Effect of CPPU on optical properties of strawberry in near-infrared range during growth.

To investigate the effect of CPPU (forchlorfenuron) on optical properties of strawberry during growth, the optical properties (absorption coefficient (µa) and reduced scattering coefficient (µs')) of strawberry treated with CPPU solutions at different concentrations (0, 2.5, 5.0 and 7.5 mg/L) were measured in white, color turning and red stages by using a single integrating sphere system over near-infrared wavelength range of 900-1700 nm. The physicochemical properties, i.e., single fruit weight, soluble solids content, firmness and moisture content, as well as microstructure of strawberry were also investigated. The results showed that in white stage, the µa of strawberry treated with 7.5 mg/L CPPU was significantly (p ≤ 0.05) lower than that of untreated strawberry at absorption peak of 1411 nm. In color turning stage, the µs' of strawberry treated with 5 mg/L CPPU was significantly lower than that of treated with 2.5 mg/L at absorption peaks of 975, 1197 and 1411 nm. In red stage, the µa of strawberry treated with 2.5 mg/L CPPU was significantly (p ≤ 0.05) different from that of treated with 7.5 mg/L at 1197 nm. The study indicates that the optical properties of strawberry were affected by CPPU, and it provides useful information for identifying CPPU treated strawberry.

Biotinylated polyaminoacid-based nanoparticles for the targeted delivery of lenvatinib towards hepatocarcinoma.

In this work, we describe the development of targeted polymeric nanoparticles loaded with lenvatinib for the treatment of hepatocellular carcinoma (HCC). A synthetic brush copolymer (PHEA-g-BIB-pButMA-g-PEG-biotin) was synthesized from α-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) by a three-step reaction involving atom transfer radical polymerisation (ATRP) to graft hydrophobic polybutylmethacrylate pendant groups and further conjugation with biotinylated polyethylene glycol via carbonate ester. Subsequently, lenvatinib-loaded nanoparticles were obtained and characterized demonstrating colloidal size, negative zeta potential, biotin exposure on the surface and the ability to release lenvatinib in a sustained manner. Lenvatinib-loaded nanoparticles were tested in vitro on HCC cells to evaluate their anticancer efficacy compared to free drug. Furthermore, the enhanced in vivo efficacy of lenvatinib-loaded nanoparticles on nude mice HCC xenograft models was demonstrated by evaluating tumor burdens, apoptotic markers and histological scores after administration of lenvatinib-nanoparticles via intraperitoneal or oral route. Finally, in vivo biodistribution studies were performed, demonstrating the ability of the prepared drug delivery systems to significantly accumulate in the solid tumor by active targeting, due to the presence of biotin on the nanoparticle surface.

Strategies and Recent Advances on Improving Efficient Antitumor of Lenvatinib Based on Nanoparticle Delivery System.

Lenvatinib (LVN) is a potentially effective multiple-targeted receptor tyrosine kinase inhibitor approved for treating hepatocellular carcinoma, metastatic renal cell carcinoma and thyroid cancer. Nonetheless, poor pharmacokinetic properties including poor water solubility and rapid metabolic, complex tumor microenvironment, and drug resistance have impeded its satisfactory therapeutic efficacy. This article comprehensively reviews the uses of nanotechnology in LVN to improve antitumor effects. With the characteristic of high modifiability and loading capacity of the nano-drug delivery system, an active targeting approach, controllable drug release, and biomimetic strategies have been devised to deliver LVN to target tumors in sequence, compensating for the lack of passive targeting. The existing applications and advances of LVN in improving therapeutic efficacy include improving longer-term efficiency, achieving higher efficiency, combination therapy, tracking and diagnosing application and reducing toxicity. Therefore, using multiple strategies combined with photothermal, photodynamic, and immunoregulatory therapies potentially overcomes multi-drug resistance, regulates unfavorable tumor microenvironment, and yields higher synergistic antitumor effects. In brief, the nano-LVN delivery system has brought light to the war against cancer while at the same time improving the antitumor effect. More intelligent and multifunctional nanoparticles should be investigated and further converted into clinical applications in the future.

The septin modifier, forchlorfenuron, activates NLRP3 via a potassium-independent mitochondrial axis.

The Nod-like receptor protein 3 (NLRP3) inflammasome is activated by stimuli that induce perturbations in cell homeostasis, which commonly converge on cellular potassium efflux. NLRP3 has thus emerged as a sensor for ionic flux. Here, we identify forchlorfenuron (FCF) as an inflammasome activator that triggers NLRP3 signaling independently of potassium efflux. FCF triggers the rearrangement of septins, key cytoskeletal proteins that regulate mitochondrial function. We report that FCF triggered the rearrangement of SEPT2 into tubular aggregates and stimulated SEPT2-independent NLRP3 inflammasome signaling. Similar to imiquimod, FCF induced the collapse of the mitochondrial membrane potential and mitochondrial respiration. FCF thereby joins the imidazoquinolines as a structurally distinct class of molecules that triggers NLRP3 inflammasome signaling independent of potassium efflux, likely by inducing mitochondrial damage.

A developed and validated centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method for rapid quantification of unbound lenvatinib in human plasma.

In clinical practice, the determination of unbound drug concentration is very important for dose adjustment and toxicity prediction because only the unbound fraction can achieve a pharmacological effect. A fast, sensitive and accurate analytical method of centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method was developed and applied to allow the quantification of unbound lenvatinib concentration. The application of linear regression analysis was used to examine the effects of centrifugal force, centrifugal time, and protein content on ultrafiltrate volume (Vu). The results indicated that the centrifugal force and centrifugal time have an influence on Vu that is significantly positive (P < 0.05). This developed method with good linearity (r2 = 0.9996), good accuracy (bias % ≤ 2.24 %), good precision (CV % ≤ 7.10 %), and good recovery (95.46 %-106.46 %) was suitable for routine clinical practice and studies. Particularly, the ultrafiltration membrane had no non-specific binding to lenvatinib. The unbound fractions can be separated in just 15 min. This method was applied to quantify clinical samples and to determine the plasma protein binding and unbound fraction of lenvatinib. This study provides a more effective and promising method for determination of unbound lenvatinib. It could be beneficial to measure the unbound concentration of lenvatinib in personalized medicine and therapeutic drug monitoring in routine clinical practice.

Photo-transformation of isoproturon under UV-A irradiation: The synergy of nitrite and natural organic matter.

Isoproturon (IPU), a widely utilized phenylurea herbicide, is recognized as an emerging contaminant. Previous studies have predominantly attributed the degradation of IPU in natural waters to indirect photolysis by natural organic matter (NOM). Here, we demonstrate that nitrite (NO2-) also serves as an important photosensitizer that induces the photo-degradation of IPU. Through radical quenching tests, we identify hydroxyl radicals (•OH) and nitrogen dioxide radicals (NO2•) originating from NO2- photolysis as key players in IPU degradation, resulting in the generation of a series of hydroxylated and nitrated byproducts. Moreover, we demonstrate a synergistic effect on the photo-transformation of IPU when both NOM and NO2- are present in the reaction mixture. The observed rate constant (kobs) for IPU removal increases to 0.0179 ± 0.0002 min-1 in the co-presence of NO2- (50 µM) and NOM (2.5 mgC/L), surpassing the sum of those in the presence of each alone (0.0135 ± 0.0004 min-1). NOM exhibits multifaceted roles in the indirect photolysis of IPU. It can be excited by UV and transformed to excited triplet states (3NOM*) which oxidize IPU to IPU•+ that undergoes further degradation. Simultaneously, NOM can mitigate the reaction by reducing the IPU•+ intermediate back to the parent IPU. However, the presence of NO2- alters this dynamic, as IPU•+ rapidly couples with NO2•, accelerating IPU degradation and augmenting the formation of mono-nitrated IPU. These findings provide in-depth understandings on the photochemical transformation of environmental contaminants, especially phenylurea herbicides, in natural waters where NOM and NO2- coexist.

Alien species water hyacinth realizes waste into treasure: The preparation of biomass sorbent to determine benzoylurea insecticides in tea products.

A fast and effective analytical method with biomass solid-phase microextraction sorbent combined with a high-performance liquid chromatography-ultraviolet detector was proposed for the determination of benzoylurea (BU) insecticides in tea products. The novel sorbent was prepared by activating and then carbonizing water hyacinth with a fast growth rate and low application value as raw material and showed a high specific surface area and multiple interactions with analytes, such as electrostatic action, hydrogen bonding, and π-π conjugation. After optimizing the three most important extraction parameters (pH [X1], sample loading rate [X2], and solution volume [X3]) by Box-Behnken design, the as-established analytical method showed good extraction performance: excellent recovery (80.13%-106.66%) and wide linear range (1-400 µg/L) with a determination coefficient of 0.9992-0.9999, a low limit of detection of 0.02-0.1 µg/L and the satisfactory practical application results in tea products. All these indicate that the water hyacinth-derived material has the potential as a solid-phase extraction sorbent for the detection and removal of BU insecticides from tea products, and at the same time, it can also achieve the effect of rational use of biological resources, maintaining ecological balance, turning waste into treasure, and achieving industrial production.

In situ formation of solidified supramolecular solvent based dispersive liquid-liquid microextraction for the enrichment of phenylurea herbicides in water, fruit juice, and milk.

A convenient, efficient, and green dispersive liquid-liquid microextraction based on the in situ formation of solidified supramolecular solvents combined with high performance liquid chromatography was developed for the determination of four phenylurea herbicides in liquid samples, including monuron, monolinuron, isoproturon, and chlortoluron. Herein, a novel supramolecular solvent was prepared by the in situ reaction of [P4448]Br and NH4PF6, which had the advantages of low melting point, high density, and good dispersibility. In addition, the microscopic morphology and physical properties of supramolecular solvent were characterized, and the extraction conditions were optimized. The results showed that the analytes had good linearity (R2 > 0.9998) within the linear range. The limits of detection and quantification for the four phenylurea herbicides were in the range of 0.13-0.19 µg L-1 and 0.45-0.65 µg L-1, respectively. The prepared supramolecular solvent is suitable for the efficient extraction of phenylurea herbicides in water, fruit juice, and milk.

Effect of forchlorfenuron and thidiazuron on kiwifruits' internal qualities, optical properties and their relationship during growth.

Forchlorfenuron (1-(2-chloropyridin-4-yl)-3-phenylurea, CPPU) and thidiazuron (N-Phenyl-N'-1,2,3-thiadiazol-5-ylurea, TDZ) are two widely used plant growth regulators in kiwifruit cultivation. They can promote fruit size, but it is unclear whether they have same effect on internal qualities, optical properties and cell structure of kiwifruit, and whether the kiwifruits treated with CPPU and TDZ can be identified based on optical properties. To answer these questions, the kiwifruits treated with 20 mg/L CPPU and 2 mg/L TDZ solutions were used as samples, and the untreated kiwifruits were used as control to investigate the optical properties (absorption coefficient µa and reduced scattering coefficient µs'), internal qualities (soluble solids content (SSC), firmness and moisture content) and microstructure of pulp tissue during the growth. Moreover, the relationship between the optical properties and internal qualities were analyzed, and the potential for identifying the kiwifruits treated with CPPU and TDZ based on optical properties was evaluated. The results showed that CPPU and TDZ increased the SSC and reduced the firmness of kiwifruits, but had some different effects on the moisture content and cell size. CPPU and TDZ did not influence the change trend of µa and µs' with wavelength, but affected their values and the relationship with internal qualities. In general, the mean µa of the kiwifruits treated with CPPU and with TDZ was the largest and the smallest at the absorption peaks (980 nm, 1190 nm and 1420 nm), respectively. The linear discriminant analysis modeling results showed that the spectra of µa with µs' had greater potential in identifying the kiwifruits treated with CPPU/TDZ with accuracy of 75.76 %.

Positive allosteric modulators of the α7 nicotinic acetylcholine receptor: SAR investigation around PNU-120596.

The α7 nicotinic acetylcholine receptor is a calcium permeable, ligand-gated ion channel that modulates synaptic transmission in the hippocampus, thalamus, and cerebral cortex. Previously disclosed work described PNU-120596 that acts as a powerful positive allosteric modulator of the α7 nicotinic acetylcholine receptor. The initial structure-activity relationships around PNU-120596 were gleaned from screening a large thiazole library. Independent systematic examination of the aryl and heteroaryl groups resulted in compounds with enhanced potency and improved physico-chemical properties culminating in the identification of 16 (PHA-758454). In the presence of acetylcholine, 16 enhanced evoked currents in rat hippocampal neurons. In a rat model of impaired sensory gating, treatment with 16 led to a reversal of the gating deficit in a dose-dependent manner. These results demonstrate that aryl heteroaryl ureas, like compound 16, may be useful tools for continued exploration of the unique biology of the α7 nicotinic acetylcholine receptor.

A Simple UPLC/MS-MS Method for Simultaneous Determination of Lenvatinib and Telmisartan in Rat Plasma, and Its Application to Pharmacokinetic Drug-Drug Interaction Study.

Lenvatinib is a multi-targeted tyrosine kinase inhibitor that inhibits tumor angiogenesis, but hypertension is the most common adverse reaction. Telmisartan is an angiotensin receptor blocker used to treat hypertension. In this study, a simple ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of lenvatinib and telmisartan, and it was applied to the pharmacokinetic drug interaction study. Plasma samples were treated with acetonitrile to precipitate protein. Water (containing 5 mM of ammonium acetate and 0.1% formic acid) and acetonitrile (0.1% formic acid) were used as the mobile phases to separate the analytes with gradient elution using a column XSelect HSS T3 (2.1 mm × 100 mm, 2.5 µm). Multiple reaction monitoring in the positive ion mode was used for quantification. The method was validated and the precision, accuracy, matrix effect, recovery, and stability of this method were reasonable. The determination of analytes was not interfered with by other substances in the blank plasma, and the calibration curves of lenvatinib and telmisartan were linear within the range of 0.2-1000 ng/mL and 0.1-500 ng/mL, respectively. The results indicate that lenvatinib decreased the systemic exposure of telmisartan. Potential drug interactions were observed between lenvatinib and telmisartan.

Comparative assessment on the probable mechanisms underlying the hepatorenal toxicity of commercial imidacloprid and hexaflumuron formulations in rats.

Pesticides are viewed as a major wellspring of ecological contamination and causing serious risky consequences for people and animals. Imidacloprid (IM) and hexaflumuron (HFM) are extensively utilized insect poisons for crop assurance on the planet. A few investigations examined IM harmfulness in rodents, but its exact mechanism hasn't been mentioned previously as well as the toxicity of HFM doesn't elucidate yet. For this reason, the present study was designed to explore the mechanism of each IM and HFM-evoked rat liver and kidney toxicity and to understand its molecular mechanism. 21 male Wistar albino rats were divided into 3 groups, as follows: group (1), normal saline; group (2), IM; and group (3), HFM. Both insecticides were orally administered every day for 28 days at a dose equal to 1/10 LD50 from the active ingredient. After 28 days postdosing, rats were anesthetized to collect blood samples then euthanized to collect liver and kidney tissue specimens. The results showed marked changes in walking, body tension, alertness, and head movement with a significant reduction in rats' body weight in both IM and HFM receiving groups. Significant increases in MDA levels and decrease of GHS levels were recorded in liver and kidney homogenates of either IM or HFM groups. Liver and kidney tissues obtained from both pesticide receiving groups showed extensive histopathological alterations with a significant increase in the serum levels of ALT, AST, urea, and creatinine and a decrease in total proteins, albumin, and globulin levels. In addition, there was upregulation of the transcript levels of casp-3, JNK, and HO-1 genes with strong immunopositivity of casp-3, TNF-á½°, and NF-KB protein expressions in the liver and kidneys of rats receiving either IM or HFM compared with the control group. In all studied parameters, HFM caused hepatorenal toxicity more than those induced by IM. We can conclude that each IM and HFM provoked liver and kidneys damage through overproduction of ROS, activation of NF-KB signaling pathways and mitochondrial/JNK-dependent apoptosis pathway.

Development of 3-(4-Chlorophenyl)-1-(phenethyl)urea Analogues as Allosteric Modulators of the Cannabinoid Type-1 Receptor: RTICBM-189 is Brain Penetrant and Attenuates Reinstatement of Cocaine-Seeking Behavior.

We have shown that CB1 receptor negative allosteric modulators (NAMs) attenuated the reinstatement of cocaine-seeking behaviors in rats. In an effort to further define the structure-activity relationships and assess the druglike properties of the 3-(4-chlorophenyl)-1-(phenethyl)urea-based CB1 NAMs that we recently reported, we introduced substituents of different electronic properties and sizes to the phenethyl group and evaluated their potency in CB1 calcium mobilization, cAMP, and GTPγS assays. We found that 3-position substitutions such as Cl, F, and Me afforded enhanced CB1 potency, whereas 4-position analogues were generally less potent. The 3-chloro analogue (31, RTICBM-189) showed no activity at >50 protein targets and excellent brain permeation but relatively low metabolic stability in rat liver microsomes. Pharmacokinetic studies in rats confirmed the excellent brain exposure of 31 with a brain/plasma ratio Kp of 2.0. Importantly, intraperitoneal administration of 31 significantly and selectively attenuated the reinstatement of the cocaine-seeking behavior in rats without affecting locomotion.

Natural inspired ligustrazine-based SLC-0111 analogues as novel carbonic anhydrase inhibitors.

Ligustrazine is the principle bioactive alkaloid in the widely-used Chinese herb Chuan Xiong rhizome. Herein, a series of novel derivatives has been designed as human carbonic anhydrases inhibitors (hCAIs) starting from the natural product Ligustrazine inserted as a tail instead of the 4-fluorophenyl tail of SLC-0111, a front-runner selective hCA IX inhibitor currently in clinical trials as antitumor/antimetastatic agent. Other derivatives were designed via incorporation of different linkers, of amide and ester type, or incorporation of different zinc anchoring groups such as secondary sulfamoyl and carboxylic acid functionalities. The newly designed molecules were prepared following different synthetic pathways, and were assessed for their inhibitory actions against four isoforms: the widespread cytosolic (hCA I and II), and the transmembrane tumor-related (hCA IX and XII). The primary sulfonamides efficiently inhibited the target hCA IX and hCA XII in the nanomolar range (KIs: 6.2-951.5 nM and 3.3-869.3 nM, respectively). The most selective hCA IX inhibitors 6c and 18 were assessed for their potential anticancer effects, and displayed anti-proliferative activity against MCF-7 cancer cell line with IC50s of 11.9 and 36.7 µM, respectively. Molecular modelling studies unveiled the relationship between structural features and inhibitory profiles against the off-target hCA II and the target, tumor-related isoforms hCA IX and XII.

Lenvatinib and Cu2-xS nanocrystals co-encapsulated in poly(D,L-lactide-co-glycolide) for synergistic chemo-photothermal therapy against advanced hepatocellular carcinoma.

Lenvatinib (LT) is gradually replacing sorafenib as an alternative targeted drug against advanced hepatocellular carcinoma (HCC). However, the anticancer effects of LT are still limited because of its low cytotoxicity, multidrug resistance (MDR), and tumor relapse. Herein, we constructed a smart biophotonic nanoplatform to overcome the barriers preventing high performance. LT and copper sulfide nanocrystals (Cu2-xS NCs) with excellent photothermal properties in the near-infrared-II (NIR-II) zone were co-encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) through nanoprecipitation. Both in vitro and in vivo evaluations demonstrated that Cu2-xS NCs enhanced the anticancer efficacy of LT, without recurrence. In addition, the presence of copper ions could allow glutathione (GHS) to be consumed and oxygen to be produced, likely suppressing the expression of P-glycoprotein (P-gp) and overcoming the issue of MDR relating to LT. More importantly, synergistic chemo-photothermal therapy with LT and Cu2-xS NCs was more effective than any single therapy or theoretical combination. This nanoplatform is promising for advancing future LT-based treatment strategies for HCC therapy.

Effect of phenylurea hydroxamic acids on histone deacetylase and VEGFR-2.

A series of phenylurea hydroxamic acids incorporating pharmacophores of inhibitors of HDAC inhibitors and VEGFR-2 has been designed. Most of the compounds show antiproliferative activity comparable to that of Vorinostat and Sorafenib, and better EPC inhibitory activity. Enzymatic assays and Western blotting results indicated that compound 14 not only inhibits HDAC but also has slight VEGFR-2 inhibitory activity. A docking study revealed that the polar hydroxamic acid retains the interaction with HDAC through a zinc ion and also interacts with some residues of the active site of VEGFR-2. Despite 14 displaying a weaker VEGFR-2 activity, a possible route to develop potent HDAC/VEGFR-2 inhibitors is suggested.

Di-anionic self-associating supramolecular amphiphiles (SSAs) as antimicrobial agents against MRSA and Escherichia coli.

Herein, we report a series of di-anionic supramolecular self-associating amphiphiles (SSAs). We elucidate the antimicrobial properties of these SSAs against both methicillin resistant Staphylococcus aureus and Escherichia coli. In addition, we show this class of compound to form both intra- and intermolecular hydrogen bonded macrocyclic structures in the solid state.

TAD1822-7 induces ROS-mediated apoptosis of HER2 positive breast cancer by decreasing E-cadherin in an EphB4 dependent manner.

HER2-positive breast cancer (HER2-BC) shows the over-expression of tyrosine kinase receptor EphB4 associated with poor disease prognosis. E-cadherin is found as a survival factor in multiple models of breast cancer by suppressing reactive oxygen-mediated apoptosis. This study confirmed that both HER2 and EphB4 are positively correlated with E-cadherin in HER2-BC. Inhibition of HER2 or EphB4 is discovered to induce ROS-dependent apoptosis by decreasing E-cadherin expression in SKBR3 and MDA-MB-453 cells. TAD1822-7 (TAD), a novel biphenyl urea taspine derivative, exhibits good growth inhibition, apoptosis induction and ROS accumulation effects on SKBR3 and MDA-MB-453 cells. Mechanistic investigation revealed that TAD blockades both EphB4 positive signal transduction and activation of HER2 signal transduction, thereby suppressing E-cadherin/TGF-ß/p-Smad2/3 signaling axis to elicit ROS-dependent endogenous mitochondrial apoptosis. Together, these findings not only provide a new approach for HER2-BC therapy but also increase our understanding of the regulating effect of E-cadherin by HER2 and EphB4 in ROS-mediated apoptosis.

Identification of effective natural PIK3CA H1047R inhibitors by computational study.

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer with a poor prognosis and a high recurrence rate. PIK3CA gene is frequently mutated in breast cancer, with PIK3CA H1047R as the hotspot mutation reported in TNBC. We used the ZINC database to screen natural compounds that could be structurally modified to develop drugs targeting the PIK3CA H1047R mutant protein in the PI3K pathway. The LibDock module showed that 2,749 compounds could strongly bind to the PIK3CA H1047R protein. Ultimately, the top 20 natural ligands with high LibDock scores were used for further analyses including assessment of ADME (absorption, distribution, metabolism, and excretion), toxicity, stability, and binding affinity. ZINC000004098448 and ZINC000014715656 were selected as the safest drug candidates with strong binding affinity to PIK3CA H1047R, no hepatotoxicity, less carcinogenicity, better plasma protein binding (PPB) properties, and enhanced intestinal permeability and absorption than the two reference drugs, PKI-402 and wortmannin. Moreover, their lower potential energies than those of PIK3CA H1047R confirmed the stability of the ligand-receptor complex under physiological conditions. ZINC000004098448 and ZINC000014715656 are thus safe and stable leads for designing drugs against PIK3CA H1047R as part of a targeted therapeutic approach for patients with TNBC.

Enzymatic and Chemical Syntheses of Vacor Analogs of Nicotinamide Riboside, NMN and NAD.

It has recently been demonstrated that the rat poison vacor interferes with mammalian NAD metabolism, because it acts as a nicotinamide analog and is converted by enzymes of the NAD salvage pathway. Thereby, vacor is transformed into the NAD analog vacor adenine dinucleotide (VAD), a molecule that causes cell toxicity. Therefore, vacor may potentially be exploited to kill cancer cells. In this study, we have developed efficient enzymatic and chemical procedures to produce vacor analogs of NAD and nicotinamide riboside (NR). VAD was readily generated by a base-exchange reaction, replacing the nicotinamide moiety of NAD by vacor, catalyzed by Aplysia californica ADP ribosyl cyclase. Additionally, we present the chemical synthesis of the nucleoside version of vacor, vacor riboside (VR). Similar to the physiological NAD precursor, NR, VR was converted to the corresponding mononucleotide (VMN) by nicotinamide riboside kinases (NRKs). This conversion is quantitative and very efficient. Consequently, phosphorylation of VR by NRKs represents a valuable alternative to produce the vacor analog of NMN, compared to its generation from vacor by nicotinamide phosphoribosyltransferase (NamPT).