ATPase Inhibitory Activity Research Articles

Robustanic acid as a glutaminase and Na+, K+-ATPase inhibitor from leaves of Eucalyptus globulus.

This study was to compare glutaminase and Na+, K+-ATPase inhibitory activities of 20 herbal extracts and investigate the isolation, structural elucidation and those inhibitory activities of three triterpenes from the selected extract of Eucalyptus globulus Labill. Three triterpenes, ursolic acid (1), robustanic acid (2) and ursolic acid lactone (3), were identified by analyzing their NMR and MS spectral data and comparison of these with reported data. The IC50 values of 1-3 and the control compound against glutaminase, 6-diazo-5-oxo-l-norleucine (DON), were 443 μM, 334 μM, 963 μM and 134 μM, respectively. The IC50 values of 1, 2 and the control compound against Na+, K+-ATPase and ouabain, were 180 μM, 56 μM and 0.5 μM, respectively. Compounds 1 and 2 may serve as potential lead compounds for the prevention and treatment of neurodegenerative and lifestyle-related diseases by targeting glutaminase and Na+, K+-ATPase. This is the first report on glutaminase and Na+, K+-ATPase inhibitory activities of 2.

Combination of Chromatographic Analysis and Chemometric Methods with Bioactivity Evaluation of the Antibacterial Properties of Helichrysum italicum Essential Oil.

Helichrysum italicum (immortelle) essential oil is one of the most popular essential oils worldwide and it has many beneficial properties, including antimicrobial. However, in this plant, the chemical diversity of the essential oil is very pronounced. The aim of this work was to process the GC-MS results of four samples of H. italicum essential oil of Serbian origin by chemometric tools, and evaluate the antimicrobial activity in vitro and in silico. Overall, 47 compounds were identified, the most abundant were γ-curcumene, α-pinene, and ar-curcumene, followed by α-ylangene, neryl acetate, trans-caryophyllene, italicene, α-selinene, limonene, and italidiones. Although the four samples of H. italicum essential oil used in this study were obtained from different producers in Serbia, they belong to the type of essential oil rich in sesquiterpenes (γ-curcumene and ar-curcumene chemotype). In vitro antimicrobial potential showed that five were sensitive among ten strains of tested microorganisms: Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Saccharomyces cerevisiae, and Candida albicans. Therefore, these microorganism models were used further for in silico molecular docking through the mechanism of ATP-ase inhibitory activity. Results showed that among all compounds from H. italicum essential oil, neryl acetate has the highest predicted binding energy. Artificial neural network modeling (ANN) showed that two major compounds γ-curcumene and α-pinene, as well as minor compounds such as trans-β-ocimene, terpinolene, terpinene-4-ol, isoitalicene, italicene, cis-α-bergamotene, trans-α-bergamotene, italidiones, trans-β-farnesene, γ-selinene, β-selinene, α-selinene, and guaiol are responsible for the antimicrobial activity of H. italicum essential oil. The results of this study indicate that H. italicum essential oil samples rich in γ-curcumene, α-pinene, and ar-curcumene cultivated in Serbia (Balkan) have antimicrobial potential both in vitro and in silico. In addition, according to ANN modeling, the proportion of neryl acetate and other compounds detected in these samples has the potential to exhibit antimicrobial activity.

Highly Selective SERCA2a Activators: Preclinical Development of a Congeneric Group of First-in-Class Drug Leads against Heart Failure.

The stimulation of sarcoplasmic reticulum calcium ATPase SERCA2a emerged as a novel therapeutic strategy to efficiently improve overall cardiac function in heart failure (HF) with reduced arrhythmogenic risk. Istaroxime is a clinical-phase IIb compound with a double mechanism of action, Na+/K+ ATPase inhibition and SERCA2a stimulation. Starting from the observation that istaroxime metabolite PST3093 does not inhibit Na+/K+ ATPase while stimulates SERCA2a, we synthesized a series of bioisosteric PST3093 analogues devoid of Na+/K+ ATPase inhibitory activity. Most of them retained SERCA2a stimulatory action with nanomolar potency in cardiac preparations from healthy guinea pigs and streptozotocin (STZ)-treated rats. One compound was further characterized in isolated cardiomyocytes, confirming SERCA2a stimulation and in vivo showing a safety profile and improvement of cardiac performance following acute infusion in STZ rats. We identified a new class of selective SERCA2a activators as first-in-class drug candidates for HF treatment.

Design, synthesis and biological evaluation of novel 5-methyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazole derivatives as potent potassium-competitive acid blockers

With the aim to discover a novel potent potassium-competitive acid blocker (P-CAB) agent, a series of 5-methyl-2,4,5,6-tetrahydropyrrolo[3,4–c]pyrazole 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 3′-((3-(2-fluorophenyl)-5-methyl-5,6-dihydropyrrolo[3,4–c]pyrazol-2(4H)-yl)methyl)-[1,1′-biphenyl]-3-carboxamide not only exhibited potent H+/K+-ATPase inhibitory activity but olso showed potent inhibitory action in vivo on histamine-stimulated gastric acid secretion. In addition, the lead compound displayed favourable oral pharmacokinetic properties in rats, which was worthy of further study as a novel P-CAB agent.

Synthesis and Pharmacological Evaluation of Novel Benzimidazole Derivatives as Antiulcer and H+ K+ ATPase Inhibitor

Aims: To Synthesis the novel substituted benzimidazole derivatives and screened Pharmacologically as antiulcer and H+ K+ ATPase inhibitor.
 Study Design: Study design as series of substituted benzimidazole derivatives prepared by three different reaction scheme and further evaluated pharmacologically in desired activity.
 Place and Duration of Study: In Patal Dhamal Wadwani College of Pharmacy Yavatmal, Maharashtra, India, between July 2014 to August 2017.
 Methodology: A series of new 2-[(substituted-pyrimidin-4-yl) sulfinyl]-1H-benzimidazole (54a-54i) were synthesized by the condensation of O-phenylenediamine, KOH and CS2 resulting potassium 1-H-benzimidazole 2-thiolate further treated with glacial acetic acid gives 1H-benzimidazole 2- thiol (2-mercaptobenzimidazole). 4-Chloro 2 Methyl, 6-Alkylpyrimidine- 4-ol prepared by ethanimidamide and alkyl acetoacetate gives 2-Methyl, 6-Alkylpyrimidine-4-ol by chlorination using thionyl chloride 4-Chloro 2 Methyl, 6-Alkylpyrimidine- 4-ol was obtained. further reacted with sodium oxide followed by m-chloroperbenzoic finally gives 2-[(substituted-pyrimidin-4-yl) sulfinyl]-1H-benzimidazole. Structural characterization of these synthesized compounds was confirmed by FT-IR, 1HNMR, and Mass spectral data. Later synthesized derivatives evaluated for their antiulcer and H+ K+ ATPase inhibitory activity by aspirin induced method and assays of H+/K+-ATPase activity respectively.
 Results: Compound 54c (74.03%), 54f (72.87%) and 54i (75.15%) shows highly significant antiulcer activity compared to standard drug and compound 54c (88.88 %), 54d (91.03 %), 54f (86.48%) and 54g (84.21%) shows highly significant antisecretory activity when compare to standard drug.
 Conclusion: Our research work provokes further to work for development of different derivatives of 2-(pyrimidinyl-sulfinyl) benzimidazole which have lesser side effect and better action than few of marketed drugs.

Chemical cues that attract cannibalistic cane toad (Rhinella marina) larvae to vulnerable embryos

Chemical cues produced by late-stage embryos of the cane toad (Rhinella marina) attract older conspecific larvae, which are highly cannibalistic and can consume an entire clutch. To clarify the molecular basis of this attraction response, we presented captive tadpoles with components present in toad eggs. As previously reported, attractivity arises from the distinctive toxins (bufadienolides) produced by cane toads, with some toxins (e.g., bufagenins) much stronger attractants than others (e.g., bufotoxins). Extracts of frozen toad parotoid glands (rich in bufagenins) were more attractive than were fresh MeOH extracts of the parotoid secretion (rich in bufotoxins), and purified marinobufagin was more effective than marinobufotoxin. Cardenolide aglycones (e.g., digitoxigenin) were active attractors, whereas C-3 glycosides (e.g., digoxin, oubain) were far less effective. A structure–activity relationship study revealed that tadpole attractant potency strongly correlated with Na+/K+ ATPase inhibitory activity, suggesting that tadpoles monitor and rapidly react to perturbations to Na+/K+ ATPase activity.

IN VITRO ANTI-ULCER ACTIVITY OF DIFFERENT EXTRACTS OF CISSUS QUADRANGULARIS

Aim:The aim of this study was undertaken to assessin vitro H+-K+ ATPase inhibitory activity of different extracts of Cissus quadrangularis Linn. Materials and Methods: Phytochemical and Phyto-analytical studies like total phenolic compound and total flavonoid contents from extract were quantified and H+-K+ ATPase inhibition assay was performed in presence of different concentrations(10,20,50 and 100 μg/ml) of standard (omeprazole),chloroform and methanolic extract. Results:The extract has shown dose dependent significant (*P < 0.05) proton pump inhibitory activity in the goat gastric mucosal homogenate which was compared to standard Omeprazole. Conclusions: Hence, from this study we have concluded that methanolic extract of C.quadrangularis has more inhibitory effect than chloroform extract.

Design, synthesis, and evaluation of a novel prodrug, a S-trityl-l-cysteine derivative targeting kinesin spindle protein.

Kinesin spindle protein (KSP) is expressed only in cells undergoing cell division, and hence represents an attractive target for the treatment of cancer. Several KSP inhibitors have been developed and undergone clinical trial, but their clinical use is limited by their toxicity to rapidly proliferating non-cancerous cells. To create new KSP inhibitors that are highly selective for cancer cells, we optimized the amino acid moiety of S-trityl-l-cysteine (STLC) derivative 1 using in silico modeling. Molecular docking and molecular dynamics simulation were performed to investigate the binding mode of 1 with KSP. Consistent with the structure activity relationship studies, we found that a cysteine amino moiety plays an important role in stabilizing the interaction. Based on these findings and the structure of GSH, a substrate of γ-glutamyltransferase (GGT), we designed and synthesized the prodrug N-γ-glutamylated STLC derivative 9, which could be hydrolyzed by GGT to produce 1. The KSP ATPase inhibitory activity of 9 was lower than that of 1, and LC-MS analysis indicated that 9 was converted to 1 only in the presence of GGT invitro. In addition, the cytotoxic activity of 9 was significantly attenuated in GGT-knockdown A549cells. Since GGT is overexpressed on the cell membrane of various cancer cells, these results suggest that compound 9 could be a promising prodrug that selectively inhibits the proliferation of GGT-expressing cancer cells.

Identification of New Hsp90 Inhibitors: Structure Based Virtual Screening, Molecular Dynamic Simulation, Synthesis and Biological Evaluation.

Heat shock protein90 (Hsp90) is overexpressed in tumor cells, thus the inhibition of the Hsp90 ATPase activity would be a meaningfully effective strategy in cancer therapy. The present work was aimed at four steps: designing new Hsp90 inhibitors as anti-cancer by a virtual screening study; synthesize designed compounds; biological evaluation of them and finally molecular dynamic (MD) simulations of best compounds. A virtual screening study was performed on a library (100 compounds) of the ZINC database with benzimidazole scaffold; then an extracted compound and two derivatives were synthesized. The anti-proliferative and ATPase inhibitory activities of these compounds were evaluated by MTT and ATPase inhibition assays, respectively. The western blot analysis was performed to the evaluation of the expression level of Hsp70 and Her2 proteins. Finally, 200 ns molecular dynamic simulation was carried out to confirm the stability of the strongest synthesized compound in Hsp90 active site. ZINC00173501 compound with an aminobenzimidazole scaffold was chosen by the virtual screening study. ZINC00173501 compound and two of its derivatives were synthesized. ATPase inhibitory activity of three synthesized compounds shown that ZINC00173501 compound was the most potent inhibitor (IC50= 8.6 μM) with the anti-proliferative activity 14.41 μM, 19.07 μM and more than 100 μM against MCF-7, HeLa and HUVEC cell lines, respectively. The high level of Hsp70 expression and low level of Her2 expression confirmed ZINC00173501 as an Hsp90 inhibitor. Finally, molecular dynamics simulation showed that ZINC00173501 was stable in Hsp90 active site during 200 ns simulation. The biological evaluation results show that 2-aminobenzimidazole scaffold could be suggested as a lead for inhibition of Hsp90.

Engineering Bafilomycin High-Producers by Manipulating Regulatory and Biosynthetic Genes in the Marine Bacterium Streptomyces lohii.

Bafilomycin A1 is the representative compound of the plecomacrolide natural product family. This 16-membered ring plecomacrolide has potent antifungal and vacuolar H+-ATPase inhibitory activities. In our previous work, we identified a bafilomycin biosynthetic gene cluster (baf) from the marine bacterium Streptomyces lohii ATCC BAA-1276, wherein a luxR family regulatory gene orf1 and an afsR family regulatory gene bafG were revealed based on bioinformatics analysis. In this study, the positive regulatory roles of orf1 and bafG for bafilomycin biosynthesis are characterized through gene inactivation and overexpression. Compared to the wild-type S. lohii strain, the knockout of either orf1 or bafG completely abolished the production of bafilomycins. The overexpression of orf1 or bafG led to 1.3- and 0.5-fold increased production of bafilomycins, respectively. A genetically engineered S. lohii strain (SLO-08) with orf1 overexpression and inactivation of the biosynthetic genes orf2 and orf3, solely produced bafilomycin A1 with the titer of 535.1 ± 25.0 mg/L in an optimized fermentation medium in shaking flasks. This recombinant strain holds considerable application potential in large-scale production of bafilomycin A1 for new drug development.

Synthesis and evaluation of Na+/K+-ATP-ase inhibiting and cytotoxic in vitro activities of oleandrigenin and its selected 17β-(butenolidyl)- and 17β-(3-furyl)- analogues

Natural cardiac-active principles built upon the 14,16β-dihydroxy-5β,14β-androstane core and bearing a heterocyclic substituent at 17β, in particular, a cardenolide - oleandrin and a bufadienolide - bufotalin, are receiving a great deal of attention as potential anticancer drugs. The densely substituted and sterically shielded ring D is the particular structural feature of these compounds. The first synthesis of oleandrigenin from easily available steroid starting material is reported here. Furthermore, selected 17β-(4-butenolidyl)- and 17β-(3-furyl)-14,16β-dihydroxy-androstane derivatives were en route synthesized and examined for their Na+/K+-ATP-ase inhibitory properties as well as cytotoxic activities in normal and cancer cell lines. It was found that the furyl-analogue of oleandrigenin/bufatalin (7) and some related 17-(3-furyl)- derivatives (19, 21) show remarkably high Na+/K+-ATP-ase inhibitory activity as well as significant cytotoxicity in vitro. In addition, oleandrigenin 2 compared to derivatives 21 and 25 induced strong apoptosis in human cervical carcinoma HeLa cells after 24 h of treatment.

Design, Synthesis and Pharmacological Evaluation of Novel Imidazopyridine Analogues as Proton Pump Antagonist

A series of novel imidazopyridine derivatives as proton pump inhibitors was designed with compounds of CID data base and explored considering AZD0865 as standard. Many compounds were identified and docked in proton pump ATPase pocket (PDB ID: 4ux2). Molecular docking studies revealed that many compounds showed good proton pump ATPase inhibitory activity. The docking poses revealed the interaction of ligands with amino acid. The standard drug AZD0865 had docking score of -7.112302 and displayed interactions with Asn138 and Asp137. A series of novel imidazopyridine derivatives as proton pump inhibitors were docked, synthesized and characterized by IR, NMR, CHN and MS spectral analysis. The target imidazopyridines were prepared from substituted 2-aminonicotinic acid and 2-bromo-1-substituted ethanone. in vitro Studies explained that few compounds exhibited moderate to good proton pump ATPase inhibitory activity in comparison with the reference drugs i.e. AZD0865. Compounds 11 and 12 shown higher activities with the IC50 4.3. Compounds 1, 4, 6, 7, 8, 10 and 13 showed weak anti-ulcer activity with its IC50 5.2, 5.8, 5.5, 5.1, 4.9, 4.6 and 5.9 and positive control AZD0865 shown IC50 2.0.

Bufadienolides from the whole plants of Helleborus foetidus and their cytotoxicity

Two undescribed bufadienolide glucosides and four undescribed bufadienolides were isolated from the whole plants of Helleborus foetidus (Ranunculaceae). Their structures were determined by extensive spectroscopic analysis and the results of hydrolytic cleavage. The isolated compounds exhibited cytotoxic activities against HL-60 and A549 cells with IC50 values ranging from 0.019 to 3.0 μM. The isolated compounds also showed the Na+/K+ ATPase inhibitory activity. The undescribed compound 16β-formyloxy-10,14-dihydroxy-5β-[(β-d-glucopyranosyl)oxy]-19-norbufa-3,20,22-trienolide induced apoptosis in HL-60 cells through a mitochondria-dependent apoptotic pathway.

Design and Synthesis of Novel Imidazopyridine Analogues and Evaluation as H+/K+-ATPase Antagonist

CID data base were explored considering AZD0865 as standard and docked in proton pump ATPase pocket (PDB ID: 4ux2) to find out novel imidazopyridine derivatives as proton pump inhibitors. A number of compounds showed good proton pump ATPase inhibitory activity as per the molecular docking study as compared to standard compound AZD0865. The compound AZD0865showed a docking score of -7.11 and revealed the interactions with amino acids Asn 138 and Asp 137. A series of novel imidazopyridine derivatives as proton pump inhibitors were docked, synthesized and characterized by IR, NMR, CHN and MS spectral analysis. The target imidazopyridines were prepared from the intermediate substituted 2-aminonicotinic acid and 2-bromo-1-substituted ethanone. in vitro pharmacological studies explained that some compounds exhibited moderate to good proton pump ATPase inhibitory activity in comparison with the reference drugs i.e. AZD0865. Compound N-(3-(aminomethyl)benzyl)-3-(benzylamino)-2-(o-tolyl)imidazo[1,2-a]pyridine-8-carboxamide and N-(3-(aminomethyl)benzyl)-3-(benzylamino)-2-(4-ethylphenyl)imidazo[1,2-a]pyridine-8-carboxamide showed higher activities with the IC50 6.2 and 6.0 μg. Many compounds showed IC50 as weak antiulcer activity as compared to positive control AZD0865.

Protective effect of the solvent extracts of Portulacca oleracea against acidified ethanol induced gastric ulcer in rabbits

Portulacca oleracea L. has been used for treatment of different ailments. The aim of this study was to investigate the effectiveness and possible mechanism of action involved in the anti gastric ulcerogenic effect of Portulacca oleracea. Methanolic extract & subsequent fractions (100, 200 and 400 mg/kg) of Portulacca oleracea (P. oleracea) were administered orally to experimental rabbits one hour before oral administration of HCl/ethanol (40:60). Anti gastric ulcerogenic potential of P. oleracea was evaluated by assessment of gastric pH, pepsin, free acidity, ulcer index, mucus content and total acidity. For the investigation of possible mechanism of action malondialdehyde (MDA), histamine, and H + K + ATPase content were determined in the stomach homogenate. Histopathological study of stomach tissue was carried out by H&E dye. Ethyl acetate fraction (EAF) of P. oleracea was the most potent fraction among all fractions that exhibited efficient protection against acidified ethanol mediated gastric-ulcer. The ethyl acetate fraction (EAF) significantly increased the pH of gastric juice, while pepsin and histamine was observed to decrease significantly in comparison to acidified ethanol group (***p ≤ 0.001). The EAF showed moderately H + K + ATPase inhibitory activity. Moreover, it was also observed that EAF decreased the malondialdehyde (MDA) level in the stomach tissue homogenate showing antioxidant effect. Histopathological studies showed that among the tested fractions, EAF significantly prevented acidified ethanol induced gastric mucosal damage. These results showed that mechanism of anti gastric ulcerogenic potential of P. oleracea could be associated with the reduction in histamine level, H + K + ATPase inhibition and reduced MDA level.

Quantitative Structure-Activity Relationship and Docking Studies on a series of H+/K+-ATPase inhibitors

Background: The Gastric H+/K+-ATPase is also known as proton pump is the enzyme responsible for the acidification of gastric juice. H+/K+ GastroEsophageal Reflux Disease (GERD) and other acid related diseases mainly depend on the inhibition of the gastric H+/K+- ATPase which will finally result in acid secretion in stomach. GERD is one of the diseases that have significant effect on the quality of human life and are the major burden on health care systems is that leads to heart burn, acid regurgitation, chest pain, epigastric pain, and respiratory conditions such as chronic cough. Hence the study of the inhibitors of Gastric H+/K+-ATPase is desired. Methods: Research and online content related to imidazo [1, 2-a]pyrazine and heterocyclic ring analogues (I) that were synthesized and evaluated for their Gastric H+/K+-ATPase inhibitory activity is reviewed, and in order to design and develop still better and more effective H+/K+-ATPase inhibitors, we have made Quantitative Structure Activity Relationship (QSAR), docking and ADMET studies on these compounds. Results: The best MLR equation based on four descriptors along with statistical parameters is obtained using Statistica dataminer software. Using the model expressed by this study we predicted some new compounds of high H+/K+-ATPase inhibition potency. Each predicted compound has very high potency with which only a few compounds of existing series can match. Conclusion: The QSAR and molecular modelling studies suggested that still better compounds can be designed if the flexibility of the molecules can be increased for which attempts can be made to have more saturated atoms in the molecules. Such a compound predicted by us was found to have interactions with the enzyme H+/K+-ATPase almost in the same manner as the FDA approved compounds, lansoprazole, pantaprazole.

Synthesis and evaluation of cytotoxic and Na+/K+-ATP-ase inhibitory activity of selected 5α-oleandrigenin derivatives

Oleandrin, the major biologically active constituent of shrub Nerium oleander preparations of which have been used in traditional Mediterranean and Asian medicine, attracts a great deal of attention due to its pronounced anticancer activity. The synthesis of oleandrigenin model, 16β-hydroxy-3β-methoxy-5α-card-20(22)-enolide 16-acetate, from androstenolone acetate through 17β-(3-furyl)-intermediates has been developed. Several related 17β-(butenolidyl)- and 17β-(furyl)-androstane derivatives were synthesized and tested for in vitro cytotoxic and Na+/K+-ATP-ase inhibitory activities. Comparison of Na+/K+-ATP-ase inhibitory and cytotoxic activity underlines complex nature of the relationship.

Antioxidant and proton potassium ATPase inhibitory activity in fruits

In the present study fruits such as Kiwi, Persimmon, Pomegranate, Dragon and Noni were screened for their antioxidant activity and H+K+ ATPase inhibitory activity. Among various mechanisms involved in the formation of gastric ulcers, free radicals generated during stress are one of the major causative factors for the gastric lesion through oxidative damage. Thus the best approach to control gastric ulcer would be to inhibit oxidative damage and acid secretion induced by the enzyme. The proton potassium ATPase inhibitory and antioxidant activity of aqueous and acetone extracts of five different fruits were investigated. The fruits were subjected to phytochemical investigations, antioxidant activity and enzyme inhibition. Among the various fruits screened Noni fruit showed 96.5% enzyme inhibition with considerable amount of phenolics and flavonoids. It showed 80% of free radical scavenging activity and 50% of anti-lipid peroxidation activity.

Antioxidant and proton potassium ATPase inhibitory activity in fruits

Antioxidant and proton potassium ATPase inhibitory activity in fruits

Oxidation of flavonolignan silydianin to unexpected lactone-acid derivative

One of the main flavonolignans from silymarin, an extract of the fruits of the milk thistle (Silybum marianum), is silydianin possessing an unusual bicyclic structure with the keto group next to the hemiacetal moiety. As its oxidation product 2,3-dehydrosilydianin was found to display strong chemoprotective activity and Na+/K+ ATPase inhibitory activity, the present work aims at the optimization of silydianin oxidation. The isolated yield of the optimized reaction was improved from 10 to 22% in a considerably shorter reaction time (24 vs. 192 h). The formation of a new compound, a lactone-acid, was observed during the optimization experiments. The structure of this new compound was elucidated and its antioxidant activity compared with those of silydianin and 2,3-dehydrosilydianin. Moreover, the high resolution crystal structure of silydianin is shown here for the first time.