humanCD38 (IC50 = 7.3 nM; mouse CD38 (IC50 = 1.9 nM); WT hCD38 (Ki = 0.3 nM)[1]
CD38 (NADase/ADP-ribosyl cyclase). 78c is a reversible, uncompetitive inhibitor of CD38. Against recombinant human CD38, the inhibition constant (Kᵢ) for the hydrolase activity is 9.7 ± 1.5 nM, and for the cyclase activity is 100 ± 28 nM (10-fold less potent). Against murine CD38, the Kᵢ is in the low nanomolar range (approximately 3.6 nM). [1,2]

Enzyme inhibition kinetics: 78c acts as an uncompetitive inhibitor of CD38, binding to the enzyme-substrate complex and decreasing both apparent Vₘₐₓ and Kₘ for NAD⁺. The inhibition is reversible. Nicotinamide (NAM), a reaction product, decreases the apparent V₀ and increases the Kᵢ for 78c, while ADP-ribose (ADPR) and cyclic ADP-ribose (cADPR) have no significant effect on these kinetic parameters. [2]
Specificity against related enzymes: 78c does not inhibit CD157 (also known as BST-1) at concentrations up to 50 nM, using either NAD⁺ or nicotinamide riboside (NR) as substrates. It also does not inhibit the ADP-ribosyl cyclase from Aplysia californica at concentrations up to 50 nM. [2]
Effect on other NAD⁺-metabolizing enzymes: 78c has no direct inhibitory or stimulatory effect on recombinant PARP1, SIRT1, or NAMPT at concentrations that effectively inhibit CD38 (up to 100 nM). [2]
Cellular NAD⁺ levels: In wild-type mouse embryonic fibroblasts (MEFs), 78c (0.2 μM for 24 hours) nearly doubled NAD⁺ levels. In CD38 knockout MEFs, 78c had no effect on NAD⁺ levels. [2]
Mechanism of NAD⁺ elevation: In co-culture experiments with CD38⁺ Jurkat T cells in the upper chamber and CD38⁻ AML12 hepatocytes in the lower chamber, 78c (0.5 μM) significantly increased NAD⁺ levels in AML12 cells. This effect was enhanced by addition of the NAD⁺ precursor NMN. When CD38 was overexpressed in 293T cells in the upper chamber, 78c reversed the CD38-mediated depletion of NMN availability to AML12 cells. [2]
Downstream signaling effects: In 293T cells expressing CD38, 78c (0.5 μM, 24 hours) reversed CD38-induced increases in p65 acetylation and pan-cellular acetylation, effects that were blocked by the sirtuin inhibitors nicotinamide and EX-527. In A549 cells, 78c activated the AMPK pathway (increased pAMPK) and decreased p70S6K and ERK phosphorylation. [2]
78c increases NAD+ levels through inhibition of CD38 NADase activity. 78c is a potent, reversible, and uncompetitive inhibitor of CD38. 78c is a specific inhibitor of CD38 and does not directly affect the activity or expression of other enzymes involved in NAD+ metabolism.[2]

Tissue NAD⁺ elevation in aged mice: In 2-year-old mice treated with 78c (10 mg/kg, i.p., twice daily for up to 14 weeks), NAD⁺ levels were significantly increased in multiple tissues including liver (>5-fold), skeletal muscle (>1.2-fold), spleen, and heart, compared to vehicle controls. In young (3-month-old) mice, 78c had minimal effect on NAD⁺ levels. [1,2]
Improvement in glucose homeostasis: Aged mice treated with 78c showed improved glucose tolerance, decreased insulin levels, reduced HOMA-IR index, and increased insulin sensitivity. The effect was blocked by co-administration of the NAMPT inhibitor FK866, confirming dependence on NAD⁺ synthesis. In progeroid P44⁺/⁺ mice, 78c also improved glucose tolerance. [2]
Improvement in physical function and muscle architecture: 78c treatment in 1- and 2-year-old mice nearly doubled maximal running distance and work performed, increased time to exhaustion, and improved spontaneous physical activity. Muscle ATP levels and ATP/O₂ coupling were increased. Histologically, 78c reduced the number of centrally located nuclei (>70% decrease), CD45⁺ inflammatory cell infiltration (>70% decrease), and necrotic myofibers (>70% decrease), and normalized myofiber size distribution. Fibrosis-related gene expression was decreased. [2]
Improvement in cardiac function: In 2-year-old mice, 78c treatment (10 weeks) reversed age-related declines in ejection fraction and fractional shortening, and reduced left ventricular volume during systole (LVVs) and isovolumetric contraction time (IVCT), restoring these parameters to levels similar to young mice. [2]
Increase in survival: 78c treatment increased overall survival in the Bub1bᴴ/⁺ mouse model of accelerated aging. [2]
Reduction in telomere-associated DNA damage: In liver and skeletal muscle of aged mice treated with 78c (14 weeks), telomere-associated foci (TAF, co-localization of γH2A.X with telomere probe) were significantly decreased, indicating reduced DNA damage. [2]
Activation of longevity pathways: In spleen and skeletal muscle of aged mice treated with 78c, there was activation of AMPK, decreased pan-acetylation, pan-succinylation, and pan-malonylation of lysine residues, and decreased phosphorylation of p70S6K and ERK. Protein PARylation was increased in the spleen. [2]
NAD levels in liver and muscle are markedly elevated by oral CD38 inhibitors (30 mg/kg; 2 hours and 6 hours) [1].

CD38 hydrolase activity assay: CD38 activity was measured using the fluorogenic substrate ε-NAD⁺ (nicotinamide 1,N⁶-ethenoadenine dinucleotide). The conversion to ε-ADPR was monitored by fluorescence (excitation 300 nm, emission 410 nm) using a fluorometer. For inhibition studies, recombinant human CD38 (rhCD38) or tissue lysates were incubated with varying concentrations of 78c in the presence of 50 μM ε-NAD⁺. [2]
CD38 cyclase activity assay: Cyclase activity was measured using nicotinamide guanine dinucleotide (NGD) as a substrate. The conversion to cyclic GDP-ribose (cGDPR) was monitored by fluorescence (excitation 300 nm, emission 410 nm). [2]
CD157 activity assay: Hydrolysis of NR or NAD⁺ by recombinant human CD157 was measured by monitoring the decrease in absorbance at 262 nm, as described in Preugschat et al. (2014). [2]
PARP1 activity assay: PARP1 activity was measured using a commercially available colorimetric kit. Recombinant PARP1 was incubated with NAD⁺ and a histone substrate in the presence or absence of 78c or the PARP inhibitor olaparib. [2]
SIRT1 activity assay: SIRT1 activity was measured using a fluorometric kit (Enzo Life Sciences). Recombinant SIRT1 was incubated with a fluorogenic substrate and NAD⁺ in the presence or absence of 78c or the SIRT1 inhibitor suramin. [2]
NAMPT activity assay: NAMPT activity was measured using a colorimetric kit (MBL International) according to the manufacturer's instructions. [2]
Biochemical Assay Details for the pIC50 Determinations against the Human and Mouse CD38 Enzymes[1]
CD38 inhibitors were tested for their capacity to inhibit human CD38 enzyme activity in a colorimetric-based assay. The extracellular domain of human CD38 was expressed in Pichia pastoris and purified to homogeneity. The enzyme activity assay was performed in a low-volume 384-well plate in a total volume of 20 μL. A range of concentrations of test compound in 200 nL of DMSO was delivered into the assay plate wells. Columns 6 and 18 of the plate contained DMSO with no compound and served as the high signal and low signal controls (no CD38 added), respectively. All additions of assay reagents to the plate were done using a Multidrop Combi, and the plate was shaken 3–5 s after each addition. CD38 (0.8 nM) was incubated with test compound in 10 μL containing 100 mM HEPES, pH 7.4, 4 mM EDTA, and 1 mM CHAPS for 30 min prior to initiation of the reaction. The reaction was initiated by a 10 μL addition containing 5 mM sodium acetate, pH 4.5, 1 mM CHAPS, 200 μM NAD, and 500 μM GW323424X. The solutions for each of the two additions were prepared fresh each day from concentrated stocks of the individual components. The final concentrations in the assay were 50 mM HEPES, 2 mM EDTA, 1 mM CHAPS, and 2.5 mM sodium acetate, 100 μM NAD, 250 μM GW323434X, and 0.4 nM CD38. GW323434X is a 4-pyridynal compound that acts as a nucleophile that participates in the base exchange reaction with the nicotinamide on NAD to form a novel dinucleotide that absorbs at 405 nm. Catalytic formation of this novel chromophore was followed in an Envision microplate reader by reading absorbance at two time points, typically 30 min apart within the first 45 min of the reaction. These time points were established empirically to ensure the rates determined were in a linear range of product formation. Data analysis was performed in the following way using ActivityBase XE (Abase XE). The data from the 15 and 45 min reads was processed by performing a subtraction function of 45 min read value minus 15 min read value for each plate well. The resulting values for noncontrol wells were converted to % inhibition using the formula 100 × ((U – C1)/(C2 – C1)), where U is the value of the test well, C1 is the average of the values of the high signal (column 6) control wells, and C2 is the average of the values of the low signal (column 18) control wells. Percent inhibition (y) was plotted versus inhibitor concentration (x), and curve fitting was performed with the following four parameter equation: y = A + ((B – A)/(1 + (10x/10C)D)), where A is the minimum response, B is the maximum response, C is the log10IC50, and D is the Hill slope. The results for each compound were recorded as pIC50 values (−C in the above equation). For the data presented in this manuscript, the pIC50 values were converted to molar IC50 values according to the equation IC50 = 10–pIC50. Statistics were performed on the IC50 values.[1]
The recombinant extracellular domain of mouse CD38 was expressed in CHO CGE cells and purified to homogeneity. The pIC50 values for the inhibitors against mouse CD38 were generated using the enzyme in a fluorescence-based assay in which the enzyme reaction occurred in a 10 μL volume in a low-volume 384-well assay plate. The assay quantitated CD38 catalyzed NAD hydrolysis over 45 min of reaction time in which the rate was linear. A range of concentrations of test compound in 100 nL of DMSO was delivered into the assay plate wells. Columns 6 and 18 of the plate contained DMSO and served as the low signal and high signal controls, respectively. Column 18 contained a potent mouse CD38 inhibitor to define the high signal (no enzyme activity) control. Additions to the plate other than compound were done using a Multidrop Combi, and the plate was shaken 3–5 s after each addition. CD38 (0.45 nM) was incubated with test compound in 5 μL containing 20 mM HEPES, pH 7.2, 1 mM EDTA, and 1 mM CHAPS for 30 min prior to initiation of the reaction. The reaction was initiated by a 5 μL addition containing 20 mM HEPES, pH 7.2, 1 mM EDTA, 1 mM CHAPS, and 60 μM NAD. The final concentrations in the assay were 20 mM HEPES, pH 7.2, 1 mM EDTA, 1 mM CHAPS, 30 μM NAD, and 0.225 nM mouse CD38. After the reaction time, the amount of NAD remaining was quatitated by converting it to NADH using alcohol dehydrogenase (ADH). The ADH was added in 5 μL containing 9U/mL ADH, 90 mM sodium pyrophosphate, pH 8.8, 90 mM ethanol, 1 mM EDTA, and 1 mM CHAPS. The alcohol dehydrogenase reaction was stopped by the addition of 5 μL of 1 M HEPES, pH 7.0, 1.0 mM EDTA, and 1 mM CHAPS containing 0.8 M dithiothreitol (DTT), and the NADH fluorescence was measured in an Envision plate reader (340 nm excitation, 460 nm emission). The solutions for each of the four additions were prepared fresh each day from concentrated stocks of the individual components, except the DTT which was prepared fresh daily from solid. In this assay, an increase in enzyme activity results in a decreased measured fluorescent signal. Each compound plate was run in duplicate with (plate A) and without (plate B) ADH. Data were acquired by reading plates in pairs and subtracting the values for plate B from plate A to obtain “corrected” data (accounts for intrinsic fluorescence from test compound). Using Abase XE, “corrected” fluorescence signals for noncontrol wells were converted to percent inhibition values using the formula 100 – 100 × ((U – C2)/(C1 – C2)), where U is the “corrected” fluorescence signal value of the test well, C1 is the average of the “corrected” fluorescence values of the low signal (column 6; full CD38 enzyme activity) control wells, and C2 is the average of the “corrected” fluorescence values of the high signal (column 18; 100% inhibited CD38 enzyme activity) control wells. Percent inhibition data were fit using the four-parameter curve fit equation described above. For the data presented in this manuscript, the pIC50 values were converted to molar IC50 values according to the equation IC50 = 10–pIC50. Statistics were performed on the IC50 values.

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Assay Details for Ki Determinations with the Human Wild-Type CD38 Enzyme[1]
The CD38-catalyzed hydrolysis of NAD resulted in a decrease in absorbance at 280 nm (using Δε280 = −1.2 mM–1 cm–1 for NAD). The fully glycosylated human recombinant enzyme used for Ki determination was purchased from R&D Systems. The enzyme was diluted 1:500 into standard buffer (Hepes (K+) pH 7.0), and the reaction was initiated using 100 μM NAD. Progress curves were fitted using a mixed inhibition model to determine Kis for individual compounds.

NAD⁺ measurement in cells: Cells were lysed in 10% trichloroacetic acid (TCA), centrifuged, and the supernatant was extracted with organic solvent (1,1,2-trichloro-1,2,2-trifluoroethane:trioctylamine, 3:1) to remove TCA. The aqueous phase was neutralized with 1M Tris (pH 8.0), and NAD⁺ was measured using a cycling assay based on the reduction of resazurin to resorufin. [2]
Co-culture experiments: AML12 cells (CD38⁻) were plated in the lower chamber of transwell plates. CD38⁺ Jurkat T cells or CD38-transfected 293T cells were plated in the upper chamber. 78c (0.5-1 μM) was added to the upper chamber, followed by NMN (100 μM). After 24 hours, AML12 cells were collected for NAD⁺ measurement. [2]
Western blot analysis: Cell or tissue lysates were prepared in NETN buffer (20 mM Tris-HCl pH 8.0, 100 mM NaCl, 1 mM EDTA, 0.5% Nonidet P-40) with protease and phosphatase inhibitors. For acetylation, succinylation, and malonylation studies, 5 mM nicotinamide and 5 μM trichostatin A were added. For PARylation studies, 100 μM tannic acid was added. Proteins were separated by SDS-PAGE, transferred to PVDF membranes, and probed with specific antibodies. [2]
Transfection and drug treatment: HEK293T cells were transfected with Flag-CD38, Flag-p65, or HA-p53 plasmids using Lipofectamine. After 20 hours, cells were treated with 78c (0.5 μM), olaparib (5 μM), EX-527 (5 μM), or nicotinamide (5 mM) for 24 hours. [2]
HEK293T were treated with 0.5 μM 78c, 5 μM olaparib (LC Laboratories), 5 μM EX-527 (Tocris), or 5 μM nicotinamide for 24 hours. MEFs were treated with 0.2 μM 78c for 24 hours. A549 cells were treated for 24 hours with vehicle (DMSO), 78c (0.2–0.5 μM) or 5 μM olaparib. A549 and 293T cells were treated with drugs in media containing 0.5% FBS and MEFs were treated in media containing 10% FBS. To test the reversibility of the CD38i, A549 cells were treated with vehicle or 0.5 μM 78c for 16 hours. Then, cells were washed and incubated with (78c) or without (78c+release) 78c for another 8 hours. Control cells were left in vehicle for the whole treatment period. After treatment, cell lysates were prepared for measurements of CD38 activity. For the co-culture experiment, AML12 cells were plated in the lower chamber and HEK293T or Jurkat T cells were plated in the upper chamber. Transfections with CD38 plasmid were done as described above. 0.5–1 μM 78c was added to the upper chamber 4 hours before addition of 100 μM NMN. 4 hours later, both chambers were incubated together for an additional 20 hours. Then AML12 cells were collected for NAD+ measurements. In experiments where AML12 cells were incubated with recombinant CD38 in the cell culture media, the first step involved incubation of the recombinant protein (100ng/mL) with 1 μM 78c for 30 minutes at 37 °C in cell culture media containing 1% FBS. After 30 minutes, the recombinant protein-78c mixture was added to the cells and 100μM NMN was added. After 18 hours, AML12 cells were collected for NAD+ measurements or Western blot.[2]

Dosing regimen: 78c was administered to C57BL/6 mice (3, 12, and 22-26 months old) and ICR mice (1-year-old) by intraperitoneal injection at 10 mg/kg/dose twice daily for 4 to 14 weeks. Control mice received vehicle (5% DMSO, 15% PEG400, 80% of 15% hydroxypropyl-γ-cyclodextrin in citrate buffer pH 6.0). For short-term treatments, mice received 15 mg/kg/dose twice daily for 8 days. [2]
\n Combination with FK866: Aged C57BL/6 mice received FK866 (25 mg/kg/dose, i.p., once daily), 78c (10 mg/kg/dose, i.p., twice daily), or a combination for 10 weeks. Vehicle controls received appropriate vehicles. [2]
\n NAD⁺ precursor combination: Aged mice received a single dose of 78c (10 mg/kg, i.p.) 16 hours before NR (100 mg/kg, gavage) and a second dose of 78c (10 mg/kg) at the time of NR administration. Mice were sacrificed 6 hours later. [2]
\n Glucose tolerance test (ipGTT): After 7 weeks of treatment, mice were fasted for 16 hours, then injected intraperitoneally with 20% dextrose (1.5 g/kg body weight). Blood glucose was measured at 0, 20, 30, 60, and 120 minutes post-injection. [2]
\n Insulin sensitivity test (ipIST): After 4 weeks of treatment, mice were fasted for 6 hours, then injected intraperitoneally with insulin (0.5 units/kg). Blood glucose was measured at 0, 20, 30, 60, and 120 minutes. [2]
\n Pyruvate tolerance test (PTT): After 9 weeks of treatment, mice were fasted for 6 hours, then injected intraperitoneally with pyruvate (1.5 g/kg). Blood glucose was measured at 0, 20, 30, 60, and 120 minutes. [2]
\n Treadmill exercise test: After 8 weeks of treatment, mice were acclimated to the treadmill (5° grade, 10 m/min for 5 minutes/day for 3 days). Exhaustion was defined as inability to remain on the treadmill despite electrical shock. Running distance, time, maximal speed, and work were calculated. A downhill exhaustion protocol (−10° angle) was used for lactate and creatine kinase measurements. [2]
\n Tissue collection for NAD⁺ measurement: Approximately 20 mg of tissue was homogenized in 10% trichloroacetic acid, centrifuged, and the supernatant extracted with organic solvent (1,1,2-trichloro-1,2,2-trifluoroethane:trioctylamine, 3:1) to remove TCA. The aqueous phase was neutralized with 1M Tris (pH 8.0) for NAD⁺ cycling assay. [2]

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\n\n\n\nAnimal/Disease Models: Diet-induced obesity (DIO) C57Bl6 mice [1]
Doses: 30 mg/kg
Route of Administration: Orally once.
Experimental Results: NAD levels in liver and muscle were Dramatically increased at both the 2-hour and 6-hour time points.

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\n\nCD38 inhibitor (78c) 78c was administered to C57BL/6 (3, 12, and 22 to 26 months old) and ICR (1-year-old) mice by intraperitoneal injection (i.p., 10 mg/kg/dose) twice daily over a period of 4 to 14 weeks. 3-month-old, 1-year-old and 2-year-old mice were treated with 78c for up to 14 weeks. Combination of 78c and FK866 was performed for 10 weeks. P44+/+ progeroid mice due to their accelerated aging were treated with 78c for 4 weeks. For the short treatment, mice received a 15 mg/kg/dose twice daily for 8 days. Control mice received vehicle (5% DMSO, 15% PEG400, 80% of 15% hydroxypropyl-γ-cyclodextrin (in citrate buffer pH 6.0)) injections. We also measured the concentration of 78c in multiple tissues and plasma. Samples and standards were extracted by protein precipitation with acetonitrile containing internal standards. The supernatant was diluted with 0.1% formic acid in water before injection into an HPLC-MS/MS system for separation and quantitation. The analytes were separated from matrix components using reverse phase chromatography on a 30x2.1 mm 5 μm Fortis Pace C18 using gradient elution at a flow rate of 0.8 mL/min. The tandem mass spectrometry analysis was carried out on SCIEX™ triple quadrupole mass spectrometer with an electrospray ionization interface, in positive ion mode. Data acquisition and evaluation were performed using Analyst® software (SCIEX™). The results of the measurements were: plasma (0.007 μg/mL); brain (0.000 μg/g); heart (0.003 μg/g); kidney (0.005 μg/g); liver (0.024 μg/g); pancreas (0.002 μg/g) and, spleen (0.0048 μg/g). We also observed that 78c could be detected in cellular extracts of cultured cells treated with different concentration of 78c.[2]

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\n\nNAMPT inhibitor: Aged C57BL/6 mice received FK866 (25 mg/kg/dose, i.p., once daily), 78c (10 mg/kg/dose, i.p., twice daily), or a combination of FK866 and 78c (same doses) for 10 weeks. Control mice received equivalent injections of vehicle for FK866 (1% Hydroxypropyl-β-cyclodextrin, 12% Propylene glycol) and vehicle for 78c (5% DMSO, 15% PEG400, 80% of 15% hydroxypropyl-γ-cyclodextrin (in citrate buffer pH 6.0)), a group was treated with 78c, and one group was treated with a combination of 78c (10 mg/kg/dose, i.p twice daily) and FK866 (25 mg/kg/dose, i.p once daily).

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\n\nNAD+ precursors: For the treatment with nicotinamide mononucleotide (NMN), C57BL/6 mice received a single dose of NMN (500 mg/kg) or vehicle (PBS) by gavage. Mice were sacrificed after 2 hours, and tissues harvested. For the study with nicotinamide riboside (NR), aged C57BL/6 mice were pretreated with a single dose of 78c (10 mg/kg, i.p). Sixteen hours later, they received NR (100 mg/kg) by gavage and a second injection of 78c (10 mg/kg). Blood was collected just prior to administration of NR, and 30 min, 1 hour, 2 hours, and 6 hours later. Control mice received NR alone (200 mg/kg), 78c alone (10 mg/kg/dose, 2 doses), or vehicle (NR=PBS; 78c=5% DMSO, 15% PEG400, 80% hydroxypropyl-γ-cyclodextrin). The mice were sacrificed 6 hours after administration of 78c and NR, and tissues were collected.[2]

Tissue distribution in mice: After intraperitoneal administration of 78c (10 mg/kg), the compound was detected in multiple tissues. Levels (μg/g) were: plasma (0.007), brain (0.000), heart (0.003), kidney (0.005), liver (0.024), pancreas (0.002), and spleen (0.0048). [2]
Pharmacokinetic modeling: The uncompetitive inhibition kinetics of 78c were mathematically modeled using steady-state equations derived from the King-Altman algorithm, accounting for the effects of reaction products (NAM, ADPR) on inhibition parameters. [2]

Tolerability in mice: Chronic administration of 78c (10 mg/kg, i.p., twice daily for up to 14 weeks) was well tolerated in aged mice, with no significant changes in body weight or overt signs of toxicity reported. [2]
Combination with FK866: Co-administration of 78c with the NAMPT inhibitor FK866 was tolerated in aged mice for 10 weeks without reported adverse effects. [2]

[1]. Discovery, Synthesis, and Biological Evaluation of Thiazoloquin(az)olin(on)es as Potent CD38 Inhibitors. J Med Chem. 2015 Apr 23;58(8):3548-71.

[2]. A Potent and Specific CD38 Inhibitor Ameliorates Age-Related Metabolic Dysfunction by Reversing Tissue NAD+ Decline. Cell Metab. 2018;27(5):1081-1095.e10.

series of thiazoquinone compounds were synthesized and found to have potent inhibitory activity against CD38. Several of these compounds also exhibited good pharmacokinetic properties and increased NAD levels in plasma, liver, and muscle tissue. In particular, after administration of compound 78c to diet-induced obese (DIO) C57Bl6 mice, NAD levels in the liver were increased by more than 5-fold and NAD levels in the muscle by more than 1.2-fold at the 2-hour time point. The compounds described herein are the most potent CD38 inhibitors reported to date among small molecule compounds. These inhibitors will help to assess in more detail how increasing NAD levels by inhibiting CD38 affects physiological function in NAD-deficient states. [1] Aging is characterized by metabolic dysfunction and frailty. Recent studies have shown that a decrease in nicotinamide adenine dinucleotide (NAD+) is a key factor contributing to age-related metabolic decline. We recently demonstrated that NADase CD38 plays a central role in age-related decline in NAD+ levels. In this study, we found that a highly effective and specific thiazoquinone CD38 inhibitor, 78c, can reverse age-related decline in NAD+ levels and improve a variety of aging-related physiological and metabolic indicators, including glucose tolerance, muscle function, exercise capacity, and cardiac function. These studies were conducted in mouse models of natural and accelerated aging. The physiological effects of 78c depend on NAD+ levels in tissues and can be reversed by inhibiting NAD+ synthesis. 78c can increase NAD+ levels, thereby activating factors associated with longevity and healthy lifespan, such as sirtuins, AMPK, and PARPs. In addition, in animals treated with 78c, we observed that some signaling pathways that negatively affect healthy lifespan (such as mTOR-S6K and ERK) were inhibited, and telomere-related DNA damage (a marker of cellular senescence) was also reduced. Our findings collectively illustrate a novel pharmacological strategy for preventing and/or reversing age-related decline in NAD+ and subsequent metabolic dysfunction. [2]

C22H27N3O3S

413.5331

413.18

C, 63.90; H, 6.58; N, 10.16; O, 11.61; S, 7.75

1700637-55-3

1700637-55-3;MDK-7553 HCl;

118736856

Light yellow to brown solid powder

3

1

6

7

29

594

0

CN1C2=C(C=C(C=C2)C3=CN=CS3)C(=CC1=O)NC4CCC(CC4)OCCOC

VJQALSOBHVEJQM-QAQDUYKDSA-N

InChI=1S/C22H27N3O3S/c1-25-20-8-3-15(21-13-23-14-29-21)11-18(20)19(12-22(25)26)24-16-4-6-17(7-5-16)28-10-9-27-2/h3,8,11-14,16-17,24H,4-7,9-10H2,1-2H3/t16-,17-

4-(((1r,4r)-4-(2-methoxyethoxy)cyclohexyl)amino)-1-methyl-6-(thiazol-5-yl)quinolin-2(1H)-one

CD38 inhibitor 78c; Compound-78c; CD38 inhibitor 1; 1700637-55-3; CD38-IN-78c; CHEMBL3426034; 4-((trans-4-(2-Methoxyethoxy)cyclohexyl)amino)-1-methyl-6-(thiazol-5-yl)quinolin-2(1H)-one; 4-[[trans-4-(2-Methoxyethoxy)cyclohexyl]amino]-1-methyl-6-(5-thiazolyl)-2(1H)-quinolinone; 4-(((1r,4r)-4-(2-Methoxyethoxy)cyclohexyl)amino)-1-methyl-6-(thiazol-5-yl)quinolin-2(1H)-one; compound 78c; CD38i_78c; 78c

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~25 mg/mL (~60.46 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (6.05 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 2.5 mg/mL (6.05 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (6.05 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 10 mg/mL (24.18 mM) in Corn Oil (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.

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Solubility in Formulation 5: 10 mg/mL (24.18 mM) in 50% PEG300 50% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)