Gastric H/K-ATPase (Ki = 120 nM)

SCH28080 [1] has a Ki of 0.12 μM and competitively inhibits K+-stimulated ATP hydrolysis. SCH28080 has an IC50 of 0.029 μM, which blocks the absorption of [14C]aminopyrine into isolated rabbit parietal cells caused by histamine [1]. Cell viability is reduced by SCH28080 in a dose-dependent manner. The IC50 values were 22.9 µM and 15.3 µM, respectively, after 2 and 24 hours of treatment. The cell viability at 100 µM was less than 10% after two hours of treatment [2]. Higher doses of SCH28080 cause apoptosis and make it cytotoxic [2]. By activating IK ATP and blocking L-type voltage-gated Ca2+ channels, SCH28080 suppresses insulin production, lowers cell viability, and causes apoptosis/necrosis in a dose-dependent manner [2].

SCH28080 (20 mg/kg; intraperitoneal injection) can suppress gastric ulcer produced by pyloric ligation in rats [3].

The novel antisecretory agents SCH 32651 and SCH 28080 were evaluated for their antisecretory activities in vitro as well as for their abilities to inhibit the (H+ + K+)-ATPase enzyme activity in preparations of microsomal membranes from rabbit fundic mucosa. SCH 32651 and SCH 28080 inhibited both the histamine- and dibutyryl cAMP-stimulated uptake of [14C]-aminopyrine into isolated parietal cells with IC50 values of about 1.5 and 0.02 microM respectively. SCH 32651 and SCH 28080 competitively inhibited the K+-stimulated hydrolysis of ATP catalyzed by the (H+ + K+)-ATPase with Ki values of 16.3 and 0.12 microM respectively. The inhibition of the enzyme by both compounds was not affected by the addition of the sulfhydryl reducing agents dithiothreitol or beta-mercaptoethanol, was readily reversible by dilution or washing, and was dependent upon the concentration of KCl used to stimulate the enzyme. These data suggest that SCH 32651 and SCH 28080 are reversible, competitive inhibitors of the K+-stimulated hydrolysis of ATP [1].

Cell viability assay [2]
Cell Types: INS-1E Cell
Tested Concentrations: 3.1 μM, 6.25 μM, 12.5 μM, 25 μM, 50 μM, 100 μM
Incubation Duration: 2 hrs (hours), 24 hrs (hours)
Experimental Results: Caused dose-dependent reduction of cell viability .

Animal/Disease Models: Male Wistar rat (280-350g), Shay rat model [3]
Doses: 20mg/kg
Route of Administration: intraperitoneal (ip) injection
Experimental Results: 91% inhibitory effect on gastric ulcer in pyloric ligated rats.

[1]. Studies on the mechanism of action of the gastric microsomal (H+ + K+)-ATPase inhibitors SCH 32651 and SCH 28080. Biochem Pharmacol. 1987 Jan 1;36(1):97-104.

[2]. The H+/K+ ATPase Inhibitor SCH-28080 Inhibits Insulin Secretion and Induces Cell Death in INS-1E Rat Insulinoma Cells. Cell Physiol Biochem. 2017;43(3):1037-1051.

[3]. Inhibitory Effects of Copiamycin A, a Macrocyclic Lactone Antibiotic, on Gastric H+,K(+)-ATPase, Acid Secretion and Ulcer Formation. Jpn J Pharmacol. 1991 Feb;55(2):283-6.

2-(2-Methyl-8-phenylmethoxy-3-imidazo[1,2-a]pyridyl)acetonitrile is an imidazopyridine compound.

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Background/Objective: Glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells involves glucose uptake and metabolism, closure of KATP channels and depolarization of the cell membrane potential (Vmem), activation of voltage-gated Ca2+ current (ICav) and Ca2+ influx, ultimately triggering hormone exocytosis. In addition to this classical pathway, KATP-independent mechanisms, such as changes in intracellular pH (pHi) or cell volume (which also affect β-cell viability), can also induce or regulate insulin release. In β-cells, pHi regulation is primarily accomplished by the Na+/H+ exchanger (NHE). In order to investigate whether there are other proton efflux mechanisms involved in pH regulation besides hydrogen hydride channels (NHE), we detected the presence of non-gastric H+/K+ ATPase in rat pancreatoma cells and evaluated the effects of the H+/K+ ATPase inhibitor SCH-28080 on insulin secretion, cell viability and apoptosis. [2] Methods: In INS-1E cell culture, the expression of H+/K+ ATPase genes and proteins was analyzed by reverse transcription PCR and Western blotting. The recovery of intracellular pH (pHi) after acute acid loading was determined by the NH4Cl prepulse method using BCEF. The amount of insulin secreted in the cell culture supernatant was determined by ELISA. Membrane potential (Vmem), K+ and Ca2+ currents were recorded using patch clamp technology. The overall cell response was determined by the rexazuri assay (cell viability) and cytotoxicity assay. Mean cell volume (MCV), cell granularity (side scatter; SSC), phosphatidylserine (PS) exposure, cell membrane integrity, caspase activity, and mitochondrial membrane potential (ΔΨm) were determined by flow cytometry. [2] Results: We found that the α subunit (HKα2) of non-gastric H+/K+ ATPase was expressed at both the mRNA and protein levels. However, the mRNA abundance of this subunit was very low in INS-1E cells compared with rat colon tissue. In the NH4Cl prepulse experiment, no K+-dependent intracellular pH recovery was observed under Na+-free extracellular conditions. Nevertheless, 20 µM SCH-28080 inhibited glucose-stimulated insulin secretion (GSIS) by about 50% within 1 hour, while basal insulin release was unaffected. The L-type ICav blocker nifedipine completely inhibited GSIS at concentrations of 10 and 20 µM. At a concentration of 20 µM, SCH-28080 exhibited inhibitory effects on ICav comparable to 20 µM nifedipine. Furthermore, it enhanced IKATP recorded at -60 mV and hyperpolarized Vmem by approximately 15 mV. Treatment with SCH-28080 for 2 h and 24 h resulted in dose-dependent inhibition of cell viability, with IC50 values of 22.9 µM and 15.3 µM, respectively. At a concentration of 20 µM, the percentages of Annexin-V+, caspase+, and propidium iodide+ cells significantly increased after 24 h and 48 h. Simultaneously, MCV was significantly decreased (apoptotic volume reduction, AVD), while SSC signaling was enhanced. At concentrations above 40–50 µM, the cytotoxicity of SCH-28080 gradually increased, leading to a sharp increase in the number of necrotic cells within 2 hours after treatment and disruption of mitochondrial membrane potential (ΔΨm) within 4 hours at concentrations of 50 and 100 µM, while concentrations of 10 and 20 µM had no effect on ΔΨm within 24 hours. [2] Conclusion: We confirmed the expression of HKα2 in rat INS-1E cells. However, the pump appeared to be nonfunctional under given conditions. Nevertheless, the H+/K+ ATPase blocker SCH-28080 still inhibited insulin secretion and induced cell death. Importantly, we found that SCH-28080 inhibited ICav and activated KATP channels, suggesting that these are novel off-targets of the inhibitor, leading to hyperpolarization of membrane potential (Vmem) and inhibition of insulin secretion.

C17H15N3O

277.3205

277.122

C, 73.63; H, 5.45; N, 15.15; O, 5.77

76081-98-6

108137

Light yellow to brown solid powder

1.16g/cm3

1.615

3.287

0

3

4

21

385

0

PYKJFEPAUKAXNN-UHFFFAOYSA-N

InChI=1S/C17H15N3O/c1-13-15(9-10-18)20-11-5-8-16(17(20)19-13)21-12-14-6-3-2-4-7-14/h2-8,11H,9,12H2,1H3

Imidazo(1,2-a)pyridine-3-acetonitrile, 2-methyl-8-(phenylmethoxy)-

SCH28080; SCH-28080; 76081-98-6; Sch 28080; Sch-28080; 2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine-3-acetonitrile; SCH28080; Schering compound 28080; S28080; 2-(8-(benzyloxy)-2-methylimidazo[1,2-a]pyridin-3-yl)acetonitrile; SCH 28080.

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 : ~100 mg/mL (~360.59 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (9.01 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 (9.01 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in 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 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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 (Please use freshly prepared in vivo formulations for optimal results.)