Search Results (233)

Biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), are crucial for physiological regulation and their imbalance poses severe health risks. Herein, we developed a pH-responsive liquid crystal (LC)-based sensing platform for detection of biothiols by doping 4-n-pentylbiphenyl-4-carboxylic acid (PBA) into 4-n-pentyl-4-cyanobiphenyl (5CB). Urease catalyzed urea hydrolysis to produce OH⁻, triggering the deprotonation of PBA, thereby inducing a vertical alignment of LC molecules at the interface corresponding to dark optical appearances. Heavy metal ions (e.g., Hg²⁺) could inhibit urease activity, under which condition LC presents bright optical images and LC molecules maintain a state of tilted arrangement. However, biothiols competitively bind to Hg²⁺, the activity of urease is maintained which enables the occurrence of urea hydrolysis. This case triggers LC molecules to align in a vertical orientation, resulting in bright optical images. This pH-driven reorientation of LCs provides a visual readout (bright-to-dark transition) correlated with biothiol concentration. The detection limits of Cys/Hcy and GSH for the PBA-doped LC platform are 0.1 μM and 0.5 μM, respectively. Overall, this study provides a simple, label-free and low-cost strategy that has a broad application prospect for the detection of biothiols. Full article

Background/Objectives: Low folate intake before and during pregnancy increases the risk of neural tube defects and other adverse outcomes. Gene variants such as MTHFR 677C>T (rs1801133) may increase risks associated with suboptimal folate intake. Our objective was to use BALB/cJ Mthfr^677C>T mice to evaluate the effects of the TT genotype and low folate diets on embryonic development and MTHFR protein expression in pregnant mice. Methods: Female 677CC (mCC) and 677TT (mTT) mice were fed control (2 mg folic acid/kg (2D)), 1 mg folic acid/kg (1D) and 0.3 mg folic acid/kg (0.3D) diets before and during pregnancy. Embryos and maternal tissues were collected at embryonic day 10.5. Embryos were examined for developmental delays and defects. Methyltetrahydrofolate (methylTHF) and total homocysteine (tHcy) were measured in maternal plasma, and MTHFR protein expression was evaluated in maternal liver. Results: MethylTHF decreased due to the experimental diets and mTT genotype. tHcy increased due to 0.3D and mTT genotype; mTT 0.3D mice had significantly higher tHcy than the other groups. MTHFR expression was lower in mTT liver than mCC. MTHFR protein expression increased due to low folate diets in mCC mice, whereas in mTT mice, MTHFR expression increased only due to 1D. Developmental delays were increased in the litters of mTT mice fed 1D and 0.3D. Conclusions: The Mthfr^677C>T mouse models the effects of the MTHFR 677TT genotype in humans and provides a folate-responsive model for examination of the effects of folate intake and the MTHFR 677C>T variant during gestation. Full article

This report presents the first method for simultaneous determination of the 2-S-lepidinium derivatives of total α-lipoic acid (LA), homocysteine (Hcy), cysteinylglycine (CysGly), and cysteine (Cys) in human saliva, using capillary electrophoresis with pH-mediated sample stacking and ultraviolet detection (CE-UV) at 355 nm. Electrophoretic separation is carried out at 20 kV and 25 °C using a standard fused silica capillary (effective length 91.5 cm, inner diameter 75 µm). The background electrolyte consists of 0.5 mol/L lithium acetate buffer, adjusted to pH 3.5 with 0.5 mol/L acetic acid. The limit of quantification was determined to be 1 µmol/L for LA and 0.17 µmol/L for Hcy, 0.11 µmol/L for CysGly, and 0.10 µmol/L for Cys in saliva samples. Calibration curves demonstrated linearity over the concentration range of 3 to 30 µmol/L for all analytes. Method precision did not exceed 4.7%, and accuracy ranged from 87.9% to 114.0%. The developed method was successfully applied to saliva samples from eleven apparently healthy volunteers to determine the content of LA, Hcy, CysGly, and Cys. The Hcy, CysGly, and Cys concentrations ranged from 0.55 to 13.76 µmol/L, 0.89 to 9.29 µmol/L, and 1.73 to 12.99 µmol/L, respectively. No LA-derived peaks were detected in the native saliva samples. Full article

Background: Homocysteine (Hcy) is a sulfur-containing amino acid crucial for various physiological processes, with elevated levels linked to cardiovascular and neurological adverse conditions. Various factors contribute to high Hcy, and past studies of impact factors relied on traditional statistical methods. Recently, machine learning (ML) techniques have greatly improved and are now widely applied in medical research. This study used four ML methods to identify key factors influencing Hcy in healthy elderly Taiwanese men, comparing their accuracy using multiple linear regression (MLR). The study seeks to improve Hcy prediction accuracy and provide insights into relevant impact factors. Methods: A total of 468 healthy elderly men were studied in terms of 33 parameters using four ML methods: random forest (RF), stochastic gradient boosting (SGB), eXtreme gradient boosting (XGBoost), and elastic net (EN). MLR served as a benchmark. Model performance was assessed using SMAPE, RAE, RRSE, and RMSE. Results: All ML methods demonstrated lower prediction errors than MLR, indicating higher accuracy. By averaging the importance scores from the four ML models, C-reactive protein (CRP) emerged as the leading impact factor for Hcy, followed by GPT, WBC, LDH, eGFR, and sport volume (SV). Conclusions: Machine learning methods outperformed MLR in predicting Hcy levels in healthy elderly Taiwanese men. CRP was identified as the most crucial factor, followed by GPT/ALT, WBC, LDH, and eGFR. Full article

Homocysteine (Hcy) is becoming a well-established risk factor for cardiovascular disease (CVD), mainly involving endothelial dysfunction and atherogenesis. Endothelial dysfunction is reflected primarily in the complex regulation of the main physiological and pathophysiological processes. There is increasing evidence regarding abnormally high concentrations of plasma total homocysteine, or plasma hyperhomocysteinemia, contributing to endothelial dysfunction, inflammation, and CVD. This clinical and experimental study examined the connection between Hcy and cardiovascular disease risk. Homocysteine is a marker of total vascular damage that must be monitored and controlled as early as possible. Dietary and lifestyle changes are recommended for most patients with hyperhomocysteinemia (Hhcy). The purpose of this paper is to review the data from the specialized literature that demonstrate that there is a direct link between endothelial injury and increased homocysteine levels, identifying existing evidence, describing new mechanisms, and exploring potential new therapeutic options. These aspects continue to be debated, and additional efforts are required to refine therapeutic strategies and to investigate the potential implications of Hcy in health and disease. Full article

Purpose: Homocysteine (HCY) metabolism is regulated by the methionine cycle, which is essential for DNA methylation and is associated with the folate cycle. This study examines the alterations in DNA methylation signature including epigenetic age changes, measure cell-free DNA (cfDNA), and HCY concentrations, and identifies genetic markers that may influence homocysteine response following folic acid (FA) supplementation in individuals with hyperhomocysteinemia (HHC). Methods: Blood samples were obtained from 43 HHC patients undergoing FA supplementation. We quantified FA and HCY levels, separated plasma and white blood cell fractions, and evaluated global DNA methylation using LINE-1 bisulfite pyrosequencing. Biological age was determined using Illumina BeadArray technology, and whole-exome sequencing was performed to investigate the patients’ genetic backgrounds. Results: Following FA supplementation, cfDNA levels significantly decreased and correlated positively with HCY (r = 0.2375). Elevated average LINE-1 methylation of cfDNA and PBMC-origin DNA was observed, with mean relative changes of 1.9% for both sample types. Regarding HCY levels, we categorized patients based on their response to FA supplementation. FA responders showed decreased HCY from 15.7 ± 5.5 to 11 ± 2.9 µmol/L, while in FA non-responders, an opposite trend was detected. The average biological age was reduced by 2.6 years, with a notable reduction observed in 80% of non-responders and 48% of responders. Sequencing identified mutations in several genes related to the one-carbon cycle, including MTRR, CHAT, and MTHFD1, with strong correlations to the non-responder phenotypes found in genes like PRMT3, TYMS, DNMT3A, and HIF3A. Conclusions: FA supplementation influences the HCY level, as well as affects the cfDNA amount and the DNA methylation pattern. However, genetic factors may play a crucial role in mediating individual responses to folate intake, emphasizing the need for personalized approaches in managing hyperhomocysteinemia. Full article

Hepatocellular carcinoma (HCC), the predominant form of primary liver cancer, remains a global health challenge with limited therapeutic options and high mortality rates. Despite advances in understanding its molecular pathogenesis, the role of metabolic reprogramming in HCC progression and therapy resistance demands further exploration. Nicotinamide N-methyltransferase (NNMT), a metabolic enzyme central to NAD⁺ and methionine cycles, has emerged as a critical regulator of tumorigenesis across cancers. However, its tissue-specific mechanisms in HCC—particularly in the context of viral hepatitis and methionine cycle dependency—remain understudied. This review systematically synthesizes current evidence on NNMT’s dual role in HCC: (1) driving NAD⁺ depletion and homocysteine (Hcy) accumulation via metabolic dysregulation, (2) promoting malignant phenotypes (proliferation, invasion, metastasis, and drug resistance), and (3) serving as a prognostic biomarker and therapeutic target. We highlight how NNMT intersects with epigenetic modifications, immune evasion, and metabolic vulnerabilities unique to HCC. Additionally, we critically evaluate NNMT inhibitors, RNA-based therapies, and non-pharmacological strategies (e.g., exercise) as novel interventions. By bridging gaps between NNMT’s molecular mechanisms and clinical relevance, this review provides a roadmap for advancing NNMT-targeted therapies and underscores the urgency of addressing challenges in biomarker validation, inhibitor specificity, and translational efficacy. Our work positions NNMT not only as a metabolic linchpin in HCC but also as a promising candidate for precision oncology. Full article

Hyperhomocysteinemia (HHcy) influences the development and progression of neurodegenerative disorders in different ways. Homocysteine (Hcy) metabolism is related to that of asymmetric dimethylarginine (ADMA) and group B vitamins. The breakdown of the pathway involving nitric oxide (NO) and ADMA can be considered one of the causes of endothelial alteration that represents a crucial step in the development of several neurodegenerative disorders. Deficiencies of vitamins other than group B ones, such as D and A, have also been associated with central nervous system disorders. The aim of this narrative review is to describe the link between HHcy, ADMA, and vitamins in Parkinson’s disease (PD), Alzheimer’s disease (AD), and multiple sclerosis (MS) in terms of dysfunctional pathways and neuropathological processes, performing a literature search from 2015 to 2025 on PubMed. This review also provides an overview of the effects of vitamin supplementation on neurodegenerative diseases. The alteration of pathways involving NO production can lead to HHcy and elevated ADMA concentrations, causing neurodegeneration through various mechanisms, while vitamin supplementation has been shown to reduce Hcy levels, although with conflicting results about the improvement in clinical symptoms. Further studies are needed to develop optimal combined therapeutic strategies. Full article

Homocysteine (Hcy) is a biothiol that plays a vital role in many physiological processes and is involved in a variety of diseases. However, it is significantly difficult to discriminate Hcy from cysteine (Cys) due to their similar chemical structures (only one methylene difference) and reactivity. In this study, a novel nanosensor was proposed to discriminate Hcy from Cys with multi-cooperative effects by using gold nanoparticles (AuNPs). The discrimination effect for Hcy originates from the interaction difference of the hydrogen bonding, steric hindrance, and carbon chain length in Hcy and Cys with AuNPs. Under the best conditions, this nanosensor has two unique advantages. Firstly, the sensor exhibits high sensitivity with detection limits of 0.1 μM through naked-eye determination and 0.008 μM through UV−vis spectroscopy analysis. Secondly, the sensor showed superior selectivity for Hcy over the other 16 natural amino acids (biothiol-containing Cys and glutathione (GSH)), and it is the first time to clearly distinguish Hcy from Cys (the Cys concentration is 40 times higher than Hcy). Furthermore, the system was further employed to detect Hcy in human serum, and the result was in agreement with that tested by clinicians via enzymatic assays, with acceptable recovery. Full article

Given the essential roles of homocysteine (Hcy) and the interference of cysteine in effectively monitoring human health, this study proposed a synergistic effect strategy that combines the unique structural and functional properties of nanoporous gold (NPG) with the selective recognition capability of a recombinant cystathionine β-synthase (CBS) for the sensitive and specific detection of Hcy. The CBS protein with specific catalytic activity for Hcy was successfully produced in recombinant Escherichia coli BL21 (pET-30a-cbs) using the cbs gene from Pseudomonas aeruginosa PAO1. The electrochemical mechanism demonstrated that the electrooxidation of H₂S, a catalytic product of the CBS, was an irreversibly surface-controlled process on the CBS/NPG/GCE electrode surface. The electrochemical detection of Hcy exhibited excellent linearity, with a high sensitivity reaching 10.43 µA mM⁻¹ cm⁻² and a low detection limit of 1.31 µM. Furthermore, the CBS/NPG/GCE biosensor was successfully used to detect Hcy in urine samples with strong anti-interference capability and high selectivity (relative standard deviation less than 2.81%), while effectively reducing the interference from cysteine. These results confirmed that the proposed CBS/NPG/GCE electrochemical sensor achieved specific, sensitive, and reliable rapid detection of homocysteine, making it highly promising for practical applications in clinical treatment and health assessment. Full article

Prenatal hyperhomocysteinemia (HCY) is associated with neurodevelopmental deficits, yet its long-term impact on hippocampal synaptic function remains poorly understood. This study examines the effects of moderate maternal HCY on excitatory synaptic transmission in the CA1 region of the dorsal hippocampus in rat offspring at juvenile (P21) and adult (P90) stages. Using field postsynaptic potential (fPSP) recordings, electron microscopy, and Western blot analysis, we observed a significant age-dependent decline in the efficiency of excitatory synaptic transmission in HCY-exposed rats. Electron microscopy revealed structural alterations, including synaptic vesicle agglutination in the stratum radiatum, suggesting impaired neurotransmitter release. Additionally, a significant reduction in pyramidal neuron density was observed in the CA1 region, although seizure susceptibility remained unchanged. Western blot analysis showed altered expression of Synapsin I, indicating presynaptic dysfunction. These findings suggest that moderate prenatal HCY leads to persistent deficits in synaptic transmission and structural integrity, potentially contributing to cognitive impairments in adulthood. Our results highlight the importance of maternal homocysteine levels in shaping hippocampal function and could offer insights into neurodevelopmental disorders associated with metabolic disturbances. Full article

Background: Patients suffering from chronic kidney disease (CKD) have a high risk of premature cardiovascular morbidity and mortality. It has been suggested that elevated homocysteine (Hcy) or disturbances in the transmethylation pathway may contribute to this high cardiovascular risk burden due to epigenetic mechanisms. The objective of this study was to explore the prognostic value of Hcy, S-adenosylhomocysteine (SAH) and S-adenosylmethionine (SAM) (one-carbon (C1)-metabolites) among patients with CKD. Methods: Plasma concentrations of Hcy, SAM and SAH were measured among 297 participants with CKD (KDIGO GFR category G2–G5). The predefined endpoint was the occurrence of major cardiovascular events (MACE), defined as carotid, coronary and peripheral arterial revascularization, stroke, acute myocardial infarction, major amputation, cardiovascular death and all-cause mortality during a median (IQR) follow-up period of 4.0 [3.2; 4.3] years. Results: Among all participants, the median (IQR) of plasma Hcy, SAH, and SAM levels were 16.6 [13.5; 21.2] µmol/L, 41.5 [26.6; 63.9] nmol/L, 183.4 [151.1; 223.5] nmol/L, respectively. Estimated glomerular filtration rate (eGFR) correlated more strongly with plasma SAH (r = −0.588) than with SAM (r = −0.497) and Hcy (r = −0.424). During the follow-up period, 55 participants experienced MACE. In a univariate Kaplan Meier analysis, all three C1-metabolites were significantly associated with the occurrence of the primary outcome. In a Cox-regression analysis, the association between Hcy and MACE was not significant after adjustment for age and sex (hazard ratio (HR) and 95% confidence intervals (95% CI) for the 3rd vs. 1st tertile = 1.804 (0.868–3.974)). Both SAH and SAM were not associated with MACE after adjustment for age, sex and additionally for renal function markers (SAH: HR 3rd vs. 1st tertile 1.645 95% (0.654–4.411); SAM: HR 3rd vs. 1st tertile 1.920 95% CI (0.764–5.138)). Conclusions: In people with CKD, plasma Hcy, SAH and SAM were not independent predictors of MACE after adjustment for age, sex and renal function. Disturbed renal function may explain elevated C1-metabolites and disturbed transmethylation, while this pathway is not likely to be an appropriate access point to modify the risk of cardiovascular events in CKD patients. Full article

Atherosclerosis is accompanied by inflammation that underlies cardiovascular disease (CVD) and its vascular manifestations, including acute stroke, myocardial infarction, and peripheral artery disease, the leading causes of morbidity/mortality worldwide. The monolayer of endothelial cells formed on the luminal surface of arteries and veins regulates vascular tone and permeability, which supports vascular homeostasis. Endothelial dysfunction, the first step in the development of atherosclerosis, is caused by mechanical and biochemical factors that disrupt vascular homeostasis and induce inflammation. Together with increased plasma levels of low-density lipoprotein (LDL), diabetes, hypertension, cigarette smoking, infectious microorganisms, and genetic factors, epidemiological studies established that dysregulated metabolism of homocysteine (Hcy) causing hyperhomocysteinemia (HHcy) is associated with CVD. Patients with severe HHcy exhibit severe CVD and die prematurely due to vascular complications. Biochemically, HHcy is characterized by elevated levels of Hcy and related metabolites such as Hcy-thiolactone and N-Hcy-protein, seen in genetic and nutritional deficiencies in Hcy metabolism in humans and animals. The only known source of Hcy in humans is methionine released in the gut from dietary protein. Hcy is generated from S-adenosylhomocysteine (AdoHcy) and metabolized to cystathionine by cystathionine β-synthase (CBS) and to Hcy-thiolactone by methionyl-tRNA synthetase. Hcy-thiolactone, a chemically reactive thioester, modifies protein lysine residues, generating N-homocysteinylated (N-Hcy)-protein. N-Hcy-proteins lose their normal native function and become cytotoxic, autoimmunogenic, proinflammatory, prothrombotic, and proatherogenic. Accumulating evidence, discussed in this review, shows that these Hcy metabolites can promote endothelial dysfunction, CVD, and stroke in humans by inducing pro-atherogenic changes in gene expression, upregulating mTOR signaling, and inhibiting autophagy through epigenetic mechanisms involving specific microRNAs, histone demethylase PHF8, and methylated histone H4K20me1. Clinical studies, also discussed in this review, show that cystathionine and Hcy-thiolactone are associated with myocardial infarction and ischemic stroke by influencing blood clotting. These findings contribute to our understanding of the complex mechanisms underlying endothelial dysfunction, atherosclerosis, CVD, and stroke and identify potential targets for therapeutic intervention. Full article

Objective: This study aims to identify whether the development of insulin resistance (IR) induced by high selenium (Se) is related to serine deficiency via the inhibition of the de novo serine synthesis pathway (SSP) by the administrations of 3-phosphoglycerate dehydrogenase (PHGDH) inhibitor (NCT503) or exogenous serine in mice. Method: forty-eight male C57BL/6J mice were randomly divided into four groups: adequate-Se (0.1 mgSe/kg), high-Se (0.8 mgSe/kg), high-Se +serine (240 mg/kg/day), and high-Se +NCT503 (30 mg/kg, twice a week) for 5 months. The glucose tolerance test (GTT) and insulin tolerance test (ITT) were used to confirm the development of IR in mice with high-Se intake, and fasting blood glucose levels were measured monthly. The Se contents in plasma and tissues were detected by ICP-MS. The levels of insulin (INS), homocysteine (HCY), and serine in plasma were tested by ELISA. Western blot analyses were conducted to evaluate the protein expressions of glutathione peroxidase 1 (GPX1), selenoprotein P (SELENOP) and PHGDH, the PI3K-AKT-mTOR pathway, folate cycle (SHMT1, MTHFR), and methionine cycle (MS). Results: An IR model was developed in mice from the high-Se group with elevated fasting blood glucose and INS levels, impaired glucose tolerance, and reduced insulin sensitivity, but not in both the high-Se +serine group and the high-Se +NCT503 group. Compared with the high-Se and high-Se +serine groups, the expressions of GPX1 and SELENOP significantly decreased for the high-Se +NCT503 group in the liver, muscle, and pancreas tissues. The expression of PHGDH of high-Se group was significantly higher than that of the adequate-Se group in the liver (p < 0.05) and pancreas (p < 0.001). Also, the expected high expression of PHGDH was effectively inhibited in mice from the high-Se +serine group but not from the high-Se +NCT503 group. The expression of p-AKT (Ser-473) for the high-Se group was significantly lower than that of the adequate-Se group in the liver, muscle, and pancreas. Conclusions: The IR induced by high-Se intake in the body has been confirmed to be partially due to serine deficiency, which led to the initiation of SSP to produce endogenous serine. The supplementations of exogenous serine or inhibitors of PHGDH in this metabolic pathway could be used for the intervention. Full article

Background/Objectives: Chronic gut dysbiosis due to a high-fat diet (HFD) instigates cardiac remodeling and heart failure with preserved ejection fraction (HFpEF), in particular, kidney/volume-dependent HFpEF. Studies report that although mitochondrial ATP citrate lyase (ACLY) supports cardiac function, it decreases more in human HFpEF than HFrEF. Interestingly, ACLY synthesizes lipids and creates hyperlipidemia. Epigenetically, ACLY acetylates histone. The mechanism(s) are largely unknown. Methods/Results: One hypothesis is that an HFD induces epigenetic folate 1-carbon metabolism (FOCM) and homocystinuria. This abrogates dipping in sleep-time blood pressure and causes hypertension and morning heart attacks. We observed that probiotics/lactobacillus utilize fat/lipids post-biotically, increasing mitochondrial bioenergetics and attenuating HFpEF. We suggest novel and paradigm-shift epigenetic mitochondrial sulfur trans-sulfuration pathways that selectively target HFD-induced HFpEF. Previous studies from our laboratory, using a single-cell analysis, revealed an increase in the transporter (SLC25A) of s-adenosine–methionine (SAM) during elevated levels of homocysteine (Hcy, i.e., homocystinuria, HHcy), a consequence of impaired epigenetic recycling of Hcy back to methionine due to an increase in the FOCM methylation of H3K4, K9, H4K20, and gene writer (DNMT) and decrease in eraser (TET/FTO). Hcy is transported to mitochondria by SLC7A for clearance via sulfur metabolomic trans-sulfuration by 3-mercaptopyruvate sulfur transferase (3MST). Conclusions: We conclude that gut dysbiosis due to HFD disrupts rhythmic epigenetic memory via FOCM and increases in DNMT1 and creates homocystinuria, leading to a decrease in mitochondrial trans-sulfuration and bioenergetics. The treatment with lactobacillus metabolites fat/lipids post-biotically and bi-directionally produces folic acid and lactone–ketone body that mitigates the HFD-induced mitochondrial remodeling and HFpEF. Full article