Search Results (592)

Background: Gallic acid (GA) is a dietary polyphenol widely found in walnuts, tea leaves, and grapes, and it is recognized for its potent antioxidant and anti-inflammatory properties. Chronic sleep deprivation (CSD) is known to disrupt redox balance, promote neuroinflammation, and impair cognition, while effective nutritional strategies to mitigate these effects remain scarce. This study was designed to evaluate the protective potential of GA against CSD-induced cognitive deficits in mice and to elucidate the underlying mechanisms. Methods: Seventy-two male ICR mice were randomly allocated to six groups, including control, CSD model, Ginkgo biloba extract, and GA at three doses (50, 100, and 200 mg/kg). After 28 days of treatment, cognitive performance was assessed using the open field test (OFT), novel object recognition (NOR), step-through passive avoidance (ST), and Morris water maze (MWM). Redox status and inflammatory mediators were determined by ELISA, while the hippocampal expression of proteins related to antioxidant defense and NF-κB signaling was analyzed by Western blotting. Results: GA supplementation improved exploratory activity, recognition memory, and spatial learning in the CSD mice. Biochemical evaluation revealed that total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) activity were restored, while malondialdehyde (MDA) levels, an indicator of lipid peroxidation, were reduced. These changes were accompanied by decreased circulating concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). At the molecular level, GA enhanced the expression of Nrf2, HO-1, and NQO1, while inhibiting p-p65, iNOS, and COX2 in the hippocampus. Conclusions: These findings demonstrate that GA alleviates CSD-induced cognitive deficits through the activation of the Nrf2/HO-1 antioxidant pathway and inhibition of NF-κB–mediated inflammatory responses. Thus, GA may represent a promising nutraceutical candidate for maintaining cognitive health under chronic sleep loss. Full article

Digital currencies, led by Bitcoin and USDT, are characterized by decentralization and anonymity, which obscure the identities of traders and create a conducive environment for illicit activities such as drug trafficking, money laundering, cyber fraud, and terrorism financing. Focusing on the USDT-TRC20 token on the Tron blockchain, we propose a two-layer transaction network-based approach for virtual currency address identity recognition for digging out hidden relationships and encrypted assets. Specifically, a two-layer transaction network is constructed: Layer A describes the flow of USDT-TRC20 between on-chain addresses over time, while Layer B represents the flow of TRX between on-chain addresses over time. Subsequently, an identity metric is proposed to determine whether a pair of addresses belongs to the same user or group. Furthermore, transaction records are systematically acquired through blockchain explorers, and the efficacy of the proposed recognition method is empirically validated using dataset from the Key Laboratory of Digital Forensics. Finally, the transaction topology is visualized using Neo4j, providing a comprehensive and intuitive representation of the traced transaction pathways. Full article

Background: Tularemia is a zoonotic infection caused by Francisella tularensis, transmitted to humans through direct contact with infected animals, arthropod bites, or by ingesting contaminated water. It commonly presents with fever, lymphadenopathy, and oropharyngeal symptoms. In Turkey, where waterborne outbreaks are frequent, tularemia remains a significant public health concern. This study aimed to compare the clinical, epidemiological, and laboratory characteristics of patients diagnosed with tularemia and those with similar clinical features but seronegative results, with the goal of identifying parameters that may assist in differential diagnosis. Methods: This retrospective study included adults (≥18 years) who presented to the Infectious Diseases Outpatient Clinic between 2016 and 2024 with suspected tularemia and were tested using a microagglutination test (MAT). Patients with a positive MAT (≥1:160) or a fourfold titre increase were classified as tularemia cases, while seronegative patients were defined as tularemia-like cases. Demographic data, clinical symptoms, epidemiological risk factors, and laboratory findings were compared between the two groups. Results: A total of 105 patients were included, 54 (51.4%) of whom were diagnosed with tularemia. The duration from symptom onset to healthcare presentation was significantly longer in tularemia cases (20.3 ± 5.7 vs. 15.7 ± 6.2 days; p < 0.001). Sore throat (66.7% vs. 43.1%; p = 0.026) and tonsillitis/pharyngitis (55.6% vs. 21.6%; p = 0.001) were significantly more prevalent in the tularemia group. Epidemiological risk factors, including rural residence (92.6%), animal husbandry (74.1%), agricultural activity (72.2%), and contact with lake or stream water, were significantly more prevalent among tularemia cases (all p < 0.001). Alanine aminotransaminase (p = 0.019) and C-reactive protein levels (p = 0.027) were significantly lower in the tularemia group. Conclusions: Tularemia cases are associated with particular epidemiological risk factors and oropharyngeal symptoms. A thorough epidemiological evaluation is crucial for diagnosis, and enhancing awareness among healthcare providers and the public may facilitate earlier recognition and management. Full article

Background/Objectives: Glioblastoma (GBM) is an aggressive primary brain tumor with limited therapeutic options despite multimodal treatment. Small interfering RNA (siRNA)-based therapeutics can silence tumor-promoting genes, but achieving efficient and tumor-specific delivery remains challenging. Lipid nanoparticles (LNPs) are promising siRNA carriers; however, conventional antibody conjugation can impair antigen recognition and complicate manufacturing. This study aimed to establish a modular Fc-binding peptide (FcBP)-mediated post-insertion strategy to enable PD-L1-targeted delivery of VEGF-siRNA via LNPs for GBM therapy. Methods: Preformed VEGF-siRNA-loaded LNPs were functionalized with FcBP–lipid conjugates, enabling non-covalent anchoring of anti-PD-L1 antibodies through Fc interactions. Particle characteristics were analyzed using dynamic light scattering and encapsulation efficiency assays. Targeted cellular uptake and VEGF gene silencing were evaluated in PD-L1-positive GL261 glioma cells. Anti-tumor efficacy was assessed in a subcutaneous GL261 tumor model following repeated intratumoral administration using tumor volume and bioluminescence imaging as endpoints. Results: FcBP post-insertion preserved LNP particle size (125.2 ± 1.3 nm), polydispersity, zeta potential, and siRNA encapsulation efficiency. Anti-PD-L1–FcBP-LNPs significantly enhanced cellular uptake (by ~50-fold) and VEGF silencing in PD-L1-expressing GL261 cells compared to controls. In vivo, targeted LNPs reduced tumor volume by 65% and markedly suppressed bioluminescence signals without inducing weight loss. Final tumor weight was reduced by 63% in the anti-PD-L1–FcBP–LNP group (656.9 ± 125.4 mg) compared to the VEGF-siRNA LNP group (1794.1 ± 103.7 mg). The FcBP-modified LNPs maintained antibody orientation and binding activity, enabling rapid functionalization with targeting antibodies. Conclusions: The FcBP-mediated post-insertion strategy enables site-specific, modular antibody functionalization of LNPs without compromising physicochemical integrity or antibody recognition. PD-L1-targeted VEGF-siRNA delivery demonstrated potent, selective anti-tumor effects in GBM murine models. This platform offers a versatile approach for targeted nucleic acid therapeutics and holds translational potential for treating GBM. Full article

Background/Objectives: Scopolamine (SCO) is widely employed as a pharmacological model of anxiety and amnesia in both rodents and zebrafish, the latter representing a valuable translational model in neuropsychopharmacology. The present study aimed to evaluate the neuroprotective and antioxidant potential of chronic administration of an ethanolic extract from Calendula officinalis flowers (CEE). Methods: Adult zebrafish (n = 10/group, both sexes) were exposed to CEE at concentrations of 1, 3, and 10 mg/L, administered daily for 22 consecutive days. After the initial 7-day pretreatment period, fish were challenged with SCO (100 μM, immersion for 30 min) followed by behavioral testing, including the Novel Tank Diving Test, Light/Dark Test, Novel Approach Test, Y-Maze, and Novel Object Recognition. Subsequently, brain homogenates were analyzed for acetylcholinesterase (AChE) activity, antioxidant enzymes (superoxide dismutase—SOD, catalase—CAT, glutathione peroxidase—GPx), reduced glutathione (GSH), protein carbonyls, and malondialdehyde (MDA). Results: Chronic CEE administration significantly attenuated scopolamine-induced anxiety-like behaviors and improved spatial memory (Y-maze) and recognition memory (NOR), as well as reduced anxiety-like behavior in the SCO-induced zebrafish model. Biochemical analyses revealed that CEE restored AChE activity, enhanced the activity of SOD, CAT, and GPx, and increased GSH levels, while concomitantly reducing protein oxidation and lipid peroxidation. The most pronounced effects were observed at 3 mg/L, which nearly normalized both behavioral and biochemical parameters. Conclusions: The CEE exerted anxiolytic and procognitive effects in zebrafish through combined cholinergic and antioxidant mechanisms. These findings highlight its translational potential as a promising candidate for the prevention and treatment of anxiety-related and cognitive disorders. Full article

In higher education, institutional quality is traditionally assessed through metrics such as academic programs, research output, educational resources, and community services. However, it is important that their activities align with student expectations, particularly in relation to interactive learning environments, learning management system interaction, curricular and co-curricular activities, accessibility, support services and other learning resources that ensure academic success and, jointly, career readiness. The growing popularity of student engagement metrics as one of the key measures to evaluate institutional efficacy is now a feature across higher education. By monitoring student engagement, institutions assess the impact of existing resources and make necessary improvements or interventions to ensure student success. This study presents a comprehensive analysis of student feedback from the StudentSurvey.ie dataset (2016–2022), which consists of approximately 275,000 student responses, focusing on student self-perception of engagement in the learning process. By using classical topic modelling techniques such as Latent Dirichlet Allocation (LDA) and Bi-term Topic Modelling (BTM), along with the advanced transformer-based BERTopic model, we identify key themes in student responses that can impact institutional strength performance metrics. BTM proved more effective than LDA for short text analysis, whereas BERTopic offered greater semantic coherence and uncovered hidden themes using deep learning embeddings. Moreover, a custom Named Entity Recognition (NER) model successfully extracted entities such as university personnel, digital tools, and educational resources, with improved performance as the training data size increased. To enable students to offer actionable feedback, suggesting areas of improvement, an n-gram and bigram network analysis was used to focus on common modifiers such as “more” and “better” and trends across student groups. This study introduces a fully automated, scalable pipeline that integrates topic modelling, NER, and n-gram analysis to interpret student feedback, offering reportable insights and supporting structured enhancements to the student learning experience. Full article

Exposure to hypoxia at high altitudes is significantly associated with impairments in learning and memory functions, as well as abnormalities in neuronal function and synaptic plasticity. Recent research has indicated that mitochondrial reactive oxygen species (mtROS) play a role in regulating microglial activation and mediating neurotoxic damage in the hippocampal CA1 region. Nicotinamide riboside (NR), upon absorption, is rapidly converted into nicotinamide adenine dinucleotide (NAD+), which is involved in the production of mitochondrial adenosine triphosphate (ATP). The potential of NR to protect dendritic spine plasticity in hippocampal CA1 neurons following hypoxia exposure, potentially through the inhibition of microglial activation, warrants further investigation. To this end, a mouse model simulating hypoxia at an altitude of 6000 m over a two-week period, along with a BV2 cells and conditional co-culture of BV2 cells and HT22 cells 1%O₂ hypoxia model, was developed. Behavioral assessments indicated that, relative to the normoxia group, mice subjected to hypoxia exhibited a significant reduction in the time spent in the target quadrant, the distance traveled within the target quadrant, the number of platform crossings, and the novel object recognition index. Furthermore, Golgi staining revealed a marked decrease in the density of dendritic spines in the hippocampal CA1 region in the hypoxia-exposed mice compared to the normoxia group. Subsequently, A daily dosage of 400 mg/kg of NR was administered for two weeks and 0.5 mM NR was used in a conditional co-culture model. Results demonstrated that, in comparison to the hypoxia group, the group receiving combined hypoxia and NR treatment showed significant improvements in the time spent in the target quadrant, the distance traveled within the target quadrant, the number of platform crossings, the novel object recognition index, and the density of dendritic spines in the hippocampal CA1 region. Additionally, transmission electron microscopy indicated a significant increase in the synaptic density of hippocampal neurons in the combined hypoxia exposure and NR treatment group compared to the hypoxia exposure group. Simultaneously, when compared to the hypoxia group, the combination of hypoxia and NR treatment resulted in an increased concentration of mitochondrial ATP. This treatment also partially restored mitochondrial membrane integrity, reduced mtROS levels, decreased the percent of Iba1⁺CD68⁺Iba1⁺ microglia, and lowered the interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNFα), and inducible nitric oxide synthase (iNOS) mRNA levels. These findings indicate that NR treatment may mitigate neurotoxic damage in the hippocampal CA1 region induced by hypoxia exposure, primarily through the attenuation of microglial activation and the reduction in mtROS production. Full article

The Okapi Wildlife Reserve (OWR) in northeastern Democratic Republic of the Congo represents both a biodiversity hotspot and the ancestral homeland of the Indigenous Mbuti and Efe peoples, whose livelihoods and knowledge systems are closely tied to forest resources. This study investigates how Indigenous knowledge and practices contribute to sustainable resource management under conditions of rapid socio-cultural transformation. A mixed-methods approach was applied, combining socio-demographic surveys (n = 80), focus group discussions, floristic inventories, and statistical analyses (ANOVA, logistic regressions, chi-square, MCA). Results show that hunting, fishing, gathering, and honey harvesting remain central livelihood activities, governed by customary taboos and restrictions that act as de facto ecological regulations. Agriculture, recently introduced through intercultural exchange with neighboring Bantu populations, complements rather than replaces traditional practices and demonstrates emerging agroecological hybridization. Nevertheless, evidence of biodiversity decline (including local disappearance of species such as Dioscorea spp.), erosion of intergenerational knowledge transmission, and increased reliance on monetary income indicate vulnerabilities. Multiple Correspondence Analysis revealed a highly structured socio-ecological gradient (98.5% variance explained; Cronbach’s α = 0.977), indicating that perceptions of environmental change are strongly coupled with demographic identity and livelihood strategies. Floristic inventories confirmed significant differences in species abundance across camps (ANOVA, p < 0.001), highlighting site-specific pressures and the protective effect of persistent customary norms. The findings underscore the resilience and adaptability of Indigenous Peoples but also their exposure to ecological and cultural disruptions. We conclude that formal recognition of Indigenous institutions and integration of their knowledge systems into co-management frameworks are essential to strengthen ecological resilience, secure Indigenous rights, and align conservation policies with global biodiversity and climate agendas. Full article

Lignin, the most abundant aromatic biopolymer, represents a key renewable feedstock for sustainable biorefineries, yet its structural complexity poses a formidable challenge for enzymatic degradation. While ligninolytic enzymes such as laccases (LACs), lignin peroxidases (LiPs), and manganese peroxidases (MnPs) exhibit remarkable catalytic versatility, the molecular mechanisms underlying their ability to balance substrate specificity and structural flexibility remain unresolved. Here, we employed all-atom molecular dynamics (MD) simulations and virtual mutagenesis to dissect the dynamic interactions between these enzymes and lignin model compound (β-O-4-linked H-type dimers). Our simulations revealed a dual recognition mechanism in which polar residues (such as Asp, Glu, Arg and His) formed hydrogen bonds with hydroxyl and keto groups near catalytic cleavage sites, ensuring precise alignment for bond scission, while aromatic residues stabilized diverse lignin conformations via hydrophobic interactions with conserved aromatic rings. Conformational dynamics of active-site residues enabled adaptive adjustments to substrate heterogeneity, reconciling enzymatic specificity with structural promiscuity. Virtual mutation experiments further demonstrated that aromatic residues were indispensable for binding stability, whereas polar residues dictated cleavage-site selectivity. These findings provide atomic-scale insights into the catalytic mechanism of ligninolytic enzymes, with implications in the rational design of superior biocatalyst for lignin biorefineries. Full article

Grape pomace (GP), a significant by-product of winemaking, is gaining increasing recognition for its potential as a source of bioactive compounds with antioxidant and cardioprotective properties. This study aimed to characterize the polyphenolic profile, fatty acid composition, and antioxidant activity of 17 GP samples from Transylvanian cultivars. Polyphenolic content was determined using the Folin–Ciocalteu method and high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC–DAD–ESI MS) analysis. Fatty acid composition was analyzed using gas chromatography with flame ionization detection (GC–FID). Antioxidant capacity was assessed using five methods, which included the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2′-azino-bis (3-ethylbenzothialzoline-6-sulfonic acid) (ABTS) radical scavenging, ferric-reducing antioxidant power (FRAP), cupric ion reducing antioxidant capacity (CUPRAC), and reducing power (RP) assays. Additionally, all extracts were analyzed by Fourier transform infrared (FTIR) spectroscopy to identify the presence of functional groups and chemical bonds associated with bioactive compounds. The results showed that Neuburger (NE), Radames (RA), and Regent (RE) cultivars had the highest phenolic concentrations, particularly of catechin, epicatechin, and procyanidin dimers. NE and Feteascǎ Regalǎ (FR) exhibited the greatest radical scavenging and electron transfer activities across multiple antioxidant assays. Rose Blaj (RB) and Astra (AS) displayed the most favorable fatty acid profiles, with high unsaturated-to-saturated fatty acid (UFA/SFA) and hypocholesterolemic-to-hypercholesterolemic fatty acid (H/H) ratios, as well as low atherogenicity (AI) and thrombogenicity (TI) indices, suggesting cardioprotective potential. Additionally, RB and NE cultivars also demonstrated a strong chelation of Cu²⁺ and Fe²⁺ ions, enhancing their antioxidant efficacy by mitigating metal-catalyzed oxidative stress. These findings underscore the potential of GP, particularly from NE, RB, RA, and AS cultivars, the last three of which were homologated in Transylvania at SCDVV Blaj, as valuable sources of health-promoting compounds for use in food, nutraceuticals, and other health-related applications. Full article

This study proposes a feature extraction scheme that fuses accelerometric (ACC) and electromyographic (EMG) data to improve shoulder movement identification in individuals with transhumeral amputation, in whom the clinical need for intuitive control strategies enabling reliable activation of full-arm prostheses is underinvestigated. A novel spatiotemporal warping feature extraction architecture was employed to realize EMG and ACC information fusion at the feature level. EMG and ACC data were collected from six participants with intact limbs and four participants with transhumeral amputation using an NI USB-6009 device at 1000 Hz to support the proposed feature extraction scheme. For each participant, a leave-one-trial-out (LOTO) training and testing approach was used for developing pattern recognition models for both the intact-limb (IL) and amputee (AMP) groups. The analysis revealed that the introduction of ACC information has a positive impact when using windows of length (WLs) lower than 150 ms. A linear discriminant analysis (LDA) classifier was able to exceed the accuracy of 90% in each WL condition and for each group. Similar results were observed for an extreme learning machine (ELM), whereas k-nearest neighbors (kNN) and an autonomous learning multi-model classifier showed a mean accuracy of less than 87% for both IL and AMP groups at different WLs, guaranteeing applicability over a large set of shallow pattern-recognition models that can be used in real scenarios. The present work lays the groundwork for future studies involving real-time validation of the proposed methodology on a larger population, acknowledging the current limitation of offline analysis. Full article

Carbapenem-resistant Acinetobacter baumannii (CRAB) bacteremia is a critical health concern associated with high morbidity and mortality and limited treatment options. Whether early initiation of concordant antibiotic therapy upon recognition of sepsis improves outcomes remains unclear. Methods: We conducted a retrospective cohort study of 413 patients diagnosed with CRAB bacteremia to evaluate the impact of early concordant antibiotic treatment (i.e., administration of in vitro active antibiotics within 24 h of blood culture collection) on 30-day mortality. Multivariable logistic regression was conducted to identify predictors of early concordant treatment and to evaluate its association with 30-day mortality. To address potential confounding by early death, a sensitivity analysis was performed which included only patients who survived at least 48 h after blood culture collection. Results: Among the study cohort, 30% (122/413) received early concordant treatment (all received colistin), while 70% (291/413) received early discordant treatment. The median age of patients receiving early concordant treatment was 69 (interquartile range (IQR), 62–78) years vs. 71 (IQR, 62–81) years in the discordant group (p = 0.1). Patients who received early concordant treatment were more likely to be mechanically ventilated (52% vs. 40%, p = 0.03) and have rectal carriage of multidrug-resistant bacteria (16% vs. 9%, p = 0.06). The 30-day mortality was 63% (260/413). In univariate analysis, survivors were more likely to have received early concordant treatment (38% vs. 25%, p = 0.005); however, this association was not statistically significant in the multivariable model (adjusted odds ratio [aOR] 0.36, 95% confidence interval [CI] 0.13–1.02, p = 0.053). Significant factors associated with 30-day mortality included age ≥65 years (aOR 4; 95% CI 1.1–17, p = 0.04) and SOFA score ≥5 points (aOR 7.14; 95% CI 2–25, p < 0.01). In the sensitivity analysis limited to patients who survived at least 48 h after blood culture collection, early concordant treatment remained unassociated with 30-day mortality (aOR 1.8; 95% CI 0.5–7, p = 0.4). Conclusions: Early concordant antibiotic treatment was not significantly associated with 30-day mortality in patients with CRAB bacteremia. Older age and SOFA score were significant predictors of mortality. Whether this finding reflects the limited efficacy of colistin, which was the predominant empiric antibiotic in this cohort, remains unclear; nevertheless, more effective therapeutic options for CRAB bacteremia are urgently needed to improve patient outcomes. Full article

The mechanisms underlying the abnormal activation of microglia affecting cognitive function under high-altitude hypobaric hypoxia (HAHH) have not been fully elucidated. This study aims to investigate the effects of HAHH on the expression of the receptor for advanced glycation end-products (RAGE) in hippocampal microglia of mice and to explore the role of RAGE inhibitors in alleviating HAHH-induced microglial inflammation and cognitive impairment. Mice were exposed to HAHH via a multi-environment simulation chamber, and RNA sequencing, qPCR, WB, flow cytometry and immunohistochemistry showed that HAHH exposome significantly increased RAGE expression in hippocampal microglia of mice (p < 0.001 vs. normoxia), which was closely related to microglial neuroinflammatory responses. RAGE inhibitor (FPS-ZM1) alleviated HAHH-induced microglial inflammation (TNF-α decreased by 64%, p < 0.001; CD86⁺ cells decreased by 42%, p < 0.001) and improved cognitive function in mice (Y-maze novel arm time: 28.08 ± 5.14 s vs. hypoxia 19.67 ± 4.68 s, p = 0.016; NORT recognition index: 0.52 ± 0.05 vs. hypoxia 0.33 ± 0.07, p < 0.001). Mechanistic studies revealed that RAGE inhibitors reduced microglial inflammation by inhibiting the MAPK pathway and decreasing nuclear translocation of NF-κB p65. Furthermore, high-mobility group box 1 (HMGB1) expression increased under hypoxic conditions (p < 0.001 vs. normoxia) and positively regulated RAGE expression. HMGB1 inhibitors reduced RAGE expression and attenuated HAHH-induced microglial inflammation. Overall, the HAHH exposome induces microglial inflammation via the HMGB1-RAGE-NF-κB pathway. RAGE and HMGB1 inhibitors may serve as novel therapeutic strategies to mitigate HAHH-induced cognitive impairment, providing a theoretical basis for the treatment of cognitive impairment. Full article

Gangliosides are essential for membrane functions, cell recognition, and maintenance of the nervous system. GM2 gangliosidosis is a group of rare genetic lysosomal storage diseases that includes Tay-Sachs disease (TSD), Sandhoff disease (SD), and AB variant. TSD and SD are characterized by deficient β-N-acetyl-hexosaminidase activity. This leads to decreased catabolism of β-N-acetyl-hexosamine-containing ganglioside GM2 in the lysosomes, damage to cells and tissues, and severe neurological symptoms. GM2 is a major ganglioside accumulating in TSD and SD, and is synthesized from GM3 by β1,4-N-acetylgalactosaminyltransferase 1 (B4GALNT1, GM2 synthase). Therapies under development for GM2 gangliosidosis include adeno-associated virus gene therapy, enzyme replacement, and substrate reduction therapy (SRT). The goal of this work was to express and purify human B4GALNT1, characterize its activity, and explore its structural features by protein modeling and substrate docking. We used a panel of synthetic compounds to study their potential inhibition of B4GALNT1 activity. This work can serve to develop SRT for GM2 gangliosidosis. Full article

S-Adenosyl-L-methionine (SAM) is a central cofactor in cellular methylation, donating methyl groups to a wide range of biological substrates. SAM analogues are promising tools for selective modulation of methyltransferase activity. Here, we investigated phosphorus-containing analogues of SAM and S-adenosyl-L-homocysteine (SAH), focusing on the H-phosphinic SAM analogue ((R,S)-SAM-P_H) with the HO(H)(O)P group replacing the carboxyl group of SAM. We examined the interaction of (R,S)-SAM-P_H with three representative methyltransferases: Dnmt1, responsible for maintenance of DNA methylation; Dnmt3a, which establishes de novo DNA methylation; and catechol-O-methyltransferase (COMT), which methylates protocatechuic aldehyde to yield vanillin and isovanillin. (R,S)-SAM-P_H is a methyl group donor for Dnmt3a and COMT, but not for Dnmt1, despite the high structural similarity of the Dnmt1 and Dnmt3a catalytic domains. These results demonstrate that targeted modification of the carboxyl group of SAM can yield analogues with specific activity towards various methyltransferases. The different recognition of (R,S)-SAM-P_H by Dnmt3a and Dnmt1 highlights its potential as a molecular probe for distinguishing de novo from maintenance DNA methylation. This work enriches our understanding of methyltransferase substrate specificity and provides a new tool for selective modulation of epigenetic processes. Full article