria

PURPOSE OF REVIEW

Primary hyperoxalurias (PHs) are rare disorders caused by the deficit of liver enzymes involved in glyoxylate metabolism. Their main hallmark is the increased excretion of oxalate leading to the deposition of calcium oxalate stones in the urinary tract. This review describes the molecular aspects of PHs and their relevance for the clinical management of patients.

RECENT FINDINGS

Recently, the study of PHs pathogenesis has received great attention. The development of novel in vitro and in vivo models has allowed to elucidate how inherited mutations lead to enzyme deficit, as well as to confirm the pathogenicity of newly-identified mutations. In addition, a better knowledge of the metabolic consequences in disorders of liver glyoxylate detoxification has been crucial to identify the key players in liver oxalate production, thus leading to the identification and validation of new drug targets.

SUMMARY

The research on PHs at basic, translational and clinical level has improved our knowledge on the critical factors that modulate disease severity and the response to the available treatments, leading to the development of new drugs, either in preclinical stage or, very recently, approved for patient treatment.

Navigating the Evolving Landscape of Primary Hyperoxaluria: Traditional Management Defied by the Rise of Novel Molecular Drugs

Primary hyperoxalurias (PHs) are inherited metabolic disorders marked by enzymatic cascade disruption, leading to excessive oxalate production that is subsequently excreted in the urine. Calcium oxalate deposition in the renal tubules and interstitium triggers renal injury, precipitating systemic oxalate build-up and subsequent secondary organ impairment. Recent explorations of novel therapeutic strategies have challenged and necessitated the reassessment of established management frameworks. The execution of diverse clinical trials across various medication classes has provided new insights and knowledge. With the evolution of PH treatments reaching a new milestone, prompt and accurate diagnosis is increasingly critical. Developing early, effective management and treatment plans is essential to improve the long-term quality of life for PH patients.

Identification and characterization of Glycolate oxidase gene family in garden lettuce (Lactuca sativa cv. 'Salinas') and its response under various biotic, abiotic, and developmental stresses

Glycolate oxidase (GLO) is an FMN-containing enzyme localized in peroxisomes and performs in various molecular and biochemical mechanisms. It is a key player in plant glycolate and glyoxylate accumulation pathways. The role of GLO in disease and stress resistance is well-documented in various plant species. Although studies have been conducted regarding the role of GLO genes from spinach on a microbial level, the direct response of GLO genes to various stresses in short-season and leafy plants like lettuce has not been published yet. The genome of Lactuca sativa cultivar 'Salinas' (v8) was used to identify GLO gene members in lettuce by performing various computational analysis. Dual synteny, protein-protein interactions, and targeted miRNA analyses were conducted to understand the function of GLO genes. The identified GLO genes showed further clustering into two groups i.e., glycolate oxidase (GOX) and hydroxyacid oxidase (HAOX). Genes were observed to be distributed unevenly on three chromosomes, and syntenic analysis revealed that segmental duplication was prevalent. Thus, it might be the main reason for GLO gene diversity in lettuce. Almost all LsGLO genes showed syntenic blocks in respective plant genomes under study. Protein-protein interactions of LsGLO genes revealed various functional enrichments, mainly photorespiration, and lactate oxidation, and among biological processes oxidative photosynthetic carbon pathway was highly significant. Results of in-depth analyses disclosed the interaction of GLO genes with other members of the glycolate pathway and the activity of GLO genes in various organs and developmental stages in lettuce. The extensive genome evaluation of GLO gene family in garden lettuce is believed to be a reference for cloning and studying functional analyses of GLO genes and characterizing other members of glycolate/glyoxylate biosynthesis pathway in various plant species.

Synthesis and hLDH Inhibitory Activity of Analogues to Natural Products with 2,8-Dioxabicyclo[3.3.1]nonane Scaffold

Human lactate dehydrogenase (hLDH) is a tetrameric enzyme present in almost all tissues. Among its five different isoforms, hLDHA and hLDHB are the predominant ones. In the last few years, hLDHA has emerged as a therapeutic target for the treatment of several kinds of disorders, including cancer and primary hyperoxaluria. hLDHA inhibition has been clinically validated as a safe therapeutic method and clinical trials using biotechnological approaches are currently being evaluated. Despite the well-known advantages of pharmacological treatments based on small-molecule drugs, few compounds are currently in preclinical stage. We have recently reported the detection of some 2,8-dioxabicyclo[3.3.1]nonane core derivatives as new hLDHA inhibitors. Here, we extended our work synthesizing a large number of derivatives (42-70) by reaction between flavylium salts (27-35) and several nucleophiles (36-41). Nine 2,8-dioxabicyclo[3.3.1]nonane derivatives showed IC₅₀ values lower than 10 µM against hLDHA and better activity than our previously reported compound 2. In order to know the selectivity of the synthesized compounds against hLDHA, their hLDHB inhibitory activities were also measured. In particular, compounds 58, 62a, 65b, and 68a have shown the lowest IC₅₀ values against hLDHA (3.6-12.0 µM) and the highest selectivity rate (>25). Structure-activity relationships have been deduced. Kinetic studies using a Lineweaver-Burk double-reciprocal plot have indicated that both enantiomers of 68a and 68b behave as noncompetitive inhibitors on hLDHA enzyme.

Molecular Mechanisms, Genotype-Phenotype Correlations and Patient-Specific Treatments in Inherited Metabolic Diseases

Advances in DNA sequencing technologies are revealing a vast genetic heterogeneity in human population, which may predispose to metabolic alterations if the activity of metabolic enzymes is affected [...].

Lactate dehydrogenase A inhibitors with a 2,8-dioxabicyclo[3.3.1]nonane scaffold: A contribution to molecular therapies for primary hyperoxalurias

Human lactate dehydrogenase A (hLDHA) is one of the main enzymes involved in the pathway of oxalate synthesis in human liver and seems to contribute to the pathogenesis of disorders with endogenous oxalate overproduction, such as primary hyperoxaluria (PH), a rare life-threatening genetic disease. Recent published results on the knockdown of LDHA gene expression as a safe strategy to ameliorate oxalate build-up in PH patients are encouraging for an approach of hLDHA inhibition by small molecules as a potential pharmacological treatment. Thus, we now report on the synthesis and hLDHA inhibitory activity of a new family of compounds with 2,8-dioxabicyclo[3.3.1]nonane core (23-42), a series of twenty analogues to A-type proanthocyanidin natural products. Nine of them (25-27, 29-34) have shown IC₅₀ values in the range of 8.7-26.7 µM, based on a UV spectrophotometric assay, where the hLDHA inhibition is measured according to the decrease in absorbance of the cofactor β-NADH (340 nm). Compounds 25, 29, and 31 were the most active hLDHA inhibitors. In addition, the inhibitory activities of those nine compounds against the hLDHB isoform were also evaluated, finding that all of them were more selective inhibitors of hLDHA versus hLDHB. Among them, compounds 32 and 34 showed the highest selectivity. Moreover, the most active hLDHA inhibitors (25, 29, 31) were evaluated for their ability to decrease the oxalate production by hyperoxaluric mouse hepatocytes (PH1, PH2 and PH3) in vitro, and the relative oxalate output at 24 h was 16% and 19 % for compounds 25 and 31, respectively, in Hoga1^-/- mouse primary hepatocyte cells (a model for PH3). These values improve those of the reference compound used (stiripentol). Compounds 25 and 31 have in common the presence of two hydroxyl groups at rings B and D and an electron-withdrawing group (NO₂ or Br) at ring A, pointing to the structural features to be taken into account in future structural optimization.

CRISPR/Cas9-mediated knock-out of AGXT1 in HepG2 cells as a new in vitro model of Primary Hyperoxaluria Type 1

AGXT1 encodes alanine:glyoxylate aminotransferase 1 (AGT1), a liver peroxisomal pyridoxal 5'-phosphate dependent-enzyme whose deficit causes Primary Hyperoxaluria Type 1 (PH1). PH1 is a rare disease characterized by overproduction of oxalate, first leading to kidney stones formation, and possibly evolving to life-threatening systemic oxalosis. A minority of PH1 patients is responsive to pyridoxine, while the option for non-responders is liver-kidney transplantation. Therefore, huge efforts are currently focused on the identification of new therapies, including the promising approaches based on RNA silencing recently approved. Many PH1-associated mutations are missense and lead to a variety of kinetic and/or folding defects on AGT1. In this context, the availability of a reliable in vitro disease model would be essential to better understand the phenotype of known or newly-identified pathogenic variants as well as to test novel drug candidates. Here, we took advantage of the CRISPR/Cas9 technology to specifically knock-out AGXT1 in HepG2 cells, a hepatoma-derived cell model exhibiting a conserved glyoxylate metabolism. AGXT1-KO HepG2 displayed null AGT1 expression and significantly reduced transaminase activity leading to an enhanced secretion of oxalate upon glycolate challenge. Known pathogenic AGT1 variants expressed in AGXT1-KO HepG2 cells showed alteration in both protein levels and specific transaminase activity, as well as a partial mitochondrial mistargeting when associated with a common polymorphism. Notably, pyridoxine treatment was able to partially rescue activity and localization of clinically-responsive variants. Overall, our data validate AGXT1-KO HepG2 cells as a novel cellular model to investigate PH1 pathophysiology, and as a platform for drug discovery and development.

Improving Treatment Options for Primary Hyperoxaluria

The primary hyperoxalurias are three rare inborn errors of the glyoxylate metabolism in the liver, which lead to massively increased endogenous oxalate production, thus elevating urinary oxalate excretion and, based on that, recurrent urolithiasis and/or progressive nephrocalcinosis. Frequently, especially in type 1 primary hyperoxaluria, early end-stage renal failure occurs. Treatment possibilities are scare, namely, hyperhydration and alkaline citrate medication. In type 1 primary hyperoxaluria, vitamin B6, though, is helpful in patients with specific missense or mistargeting mutations. In those vitamin B6 responsive, urinary oxalate excretion and concomitantly urinary glycolate is significantly decreased, or even normalized. In patients non-responsive to vitamin B6, RNA interference medication is now available. Lumasiran® is already available on prescription and targets the messenger RNA of glycolate oxidase, thus blocking the conversion of glycolate into glyoxylate, hence decreasing oxalate, but increasing glycolate production. Nedosiran blocks liver-specific lactate dehydrogenase A and thus the final step of oxalate production. Similar to vitamin B6 treatment, where both RNA interference urinary oxalate excretion can be (near) normalized and plasma oxalate decreases, however, urinary and plasma glycolate increases with lumasiran treatment. Future treatment possibilities are on the horizon, for example, substrate reduction therapy with small molecules or gene editing, induced pluripotent stem cell-derived autologous hepatocyte-like cell transplantation, or gene therapy with newly developed vector technologies. This review provides an overview of current and especially new and future treatment options.