Search Results (167)

Tryptophan (TRP) metabolism has emerged as a critical interface linking inflammation, immune regulation, oxidative stress, and cellular energetics. The kynurenine pathway, the predominant route of TRP degradation, is highly responsive to inflammatory stimuli and generates a spectrum of bioactive metabolites with divergent and context-dependent biological effects. Indoleamine 2,3-dioxygenase 1 (IDO1)-mediated TRP catabolism integrates immune activation with downstream metabolic signaling, influencing redox homeostasis, endothelial function, and mitochondrial energetics, in part by regulating nicotinamide adenine dinucleotide (NAD⁺) synthesis. Alterations in TRP metabolism are consistently observed across cardiometabolic diseases, including obesity, type 2 diabetes (T2D), atherosclerosis, myocardial infarction (MI), and heart failure with preserved ejection fraction (HFpEF), where they are associated with disease severity and adverse outcomes. Importantly, emerging data suggest that cardiometabolic phenotypes are determined not by pathway activation alone, but by the relative distribution of flux across downstream metabolic branches. Depending on the tissue compartment and stage of the disease, different biological effects may be contributed by redox-active kynurenine 3-monooxygenase (KMO)/3-hydroxykynurenine (3-HK)/quinolinic acid (QA) pathways, 3-hydroxyanthranilic acid (3-HAA)-mediated lipid and inflammasome regulation, microbiome-derived indoles, and NAD⁺-generating pathways. This review synthesizes current evidence using a branch-specific and context-dependent framework. We discuss the utility and limitations of the kynurenine-to-tryptophan ratio (KTR) as an upstream biomarker, the need for downstream metabolite panels, and therapeutic opportunities aimed at pathway modulation rather than broad inhibition. Future studies integrating temporal profiling, spatial and cell-specific approaches, large-animal models, and pathway-informed clinical trials will be essential to define causal mechanisms and enable precision therapeutic translation. Full article

Nicotinamide adenine dinucleotide (NAD⁺) and its reduced form, NADH, are essential coenzymes that play central roles in cellular redox homeostasis, energy metabolism, DNA repair, and signaling. Cellular NAD⁺ levels are maintained by a dynamic balance between the de novo Preiss–Handler, and salvage synthesis pathways, and consumption by enzymes like sirtuins, PARPs, and CD38. Among these, the nicotinamide Phosphoribosyltransferase (NAMPT)-driven salvage pathway represents the predominant route of NAD+ synthesis. The specific regulation of NAD (NAD⁺ and NADH) levels across distinct subcellular compartments has emerged as a critical determinant of cellular function but it remains poorly understood. Dysregulation of NAD metabolism is a hallmark of aging and various pathologies, including cancer, neurodegenerative disorders, and metabolic diseases, making strategies to modulate NAD levels a promising therapeutic frontier. This review provides the first integrated overview of NAD concentrations across cellular compartments (cytosol, mitochondria, nucleus, endoplasmic reticulum, Golgi, peroxisomes, and the extracellular space) together with measurement and modulation strategies. We summarize current knowledge on NAD distribution within organelles, address key challenges in accurate quantification, and highlight established and emerging approaches for both global and compartment-specific analysis. Finally, we discuss therapeutic strategies, from NAD⁺ precursor supplementation to enzyme modulators and gene therapy, highlighting both their translational potential and current limitations in treating diverse diseases and prolonging life and health span. Full article

Food-grade microorganisms utilize core cofactors, such as nicotinamide adenine dinucleotide (NAD) and its phosphate form (NADP), to mediate redox reactions and regulate energy metabolism homeostasis as well as biosynthesis of functional components. In metabolic engineering, perturbation of the NAD(P)⁺/NAD(P)H network may significantly disrupt intracellular redox homeostasis, leading to impaired strain growth and limited synthesis of targeted functional products. This review systematically examines the latest research progress in the field of food-grade microbial cofactor engineering, focusing on the key mechanisms and synergistic pathways of core strategies, such as metabolic flux optimization and cofactor regeneration systems, in maintaining cellular redox homeostasis and enhancing the biosynthesis of functional ingredients. Future research should focus on exploring the potential for integrating multi-omics approaches and intelligent control technologies, proposing innovative approaches to address the challenges of industrialized production, and providing theoretical support for food biomanufacturing. Full article

Cosmetic dermatology has largely focused on topical applications targeting the stratum corneum. However, emerging evidence suggests that visible aging is a systemic readout of internal “organ clocks” and molecular dysregulation across the epidermis and dermis. This review proposes an “inside–out strategy” that seeks to re-conceptualize aesthetic vitality as a measurable indicator of systemic physiological resilience. The author describes theoretically proposed organ–skin axes, including the role of molecular signaling of kidney-derived klotho (KL1 fragment) via FGFR1-α–klotho complexes and muscle-derived irisin through the AMPK/PGC-1-α pathway in modulating skin homeostasis. Drawing on recent breakthroughs in non-human primate models (2023–2025), this synthesis explores the potential of systemic interventions—including nicotinamide adenine dinucleotide (NAD+) precursors (sirtuin 1 SIRT1 activators), senolytics (targeting BCL-2/p16), and glucagon-like peptide-1 (GLP-1) receptor agonists—as candidates to potentially synchronize these internal clocks. Furthermore, the review identifies direct regenerative interventions, such as retinoids (RAR/RXR signaling), chemical peels (HIF-1-α induction), exosomes (miR-21/29 delivery), and poly-L-lactic acid PLLA (mechanotransduction via YAP/TAZ), positioning them as potential physical and chemical epigenetic modulators that may support the restoration of cellular transcriptional fidelity. This article proposes a new paradigm for regenerative aesthetics that focuses on restoring the youthful phenotype by optimizing systemic molecular crosstalk and epigenetic transcriptional fidelity. Full article

Triazolopyrimidine sulfonamide herbicides, a prominent class of acetohydroxyacid synthase (AHAS) inhibitors, are exceptionally effective in controlling weeds in agricultural settings. To overcome metabolic resistance caused by the 5-demethylation of pyroxsulam, we sought to replace its 5-methoxy group on the triazolopyrimidine ring with alkyl substituents. This led to the synthesis of a series of N-(7-oxo-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)arylsulfon-amides, which displayed significant structural diversification potential, culminating in the identification of the herbicidal hit compound I-20. However, the suboptimal lipophilicity compromised its herbicidal efficacy. To rectify this limitation, we modified the 7-carbonyl group to a tert-butoxy group, resulting in the highly active compound I-29. This compound demonstrated herbicidal activity comparable to or exceeding that of penoxsulam against various tested weeds, establishing it as a promising new lead compound and a candidate herbicide for further investigation. Subsequent studies revealed that I-29 exhibited a receptor binding mode and herbicidal activity profiles that closely aligned with those of penoxsulam. Moreover, its spatial structure was found to be even more conducive to inhibiting flavin adenine dinucleotide (FAD)-mediated AHAS activity. This research not only sheds light on addressing the challenge of 5-demethylation metabolic resistance in triazolopyrimidine sulfonamide herbicides but also offers new avenues for the development of AHAS-inhibiting triazolopyrimidine sulfonamide herbicides. Full article

Background: Hyperuricemia (HUA) is a metabolic disorder that severely threatens human health. Chronic uric acid (UA) overload promotes the progression of tubulointerstitial fibrosis (TIF), leading to impaired UA excretion. Our previous studies identified HIPK2 inhibitor XRF-1021, which exhibits robust anti-TIF activity and lowers UA levels in vivo. This study aimed to elucidate its UA-lowering mechanism and therapeutic potential for HUA. Methods: Uricase and xanthine oxidase (XOD) assays were performed to assess effects on UA degradation/production. HEK293T cells transiently expressing UA transporters and gene-knockdown rats were used to evaluate transporter inhibition, while HK-2 cells were analyzed by Western blot. Pharmacokinetics were characterized in rats. Efficacy was tested in potassium oxonate-induced acute HUA rats, diet/adenine-induced chronic HUA quails, and adenine-induced mice with HUA secondary to TIF. Maximum tolerated dose and long-term toxicity were assessed in rats. Results: XRF-1021 neither activated uricase nor inhibited XOD, indicating no direct effect on UA catabolism or synthesis. Instead, XRF-1021 inhibited URAT1 and GLUT9, reducing renal UA reabsorption, while sparing OAT3, OAT4, and ABCG2 activity and upregulating OAT3 and NPT4, suggesting minimal risk of disrupting drug or uremic toxin handling. XRF-1021 showed dose-dependent systemic exposure in rats, lowered serum UA, and provided renal protection in vivo. LD₅₀ values were 2345.4 mg/kg (male) and 1078.9 mg/kg (female), with no obvious toxicity after long-term dosing. Conclusions: XRF-1021 lowers UA by inhibiting URAT1 and GLUT9 to enhance renal UA excretion and provides kidney protection, supporting XRF-1021 as a promising candidate for HUA therapy. Full article

Background/Objectives: Adenine derivatives are promising anticancer scaffolds, but their cellular mechanisms remain unclear. This study aimed to synthesize adenine–hydrazone hybrids and evaluate their cytotoxic effects in human lung adenocarcinoma (A549) cells. Methods: A series of adenine–hydrazone compounds (3a–r) was synthesized and tested for cytotoxicity in A549 and MRC-5 cells. Selected compounds were further analyzed for LDH release, oxidative stress markers, ROS production, mitochondrial membrane potential, cell-cycle distribution, apoptosis, and in silico docking against VEGFR2, ALK5, and EGFR. Results: Compounds with electron-withdrawing or donor–acceptor substituents showed the highest cytotoxicity, while halogenated and methoxy analogs were moderately active. Among the synthesized derivatives, 4F-substituted derivatives (3c) showed more activity than 2F- and 3F-substituted ones (3a and 3b). 4F- and 3Br-substituted derivatives (3f) showed more activity than only 4F-substituted ones (3c). 4-Nitro-substituted derivative (3i) showed more activity than 4F- (3c), 4Cl- (3d) and 4OMe- (3h) derivatives. Trimethoxy-substituted derivative (3l) showed more activity than di- and mono-substituted methoxy derivatives (3g, 3h, 3j and 3k). Among the salicyl aldehydederivatives (3m–r), 4-N(et)₂-substituted derivative (3r) showed more activity than non-substituted (3m), 5Br-(3n), 5Cl-(3o), 5Me (3p) and 3OCH₃ (3q) derivatives. Treatment induced oxidative stress, mitochondrial depolarization, Sub-G1 cell-cycle accumulation, and apoptosis. Docking studies indicated strong binding to VEGFR2 and ALK5, suggesting dual inhibition as a potential mechanism. Conclusions: Adenine–hydrazone derivatives exert substituent-dependent anticancer effects by inducing redox imbalance-associated mitochondrial dysfunction and regulated cell death. These results highlight their potential as lead structures for lung cancer therapy. Full article

Mitochondria govern energy transfer, redox balance, and cell fate. Tryptophan catabolism generates kynurenines (KYNs) that can tune mitochondrial function, with growing evidence that G protein-coupled receptor 35 (GPR35), aryl hydrocarbon receptor (AhR), and N-methyl-D-aspartate receptors (NMDA receptors) link extracellular cues to adenosine 5 prime triphosphate (ATP) maintenance, calcium (Ca²⁺) handling, mitophagy, and inflammasome control. In parallel, quinolinic acid (QA)-driven de novo nicotinamide adenine dinucleotide (NAD⁺) synthesis connects KYN flux to tricarboxylic acid (TCA) cycle activity and sirtuin programs across tissues. Key gaps remain: receptor pharmacology is rarely integrated with NAD⁺ economics and respiration, and clinical workflows still lack single-run assays that quantify both kynurenine and TCA nodes. We therefore integrate receptor proximal signaling, QA-driven NAD⁺ supply, and unified liquid chromatography–mass spectrometry (LC-MS) measurement into one translational framework spanning kynurenic acid (KYNA), KYN, 3-hydroxykynurenine (3-HK), and QA, using mitochondrial endpoints as the common readout. We synthesize evidence for mitochondrial GPR35 signaling that preserves ATP, AhR programs that tune oxidative defenses and mitophagy, and NMDA receptor antagonism that limits excitotoxic stress. These mechanisms are linked to QA-dependent NAD⁺ biogenesis and alpha ketoglutarate control points, then aligned with chromatography and ionization choices suited to routine LC-MS workflows. This receptor to organelle framework couples KYN flux to respiratory control and provides a practical roadmap for standardized single-run LC-MS panels. It can strengthen target validation in ischemia, neurodegeneration, psychiatry, and oncology while improving biomarker qualification through harmonized analytics and decision-grade readouts. Full article

DNA interstrand cross-links (ICLs) are among the most cytotoxic forms of DNA damage, arising when the two strands of the DNA helix are covalently linked by crosslink-inducing agents such as bifunctional alkylating agents and reactive aldehydes. Several studies have demonstrated that ICLs can also be induced by reactive oxygen and nitrogen species. We previously reported that under oxidative conditions, the major oxidative adenine lesion 7,8-dihydro-8-oxoadenine (oxoA) can efficiently generate a novel class of oxoA-G ICLs, structurally resembling guanine–guanine (G–G) cross-links that can be induced by reactive nitrogen species. To investigate the mutagenic potential of these oxidation-induced ICLs in cells, we employed a SupF-based mutagenesis assay using bacterial cells. A single site-specific oxoA–G ICL was synthesized and incorporated into a plasmid, which was then introduced into an E. coli reporter strain to assess mutation profiles induced by both oxoA and oxoA–G ICLs. Our results show that oxoA–G ICLs cause A-to-C/T and G-to-C transversion mutations at the oxoA-G cross-link site, demonstrating highly promutagenic nature of the lesion in bacterial cells. We propose that the oxoA–G ICL may promote transversion mutations, likely driven by a syn conformer of unhooked oxoA-G ICL repair intermediates during translesion synthesis. Full article

Background/Objectives: Caffeic acid is a hydroxycinnamic acid that has a wide range of applications in the medical field. The synthesis of caffeic acid using microbial fermentation technology is an environmentally friendly method. Methods: By engaging various enzymes, specifically 4-hydroxyphenylacetate 3-monooxygenase (HpaB), sourced from diverse bacterial strains, we successfully engineered a functional version of this enzyme within Escherichia coli, enabling the production of caffeic acid. In addition to the two common tyrosine ammonia lyases (TAL) and HpaC, different combinations of HpaB demonstrated varying abilities in converting the substrate L-tyrosine into the desired product, caffeic acid. Results: Under shake-flask culture conditions, the highest yield of caffeic acid was achieved with an enzyme mixture containing HpaB from Escherichia coli, reaching 75.88 mg/L. Enhancing the activity of the rate-limiting enzyme through engineering could potentially increase caffeic acid titer. This study aims to conduct a semi-rational design of HpaB through structure-based approaches to screen for mutants that can enhance the production of caffeic acid. Initially, the predicted three-dimensional structure of HpaB was generated using AlphaFold2, and subsequent analysis was conducted to pinpoint the critical mutation sites within the substrate-binding pocket. Five key amino acid residues (R113, Y117, H155, S210 and Y461) located in the vicinity of the flavin adenine dinucleotide binding domain in HpaB from Escherichia coli could be instrumental in modulating enzyme activity. Subsequently, the mutant S210G/Y117A was obtained by iterative saturation mutagenesis, which increased the titer of caffeic acid by 1.68-fold. The caffeic acid titer was further improved to 2335.48 mg/L in a 5 L fermenter. The findings show that the yield of caffeic acid was significantly enhanced through the integration of semi-rational design and fermentation process optimization. Full article

Exogenous cytokinin supply is a crucial factor during the in vitro shoot multiplication of apples. Meta-topolin has been shown to cause improved multiplication rate, higher quality in vitro shoots with better rooting, and acclimatization ability than the widely used benzyl adenine. The effects of benzyl adenine and meta-topolin on mRNA transcription in in vitro shoots were analyzed by using mRNA-seq, bioinformatics analysis, GO annotation, and KEGG mapping. The present investigations revealed that there were about 6-fold more significantly up-, or down-regulated genes (DEGs) in shoots grown on the benzyl adenine-containing medium than in those grown on the meta-topolin-containing medium. DEG analyses showed that WRKYs, bHLH, and MYB were the most affected transcription factors after both cytokinin treatments, while the expression of MIKC-type MADS-box, ERF, and AP2 transcription factors changed only after benzyl adenine treatment. DEGs related to auxin transport and signaling, as well as auxin synthesis, were differently affected by the two cytokinins. The DEG encoding cytokinin hydroxylase-like protein and related to trans-zeatin biosynthesis was up-regulated only after benzyl adenine treatment. The DEG encoding gibberellin 20 oxidase 2-like was down-regulated after a benzyl adenine supply while it was up-regulated after a meta-topolin supply. Changes in the cytokinin–auxin balance and gibberellin biosynthesis in in vitro shoots may contribute to the morphological differences previously observed for the two cytokinins. Full article

Nucleopeptides (NPs) are unnatural hybrid polymers designed by coupling nucleobases to the side chains of amino acid residues within peptides. In this study, we present the synthesis of an Fmoc-protected nucleobase amino acid (NBA) monomer (Fmoc-1,4-TzlNBA_A) with adenine attached to the side chain of L-homoazidoalanine (Aha) through a 1,4-linked-1,2,3-triazole. The coupling was accomplished by a Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) of Fmoc-Aha and N9-propargyladenine. Subsequently, a homotrinucleopeptide (HalTzl_AAA) containing three 1,4-TzlNBA_A residues was synthesized, using different solid-phase peptide synthesis (SPPS) approaches, and its ability to recognize U-rich motifs of RNAs involved in the HIV replication cycle was studied using circular dichroism (CD) and fluorescence spectroscopy. CD curves confirmed the binding of HalTzl_AAA to U-rich motifs of the transactivation responsive element (TAR UUU RNA HIV-1) bulge and the anticodon stem–loop domain of human tRNALys3 (ASLLys3) by a decrease in the positive ellipticity band intensity around 265 nm during the complexation. 5′-(FAM(6))-labeled TAR UUU and hASLLys3 were used for fluorescence anisotropy binding studies. Fluorescence data revealed that HalTzl_AAA bound TAR’s UUU bulge with a moderate affinity (K_d ≈ 38 µM), whereas the ASLLys3 UUUU-containing loop sequence was recognized with 2.5 times lower affinity (with K_d ≈ 75 µM). Both the standard SPPS method and its variants, which involved the attachment of adenine to the L-Aha side chain using the click reaction during the synthesis on the resin or after the nucleopeptide cleavage, were characterized by a similar efficiency and yield. The CD and fluorescence results demonstrated that HalTzl_AAA recognized the U-rich sequences of the RNAs with moderate and varied affinities. It is likely that both the hydrogen bonds associated with the complementarity of the interacting sequences and the conformational aspects associated with the high conformational dynamics of U-rich motifs are important in the recognition process. The nucleopeptide represents a new class of RNA binders and may be a promising scaffold for the development of new antiviral drugs. Full article

Nicotinamide adenine dinucleotide (NAD⁺) serves as a critical cofactor in redox reactions and metabolic transformations catalyzed by NAD-dependent enzymes and is essential for bacterial survival and virulence. The biosynthesis of NAD⁺ in the cariogenic pathogen Streptococcus Sobrinus (S. sobrinus), a pivotal participant in oral cavities of children and adolescents with a history of caries, has yet to be explored. Bioinformatics, genetics, and biochemical techniques were used to identify NAD⁺ biosynthesis pathways and corresponding regulator in S. Sobrinus. S. sobrinus lacks de novo NAD⁺ synthesis pathway but comprises NA and Nam salvage pathway I (PncA-PncB-NadD-NadE) and PnuC-NadR salvage pathway III. NiaY and PnuC were involved in the salvage pathways. N-terminal domain of SsNrtR regulator was identified as DNA-binding domain binding to the pnuC and pncB probe, and addition of ADP-ribose reversed the binding of SsNrtR to the target promoters to regulate NAD⁺ salvage pathways. C-terminal domain of SsNrtR was non-catalytic, consistent with loss of Nudix motif conservation. Furthermore, the abrogation of niaR compromised multiple pathogenic traits, including cellular proliferation, acidogenesis, and the architecture/mechanical integrity of biofilms. Consequently, this mutant exhibited attenuated virulence in a rat caries model. Our findings conclusively demonstrate that SsNrtR-mediated regulation of NAD⁺ homeostasis is a critical determinant of the cariogenic potential of S. sobrinus. This study identifies SsNrtR as a previously uncharacterized NAD⁺-responsive regulator that integrates metabolic homeostasis with the control of virulence in Streptococcus sobrinus. These findings elucidate a novel metabolic–virulence regulatory axis in this species and position SsNrtR as a promising target for the development of anti-caries interventions. Full article

Glaucoma continues to be a primary contributor to permanent vision loss worldwide, frequently advancing even when intraocular pressure management is clinically adequate. Accumulating research emphasizes the metabolic susceptibility of retinal ganglion cells (RGCs), specifically concerning the progressive depletion of nicotinamide adenine dinucleotide (NAD⁺), a pivotal coenzyme fundamental to mitochondrial energy production and cellular survival mechanisms. As a key biosynthetic precursor in NAD⁺ synthesis pathways, nicotinamide (NAM), a form of vitamin B3, has exhibited significant neuroprotective properties across various preclinical experimental models and preliminary clinical investigations, demonstrating enhanced preservation of RGC morphology and physiological function. This comprehensive review systematically examines the current body of evidence supporting NAM’s therapeutic utility in glaucomatous neuroprotection, focusing particularly on underlying metabolic pathways, obstacles in clinical translation, and prospective therapeutic applications. Through systematic integration of data from cellular and molecular research, animal experimental studies, and population-based epidemiological investigations, we establish a conceptual framework for repurposing NAM as an innovative complementary therapeutic strategy in comprehensive glaucoma care, addressing key considerations for future clinical development including optimal dosing strategies, delivery mechanisms, and patient selection criteria for maximizing therapeutic outcomes in this challenging neurodegenerative condition. Full article

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a second messenger that stimulates intracellular Ca²⁺ release in both mammalian cells and echinoderm egg homogenates. A NAADP linked covalently to a stable long-wavelength fluorescent dye would be a useful probe with which to characterize NAADP–receptor interactions in solution and potentially to determine intracellular-binding localization. We report the synthesis of a BODIPY-NAADP covalent conjugate made through linking the carboxyl group of BODIPY FL to the primary amino group of 5-(3-aminopropyl)-NAADP through amide bond formation. The starting pyridine dinucleotide analog, 5-(3-aminopropyl)-NAADP was available through enzyme-catalyzed base exchange between NADP and a substituted nicotinic acid analog. The resulting 5-BODIPY-NAADP conjugate was purified to homogeneity using ion-exchange chromatography, was produced in milligram quantities, and its spectroscopic properties were characterized. Full article