Huangqin decoction attenuates spared nerve injury (SNI)-induced neuropathic pain by modulating microglial M1/M2 polarization partially mediated by intestinal nicotinamide metabolism.

BACKGROUND: The incidence of neuropathic pain is progressively increasing over time. The activation of M1-type microglia plays a crucial role in the initiation and progression of neuropathic pain. Huangqin Decoction (HQD) is traditionally used to alleviate dysentery and abdominal pain. However, it remains unclear whether HQD can effectively mitigate neuropathic pain and the underlying mechanisms. PURPOSE: The present study aims to investigate the impact of HQD on neuropathic pain induced by spared nerve injury (SNI) in mice, and to elucidate whether the analgesic effect of HQD is associated with microglia polarization. METHODS: The analgesic effect of HQD on SNI mice was investigated through assessments of mechanical pain threshold, thermal pain threshold, cold pain threshold, and motor ability. We elucidated the molecular mechanisms of HQD in alleviating SNI-induced neuropathic pain by focusing on microglia polarization and intestinal metabolite abnormalities. The expression levels of markers associated with microglia polarization (Iba-1, CD68, CD206, iNOS) was detected by immunofluorescence and Western blot, and the levels of inflammatory factors (IL-4, IL-10, IL-6, TNF-α) were assessed by ELISA. UPLC-QTOF-MS metabolomics was utilized to identify differential metabolites in the intestines of SNI mice. We screened the differential metabolites related to microglial polarization by correlation analysis, subsequently nicotinamide was selected for validation in LPS-induced BV-2 cells. RESULTS: Our findings demonstrated that HQD (20 g/kg) significantly enhanced the mechanical pain threshold, thermal pain threshold, and cold pain threshold, and protected the injured DRG neurons of SNI mice. Moreover, HQD (20 g/kg) obviously suppressed the expression of microglia M1 polarization markers (Iba-1, CD68, iNOS, IL-6, TNF-α), and promoted the expression of microglia M2 polarization markers (CD206, IL-10, IL-4) in the spinal cord of SNI mice. Additionally, HQD (20 g/kg) prominently ameliorated intestinal barrier damage by upregulating Claudin 1 and Occludin expression in the colon of SNI mice. Furthermore, HQD (20 g/kg) rectified 19 metabolite abnormalities in the intestine. Notably, nicotinamide (100 µM), an amide derivative with anti-inflammatory property, effectively suppresses microglia activation and polarization in LPS-induced BV-2 cells by downregulating IL-6 level and CD68 expression while upregulating IL-4 level and CD206 expression. CONCLUSION: In summary, HQD alleviates neuropathic pain in SNI mice by regulating the activation and polarization of microglia, partially mediated through intestinal nicotinamide metabolism.

CARDIOPROTECTIVE EFFECT OF GLYCYRRHIZA GLABRA EXTRACT AND GLYCYRRHIZA GLABRA SILVER NANOPARTICLE AGAINST ALLOXAN AND NICOTINAMIDE INDUCED DIABETIC CARDIAC INJURY IN RATS.

Objective - to study the Cardioprotective effect of Glycyrriza glabra ethanolic extract and Glycyrrhiza glabra Silver nanoparticle against alloxan and nicotinamide-induced diabetic cardiac injury in adult female Rats. The current study was performed on 36 days in which the G. glabra extract and G. glabra extract loaded on Silver nanoparticles were given to alloxan and nicotinamide-induced diabetic cardiac injured rats. The Cardioprotective effect has been evaluated biochemically. The results of induction of diabetic cardiac injury for 36 days showed a significantly increased (P˂0.05) serum Cardiac Troponin I (cTn-I) and Creatine Kinase (CK-MB) concentration in the diabetic cardiac injury induced (G2) group when compared with the control group (G1), and showed a significant decrease (P˂0.05) in the serum cTn-I and CK-MB concentration in (G3) group (received G. glabra extract) and (G4) group (G.glabra loaded on silver nanoparticle) in comparison with G2. This study concluded that Glycyrriza glabra extract and Glycyrrhiza glabra Silver nanoparticle have a significant Cardioprotective effect induced by alloxan and nicotinamide.

Nicotinamide Riboside Augments Human Macrophage Migration via SIRT3-Mediated Prostaglandin E2 Signaling.

NAD+ boosting via nicotinamide riboside (NR) confers anti-inflammatory effects. However, its underlying mechanisms and therapeutic potential remain incompletely defined. Here, we showed that NR increased the expression of CC-chemokine receptor 7 (CCR7) in human M1 macrophages by flow cytometric analysis of cell surface receptors. Consequently, chemokine ligand 19 (CCL19, ligand for CCR7)-induced macrophage migration was enhanced following NR administration. Metabolomics analysis revealed that prostaglandin E2 (PGE2) was increased by NR in human monocytes and in human serum following in vivo NR supplementation. Furthermore, NR-mediated upregulation of macrophage migration through CCL19/CCR7 was dependent on PGE2 synthesis. We also demonstrated that NR upregulated PGE2 synthesis through SIRT3-dependent post-transcriptional regulation of cyclooxygenase 2 (COX-2). The NR/SIRT3/migration axis was further validated using the scratch-test model where NR and SIRT3 promoted more robust migration across a uniformly disrupted macrophage monolayer. Thus, NR-mediated metabolic regulation of macrophage migration and wound healing may have therapeutic potential for the topical management of chronic wound healing.

Drug-Induced Liver Injury During a Glaucoma Neuroprotection Clinical Trial.

ABSTRACT: There are several ongoing, worldwide clinical trials with a cumulative target enrollment of over 1300 participants on the role of nicotinamide (a specific form of vitamin B3) as a therapeutic neuroprotective treatment for glaucoma. We describe a serious adverse event of drug-induced liver injury (DILI) likely related to the use of 3 g/day nicotinamide in a glaucoma clinical trial (clinicaltrials.gov identifier: NCT05695027) based in the United States. This report is important to share with the medical community, as other participants in glaucoma nicotinamide trials globally may have similar adverse events and many patients are using nicotinamide as a health supplement without medical supervision. We recommend that investigators, physicians, and patients remain vigilant about DILI as they seek novel vision-preserving neuroprotective therapies.

The Effect of Niacinamide Supplementation on Phosphate Concentrations in Dutch Dialysis Patients: A Randomized Crossover Trial.

OBJECTIVE: Hyperphosphatemia is a common complication in patients with kidney failure, despite the use of phosphate binders. Vitamin B3, either in the form of niacin or niacinamide (NAM), shows potential as "add-on" treatment to reduce serum phosphate concentrations in this population. NAM seems to lack many of the side effects that are observed with niacin. The aim of this study was to investigate whether NAM is an effective and acceptable treatment in reducing serum phosphate concentrations in patients with kidney failure. METHODS: DiaNia was a double-blind placebo-controlled randomized crossover trial, comparing NAM (250-500 mg/day) to placebo as "add-on" treatment to an individual treatment with approved phosphate binders for 12 weeks in patients receiving hemodialysis. The primary outcome was serum phosphate concentrations, and the secondary outcomes were platelet counts as well as drop-outs due to side effects. Data were analyzed using both per-protocol and intention-to-treat analyses. RESULTS: Mean age of the per-protocol population (n = 26) was 63.6 ± 17.2 years and 53.8% were men. NAM treatment significantly reduced serum phosphate with 0.59 mg/dL (p = .03). Linear mixed-effects models demonstrated superiority of 12 weeks NAM over 12 weeks placebo with a between-treatment difference of 0.77 mg/dL (95% CI 0.010, 1.43; P = .03). Similar results, although not significant, were found in the intention-to-treat population. We found no between-treatment differences in platelet counts and during the NAM treatment we observed 3 drop-outs due to side effects (8.6%). CONCLUSION: NAM is effective in reducing serum phosphate concentrations in patients with kidney failure receiving hemodialysis. In addition, NAM is well-tolerated and seems not to increase the risk of thrombocytopenia. Thus, NAM can be valuable as "add-on" treatment to combat hyperphosphatemia in patients with kidney failure. However, more research in larger populations is needed to confirm this.

Understanding Sorafenib-Induced Cardiovascular Toxicity: Mechanisms and Treatment Implications.

Tyrosine kinase inhibitors (TKIs) have been recognized as crucial agents for treating various tumors, and one of their key targets is the intracellular site of the vascular endothelial growth factor receptor (VEGFR). While TKIs have demonstrated their effectiveness in solid tumor patients and increased life expectancy, they can also lead to adverse cardiovascular effects including hypertension, thromboembolism, cardiac ischemia, and left ventricular dysfunction. Among the TKIs, sorafenib was the first approved agent and it exerts anti-tumor effects on hepatocellular carcinoma (HCC) and renal cell carcinoma (RCC) by inhibiting angiogenesis and tumor cell proliferation through targeting VEGFR and RAF. Unfortunately, the adverse cardiovascular effects caused by sorafenib not only affect solid tumor patients but also limit its application in curing other diseases. This review explores the mechanisms underlying sorafenib-induced cardiovascular adverse effects, including endothelial dysfunction, mitochondrial dysfunction, endoplasmic reticulum stress, dysregulated autophagy, and ferroptosis. It also discusses potential treatment strategies, such as antioxidants and renin-angiotensin system inhibitors, and highlights the association between sorafenib-induced hypertension and treatment efficacy in cancer patients. Furthermore, emerging research suggests a link between sorafenib-induced glycolysis, drug resistance, and cardiovascular toxicity, necessitating further investigation. Overall, understanding these mechanisms is crucial for optimizing sorafenib therapy and minimizing cardiovascular risks in cancer patients.

Effects of Physalis peruviana L. (leaf crude extracts) on blood glucose and functional biomarkers in streptozotocin-nicotinamide-induced diabetic rats.

Promoting antidiabetic phytomedicines necessitates evidence-based preclinical investigations, particularly in animal models. The present study investigated the validity of using the streptozotocin-nicotinamide-induced type 2 diabetic (STZ/NA-induced T2DM) model to evaluate the effects of Physalis peruviana leaf crude extracts on controlling blood glucose levels and regulating physiological biomarkers in rats. Aqueous and methanol extracts dissolved in carboxymethylcellulose 1% (100, 200, mg/kg/day) were administered orally to STZ/NA-induced T2DM rats alongside glibenclamide (5 mg/kg) as the standard drug for four weeks. Blood samples were collected in fasting rats on days 1, 7, 14, 21, and 28 to measure glucose concentration, lipoprotein-cholesterol, and common serum biomarkers. Nutrition characteristics were also monitored, as well as the pancreas histology. Administration of STZ/NA in Wistar rats induced the T2DM significantly lower than did STZ alone (glycaemia 200 vs 400 mg/dL). The significant effects observed with plant extracts compared to untreated diabetic rats were blood glucose reduction (28-52 %), HDL-C increase, LDL-C decrease, ALAT increase, WBC increase, body weight gain (24%), and pancreas protection. The findings confirm the antidiabetic effect of P. peruviana in T2DM animal model.

The therapeutic perspective of NAD+ precursors in age-related diseases.

Nicotinamide adenine dinucleotide (NAD+) is the fundamental molecule that performs numerous biological reactions and is crucial for maintaining cellular homeostasis. Studies have found that NAD+ decreases with age in certain tissues, and age-related NAD+ depletion affects physiological functions and contributes to various aging-related diseases. Supplementation of NAD+ precursor significantly elevates NAD+ levels in murine tissues, effectively mitigates metabolic syndrome, enhances cardiovascular health, protects against neurodegeneration, and boosts muscular strength. Despite the versatile therapeutic functions of NAD+ in animal studies, the efficacy of NAD+ precursors in clinical studies have been limited compared with that in the pre-clinical study. Clinical studies have demonstrated that NAD+ precursor treatment efficiently increases NAD+ levels in various tissues, though their clinical proficiency is insufficient to ameliorate the diseases. However, the latest studies regarding NAD+ precursors and their metabolism highlight the significant role of gut microbiota. The studies found that orally administered NAD+ intermediates interact with the gut microbiome. These findings provide compelling evidence for future trials to further explore the involvement of gut microbiota in NAD+ metabolism. Also, the reduced form of NAD+ precursor shows their potential to raise NAD+, though preclinical studies have yet to discover their efficacy. This review sheds light on NAD+ therapeutic efficiency in preclinical and clinical studies and the effect of the gut microbiota on NAD+ metabolism.

Protective Effect of Betulin on Streptozotocin-Nicotinamide-Induced Diabetes in Female Rats.

Type 2 diabetes is characterized by hyperglycemia and a relative loss of ß-cell function. Our research investigated the antidiabetic potential of betulin, a pentacyclic triterpenoid found primarily in birch bark and, intriguingly, in a few marine organisms. Betulin has been shown to possess diverse biological activities, including antioxidant and antidiabetic activities; however, no studies have fully explored the effects of betulin on the pancreas and pancreatic islets. In this study, we investigated the effect of betulin on streptozotocin-nicotinamide (STZ)-induced diabetes in female Wistar rats. Betulin was prepared as an emulsion, and intragastric treatments were administered at doses of 20 and 50 mg/kg for 28 days. The effect of treatment was assessed by analyzing glucose parameters such as fasting blood glucose, hemoglobin A1C, and glucose tolerance; hepatic and renal biomarkers; lipid peroxidation; antioxidant enzymes; immunohistochemical analysis; and hematological indices. Administration of betulin improved the glycemic response and decreased α-amylase activity in diabetic rats, although insulin levels and homeostatic model assessment for insulin resistance (HOMA-IR) scores remained unchanged. Furthermore, betulin lowered the levels of hepatic biomarkers (aspartate aminotransferase, alanine aminotransferase, and alpha-amylase activities) and renal biomarkers (urea and creatine), in addition to improving glutathione levels and preventing the elevation of lipid peroxidation in diabetic animals. We also found that betulin promoted the regeneration of ß-cells in a dose-dependent manner but did not have toxic effects on the pancreas. In conclusion, betulin at a dose of 50 mg/kg exerts a pronounced protective effect against cytolysis, diabetic nephropathy, and damage to the acinar pancreas and may be a potential treatment option for diabetes.

Oral intake of bucillamine, carvedilol, metformin, or phenformin does not protect against UVR-induced squamous cell carcinomas in hairless mice.

Squamous cell carcinoma represents the second most common type of keratinocyte carcinoma with ultraviolet radiation (UVR) making up the primary risk factor. Oral photoprotection aims to reduce incidence rates through oral intake of photoprotective compounds. Recently, drug repurposing has gained traction as an interesting source of chemoprevention. Because of their reported photoprotective properties, we investigated the potential of bucillamine, carvedilol, metformin, and phenformin as photoprotective compounds following oral intake in UVR-exposed hairless mice. Tumour development was observed in all groups in response to UVR, with only the positive control (Nicotinamide) demonstrating a reduction in tumour incidence (23.8%). No change in tumour development was observed in the four repurposed drug groups compared to the UV control group, whereas nicotinamide significantly reduced carcinogenesis (P = 0.00012). Metformin treatment significantly reduced UVR-induced erythema (P = 0.012), bucillamine and phenformin increased dorsal pigmentation (P = 0.0013, and P = 0.0005), but no other photoprotective effect was observed across the repurposed groups. This study demonstrates that oral supplementation with bucillamine, carvedilol, metformin, or phenformin does not affect UVR-induced carcinogenesis in hairless mice.

A metabolic signature for NADSYN1-dependent congenital NAD deficiency disorder.

Nicotinamide adenine dinucleotide (NAD) is essential for embryonic development. To date, biallelic loss-of-function variants in 3 genes encoding nonredundant enzymes of the NAD de novo synthesis pathway - KYNU, HAAO, and NADSYN1 - have been identified in humans with congenital malformations defined as congenital NAD deficiency disorder (CNDD). Here, we identified 13 further individuals with biallelic NADSYN1 variants predicted to be damaging, and phenotypes ranging from multiple severe malformations to the complete absence of malformation. Enzymatic assessment of variant deleteriousness in vitro revealed protein domain-specific perturbation, complemented by protein structure modeling in silico. We reproduced NADSYN1-dependent CNDD in mice and assessed various maternal NAD precursor supplementation strategies to prevent adverse pregnancy outcomes. While for Nadsyn1+/- mothers, any B3 vitamer was suitable to raise NAD, preventing embryo loss and malformation, Nadsyn1-/- mothers required supplementation with amidated NAD precursors (nicotinamide or nicotinamide mononucleotide) bypassing their metabolic block. The circulatory NAD metabolome in mice and humans before and after NAD precursor supplementation revealed a consistent metabolic signature with utility for patient identification. Our data collectively improve clinical diagnostics of NADSYN1-dependent CNDD, provide guidance for the therapeutic prevention of CNDD, and suggest an ongoing need to maintain NAD levels via amidated NAD precursor supplementation after birth.

Impacts of H2O2, SARM1 inhibition, and high NAm concentrations on Huntington's disease laser-induced degeneration.

Axonal degeneration is a key component of neurodegenerative diseases such as Huntington's disease (HD), Alzheimer's disease, and amyotrophic lateral sclerosis. Nicotinamide, an NAD+ precursor, has long since been implicated in axonal protection and reduction of degeneration. However, studies on nicotinamide (NAm) supplementation in humans indicate that NAm has no protective effect. Sterile alpha and toll/interleukin receptor motif-containing protein 1 (SARM1) regulates several cell responses to axonal damage and has been implicated in promoting neuronal degeneration. SARM1 inhibition seems to result in protection from neuronal degeneration while hydrogen peroxide has been implicated in oxidative stress and axonal degeneration. The effects of laser-induced axonal damage in wild-type and HD dorsal root ganglion cells treated with NAm, hydrogen peroxide (H2O2), and SARM1 inhibitor DSRM-3716 were investigated and the cell body width, axon width, axonal strength, and axon shrinkage post laser-induced injury were measured.

Personalized Porous Gelatin Methacryloyl Sustained-Release Nicotinamide Protects Against Noise-Induced Hearing Loss.

There are no Food and Drug Administration-approved drugs for treating noise-induced hearing loss (NIHL), reflecting the absence of clear specific therapeutic targets and effective delivery strategies. Noise trauma is demonstrated results in nicotinamide adenine dinucleotide (NAD+) downregulation and mitochondrial dysfunction in cochlear hair cells (HCs) and spiral ganglion neurons (SGNs) in mice, and NAD+ boosted by nicotinamide (NAM) supplementation maintains cochlear mitochondrial homeostasis and prevents neuroexcitatory toxic injury in vitro and ex vivo, also significantly ameliorated NIHL in vivo. To tackle the limited drug delivery efficiency due to sophisticated anatomical barriers and unique clearance pathway in ear, personalized NAM-encapsulated porous gelatin methacryloyl (PGMA@NAM) are developed based on anatomy topography of murine temporal bone by micro-computed tomography and reconstruction of round window (RW) niche, realizing hydrogel in situ implantation completely, NAM sustained-release and long-term auditory preservation in mice. This study strongly supports personalized PGMA@NAM as NIHL protection drug with effective inner ear delivery, providing new inspiration for drug-based treatment of NIHL.

Indole-3-Propionic Acid Protects Against Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is a common but poorly understood form of heart failure, characterized by impaired diastolic function. It is highly heterogeneous with multiple comorbidities, including obesity and diabetes, making human studies difficult. METHODS: Metabolomic analyses in a mouse model of HFpEF showed that levels of indole-3-propionic acid (IPA), a metabolite produced by gut bacteria from tryptophan, were reduced in the plasma and heart tissue of HFpEF mice as compared with controls. We then examined the role of IPA in mouse models of HFpEF as well as 2 human HFpEF cohorts. RESULTS: The protective role and therapeutic effects of IPA were confirmed in mouse models of HFpEF using IPA dietary supplementation. IPA attenuated diastolic dysfunction, metabolic remodeling, oxidative stress, inflammation, gut microbiota dysbiosis, and intestinal epithelial barrier damage. In the heart, IPA suppressed the expression of NNMT (nicotinamide N-methyl transferase), restored nicotinamide, NAD+/NADH, and SIRT3 (sirtuin 3) levels. IPA mediates the protective effects on diastolic dysfunction, at least in part, by promoting the expression of SIRT3. SIRT3 regulation was mediated by IPA binding to the aryl hydrocarbon receptor, as Sirt3 knockdown diminished the effects of IPA on diastolic dysfunction in vivo. The role of the nicotinamide adenine dinucleotide circuit in HFpEF was further confirmed by nicotinamide supplementation, Nnmt knockdown, and Nnmt overexpression in vivo. IPA levels were significantly reduced in patients with HFpEF in 2 independent human cohorts, consistent with a protective function in humans, as well as mice. CONCLUSIONS: Our findings reveal that IPA protects against diastolic dysfunction in HFpEF by enhancing the nicotinamide adenine dinucleotide salvage pathway, suggesting the possibility of therapeutic management by either altering the gut microbiome composition or supplementing the diet with IPA.

Astaxanthin Augmented the Anti-Hepatocellular Carcinoma Efficacy of Sorafenib Through the Inhibition of the JAK2/STAT3 Signaling Pathway and Mitigation of Hypoxia within the Tumor Microenvironment.

SCOPE: The optimization of anti-cancer drug effectiveness through dietary modifications has garnered significant attention among researchers in recent times. Astaxanthin (AST) has been identified as a safe and biologically active dietary supplement. METHODS AND RESULTS: The tumor-bearing mice are treated with sorafenib, along with supplementation of 60 mg kg-1 AST during the treatment. The coadministration of AST and a subclinical dosage of 10 mg kg-1 sorafenib demonstrates a tumor inhibition rate of 76.5%, which is notably superior to the 45% inhibition rate observed with the clinical dosage of 30 mg kg-1 sorafenib (p < 0.05). The administration of AST leads to a tumor inhibition increase of around 25% when combined with the clinical dose of 30 mg kg-1 sorafenib (p <0.05). AST enhances the inhibitory effect of sorafenib on tumor angiogenesis through the JAK2/STAT3 signaling pathway. Furthermore, AST exhibits a reduction in hypoxia within the tumor microenvironment. CONCLUSION: The results suggest that AST supplement enhances the inhibitory effects of sorafenib on hepatocellular carcinoma. This study presents a new dietary management program for oncology patients.

Long-Term Nicotinamide Riboside Use Improves Coordination and Eye Movements in Ataxia Telangiectasia.

BACKGROUND: Supplementation of nicotinamide riboside (NR) ameliorates neuropathology in animal models of ataxia telangiectasia (A-T). In humans, short-term NR supplementation showed benefits in neurological outcome. OBJECTIVES: The study aimed to investigate the safety and benefits of long-term NR supplementation in individuals with A-T. METHODS: A single-arm, open-label clinical trial was performed in individuals with A-T, receiving NR over a period of 2 years. Biomarkers and clinical examinations were used to assess safety parameters. Standardized and validated neuromotor tests were used to monitor changes in neurological symptoms. Using generalized mixed models, test results were compared to expected disease progression based on historical data. RESULTS: NAD+ concentrations increased rapidly in peripheral blood and stabilized at a higher level than baseline. NR supplementation was well tolerated for most participants. The total scores in the neuromotor test panels, as evaluated at the 18-month time point, improved for all but one participant, primarily driven by improvements in coordination subscores and eye movements. A comparison with historical data revealed that the progression of certain neuromotor symptoms was slower than anticipated. CONCLUSIONS: Long-term use of NR appears to be safe and well tolerated, and it improves motor coordination and eye movements in patients with A-T of all ages. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

N1-methylnicotinamide impairs gestational glucose tolerance in mice.

N1-methylnicotinamide (MNAM), a product of methylation of nicotinamide through nicotinamide N-methyltransferase, displays antidiabetic effects in male rodents. This study aimed to evaluate the ameliorative potential of MNAM on glucose metabolism in a gestational diabetes mellitus (GDM) model. C57BL/6N mice were fed with a high-fat diet (HFD) for 6 weeks before pregnancy and throughout gestation to establish the GDM model. Pregnant mice were treated with 0.3% or 1% MNAM during gestation. MNAM supplementation in CHOW diet and HFD both impaired glucose tolerance at gestational day 14.5 without changes in insulin tolerance. However, MNAM supplementation reduced hepatic lipid accumulation as well as mass and inflammation in visceral adipose tissue. MNAM treatment decreased GLUT4 mRNA and protein expression in skeletal muscle, where NAD+ salvage synthesis and antioxidant defenses were dampened. The NAD+/sirtuin system was enhanced in liver, which subsequently boosted hepatic gluconeogenesis. GLUT1 protein was diminished in placenta by MNAM. In addition, weight of placenta, fetus weight, and litter size were not affected by MNAM treatment. The decreased GLUT4 in skeletal muscle, boosted hepatic gluconeogenesis and dampened GLUT1 in placenta jointly contribute to the impairment of glucose tolerance tests by MNAM. Our data provide evidence for the careful usage of MNAM in treatment of GDM.

Synthesis, Optimization, and Structure-Activity Relationships of Nicotinamide Phosphoribosyltransferase (NAMPT) Positive Allosteric Modulators (N-PAMs).

Depletion of nicotinamide adenine dinucleotide (NAD+) is associated with aging and disease, spurring the study of dietary supplements to replenish NAD+. The catabolism of NAD+ to nicotinamide (NAM) requires the salvage of NAM to replenish cellular NAD+, which relies on the rate-limiting enzyme nicotinamide phosphoribosyltransferase (NAMPT). Pharmacological activation of NAMPT provides an alternative to dietary supplements. Screening for activators of NAMPT identified small molecule NAMPT positive allosteric modulators (N-PAMs). N-PAMs bind to the rear channel of NAMPT increasing enzyme activity and alleviating feedback inhibition by NAM and NAD+. Synthesis of over 70 N-PAMs provided an excellent correlation between rear channel binding affinity and potency for enzyme activation, confirming the mechanism of allosteric activation via binding to the rear channel. The mechanism accounts for higher binding affinity leading to loss of efficacy. Enzyme activation translated directly to elevation of NAD+ measured in cells. Optimization led to an orally bioavailable N-PAM.

SBA-15- and SBA-16-Functionalized Silicas as New Carriers of Niacinamide.

Amorphous silica as a food additive (E 551) is used in food materials (e.g., sweeteners, dairy products) for its anti-caking properties. The physicochemical properties of SiO2 also make it suitable to serve as a carrier of active substances in functional foods, dietary supplements, and drugs. Deficiency of niacinamide (vitamin B3, niacin) leads to several pathologies in the nervous system and causes one of the nutritional diseases called pellagra. The present study focuses on the use of hybrid ordered mesoporous silicas (SBA-15/SBA-16) functionalized with amino groups introduced through grafting or co-condensation with (N-vinylbenzyl)aminoethylaminopropyltrimethoxysilane (Z-6032) as novel carriers of niacinamide. They combine the characteristics of a relatively stable and chemically inert amorphous silica matrix with well-defined structural/textural parameters and organic functional groups that give specific chemical properties. The highest degree of carrier loading with niacinamide (16 wt.%) was recorded for the unmodified SBA-15. On the other hand, the highest degree of niacinamide release characterizes the functionalized SBA-15 sample (60% after 24 h), indicating that the presence of amino groups affects the release profile of niacinamide from the structure of the mesoporous silica.

NR-SAFE: a randomized, double-blind safety trial of high dose nicotinamide riboside in Parkinson's disease.

Nicotinamide adenine dinucleotide (NAD) replenishment therapy using nicotinamide riboside (NR) shows promise for Parkinson's disease (PD) and other neurodegenerative disorders. However, the optimal dose of NR remains unknown, and doses exceeding 2000 mg daily have not been tested in humans. To evaluate the safety of high-dose NR therapy, we conducted a single-center, randomized, placebo-controlled, double-blind, phase I trial on 20 individuals with PD, randomized 1:1 on NR 1500 mg twice daily (n = 10) or placebo (n = 10) for four weeks. The trial was conducted at the Department of Neurology, Haukeland University Hospital, Bergen, Norway. The primary outcome was safety, defined as the frequency of moderate and severe adverse events. Secondary outcomes were tolerability defined as frequency of mild adverse events, change in the whole blood and urine NAD metabolome, and change in the clinical severity of PD, measured by MDS-UPDRS. All 20 participants completed the trial. The trial met all prespecified outcomes. NR therapy was well tolerated with no moderate or severe adverse events, and no significant difference in mild adverse events. NR therapy was associated with clinical improvement of total MDS-UPDRS scores. However, this change was also associated with a shorter interval since the last levodopa dose. NR greatly augmented the blood NAD metabolome with up to 5-fold increase in blood NAD+ levels. While NR-recipients exhibited a slight initial rise in serum homocysteine levels, the integrity of the methyl donor pool remained intact. Our results support extending the dose range of NR in phase II clinical trials to 3000 mg per day, with appropriate safety monitoring. Clinicaltrials.gov identifier: NCT05344404.