ATPase Inhibitory Activity Research Articles

Novel, potent, orally bioavailable and selective mycobacterial ATP synthase inhibitors that demonstrated activity against both replicating and non-replicating M. tuberculosis

The mycobacterial F0F1-ATP synthase (ATPase) is a validated target for the development of tuberculosis (TB) therapeutics. Therefore, a series of eighteen novel compounds has been designed, synthesized and evaluated against Mycobacterium smegmatis ATPase. The observed ATPase inhibitory activities (IC50) of these compounds range between 0.36 and 5.45μM. The lead compound 9d [N-(7-chloro-2-methylquinolin-4-yl)-N-(3-((diethylamino)methyl)-4-hydroxyphenyl)-2,3-dichlorobenzenesulfonamide] with null cytotoxicity (CC50>300μg/mL) and excellent anti-mycobacterial activity and selectivity (mycobacterium ATPase IC50=0.51μM, mammalian ATPase IC50>100μM, and selectivity >200) exhibited a complete growth inhibition of replicating Mycobacterium tuberculosis H37Rv at 3.12μg/mL. In addition, it also exhibited bactericidal effect (approximately 2.4log10 reductions in CFU) in the hypoxic culture of non-replicating M. tuberculosis at 100μg/mL (32-fold of its MIC) as compared to positive control isoniazid [approximately 0.2log10 reduction in CFU at 5μg/mL (50-fold of its MIC)]. The pharmacokinetics of 9d after p.o. and IV administration in male Sprague–Dawley rats indicated its quick absorption, distribution and slow elimination. It exhibited a high volume of distribution (Vss, 0.41L/kg), moderate clearance (0.06L/h/kg), long half-life (4.2h) and low absolute bioavailability (1.72%). In the murine model system of chronic TB, 9d showed 2.12log10 reductions in CFU in both lung and spleen at 173μmol/kg dose as compared to the growth of untreated control group of Balb/C male mice infected with replicating M. tuberculosis H37Rv. The in vivo efficacy of 9d is at least double of the control drug ethambutol. These results suggest 9d as a promising candidate molecule for further preclinical evaluation against resistant TB strains.

Synthesis and Characterization of Triazole-Linked Bistetrahydrobenzofuran Derivatives as Anti-Ulcer Agents

A pair of triazole-linked bistetrahydrobenzofuran derivatives were prepared in high yields through Cu (II)-catalyzed click reaction under mild conditions. All of the intermediates and target compounds were characterized by NMR, IR, ESI-MS and elemental analysis. Thein vitroH+/K+-ATPase inhibitory effect for the target compounds were also evaluated by MTT methods, and the (E)-isomer of the bistetrahydrobenzofurans exhibited the better H+/K+-ATPase inhibitory activities than the commercial omeprazole with the IC50of 37.90 μM. The bioactive compound might be potentially used as anti-ulcer agents in the treatment of acid-related diseases.

Structures, chemotaxonomic significance, cytotoxic and Na(+),K(+)-ATPase inhibitory activities of new cardenolides from Asclepias curassavica.

Five new cardenolide lactates (1–5) and one new dioxane double linked cardenolide glycoside (17) along with 15 known compounds (6–16 and 18–21) were isolated from the ornamental milkweed Asclepias curassavica. Their structures were elucidated by extensive spectroscopic methods (IR, UV, MS, 1D- and 2D-NMR). The molecular structures and absolute configurations of 1–3 and 17 were further confirmed by single-crystal X-ray diffraction analysis. Simultaneous isolation of dioxane double linked cardenolide glycosides (17–21) and cardenolide lactates (1–5) provided unique chemotaxonomic markers for this genus. Compounds 1–21 were evaluated for the inhibitory activities against DU145 prostate cancer cells. The dioxane double linked cardenolide glycosides showed the most potent cytotoxic effect followed by normal cardenolides and cardenolide lactates, while the C21 steroids were non-cytotoxic. Enzymatic assay established a correlation between the cytotoxic effects in DU145 cancer cells and the Ki for the inhibition of Na(+),K(+)-ATPase. Molecular docking analysis revealed relatively strong H-bond interactions between the bottom of the binding cavity and compounds 18 or 20, and explained why the dioxane double linked cardenolide glycosides possessed higher inhibitory potency on Na(+),K(+)-ATPase than the cardenolide lactate.

ChemInform Abstract: Synthesis, Structure and H+/K+‐ATPase Inhibitory Activity of Novel Triazolyl Substituted Tetrahydrobenzofuran Derivatives via One‐Pot Three‐Component Click Reaction.

AbstractA CuI‐catalyzed three‐component alkyne‐azide cycloaddition in the presence of an excess of secondary amine is used for the synthesis of triazolyl‐substituted tetrahydrobenzofuran derivatives.

C23 Steroids from the Venom of Bufo bufo gargarizans

Five new C23 steroids (1-5) together with five known bufadienolides (6-10) were isolated from the venom of Bufo bufo gargarizans (ChanSu in Chinese). The structures of the new steroids were elucidated by extensive spectroscopic methods in combination with X-ray diffraction analysis. Among these C23 steroids, only compound 3 showed cytotoxicities against HepG2 and A549 cancer cells, with respective IC50 values of 26.8 ± 8.3 and 45.6 ± 2.5 μM. In contrast, the bufadienolides (7-10) displayed potent inhibitory activities against these cancer cells, with respective IC50 values in the ranges 0.5-5.5 and 0.6-6.5 μM, but relatively less cytotoxicity on normal mouse spleen cells. In addition, the Na(+)/K(+)-ATPase inhibitory activities of 2, 5, and 7 revealed that the lactone moiety of a bufadienolide was important for the inhibitory activity.

Synthesis, Structure and Gastric H<sup>+</sup>/K<sup>+</sup>-ATPase Inhibitory Activities of Bisabolonalone Hydrazone Carboxamides

Five novel bisabolonalone hydrazone carboxamides were synthesized as potential anti-ulcer agents. Their structures were characterized by NMR, IR and ESI-MS. All of the compounds possessed the better H+/K+-ATPase inhibitory activity than the commercial omeprazole with the IC50 of 18~68 μM in vitro. These compounds could be potentially use for the treatment of ulcer related diseases.

Synthesis and <i>In Vitro</i> Anti-Ulcer Effect of Bisabolangelone Oxime Ether Derivatives

Four bisabolangelone oxime ether derivatives were synthesized and separated as potential anti-ulcer agents. Their structures were characterized by NMR, IR and ESI-MS. Preliminarily H+/K+-ATPase activity evaluation indicated that all the target oxime ethers exhibited the better H+/K+-ATPase inhibitory activities than the commercial omeprazole with the IC50of 17~46 μM. These compounds might be used as potential anti-ulcer agents in the treatment of acid-related diseases.

Synthesis and Structure Elucidation of Novel Oxime Ether Type H/K+-ATPase Inhibitors

Six 6,6-dimethyl-2-phenyl-6,7-dihydrobenzofuran-4(5H)-one oxime derivatives were synthesized, characterized and evaluated as potential anti-ulcer agents. Most of the target compounds exhibited better H+/K+-ATPase inhibitory activity than commercial revaprazan, and both of the two O-propyl oxime ethers displayed the most potent activities with IC50˰̵̱̼͆̓ͅ˰̵̼̓̓˰̸̱̈́̾˰́̀˰μ̝˾ These compounds could be potentially used for the treatment of ulcer disease.

The H+/K+-ATPase inhibitory activities of Trametenolic acid B from Trametes lactinea (Berk.) Pat, and its effects on gastric cancer cells

Trametenolic acid B (TAB), the bioactive component in the Trametes lactinea (Berk.) Pat, was reported to possess cytotoxic activities and thrombin inhibiting effects. This study was performed to investigate the effects of TAB on H+/K+-ATPase and gastric cancer. The H+/K+-ATPase inhibitory activity was determined by gastric parietal cells. Compared to the normal control group, TAB (10, 20, 40 and 80μg/mL) inhibited the H+/K+-ATPase activity by 15.97, 16.96, 24.86 and 16.25%, respectively. In the study, 36 Kunming mice were randomly divided into six groups: control, model, TAB-L (TAB, 5mg/kg/day, i.g.), TAB-M (TAB, 20mg/kg/day, i.g.), TAB-H (TAB, 40mg/kg/day, i.g.) and omeprazole (OL, 10mg/kg/day, i.g.). All mice except the control group were administrated with anhydrous alcohol (5.0mL/kg, i.g.) for induced gastric-ulcer 1h after the 5th day. At the same time, the control mice were given the same volume of physiological saline. After 4h, TAB was evaluated for H+/K+-ATPase inhibitory activities of ulcerative gaster, gastric ulcer index and ulcer inhibition. In vitro, the anti-proliferation effect of TAB to gastric cancer cell (HGC-27) in acid environment was detected by MTT, and the apoptosis morphological changes were also observed by Hoechst 33258 dye assay. The results indicated that TAB inhibited moderately H+/K+-ATPase activity in vitro. Compared to the model group, TAB showed anti-ulcer effects in gastric tissue with the dosages of 20 and 5mg/kg in vivo. Apart from that, TAB could selectively inhibit gastric cancer cell viability and reduce cell apoptosis against HGC-27 cells at low doses in acid environment.

Synthesis, Structure and H+/K+‐ATPase Inhibitory Activity of Novel Triazolyl Substituted Tetrahydrobenzofuran Derivatives via One‐pot Three‐component Click Reaction

AbstractEleven triazolyl substituted tetrahydrobenzofuran derivatives were synthesized in high yields as novel H+/K+‐ATPase inhibitor via one‐pot CuI‐catalyzed three‐component click reaction of azide, secondary amine and 3‐bromopropyne under mild conditions in water. Their structures were characterized by NMR, IR, ESI‐MS, elemental analysis and single‐crystal X‐ray diffraction analysis. Most of the target compounds exhibited better H+/K+‐ATPase inhibitory activity than commercial omeprazole with IC50 values less than 15 µmol·L−1. The initial structure‐activity analysis suggested that the triazole substituted by cycloalkyl, aromatic ring or O‐containing side‐chain seemed to be beneficial for enhancing the activity.

In vitro antioxidant and H+, K+-ATPase inhibition activities of Acalypha wilkesiana foliage extract

Aims:The aim of this study was to evaluate the antioxidant activty and anti-acid property of Acalypha wilkesiana foliage extract.Materials and Methods:Hot and cold aqueous extracts were prepared from healthy leaves of A. wilkesiana. Free radical scavenging activity and H+, K+-ATPase inhibition activities of aqueous foliage extracts was screened by in vitro models.Statistical Analysis Used:All experiments were performed in triplicate and results are expressed as mean ± SEM.Results:A. wilkesiana hot aqueous extract (AWHE) showed significant antioxidants and free radical scavenging activity. Further, AWHE has shown a potent H+, K+-ATPase inhibitory activity (IC50: 51.5 ± 0.28 μg/ml) when compare to standard proton pump inhibitor omeprazole (56.2 ± 0.64 μg/ml); however, latter activity is equal to A. wilkesiana cold aqueous extract (AWCE). Quantitative analysis of AWHE has revealed more content of phenols and flavonoids; this is found to be the reason for good antioxidant activity over AWCE. Molecular docking was carried out against H+, K+-ATPase enzyme crystal structure to validate the anti-acid activity of A. wilkesiana major phytochemicals.Conclusions:The present study indicates that the constituents of AWHE and AWCE have good antacid and free radical scavenging activity.

Steroidal and Phenolic Glycosides from the Bulbs of Lilium pumilum DC and Their Potential Na+/K+ ATPase Inhibitory Activity

A new steroidal saponin, named pumilum A (1), and a new phenolic glycoside, threo-1-(4′-hydroxy-2′-methoxyphenyl)-2-(2′′,4′′-dihydroxyphenyl)-1,3-propanediol-4′-O-β-D-glucopyranoside (7) were isolated from the methanolic extract of the bulbs of Lilium pumilum DC, along with five known steroidal saponins. Their chemical structures were elucidated on the basis of detailed spectroscopic analysis, including 1D and 2D NMR techniques and chemical methods. In addition, the inhibitory activity of all the isolates on Na+/K+ ATPase was evaluated.

Discovery of a Novel Pyrrole Derivative 1-[5-(2-Fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methylmethanamine Fumarate (TAK-438) as a Potassium-Competitive Acid Blocker (P-CAB)

In our pursuit of developing a novel and potent potassium-competitive acid blocker (P-CAB), we synthesized pyrrole derivatives focusing on compounds with low log D and high ligand-lipophilicity efficiency (LLE) values. Among the compounds synthesized, the compound 13e exhibited potent H(+),K(+)-ATPase inhibitory activity and potent gastric acid secretion inhibitory action in vivo. Its maximum efficacy was more potent and its duration of action was much longer than those of proton pump inhibitors (PPIs). Therefore, compound 13e (1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methylmethanamine fumarate, TAK-438) was selected as a drug candidate for the treatment of gastroesophageal reflux disease (GERD), peptic ulcer, and other acid-related diseases.

Discovery, synthesis, and biological evaluation of novel pyrrole derivatives as highly selective potassium-competitive acid blockers

To discover a gastric antisecretory agent more potent than existing proton pump inhibitors, novel pyrrole derivatives were synthesized, and their H+,K+-ATPase inhibitory activities and inhibitory action on histamine-stimulated gastric acid secretion in rats were evaluated. Among the compounds synthesized, compound 17a exhibited selective and potent H+,K+-ATPase inhibitory activity through reversible and K+-competitive ionic binding; furthermore, compound 17c exhibited potent inhibitory action on histamine-stimulated gastric acid secretion in rats and Heidenhain pouch dogs.

In vitro Na+/K+-ATPase inhibitory activity and antimicrobial activity of sesquiterpenes isolated from Thujopsis dolabrata

A series of sesquiterpenes and hinokitiol-related compounds (1-15) was isolated from the essential oil of Thujopsis dolabrata Sieb. et Zucc. var. hondai Makino, and their structures were determined by combined spectroscopic analyses. The inhibitory effects of these compounds on microbial cell growth and Na(+)/K(+)-ATPase were evaluated in vitro. It was found that (-)-elema-1,3,11(13)-trien-12-ol (5), α,β,γ-costol (8), and chamigrenol (11) inhibit the activities of Na(+)/K(+)-ATPase, with IC(50) values of 11.2 ± 0.11, 12.2 ± 0.09, and 15.9 ± 0.54 μg/mL, respectively. Thujopsene (1), cedrol (9), γ-cuparenol (10), and chamigrenol (11) showed potent antibacterial activity, with MIC values in the range of 25-50 μg/mL, and β-thujaplicin (12) exhibited a broad spectrum of antibacterial and antifungal activity. These results indicate that these isolated compounds are promising candidates for the development of potent Na(+)/K(+) ATPase inhibitors and antimicrobial agents.

Gastroprotective effect of anti-cancer compound rohitukine: possible role of gastrin antagonism and H+ K+-ATPase inhibition

The present study was designed to evaluate the anti-ulcerogenic properties of an alkaloid chromane, rohitukine from Dysoxylum binectariferum. Anti-ulcer potential of rohitukine was assessed in cold restrained, pyloric ligated and ethanol induced ulcers in rats. In addition, rohitukine was tested in vitro for H(+) K(+)-ATPase inhibitory activity in gastric microsomes. Moreover, we studied the role of rohitukine on the cytosolic concentration of Ca(2+) in parietal cell-enriched cell suspension in order to ascertain its mechanism of action. Cytoprotective activity was evaluated through PGE(2) level. Rohitukine significantly attenuated the ulcers in cold restraint ulcer (CRU) model in a dose-related manner. Moreover, it significantly lowered the free acidity and pepsin activity in pyloric ligated rats while improved the depleted level of mucin. Furthermore, rohitukine significantly reversed the cold restrained-induced increase in gastrin level. Our in vitro study revealed that rohitukine moderately inhibited the microsomal H(+) K(+)-ATPase activity with respect to positive control omeprazole. Furthermore, rohitukine potently antagonized the gastrin-elicited increase in cytosolic Ca(2+) level in parietal cell-enriched suspension. In ethanol-induced gastric lesions in rats, rohitukine significantly inhibited the formation of erosions and increased PGE(2) content showing more potency than reference drug sucralfate. Our results thus suggest that rohitukine possess significant anti-ulcer and anti-gastrinic activity in rats. It is likely that gastro-protective influences of rohitukine are dependent partly on its acid-lowering potential and partly on cytoprotective property. The acid-reducing effect of rohitukine might be attributed to its lowering effect on gastrin production and/or antagonism of gastrin-evoked functional responses of parietal cells. Thus, rohitukine represent a useful agent in the treatment of peptic ulcer disease.

Synthesis, biological evaluation, and molecular docking study of 3-(3′-heteroatom substituted-2′-hydroxy-1′-propyloxy) xanthone analogues as novel topoisomerase IIα catalytic inhibitor

Epoxide ring-opened xanthone derivatives were synthesized and tested for their topoisomerase inhibitory activity and cytotoxicity. Most of the compounds showed topo IIα specific inhibitory activity. To clarify the mechanism of action of these compounds, the most potent compound (compound 14) of the synthesized analogues was further studied by testing its ATPase inhibitory activity and through molecular docking experiments. The results showed that the topo IIα inhibitory activity of compound 14 was inversely proportional to ATP concentration. In the ATPase inhibitory test, ATP hydrolysis was reduced less efficiently by compound 14 (28.5 ± 4.6%) than novobiocin (60.4 ± 8.1%). Molecular docking study revealed compound 14 to have a stable binding pattern to the ATP-binding domain of human topo II.

Gastroprotective Effect of Ginger Rhizome (Zingiber officinale) Extract: Role of Gallic Acid and Cinnamic Acid in H+, K+‐ATPase/H. pylori Inhibition and Anti‐Oxidative Mechanism

Zinger officinale has been used as a traditional source against gastric disturbances from time immemorial. The ulcer-preventive properties of aqueous extract of ginger rhizome (GRAE) belonging to the family Zingiberaceae is reported in the present study. GRAE at 200 mg kg−1 b.w. protected up to 86% and 77% for the swim stress-/ethanol stress-induced ulcers with an ulcer index (UI) of 50 ± 4.0/46 ± 4.0, respectively, similar to that of lansoprazole (80%) at 30 mg kg−1 b.w. Increased H+, K+-ATPase activity and thiobarbituric acid reactive substances (TBARS) were observed in ulcer-induced rats, while GRAE fed rats showed normalized levels and GRAE also normalized depleted/amplified anti-oxidant enzymes in swim stress and ethanol stress-induced animals. Gastric mucin damage was recovered up to 77% and 74% in swim stress and ethanol stress, respectively after GRAE treatment. GRAE also inhibited the growth of H. pylori with MIC of 300 ± 38 μg and also possessed reducing power, free radical scavenging ability with an IC50 of 6.8 ± 0.4 μg mL−1 gallic acid equivalent (GAE). DNA protection up to 90% at 0.4 μg was also observed. Toxicity studies indicated no lethal effects in rats fed up to 5 g kg−1 b.w. Compositional analysis favored by determination of the efficacy of individual phenolic acids towards their potential ulcer-preventive ability revealed that between cinnamic (50%) and gallic (46%) phenolic acids, cinnamic acid appear to contribute to better H+, K+-ATPase and Helicobacter pylori inhibitory activity, while gallic acid contributes significantly to anti-oxidant activity.

6-alkylsalicylic acid analogues inhibit in vitro ATPase activity of heat shock protein 90

The molecular chaperone heat shock protein 90 (Hsp90) is responsible for maintaining the correct folding and stability of many signaling proteins. It is a promising target of cancer therapeutics and several other diseases, including neurodegenerative disease, nerve injuries, inflammation, and infection. In an effort to identify new Hsp90 inhibitors from natural sources using an in vitro ATPase inhibition assay, two 6-alkylsalicylic acid analogues, salaceyin A and B were identified from the culture extract of Streptomyces. Salaceyin A and B exhibited moderate ATPase inhibitory activities with IC(50) values of 68.3 and 65.2 μM, respectively. Binding of salaceyins to human Hsp90α was examined by competition binding experiments with ATP-Sepharose beads. However, the compounds exhibited no degradation activity of Hsp90 client proteins, Her2, c-Raf, or Akt.

Inhibition of gastric H+, K+-ATPase by novel thiazolidinone derivatives

In a program to identify new anti-ulcer compounds, a series of novel substituted thiazolidinone derivatives 5(a–j) were synthesized and screened for their in vitro H+, K+-ATPase inhibitory activity. The synthesized compounds were characterized by nuclear magnetic resonance (1H-NMR), liquid chromatography-mass spectrometry (LCMS) and fourier transform infrared (FTIR) analysis. We have briefly investigated the structure–activity relation (SAR) studies and reveal that the nature of position of the fluorine atom influences the anti-ulcer activity. Among the synthesized compounds 5b, 5c and 5e showed 4 and 10-fold higher H+, K+-ATPase activity when compared with those of other derivatives 5a, 5f, 5g and 5j, respectively. H+, K+-ATPase activity of 5b, 5c and 5e were comparable with those of known H+, K+-ATPase blocker lansoprazole which is a potential anti-ulcer drug.