The nicotinamide adenine dinucleotide (NAD + ) is an important redox cofactor that plays a major role in energy metabolism. This review provides an overview of the current understanding of NAD + in cardiovascular diseases. Activation of the rate-limiting enzyme nicotinamide phosphoribosyltransferase (NAMPT), a key component of the NAD + salvage pathway, is emerging as an alternative method to replenish the cycling NAD + pools and to alleviate the cardiovascular pathophysiology driven by NAD + depletion. The NAD + -dependent sirtuins play an important role in cellular metabolism and integrate the circadian signaling of clock controlled Nampt oscillation and thereby NAD + synthesis. An imbalance in the NAD + /NADH ratio caused by NAD + depletion is implicated in various diseases, including metabolic disease, aging, and cancer. The cellular NAD + content is decreased in cardiovascular diseases and heart failure. Lack of NAD + in cardiomyocytes leads to mitochondrial dysfunction, increased reactive oxygen species (ROS) production and cell death. The supplementation of NAD + and its precursors such as nicotinic acid (NA), nicotinamide (NAM), nicotinamide mononucleotide (NMN), and nicotinamide riboside (NR) are currently being evaluated in clinical trials. This review mainly focuses on the role of NAD + in cardiovascular diseases and therapeutics.

Mesenchymal stromal cells (MSCs) are promising candidates for regenerative medicine due to their multi-lineage differentiation, immunomodulatory properties, and paracrine effects. Old individuals are the prime target population for cell-based therapies. Donor age significantly hinders the efficacy of autologous cell therapy due to the low quantity and senescent profile of isolated stem cells from aged individuals. Dysregulation of the AMPK-mTOR-autophagy pathway challenges the attenuation of senescence-associated features in aged stem cells. Here, we evaluated the effects of short-term treatment with rapamycin and nicotinamide (NAM) on the attenuation of senescence-associated features in aged MSCs. Aged MSCs were isolated from elderly donors and cultured in the medium supplemented with rapamycin (10 nM) and NAM (5 mM) for the duration of a culture passage. Cell proliferation, expression of CKIs, ROS, senescence-associated changes, senescence-associated secretory phenotype (SASP) profile, and osteogenic differentiation were investigated. Furthermore, AMPK, mTORC1, and mTORC2 activity and level of autophagy were evaluated. Aged MSCs treated with rapamycin and NAM exhibited increased replicative capacity and decreased p16 and p21 expression. In contrast to the senescent profile of aged MSCs, rapamycin, and NAM attenuated the senescence-associated changes, including decreased β-galactosidase expression, dysfunctional lysosomes, reduced total cellular ROS, and improved osteogenic differentiation. Treatment with these compounds reduced pro-inflammatory cytokines, IL-1β and IL-6. These partial reversal of senescence-associated features by rapamycin and NAM were associated with altered AMPK, mTORC1 and mTORC2 activity, and autophagy modulation. Short-term in vitro treatment with rapamycin and NAM can potentially yield high-quality autologous MSCs with improved functional characteristics, possibly improving clinical outcomes of cell-based therapies in the elderly population. These short-term in vitro findings require confirmation in further preclinical studies to assess long-term stability and in vivo relevance.

Salidroside suppresses hypoxia-induced ocular angiogenesis by modulating the acetylation of PFKFB3 protein in endothelial cells and regulating glycolytic activity.

Biosensor-driven adaptive laboratory evolution and modular pathway engineering for high-level production of nicotinamide mononucleotide in yeast.

The present investigation aimed to develop and comparatively validate a reversed-phase high-performance liquid chromatographic (RP-HPLC) method and a chemometric-assisted UV spectrophotometric method for the simultaneous estimation of Pyridoxine Hydrochloride (PYR) and Nicotinamide (NIC) in pharmaceutical formulations. Chemometric analysis using Partial Least Squares (PLS) regression was employed to overcome spectral overlap limitations encountered in conventional spectrophotometric analysis. RP-HPLC separation was achieved using a C18 column under optimized chromatographic conditions with an isocratic mobile phase system. The developed analytical methods were validated according to International Conference on Harmonisation (ICH) guidelines with respect to linearity, accuracy, precision, robustness, reproducibility, specificity, limit of detection, and limit of quantitation. The chemometric-assisted spectrophotometric method demonstrated excellent predictive capability with satisfactory calibration and validation performance. The RP-HPLC method exhibited sharp peak resolution, acceptable retention times, high theoretical plate count, and minimal tailing. Both analytical methods showed good linearity over the selected concentration ranges with correlation coefficients approaching unity. Recovery studies confirmed the accuracy of the developed methods with percentage recoveries within acceptable limits. Statistical analysis demonstrated no significant difference between the proposed RP-HPLC and chemometric-assisted methods regarding quantitative estimation of both analytes. The comparative evaluation established that the chemometric-assisted spectrophotometric method provides a rapid, economical, and environmentally friendly alternative to chromatographic analysis, whereas RP-HPLC offers superior selectivity and sensitivity for routine quality control applications. The developed methods were successfully applied for simultaneous estimation of Pyridoxine HCl and Nicotinamide in marketed pharmaceutical formulations.

Nicotinamide enhances lipid deposition and thermogenesis in goat brown adipocytes.

Juvenile Idiopathic Arthritis (JIA) is the most common rheumatic disease in children and is characterized by chronic joint inflammation driven by immune dysregulation. A disturbed regulatory T (Treg) cell-effector T cell axis has been demonstrated in these patients which contributes to a dysregulated immune tolerance in JIA. Therefore, strategies to enhance Treg numbers and suppressive capacity to restore immune homeostasis represent a promising therapeutic approach. Nicotinamide (NAM), a form of vitamin B₃ and precursor of nicotinamide adenine dinucleotide (NAD⁺), has emerged as an immunomodulator capable of promoting Treg cell function. Here, we investigate the effects of NAM on Treg percentages and suppressive capacity in mononuclear cells derived from peripheral blood (PBMCs) and synovial fluid of JIA patients (SFMCs). In an exploratory pilot phase II clinical study, NAM concentrations were measured in paired blood plasma and SF from 6 JIA patients after oral administration of daily 1.8g/m2 for three days. NAM treatment significantly increased the proportion of FOXP3-expressing CD4+ T cells in both PBMCs and SFMCs and Treg suppressive capacity in PBMCs from healthy controls in vitro. Comparable NAM concentrations were detected in plasma and SF following oral administration, demonstrating its ability to penetrate the inflamed joint environment. Given its established safety in both adults and children, NAM represents a promising future candidate for adjunctive therapy in JIA by restoring the balance between regulatory and effector T cells. Further clinical and mechanistic studies are warranted to define optimal dosing regimens and its place in the long-term treatment strategy of JIA. Assessing penetration of high dose nicotinamide (Vitamin B3) in synovial fluid. EudraCT Number: 2018-002245-11, start date Jan 16th, 2019.

Sublingual administration of nicotinamide mononucleotide (NMN) is hypothesized to enhance systemic bioavailability by bypassing hepatic first-pass metabolism, a significant limitation of oral intake. However, direct comparative evidence in humans has been lacking. This study aimed to compare the acute pharmacokinetics of NMN following single-dose oral and sublingual administration in a randomized, two-period crossover trial involving 14 healthy adult males. Participants received NMN via both routes, separated by an 8-day washout period. Blood samples were collected for 60min post-administration to measure NMN and its metabolites, including nicotinamide (NAM), nicotinamide adenine dinucleotide (NAD⁺), and the terminal catabolites N1-methyl-2-pyridone-5-carboxamide (2PY) and N1-methyl-4-pyridone-3-carboxamide (4PY). The incremental area under the curve (iAUC) was significantly higher for the terminal metabolites 2PY and 4PY following sublingual administration compared to the oral route. In contrast, no significant differences were found for the blood concentrations of NMN, NAM, or NAD⁺ between methods. Both administration routes were well-tolerated, with no adverse events reported. These findings provide the first direct evidence in humans that sublingual administration leads to a more rapid increase in the terminal metabolites (2PY and 4PY) over 0-60min, although the metabolic origin of these increases could not be distinguished in the present study.

Oxalate​​ is widely distributed and serves various functional roles in plants. However, its biosynthetic pathway and regulatory mechanisms ​​remain​​ poorly defined. In this study, we further investigated the mechanism of oxalate accumulation using rice (Oryza sativa) CRISPR-Cas9-generated nitrate reductase (NR)​​ and ​​nitrite reductase (NiR)​​ mutants, combined with different treatments. Both NR and NiR mutants exhibited significantly reduced oxalate levels. The reduced oxalate in NR and NiR mutants was restored by nitrite and nitrate, respectively, whereas ammonium had no effect​​, indicating that both nitrate and nitrite reduction, rather than the subsequent ammonium assimilation, are involved in modulating oxalate accumulation in rice. Furthermore, various organic acids, ​​including​​ glycolate, glyoxylate, glycerate, and oxaloacetate, markedly stimulated oxalate content. Transcriptomic and metabolomic analyses revealed that oxalate levels were closely and positively associated with the expression of glycolytic and tricarboxylic acid (TCA) cycle genes and the content of their intermediate metabolites. Treatment with glycolytic intermediates (phosphoenolpyruvate (PEP) and 3-phosphoglycerate (3PGA)) and inhibitors (iodoacetate (IOA)and 3-bromopyruvate (BrPA)) further confirmed that glycolysis drives oxalate synthesis in rice. Nicotinamide (NAM), a NAD precursor, also restored the oxalate content, suggesting that NAD/NADH may play a mediatory role in oxalate regulation through both nitrate and nitrite reduction. Collectively, our results demonstrate that oxalate accumulation is intimately associated with glycolysis in rice, rather than with photorespiration, which instead regulates oxalate accumulation indirectly via the glycerate-mediated​​ impact on glycolysis.​​.

Renal carcinoma ranks among the most lethal cancers, primarily attributed to its atypical symptoms and high metastatic potential. The metabolism of nicotinamide (NAM) plays a significant role in the progression of various tumors. However, investigations into the impact of the NAM metabolism-related signature (NMRS) in kidney renal clear cell carcinoma (KIRC) remain insufficient. Clinical and RNA sequencing data (RNA-seq) from 541 KIRC tissues and 72 adjacent normal tissues were extracted from TCGA. NAM metabolism-related genes (NMRGs) were identified through the Molecular Signatures Database. Cox regression analyses (univariate/multivariate) were conducted to develop NMRS. Time-dependent ROC curve analysis showed that this method had good accuracy in predicting 1-year (AUC = 0.691), 3-year (AUC = 0.749), and 5-year (AUC = 0.764) survival. The Receiver Operating Characteristic (ROC) curve from the external RECA-EU dataset (AUC = 0.682) highlights the accurate prognostic assessment of the NMRS. Overall survival (OS) rates across distinct risk groups were compared using KM analysis. The Cox proportional hazards model assessed the influence of clinicopathological factors and risk scores on survival outcomes (HR = 1.437, 95% CI [1.232–1.676]; P < 0.001). Evaluation of the immune microenvironment employed the ESTIMATE and CIBERSORT methods, while enrichment analysis examined biological significance. Correlation analysis determined the link between the expression of checkpoint genes and risk scores. StarBase and miRTarBase facilitated the prediction of target miRNAs and lncRNAs bindingto NMRGs. This study presents a novel framework for identifying prognostic biomarkers and therapeutic targets in KIRC.

Colitis-associated cancer (CAC) is a serious complication of inflammatory bowel disease (IBD). Recent evidence has indicated that Fusobacterium nucleatum (F. nucleatum) may promote intestinal inflammation and carcinogenesis. However, the effects of F. nucleatum on the cancerous transformation of IBD, along with its underlying mechanisms, remain poorly understood. Our findings revealed that F. nucleatum was enriched in 57.1% of CAC tissues, which was higher than that in ulcerative colitis (UC, 53.0%), Crohn's disease (CD, 55.6%), and colorectal cancer (CRC, 53.7%) tissues. Furthermore, we demonstrated that F. nucleatum modulated nicotinamide (NAM) metabolism to promote the proliferation of CAC. Mechanistically, F. nucleatum upregulated NNMT to increase PARP1 expression, thereby activating MAPK signalling pathway. These findings provide insight into F. nucleatum-induced metabolic dysregulation and inflammatory cancer development and may propose novel intervention strategies for the prevention and treatment of microbial-associated inflammatory carcinogenesis.

The ADP-ribosylation of proteins is a versatile, reversible, posttranslational modification involved in the dynamic regulation of numerous cellular processes. Human ADP-ribosyltransferase 1 (hsART1, EC: 2.4.2.31) is a membrane-associated, GPI-anchored, mono-ADP-ribosyltransferase selective for mono-ADP ribosylation (MARylation) of L-arginine residues. Dysregulation of hsART1 activity has been shown to permit immune cell evasion in non-small cell lung cancer (NSCLC) through elevated MARylation at Arg125 of the purinergic type 2 receptor (P2X7) in P2X7-positive T cells, resulting in NAD+-induced cell death (NICD) of tumor-penetrating immune cells. With hsART1 emerging as an immunotherapy target in select cancers, there is a need to develop small-molecule inhibitors. The transition state (TS) for the MARylation of P2X7 peptide was determined from kinetic isotope effect (KIE) measurements of 3H-, 14C-, 18O-, and 15N-labeled NAD+ substrates. Quantum mechanical (QM) calculations of the reaction coordinate, mapped with experimental KIEs, identify a TS geometry consistent with a highly dissociative, asymmetric, concerted mechanism with minimal contributions from the leaving group nicotinamide (NAM) and minor contributions from the incoming L-arginine guanidinium. The absence of a normal deuterium solvent isotope effect identifies a positively charged guanidinium nucleophile, leading to a dication N-ribosyltransferase mechanism. Together with the unusual, normal 18O-O4' KIE, we identified unique charge accumulation across the oxocarbenium at the TS caused by an increased bond order between the C1'-C2', and decreased bond order between the C4'-O4' of the nicotinamide mononucleotide ribose. This is the first L-arginine-specific ADP-ribosylation TS to be characterized, a step toward the design of TS analogs.

Epithelial barrier disruption is a hallmark of allergic skin diseases. Sodium dodecyl sulfate (SDS), a surfactant in household cleaning products, is known to impair the barrier. We used a physiologically relevant exvivo human skin combined with real-time electrical impedance spectroscopy (EIS) to monitor barrier integrity after SDS exposure. Multi-omics analyses, including RNA sequencing and proximity extension-based proteomics, characterized molecular responses. Barrier permeability and oxidative stress were evaluated in primary keratinocytes, and the protective effects of N-acetylcysteine (NAC) and nicotinamide (NAM) were assessed in both air-liquid interface keratinocyte cultures and exvivo skins. Even a 1-min SDS exposure caused a rapid EIS decline, indicating immediate barrier compromise. 5-min exposures produced dose-dependent EIS decline with broad suppression of barrier and immune mediators (e.g., CXCL11, MCP4, and HNMT), 6-h exposure sustained skin barrier loss and associated inflammatory and remodeling programs. Proteomic signatures highlighted AREG, JUN, and ITGA6 can track skin damage, while CST5 and PRDX1 correlated with the preservation. Transcriptomics corroborated these changes, showing up-regulation of stress and repair programs-endoplasmic reticulum stress, oxidative stress, sphingolipid biosynthesis, and epidermal differentiation pathways. NAC/NAM reduced SDS-induced reactive oxygen species, cytotoxicity, and permeability in primary keratinocytes, and restored EIS values in exvivo skin. Short-term SDS exposure rapidly disrupts human skin barrier integrity through oxidative stress-driven suppression of structural/immune mediators and activation of stress/remodeling pathways. NAC and NAM effectively mitigated damages, highlighting antioxidants as preventive interventions for surfactant-induced skin barrier dysfunction.

Fusobacterium nucleatum contributes to the progression of colorectal cancer (CRC). Nicotinamide (NAM), a safe, cost-effective, and water-soluble form of vitamin B3, has been shown to inhibit the virulence of various microorganisms. However, its effect on F. nucleatum pathogenicity remains unclear. In this study, we evaluated the effects of NAM on the pathogenic traits of F. nucleatum. A quarter of the minimum inhibitory concentration of NAM (~50 mM) was found to simultaneously inhibit bacterial growth, biofilm formation, and the adhesion and invasion of CRC cells. Transcriptomic analysis of F. nucleatum treated at this concentration revealed that 257 genes were upregulated and 316 genes were downregulated. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology functional enrichment analyses indicated that these differentially expressed genes are involved in multiple pathways, including oxidative phosphorylation, biofilm formation, two-component systems, ATP synthesis, and other processes. Furthermore, we showed that NAM, as a class III histone deacetylase inhibitor, could inhibit the deacetylase activity of CobB, thereby increasing the acetylation level of the FomA and reducing its binding ability to CRC cells. In summary, these findings suggest that NAM can attenuate multiple virulence traits of F. nucleatum and may serve as a promising F. nucleatum-targeted strategy for prevention and treatment of CRC.

This work addresses a key challenge in scaling up mechanochemical synthesis: deriving a kinetic model when unpredictable formation and intricate interaction of multiple crystalline phases occur during solid-state transformations. Reaction kinetics translate our understanding of chemical processes into mathematical rate expressions used for reactor design and evaluation, thus representing a challenge to be addressed for the scale up at the industrial level. Choosing co-crystallization of chloro-3-sulfamoylbenzoic acid (CSBA) and isonicotinamide (INA) as a model system, at first we employ time-resolved in situ powder X-ray diffraction (PXRD) and multivariate curve resolution-Alternating Least Squares (MCR-ALS) analysis to quantify and resolve the evolution of crystalline intermediates under varying methanol-assisted conditions. Our data show that even small changes in the amount of methanol can dramatically alter the kinetic profile, stabilise transient phases (including some that were previously unreported) and alter the overall reaction pathway. We then demonstrate the robust deconvolution of overlapping phases and the extraction of quantitative rate parameters that rationalize the observed behaviour by integrating kinetic modelling as a soft-hard constraint in the MCR-ALS workflow. The validation of the established MCR-ALS workflow is achieved by applying a phenomenological kinetic modelling tailored to rationalize the mechanochemical reaction rates. These results establish a broadly applicable platform for analysing and controlling the complex phase evolution, along with the derivation of a kinetic model instrumental to mechanochemical process development and scaling up, thereby supporting the transition of sustainable solid-state syntheses from the laboratory to industry.

Deoxynivalenol (DON) is a globally prevalent mycotoxin that threatens food and feed safety via severe multi-organ toxicity. Previous studies indicate that DON induces cellular energy metabolism dysregulation by triggering oxidative stress and impairing mitochondrial function. During this process, nicotinamide adenine dinucleotide (NAD+), a central coenzyme in cellular energy metabolism, frequently exhibits significantly decreased intracellular levels or even complete depletion. However, the molecular mechanisms underlying the disruption of NAD+ homeostasis by DON exposure, as well as the development of targeted countermeasures, remain elusive. Using human embryonic kidney 293T (HEK293T) cells as an in vitro renal toxicity model, we dissected DON-induced NAD+ dysregulation and evaluated the protective potential of nicotinamide (NAM). DON caused significant NAD+ depletion in porcine serum (in vivo) and HEK293T cells (in vitro), which was confirmed as a key driver of cytotoxicity. Mechanistically, although DON binds and inhibits nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ salvage pathway, neither NAMPT knockdown and overexpression nor nicotinamide mononucleotide (NMN) supplementation rescued DON-induced toxicity. Instead, DON dose-dependently activated poly(ADP-ribose) polymerase 1 (PARP1), the primary intracellular NAD+-consuming enzyme, to accelerate NAD+ depletion. PARP1 knockdown markedly attenuated DON-induced cytotoxicity, identifying PARP1 hyperactivation as the core toxic mechanism. NAM dose-dependently suppressed PARP1 activity, replenished NAD+ pools, and reversed cell injury. These findings establish PARP1-driven NAD+ depletion as an important mechanism of DON-induced renal toxicity, providing a promising intervention candidate for mitigating DON toxicity in food safety.

In aquatic invertebrates, hemolymph is critical for host–environment interaction. Although maintaining microbial homeostasis in hemolymph is significant for disease pathogenesis, the key regulatory mechanisms remain elusive. This study investigates the essential role of the respiratory glycoprotein hemocyanin (HMC) in modulating hemolymph microbial composition in penaeid shrimp. Hemocyanin-depleted shrimp infected with Vibrio parahaemolyticus (Vp) exhibited disruptions in the niacinamide (NAM) salvage pathway, attenuated plasma niacinamide and nicotinamide adenine dinucleotide (NAD) levels, and reduced transcripts of key enzymes. These alterations correlated with an increased total bacterial load and a higher abundance of opportunistic pathogens like Vibrio and Shewanella. Hemocyanin likely modulates niacinamide metabolism through interactions with Litopenaeus vannamei nicotinamide riboside kinase 1 (LvNRK1), sirtuin 2 (LvSIRT2), and sirtuin 6 (LvSIRT6). Remarkably, niacinamide supplementation after hemocyanin knockdown restored hemolymph microbial balance, reduced Vibrio dominance, and improved shrimp survival against V. parahaemolyticus infection, but not Gram-positive Staphylococcus aureus (Sa). These findings provide novel insights into the pivotal role of niacinamide metabolism in regulating shrimp hemolymph microbial composition via hemocyanin.

Uncovering the potential role of nicotinamide as a radioprotective agent in rats.

Muscle Stem Cells (MuSCs) drive muscle regeneration and slow pathological progression of muscle diseases. In preclinical models, nicotinamide (NAM) and pyridoxine (PN) synergistically increased MuSC proliferation and differentiation, and accelerated muscle regeneration. Herein we tested if NAM/PN could enhance MuSC activity and muscle regeneration in a randomized, placebo-controlled clinical trial. Men aged 18-49 years were supplemented daily with 714mg NAM and 19mg PN, or placebo, for 9 days following one session of damaging unilateral eccentric muscle contractions. The primary endpoint was MuSC activity via immunohistofluorescence on biopsy sections from the vastus lateralis muscle. Histological markers of muscle regeneration constituted secondary outcomes, and muscle damage was validated with clinical markers. 39 out of 43 enrolled participants completed the study. Supplementation of NAM/PN was well tolerated and increased blood concentrations of NAM and PN vitamers. 8 days after the contraction protocol, the number of Pax7, MyoD, and myogenin positive cells per damaged fiber was significantly higher in NAM/PN vs placebo groups (+29%-67%). NAM/PN also increased the proportion of regenerating fibers (+37%). Daily oral NAM/PN supplementation after high intensity muscle contractions enhances MuSC activity and accelerates muscle regeneration and repair, providing new opportunities for therapeutic applications in muscle recovery and muscle wasting disorders.

NNMT as a therapeutic target in fibrosis: Insights from the heart, liver, kidneys, and lungs.