Natural compounds as lactate dehydrogenase inhibitors: potential therapeutics for lactate dehydrogenase inhibitors-related diseases

Multifaceted roles of lactate dehydrogenase in liver cancer (Review)

Hepatocellular carcinoma (HCC) has high morbidity and mortality rates, and metabolic reprogramming of HCC cells supports the proliferation and development of tumor cells. Lactate dehydrogenase (LDH), a key metabolic enzyme, can maintain the rapid proliferative demand of tumor cells by promoting glycolysis and lactate production in HCC cells. In addition, LDH regulates redox homeostasis and influences lipid synthesis and signaling pathways, further promoting tumor invasion and metastasis. In the tumor microenvironment, LDH affects the function of immune cells and stromal cells by regulating the lactate concentration in and promoting the immune escape and angiogenesis of tumor cells. Since elevated levels of LDH are closely associated with tumor load, invasiveness and poor prognosis, LDH also has promising applications in the early diagnosis, treatment and prognostic assessment of HCC. The present study reviewed the roles of LDH in the occurrence, development, diagnosis, prognosis and treatment of HCC and explored its value as an important biomarker and potential therapeutic target, with the aim of providing a comprehensive reference for HCC‑related research and clinical practice.

Oroxylin A ameliorates non-alcoholic fatty liver disease by modulating oxidative stress and ferroptosis through the Nrf2 pathway

Non-alcoholic fatty liver disease (NAFLD) is a prevalent and progressive liver disorder posing a global health challenge. Oroxylin A, a naturally occurring flavonoid, with a broad spectrum of pharmacological activities. This study aimed to explore the therapeutic potential of oroxylin A and unravel its molecular mechanisms in mitigating high-fat diet (HFD)-induced NAFLD in murine models. Wild-type (WT) and nuclear factor erythroid 2-related factor 2 knockout (Nrf2-/-) mice were administered a HFD to generate in vivo models, while free fatty acids-treated HepG2 cells served as the in vitro model. To investigate the effects of oroxylin A, serum and liver biochemical markers, hepatic histology, lipid metabolism, and oxidative stress were assessed in a NAFLD mouse model. The underlying mechanisms of oroxylin A were further explored through Western blotting, immunohistochemistry, and immunofluorescence analysis. Oroxylin A mitigated hepatic steatosis and injury by reducing liver index, AST, ALT, TG, and TC levels, improving histology, and restoring lipid metabolism. Glucose and insulin tolerance tests demonstrated improved glucose homeostasis and insulin sensitivity. Moreover, oroxylin A suppressed inflammation, apoptosis, and fibrosis, while enhancing antioxidant defenses, and improving mitochondrial function. Mechanistically, oroxylin A activated the Keap1/Nrf2/GPX4/SLC7A11 axis, upregulating Nrf2 and HO-1. These effects were abolished in Nrf2-/- mice. In vitro results were consistent, and molecular docking, dynamics simulations, and CETSA confirmed its direct Keap1 binding. Oroxylin A protects against NAFLD by modulating the Nrf2 pathway, reducing oxidative stress and ferroptosis, making it a promising candidate for clinical NAFLD therapy.

Colemanite and biological disruptions: Behavioral, neurological, and physiological findings

Colemanite (COL), a boron-containing mineral, has shown potential therapeutic applications, particularly in the fields of drug delivery and bone health. However, despite its promising bioactive properties, there is a lack of comprehensive toxicological data on its safety, especially regarding its potential medical use. Previous studies have primarily focused on its industrial applications, with limited investigation into its biological effects. This gap in knowledge prompted the current study, which aimed to investigate the subacute toxicity of colemanite in rats using behavioral, hematological, biochemical, genotoxic, and histopathological analyses. Over a 7-day period, rats were treated with doses of 10, 30, and 300 mg/kg. Behavioral assessments, including locomotor activity and elevated plus maze tests, indicated enhanced exploratory behaviors, indicating heightened curiosity or activity and no alterations in motor coordination or anxiety-like behaviors. Hematological findings revealed dose-dependent reductions in hematocrit, hemoglobin, and red blood cell counts, while biochemical analyses showed elevated aspartate aminotransferase, lactate dehydrogenase, and cholesterol levels at higher doses, suggesting hepatotoxicity and lipid metabolism disruption. Genotoxicity analysis demonstrated increased micronucleus formation at 30 and 300 mg/kg, indicative of chromosomal instability possibly linked to oxidative stress. Histopathological evaluations revealed mild hepatocyte degeneration and hyperemia in the liver and brain tissues at the highest dose. Importantly, no significant toxic effects were observed at the 10 mg/kg dose. These findings highlight the dose-dependent toxicity of colemanite, with low doses exhibiting a favorable safety profile. This study underscores the need for dose optimization and further research to elucidate the molecular mechanisms underlying colemanite's toxicological effects, including its impact on various organs over both short-term and long-term exposures. Additionally, future studies should focus on assessing the human relevance of these effects to ensure its safe and effective therapeutic application.

Discovery of a novel alpha isoform of the long-known enzyme LDHA provides new insights into cancer research

Lactate dehydrogenase A is a key enzyme in energy metabolism, with significant roles in cancer progression. Huang et al. identified LDHAα, a novel LDHA isoform derived from an alternative transcript initiated at AUG198, producing a protein 3 kDa larger than canonical LDHA. LDHAα exhibits enhanced glycolytic activity and promotes glucose uptake, lactate production, and tumor growth more effectively than LDHA. Regulated by c-MYC and FOXM1, LDHAα is mainly cytoplasmic and serves as a potential cancer biomarker and therapeutic target. These findings highlight LDHAα's unique role in cancer metabolism and its potential for advancing targeted cancer therapies.

Nephroprotective and Antioxidant Effects of Jatropha dioica Extract Against Ischemia-Reperfusion Injury in Wistar Rats

Plant extracts with antioxidant activities have shown nephroprotection against IR injury. Jatropha dioica (Jd) possesses antioxidant activity. Our aim was to evaluate the effects of a hydroalcoholic Jd extract against IR injury in Wistar rats. Rats were divided into groups (n = 6): sham (SH); no toxicity (JdTox; 300 mg/kg/day of extract for 7 days); IR (on day 7 [I: 45 min/R: 24 h]); and Jd+IR (same treatment as JdTox; same surgical procedure as IR). AST and LDH were significantly lower in the JdTox. IR exhibited significantly higher CrS, BUN, and MDA compared with SH; Jd+IR showed reductions in these markers. GSH and SOD levels were significantly lower in IR compared with SH; an increase in these markers was observed in the Jd+IR. Histologically, IR showed significant increases in medullary tubular necrosis, medullary protein casts, and medullary vascular congestion compared with SH and JdTox. In Jd+IR, a significant decrease was observed only in medullary tubular necrosis. Therefore, the evaluated hydroalcoholic Jd extract dose showed no nephrotoxicity and hepatotoxicity. Jd extract pretreatment attenuated IR-induced renal injury, as evidenced by the improved serum markers of renal damage and oxidative stress.

Type 3 diabetes and metabolic reprogramming of brain neurons: causes and therapeutic strategies

Abnormal glucose metabolism inevitably disrupts normal neuronal function, a phenomenon widely observed in Alzheimer's disease (AD). Investigating the mechanisms of metabolic adaptation during disease progression has become a central focus of research. Considering that impaired glucose metabolism is closely related to decreased insulin signaling and insulin resistance, a new concept "type 3 diabetes mellitus (T3DM)" has been coined. T3DM specifically refers to the brain's neurons becoming unresponsive to insulin, underscoring the strong link between diabetes and AD. Recent studies reveal that during brain insulin resistance, neurons exhibit mitochondrial dysfunction, reduced glucose metabolism, and elevated lactate levels. These findings suggest that impaired insulin signaling caused by T3DM may lead to a compensatory metabolic shift in neurons toward glycolysis. Consequently, this review aims to explore the underlying causes of T3DM and elucidate how insulin resistance drives metabolic reprogramming in neurons during AD progression. Additionally, it highlights therapeutic strategies targeting insulin sensitivity and mitochondrial function as promising avenues for the successful development of AD treatments.

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.

The potential role of alkaline diets in prevention of calcium oxalate kidney stone formation

Formation of kidney stones is considered a major global problem. Diet plays an important role in the management of kidney stone formation. The main goal of the present research was to evaluate the protective role of fruit and vegetable mixtures as models of an alkaline diet on formation of kidney stones in rats and to conduct molecular docking study. The chemical compositions, phenolic compound profile, β-carotene content, vitamin C and antioxidant activity of both mixtures were assessed. Fruit (-42.419 ) and vegetable (-11.13) mixtures recorded a negative potential renal acid load in the presence of macro-/micro-nutrients, β-carotene and phenolic compounds; chlorogenic acid was the major content in both mixtures. Both mixtures exhibited high antioxidant activity. Molecular docking study proved that rutin displayed the highest binding affinities for glycolate oxidase (-11.8 kcal mol-1) and lactate dehydrogenase (-10.1 kcal mol-1). The kidney stone model in rats exhibited metabolic acidosis in the urinary profile through reduction of citrate; Ca, Mg and K excretion and elevation of oxalate, creatinine, creatinine clearance, uric acid, urea and protein. Additionally, there was a significant reduction in plasma Ca, Mg and K levels, while liver and kidney function parameters improved significantly. Fruit and vegetable mixtures as models of an alkaline diet proved improvement in all the parameters. Histopathological examination of kidney sections of the kidney stone model showed crystal deposition, inflammation, and severe necrosis. Kidney sections of alkaline diet models indicated mild and moderate changes. Conclusion: The results of this study proved that both alkaline diet models were effective in protecting against kidney stone formation in vivo and in molecular docking studies.

Targeting Glucose Metabolism: A Novel Therapeutic Approach for Parkinson's Disease

Glucose metabolism is essential for the maintenance and function of the central nervous system. Although the brain constitutes only 2% of the body weight, it consumes approximately 20% of the body's total energy, predominantly derived from glucose. This high energy demand of the brain underscores its reliance on glucose to fuel various functions, including neuronal activity, synaptic transmission, and the maintenance of ion gradients necessary for nerve impulse transmission. Increasing evidence shows that many neurodegenerative diseases, including Parkinson's disease (PD), are associated with abnormalities in glucose metabolism. PD is characterized by the progressive loss of dopaminergic neurons in the substantia nigra, accompanied by the accumulation of α-synuclein protein aggregates. These pathological features are exacerbated by mitochondrial dysfunction, oxidative stress, and neuroinflammation, all of which are influenced by glucose metabolism disruptions. Emerging evidence suggests that targeting glucose metabolism could offer therapeutic benefits for PD. Several antidiabetic drugs have shown promise in animal models and clinical trials for mitigating the symptoms and progression of PD. This review explores the current understanding of the association between PD and glucose metabolism, emphasizing the potential of antidiabetic medications as a novel therapeutic approach. By improving glucose uptake and utilization, enhancing mitochondrial function, and reducing neuroinflammation, these drugs could address key pathophysiological mechanisms in PD, offering hope for more effective management of this debilitating disease.

Accurate evaluation of drug effect on the LDH activity of live cells: dual measurement of live cell number by fluorescent staining of nucleus and LDH activity by formazan

Effect of drugs on the intracellular activity of lactate dehydrogenase (LDH) has been measured by using water-soluble tetrazolium (WST). Because the assay is usually conducted in the presence of dead cells, net activity of live cells is not evaluated. Here, we reported the assay of the net intracellular LDH activity of live cells by counting the live cells using fluorescent staining of nucleus. By using a deep red fluorescent dye, dual measurements of fluorescence signal of nucleus and absorbance of WST could be conducted with transparent 96-well-plates. We found that conventional assay in the presence of dead cells overestimate the effect of drugs on the LDH activity.

The Inhibitory Effects of the Natural Stilbene Piceatannol on Lactate Transport In Vitro Mediated by Monocarboxylate Transporters

SCOPE

Lactate, a signaling molecule and energy source, crosses membranes through monocarboxylate transporters (MCTs). MCT1 and MCT4 are potential cancer drug targets due to their role in metabolic reprogramming of cancer cells. Stilbenes, plant secondary metabolites found in several food sources, have anticancer effects, though their mechanisms of action are not well understood. This study links the anticancer activity of natural stilbenes to tumor cell lactate metabolism.

METHODS AND RESULTS

The impact of resveratrol, pinostilbene, pterostilbene, rhapontigenin, and piceatannol on lactate transport is studied using a fluorescence resonance energy transfer (FRET)-based lactate sensor. The viability and migration of cells expressing MCT1 or MCT4 are also evaluated. Piceatannol inhibits MCT1 effectively at low micromolar concentrations, with less effect on MCT4. All stilbenes significantly reduce cell viability and migration.

CONCLUSIONS

These findings indicate that both MCTs are stilbene targets, with piceatannol highlighted as a cost-effective, low-toxicity compound for studying MCTs in cancer, providing a new mechanism of action of the therapeutic and nutraceutical effects of natural polyphenols. This enriches the understanding of dietary polyphenols in cancer prevention and therapy.

Altered metabolism in cancer: insights into energy pathways and therapeutic targets

Cancer cells undergo significant metabolic reprogramming to support their rapid growth and survival. This study examines important metabolic pathways like glycolysis, oxidative phosphorylation, glutaminolysis, and lipid metabolism, focusing on how they are regulated and their contributions to the development of tumors. The interplay between oncogenes, tumor suppressors, epigenetic modifications, and the tumor microenvironment in modulating these pathways is examined. Furthermore, we discuss the therapeutic potential of targeting cancer metabolism, presenting inhibitors of glycolysis, glutaminolysis, the TCA cycle, fatty acid oxidation, LDH, and glucose transport, alongside emerging strategies targeting oxidative phosphorylation and lipid synthesis. Despite the promise, challenges such as metabolic plasticity and the need for combination therapies and robust biomarkers persist, underscoring the necessity for continued research in this dynamic field.

Lactate-Induced HBEGF Shedding and EGFR Activation: Paving the Way to a New Anticancer Therapeutic Opportunity

Cancer cells can release EGF-like peptides, acquiring the capacity of autocrine stimulation via EGFR-mediated signaling. One of these peptides (HBEGF) was found to be released from a membrane-bound precursor protein and is critically implicated in the proliferative potential of cancer cells. We observed that the increased lactate levels characterizing neoplastic tissues can induce the release of uPA, a protease promoting HBEGF shedding. This effect led to EGFR activation and increased ERK1/2 phosphorylation. Since EGFR-mediated signaling potentiates glycolytic metabolism, this phenomenon can induce a self-sustaining deleterious loop, favoring tumor growth. A well characterized HBEGF inhibitor is CRM197, a single-site variant of diphtheria toxin. We observed that, when administered individually, CRM197 did not trigger evident antineoplastic effects. However, its association with a uPA inhibitor caused dampening of EGFR-mediated signaling and apoptosis induction. Overall, our study highlights that the increased glycolytic metabolism and lactate production can foster the activated state of EGFR receptor and suggests that the inhibition of EGFR-mediated signaling can be attempted by means of CRM197 administered with an appropriate protease inhibitor. This attempt could help in overcoming the problem of the acquired resistance to the conventionally used EGFR inhibitors.

Natural flavonoids as promising lactate dehydrogenase A inhibitors: Comprehensive in vitro and in silico analysis

The inhibitory potential of 17 flavonoids on lactate dehydrogenase A (LDHA), a key enzyme in the downstream process of aerobic glycolysis in cancer cells, is investigated. Fisetin exhibited excellent inhibitory activity (IC50 = 0.066 µM). Quercetin 3-β-D-glucoside, quercetin 3-galactoside, luteolin, neoeriocitrin, and luteolin 7-O-β-D-glucoside showed good inhibitory activity (IC50 = 1.397-15.730 µM). Biochanin A, baicalein, quercetin, scutellarein-7-glucuronide, diosmetin, baicalein 7-O-β-D-glucuronide, and apigenin 7-apioglucoside demonstrated moderate inhibitory activity (IC50 = 33.007-86.643 µM). Eriodictyol, quercetin 7-O-β-D-glucoside, apigenin 7-O-β-D-glucoside, and epicatechin were inactive. The Lineweaver-Burk plot showed that fisetin competitively inhibits NADH binding (Ki = 0.024 µM). Ki values for other compounds were calculated using the Cheng-Prusoff equation (Ki = 0.2799-2.1661 µM). The study revealed that the inhibitory effect of flavonoids varies with the number and position of OH groups and bound sugars. Molecular docking analyses indicated that flavonoids exhibited strong interactions with the NADH binding site of LDHA through hydrophobic interactions and hydrogen bonds. Molecular dynamic simulations tested the stability of the fisetin-LDHA complex over 100 ns and showed fisetin's high binding affinity to LDHA, maintaining strong hydrogen bonds. The binding energy of fisetin with LDHA was -33.928 kcal/mol, indicating its effectiveness as an LDHA inhibitor. Consequently, flavonoids identified as strong inhibitors could be potential cancer treatment sources through LDHA inhibition.

Songorine modulates macrophage polarization and metabolic reprogramming to alleviate inflammation in osteoarthritis

Introduction

Osteoarthritis (OA) is a prevalent joint disorder characterized by multifaceted pathogenesis, with macrophage dysregulation playing a critical role in perpetuating inflammation and joint degeneration.

Methods

This study focuses on Songorine, derived from Aconitum soongaricum Stapf, aiming to unravel its therapeutic mechanisms in OA. Comprehensive analyses, including PCR, Western blot, and immunofluorescence, were employed to evaluate Songorine's impact on the joint microenvironment and macrophage polarization. RNA-seq analysis was conducted to unravel its anti-inflammatory mechanisms in macrophages. Metabolic alterations were explored through extracellular acidification rate monitoring, molecular docking simulations, and PCR assays. Oxygen consumption rate measurements were used to assess mitochondrial oxidative phosphorylation, and Songorine's influence on macrophage oxidative stress was evaluated through gene expression and ROS assays.

Results

Songorine effectively shifted macrophage polarization from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype. Notably, Songorine induced metabolic reprogramming, inhibiting glycolysis and promoting mitochondrial oxidative phosphorylation. This metabolic shift correlated with a reduction in macrophage oxidative stress, highlighting Songorine's potential as an oxidative stress inhibitor.

Discussion

In an in vivo rat model of OA, Songorine exhibited protective effects against cartilage damage and synovial inflammation, emphasizing its therapeutic potential. This comprehensive study elucidates Songorine's multifaceted impact on macrophage modulation, metabolic reprogramming, and the inflammatory microenvironment, providing a theoretical foundation for its therapeutic potential in OA.

Effects of Aerobic Treadmill Training on Oxidative Stress Parameters, Metabolic Enzymes, and Histomorphometric Changes in Colon of Rats with Experimentally Induced Hyperhomocysteinemia

The aim of this study was to investigate the effects of aerobic treadmill training regimen of four weeks duration on oxidative stress parameters, metabolic enzymes, and histomorphometric changes in the colon of hyperhomocysteinemic rats. Male Wistar albino rats were divided into four groups (n = 10, per group): C, 0.9% NaCl 0.2 mL/day subcutaneous injection (s.c.) 2x/day; H, homocysteine 0.45 µmol/g b.w./day s.c. 2x/day; CPA, saline (0.9% NaCl 0.2 mL/day s.c. 2x/day) and an aerobic treadmill training program; and HPA, homocysteine (0.45 µmol/g b.w./day s.c. 2x/day) and an aerobic treadmill training program. The HPA group had an increased level of malondialdehyde (5.568 ± 0.872 μmol/mg protein, p = 0.0128 vs. CPA (3.080 ± 0.887 μmol/mg protein)), catalase activity (3.195 ± 0.533 U/mg protein, p < 0.0001 vs. C (1.467 ± 0.501 U/mg protein), p = 0.0012 vs. H (1.955 ± 0.293 U/mg protein), and p = 0.0003 vs. CPA (1.789 ± 0.256 U/mg protein)), and total superoxide dismutase activity (9.857 ± 1.566 U/mg protein, p < 0.0001 vs. C (6.738 ± 0.339 U/mg protein), p < 0.0001 vs. H (6.015 ± 0.424 U/mg protein), and p < 0.0001 vs. CPA (5.172 ± 0.284 U/mg protein)) were detected in the rat colon. In the HPA group, higher activities of lactate dehydrogenase (2.675 ± 1.364 mU/mg protein) were detected in comparison to the CPA group (1.198 ± 0.217 mU/mg protein, p = 0.0234) and higher activities of malate dehydrogenase (9.962 (5.752-10.220) mU/mg protein) were detected in comparison to the CPA group (4.727 (4.562-5.299) mU/mg protein, p = 0.0385). Subchronic treadmill training in the rats with hyperhomocysteinemia triggers the colon tissue antioxidant response (by increasing the activities of superoxide dismutase and catalase) and elicits an increase in metabolic enzyme activities (lactate dehydrogenase and malate dehydrogenase). This study offers a comprehensive assessment of the effects of aerobic exercise on colonic tissues in a rat model of hyperhomocysteinemia, evaluating a range of biological indicators including antioxidant enzyme activity, metabolic enzyme activity, and morphometric parameters, which suggested that exercise may confer protective effects at both the physiological and morphological levels.

Natural Product-Based Glycolysis Inhibitors as a Therapeutic Strategy for Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor-Resistant Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide. Targeted therapy against the epidermal growth factor receptor (EGFR) is a promising treatment approach for NSCLC. However, resistance to EGFR tyrosine kinase inhibitors (TKIs) remains a major challenge in its clinical management. EGFR mutation elevates the expression of hypoxia-inducible factor-1 alpha to upregulate the production of glycolytic enzymes, increasing glycolysis and tumor resistance. The inhibition of glycolysis can be a potential strategy for overcoming EGFR-TKI resistance and enhancing the effectiveness of EGFR-TKIs. In this review, we specifically explored the effectiveness of pyruvate dehydrogenase kinase inhibitors and lactate dehydrogenase A inhibitors in combating EGFR-TKI resistance. The aim was to summarize the effects of these natural products in preclinical NSCLC models to provide a comprehensive understanding of the potential therapeutic effects. The study findings suggest that natural products can be promising inhibitors of glycolytic enzymes for the treatment of EGFR-TKI-resistant NSCLC. Further investigations through preclinical and clinical studies are required to validate the efficacy of natural product-based glycolytic inhibitors as innovative therapeutic modalities for NSCLC.