Crystal structures of the gastric proton pump.

The gastric proton pump-the H+, K+-ATPase-is a P-type ATPase responsible for acidifying the gastric juice down to pH 1. This corresponds to a million-fold proton gradient across the membrane of the parietal cell, the steepest known cation gradient of any mammalian tissue. The H+, K+-ATPase is an important target for drugs that treat gastric acid-related diseases. Here we present crystal structures of the H+, K+-ATPase in complex with two blockers, vonoprazan and SCH28080, in the luminal-open state, at 2.8 Å resolution. The drugs have partially overlapping but clearly distinct binding modes in the middle of a conduit running from the gastric lumen to the cation-binding site. The crystal structures suggest that the tight configuration at the cation-binding site lowers the pK a value of Glu820 sufficiently to enable the release of a proton even into the pH 1 environment of the stomach.

A comparative study of chiral separation of proton pump inhibitors by supercritical fluid chromatography and high-performance liquid chromatography.

A comparative study of chiral separation of pantoprazole and rabeprazole is carried out using supercritical fluid chromatography and high-performance liquid chromatography. The columns used were Chiralpak IA and Chiralpak IE. The best mobile phase in supercritical fluid chromatography was carbon dioxide-0.2% triethylamine in methanol (60:40) and 0.1% triethylamine in n-hexane-ethanol (50:50) in high-performance liquid chromatography. For supercritical fluid chromatography, values of the retention factor of pantoprazole enantiomers were 3.97 and 4.88. These values for rabeprazole enantiomers were 6.10 and 7.52. The values of separation and resolution factor for pantoprazole and rabeprazole were 1.23 and 1.23 and 2.20 and 3.36, respectively. Similarly, for high-performance liquid chromatography, the values of retention factor for enantiomers of pantoprazole were 4.02 and 7.32. These values for rabeprazole enantiomers were 5.32 and 7.88, respectively. The values of separation and resolution factor for pantoprazole and rabeprazole were 1.82 and 1.48 and 9.22 and 6.58, respectively. A comparison was carried out, which confirmed supercritical fluid chromatography as the best method due to its fastness, eco-friendly, and inexpensiveness. The reported methods are effective, efficient, and reproducible and may be used to separate and identify pantoprazole and rabeprazole in any unknown samples.

Controlled release floating drug delivery system for proton pump inhibitors lansoprazole: In-vitro, In-vivo floating and pharmacokinetic evaluation.

Lansoprazole (LPZ) show poor bioavailability because of first pass effect and absorption factors. The floating delivery systems could reduce fluctuations in plasma drug concentration through maintaining desirable plasma drug concentration. The objective of present study was to enhance bioavailability despite first pass effect through continuous availability of drug from floating system. Gum tragacanth (GT) and itaconic acid (IA) based floating hydrogels (FH) were synthesized. Parameters optimized were; microwave radiation exposure time, pH, GT:IA ratio and concentration of the glutaraldehyde. Optimized FH were evaluated for entrapment efficiency (% EE), in-vitro release, FTIR, SEM, and in- vitro and in-vivo floating study. Finally, pharmacokinetic was evaluated in ulcer-induced SD rats. Grafting percentage, swelling ratio and %EE of LPZ was 115%, Ì´250% and 90%, respectively. Microwave radiation exposure time, pH of reaction medium, GT:IA ratios and cross linker concentration were 2 min, pH 5, ratios 2:1 and 0.02%, respectively. The optimized FH showed acceptable floating behavior. The X-ray images revealed that hydrogels remained floated over gastric contents up to 24 hours. The in-vitro release and pharmacokinetics revealed availability of LPZ upto to 24h in-vitro and in ulcer-induced SD rats, respectively. The present hydrogels based floating system of lansoprazole is capable to extend the gastric residence time upto 24 hours.

Inhibition of gastric H+,K+-ATPase by new dihydropyrazole derivative KYY-008.

The gastric proton pump (H+,K+-ATPase) responsible for the H+ secretion of gastric acid is an essential therapeutic target for acid-related diseases. H+,K+-ATPase belongs to a P2-type ATPase family. Here, we examined the effects of a newly synthesized dihydropyrazole derivative KYY-008 on the H+,K+-ATPase. KYY-008 concentration-dependently inhibited the enzyme activity of the ATPase in the membrane fractions prepared from isolated hog gastric mucosa and from human kidney HEK293 cells in which gastric H+,K+-ATPase is exogenously expressed. The IC50 values in these samples were 3.4 µM and 3.7 µM, respectively. In addition, KYY-008 significantly inhibited the H+,K+-ATPase-derived H+ uptake into the tightly sealed vesicles prepared from the hog gastric mucosa. In contrast, KYY-008 has no effect on the activities of other P2-type ATPases such as Na+,K+-ATPase and Ca2+-ATPase. KYY-008 did not change the ionic currents of voltage-dependent Ca2+ channels, that were potential targets for some dihydropyrazole derivatives. Together, we discovered a new dihydropyrazole derivative which acts as a selective inhibitor of gastric H+,K+-ATPase.

RGD-modified multifunctional nanoparticles encapsulating salvianolic acid A for targeted treatment of choroidal neovascularization.

BACKGROUND: The development of alternative anti-angiogenesis therapy for choroidal neovascularization (CNV) remains a great challenge. Nanoparticle systems have emerged as a new form of drug delivery in ocular diseases. Here, we report the construction and characterization of arginine-glycine-aspartic acid (RGD)-conjugated polyethyleneimine (PEI) as a vehicle to load antioxidant salvianolic acid A (SAA) for targeted anti-angiogenesis therapy of CNV. In this study, PEI was consecutively modified with polyethylene glycol (PEG) conjugated RGD segments, 3-(4'-hydroxyphenyl) propionic acid-Osu (HPAO), and fluorescein isothiocyanate (FI), followed by acetylation of the remaining PEI surface amines to generate the multifunctional PEI vehicle PEI.NHAc-FI-HPAO-(PEG-RGD) (for short, RGD-PEI). The formed RGD-PEI was utilized as an effective vehicle platform to load SAA. RESULTS: We showed that RGD-PEI/SAA complexes displayed desirable water dispersibility, low cytotoxicity, and sustainable release of SAA under different pH conditions. It could be specifically taken up by retinal pigment epithelium (RPE) cells which highly expressed ɑvß5 integrin receptors in vitro and selectively accumulated in CNV lesions in vivo. Moreover, the complexes displayed specific therapeutic efficacy in a mouse model of laser induced CNV, and the slow elimination of the complexes in the vitreous cavity was verified by SPECT imaging after 131I radiolabeling. The histological examinations further confirmed the biocompatibility of RGD-PEI/SAA. CONCLUSIONS: The results suggest that the designed RGD-PEI/SAA complexes may be a potential alternative anti-angiogenesis therapy for posterior ocular neovascular diseases.

Effect of Elevated pH on the Commercial Enteric-Coated Omeprazole Pellets Resistance: Patent Review and Multisource Generics Comparison.

Omeprazole is a widely used over-the-counter (20 mg) proton pump inhibitor, usually supplied as oral enteric-coated pellets intended to release at pH 5.5 and higher; however, it is sensitive to acidic pH. The likelihood of elevated gastric pH in practice is very high for patients; thus, the aim of this study was to investigate the effect of elevated pH on the performance of commercial omeprazole pellets. Commercial enteric-coated delayed-release pellets were tested with water uptake-weight loss (WU-WL) test at pH range between 1.2 and 4.5 in addition to "gastric" (pH 1.2 or 4.5) and "intestinal" (pH 7.4) phase dissolution tests. The range of physical characteristics of pellets was determined with a single pellet size and sedimentation time measurement, followed by the application of modified Stokes' Law equation. The coefficient of variation of pellet size and density, and volume-density determination coefficient (R2) as descriptors of coating thickness and microstructure variability, degree of ionisation of enteric polymers, aqueous solubility and molecular weight of plasticisers have been found useful to explain commercial delayed-release pellets behaviour during WU-WL and dissolution test. Investigated commercial delayed-release pellets demonstrated pH-dependent WU-WL results. "Gastric phase" dissolution testing of pellets at pH 4.5 showed the highest omeprazole degradation (48.1%) for Nosch Labs, intermediate values of dose loss (23.4% and 17.1%) for Teva and UQUIFA delayed-release pellets, respectively. Lab Liconsa pellets have been found as the least susceptible (3.2% of dose loss). Additionally, "gastric phase" dissolution test at pH 4.5 significantly influenced omeprazole release during the "intestinal phase". The risk of inadequate therapy associated with intake of investigated enteric-coated delayed-release pellets at elevated gastric pH has been found as minimal for Lab Liconsa and has increased from UQUIFA and Teva to Nosh Labs pellets.

Solid self-nanoemulsifying drug delivery system filled in enteric coated hard gelatin capsules for enhancing solubility and stability of omeprazole hydrochloride.

Omeprazole has poor water solubility, low stability in acidic solutions, and is subject to first pass metabolism resulting in low bioavailability. The objective was to enhance the dissolution and stability by preparing a solid-self nanoemulsifying drug delivery system (SNEDDS) and filling it in enteric coated HGCs. Drug solubility in many oils, surfactants, and cosurfactants was studied. Different SNEDDS were prepared and ternary phase diagrams were constructed. The optimum SNEDDS was evaluated. It was converted into solid by adsorption onto Neusilin® US2, and evaluated. Emulsions formed using Capryol 90, Cremophor RH 40, and ethanol formed spontaneously and were clear. Droplet size was 19.11 ± 3.11 nm, PDI was 0.18 ± 0.05, and zeta potential was -3.9 ± 1.56 mV. Non-medicated SNEDDS was thermodynamically stable. Cloud point was 88 ± 2 °C. Encapsulation efficiency and drug loading of solid-SNEDDS were 98.56 ± 0.44 and 1.29 ± 0.01%, respectively. Flow properties were much enhanced. Crystalline drug was adsorbed/precipitated onto Neusilin® US2 in amorphous form. Dissolution rate was enhanced as compared to commercial products and unprocessed drug. The drug was unstable at the accelerated stability conditions. Accordingly, the traditional stability study at 25 °C should be conducted. In conclusion, the solid-SNEDDS filled in enteric coated HGCs enhanced the dissolution rate and stability in acidic pH.

Revaprazan-loaded surface-modified solid dispersion: physicochemical characterization and in vivo evaluation.

The purpose of this research was to develop a novel revaprazan-loaded surface-modified solid dispersion (SMSD) with improved drug solubility and oral bioavailability. The impact of carriers on aqueous solubility of revaprazan was investigated. HPMC and Cremophor A25 were selected as an appropriate polymer and surfactant, respectively, due to their high drug solubility. Numerous SMSDs were prepared with various concentrations of carriers, using distilled water, and the drug solubility of each was assessed. Moreover, the physicochemical properties, dissolution and pharmacokinetics of selected SMSD in rats were assessed in comparison to revaprazan powder. Of the SMSDs assessed, the SMSD composed of revaprazan/HPMC/Cremophor A25 at the weight ratio of 1:0.28:1.12 had the most enhanced drug solubility (∼6000-fold). It was characterized by particles with a relatively rough surface, suggesting that the carriers were attached onto the surface of the unchanged crystalline revaprazan powder. It had a significantly higher dissolution rate, AUC and Cmax, and a faster Tmax value in comparison to revaprazan powder, with a 5.3-fold improvement in oral bioavailability of revaprazan. Therefore, from an environmental perspective, this SMSD system prepared with water, and without organic solvents, should be recommended as a revaprazan-loaded oral pharmaceutical alternative.

Delayed-type hypersensitivity reactions induced by proton pump inhibitors: A clinical and in vitro T-cell reactivity study.

BACKGROUND: Proton pump inhibitors (PPIs) have been known to induce type I hypersensitivity reactions. However, severe delayed-type hypersensitivity reactions (DHR) induced by PPI, such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), or drug rash with eosinophilia and systemic symptoms (DRESS), are rarely reported. We conducted a study of a large series of PPI-related DHR, followed up their tolerability to alternative anti-ulcer agents, and investigated the T-cell reactivity to PPI in PPI-related DHR patients. METHODS: We retrospectively analyzed patients with PPI-related DHR from multiple medical centers in Taiwan during the study period January 2003 to April 2016. We analyzed the causative PPI, clinical manifestations, organ involvement, treatment, and complications. We also followed up the potential risk of cross-hypersensitivity or tolerability to other PPI after their hypersensitivity episodes. Drug lymphocyte activation test (LAT) was conducted by measuring granulysin and interferon-γ to confirm the causalities. RESULTS: There were 69 cases of PPI-related DHR, including SJS/TEN (n=27) and DRESS (n=10). The LAT by measuring granulysin showed a sensitivity of 59.3% and specificity of 96.4%. Esomeprazole was the most commonly involved in PPI-related DHR (51%). Thirteen patients allergic to one kind of PPI could tolerate other structurally different PPI without cross-hypersensitivity reactions, whereas three patients developed cross-hypersensitivity reactions to alternative structurally similar PPI. The cross-reactivity to structurally similar PPI was also observed in LAT assay. CONCLUSIONS: PPIs have the potential to induce life-threatening DHR. In patients when PPI is necessary for treatment, switching to structurally different alternatives should be considered.

Multi-targeted dihydrazones as potent biotherapeutics.

Hydrazone compounds were considered as a useful moiety in drug design development. Therefore, these studies were aimed at the synthesis of new dihydrazones and were screened for their in vitro H+/K+-ATPase and anti-inflammatory activities. The results revealed that compounds 9 (22 ±â€¯0.62 µg/mL), 10 (26 ±â€¯0.91 µg/mL), 15 (24 ±â€¯0.44 µg/mL), 16 (28 ±â€¯0.63 µg/mL), 17 (12 ±â€¯0.38 µg/mL), 18 (14 ±â€¯0.47 µg/mL), 19 (26 ±â€¯0.54 µg/mL), 20 (16 ±â€¯0.41 µg/mL), 25 (06 ±â€¯0.68 µg/mL) and 26 (08 ±â€¯0.43 µg/mL) showed excellent H+/K+-ATPase activity and their IC50 value were lower than the standard drug Omerazole (48 ±â€¯0.12 µg/mL). Compounds 5 (28 ±â€¯0.65 µg/mL), 6 (24 ±â€¯0.61 µg/mL), 7 (28 ±â€¯0.64 µg/mL), 8 (26 ±â€¯0.45 µg/mL), 11 (30 ±â€¯0.74 µg/mL), 12 (28 ±â€¯0.40 µg/mL), 13 (32 ±â€¯0.24 µg/mL), 14 (30 ±â€¯0.55 µg/mL) and 21 (08 ±â€¯0.47 µg/mL), 22 (12 ±â€¯0.47 µg/mL), 23 (10 ±â€¯0.51 µg/mL) and 24 (14 ±â€¯0.84 µg/mL) showed better anti-inflammatory activity compared to standard indomethacin (44 ±â€¯0.15 µg/mL). The structure activity relationship (SAR) showed that, electron donating groups (OH, OCH3) favored the H+/K+-ATPase and antioxidants activity, whereas, electron withdrawing groups (F, Cl, Br and NO2) favored the anti-inflammatory activity. Furthermore, molecular docking study was performed to investigate the binding interactions of the most active analogs with the active site of H+/K+-ATPase enzyme. Compounds 25 (G-score = -9.063) and 26 (G-score = -8.977) showed the highest docking G-scores for H+/K+-ATPase inhibition activity.

Mass balance and metabolism of Z-215, a novel proton pump inhibitor, in healthy volunteers.

The human mass balance of [14 C]Z-215, a novel proton pump inhibitor, was characterised in six healthy male volunteers following single oral administration of [14 C]Z-215 (20 mg, 3.7 MBq) to determine the elimination pathway of Z-215 and the distribution of its metabolites in plasma, urine, and faeces (NCT02618629). [14 C]Z-215 was rapidly absorbed, with a Cmax of 434 ng/mL at 0.38 h for Z-215 and 732 ng eq./mL at 0.5 h for total radioactivity. Means of 59.61% and 31.36% of the administered radioactive dose were excreted in urine and faeces, respectively, within 168 h post-dose. The majority of the dose was recovered within 24 h in urine and 96 h in faeces. Unchanged Z-215 was excreted in urine at trace levels but was not detected in faeces. The main components in plasma were Z-215 and Z-215 sulphone, accounting for 29.8% and 13.3% of the total circulating radioactivity, respectively. Additionally, Z-215 was metabolised through oxidation, reduction and conjugation. Our in vitro Z-215 metabolism study showed that the major isozyme contributing to the oxidation of Z-215, including the formation of Z-215 sulphone, was CYP3A4. In conclusion, Z-215 is well absorbed in humans and primarily eliminated via metabolism, where CYP3A4 plays an important role.

Assessing the bioequivalence of over-the-counter esomeprazole banded capsules and multiple-unit pellet system tablets
.

OBJECTIVE: To demonstrate bioequivalence between two esomeprazole formulations under fasted and fed conditions. MATERIALS: Esomeprazole 20 mg multiunit pellet system (test; MUPS) tablets and over-the-counter esomeprazole 20 mg banded capsules (reference). MATERIALS AND METHODS: This open-label, randomized, 6-period crossover study assigned healthy males and females to receive single doses of each study drug under fasted or fed conditions. The primary pharmacokinetic endpoints were esomeprazole area under the concentration-time curve from time zero to infinity (AUCinf) and maximum observed concentration (Cmax). For endpoints with high within-subject standard deviations of the reference product (Swr ≥ 0.294), a reference scaled average bioequivalence (RSAB) approach was used. For endpoints not highly variable (Swr < 0.294), an unscaled approach was used. In the RSAB, bioequivalence was defined as the 95% criteria bound (CB) ≤ 0 and geometric mean ratios (GMRs) within 0.80, 1.25. For the unscaled approach, bioequivalence was defined as 90% confidence intervals (CIs) of the GMR being within 80%, 125%. RESULTS: 60 subjects were randomized, and 46 subjects (76.7%) completed all study periods. For esomeprazole AUCinf, the variability of the reference product was low (Swr = 0.202), so the unscaled approach was used. The GMR (90% CI) was 0.948 (0.890 - 1.010), indicating bioequivalence. For the comparison of esomeprazole Cmax, the variability of the reference product was high (Swr = 0.304), so the RSAB approach was used. The GMR (95% CB) was 1.009 (-0.050), indicating bioequivalence. CONCLUSION: Esomeprazole 20 mg MUPS tablets and banded capsules were found to be bioequivalent based on the AUCinf and Cmax in the fasted state.
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Stereoselective Inhibition of Renal Basolateral Human Organic Anion Transporter 3 by Lansoprazole Enantiomers.

Lansoprazole, a proton pump inhibitor, potently inhibits human organic anion transporter, hOAT3 (SLC22A8). Lansoprazole has an asymmetric atom in its structure and is clinically administered as a racemic mixture of (R)-and (S)-enantiomers. However, little is known about the stereoselective inhibitory potencies of lansoprazole against hOAT3 and its homolog, hOAT1. In the present study, the stereoselective inhibitory effect of lansoprazole was evaluated using hOAT1-and hOAT3-expressing cultured cells. hOAT1 and hOAT3 transported [14C]p-aminohippurate and [3H]estrone-3-sulfate (ES) with Michaelis-Menten constants of 29.8 ± 4.0 and 30.1 ± 9.0 µmol/L respectively. Lansoprazole enantiomers inhibited hOAT1- and hOAT3-mediated transport of each substrate in a concentration-dependent manner. The IC50 value of (S)-lansoprazole against hOAT3-mediated transport of [3H]ES (0.61 ± 0.08 µmol/L) was significantly lower than that of (R)-lansoprazole (1.75 ± 0.31 µmol/L). In contrast, stereoselectivity was not demonstrated for the inhibition of hOAT1. Furthermore, (S)-lansoprazole inhibited hOAT3-mediated transport of pemetrexed and methotrexate (hOAT3 substrates) more strongly than the corresponding (R)-lansoprazole. This study is the first to demonstrate that the stereoselective inhibitory potency of (S)-lansoprazole against hOAT3 is greater than that of (R)-lansoprazole. The present findings provide novel information about the drug interactions associated with lansoprazole.

Bone-targeting liposome formulation of Salvianic acid A accelerates the healing of delayed fracture Union in Mice.

Delayed fracture union is a significant clinical challenge in orthopedic practice. There are few non-surgical therapeutic options for this pathology. To address this challenge, we have developed a bone-targeting liposome (BTL) formulation of salvianic acid A (SAA), a potent bone anabolic agent, for improved treatment of delayed fracture union. Using pyrophosphorylated cholesterol as the targeting ligand, the liposome formulation (SAA-BTL) has demonstrated strong affinity to hydroxyapatite in vitro, and to bones in vivo. Locally administered SAA-BTL was found to significantly improve fracture callus formation and micro-architecture with accelerated mineralization rate in callus when compared to the dose equivalent SAA, non-targeting SAA liposome (SAA-NTL) or no treatment on a prednisone-induced delayed fracture union mouse model. Biomechanical analyses further validated the potent therapeutic efficacy of SAA-BTL. These results support SAA-BTL formulation, as a promising therapeutic candidate, to be further developed into an effective and safe clinical treatment for delayed bone fracture union.

Inhibition of Gastric H+,K+-ATPase Activity in Vitro by Dissolution Media of Original Brand-Name and Generic Tablets of Lansoprazole, a Proton Pump Inhibitor.

To investigate the inhibitory effect of a commercial proton pump inhibitor (lansoprazole) on the gastric proton pump H+,K+-ATPase in vitro, we used orally disintegrating (OD) tablets including original brand-name and generic tablets. In the course of the development of generic products, dissolution and clinical tests are necessary to ensure their bioequivalence to the original brand-name products; by contrast, there is almost no opportunity to demonstrate their activity in vitro. This study initially compared the similarity of the dissolution of test generic tablets with that of the original brand-name tablets. The dissolution tests for 15 and 30-mg lansoprazole tablets found their dissolution properties were similar. Subsequently, the dissolution media were sampled and then their effects on the H+,K+-ATPase activity were measured using tubulovesicles prepared from the gastric mucosa of hogs. We confirmed that the inhibitory effects of the generic tablets on H+,K+-ATPase activity were consistent with those of the original brand-name tablets. Furthermore, lansoprazole contents in each tablet estimated from their inhibitory effects were in good agreement with their active pharmaceutical ingredient content. To our knowledge, this is the first technical report to compare the in vitro biochemical activity of lansoprazole OD tablets between the original brand-name and generic commercial products.

Development and pharmacokinetic evaluation of alginate-pectin polymeric rafts forming tablets using box behnken design.

Raft is an emerging drug delivery system, which is suitable for controlled release drug delivery and targeting. The present study aimed to evaluate the physico-chemical properties of raft, in vitro release of pantoprazole sodium sesquihydrate and conduct bioavailability studies. Box behnken design was used with three independent and dependent variables. Independent variables were sodium alginate (X1), pectin (X2) and hydroxypropyl methyl cellulose K100M (X3) while dependent variables were percentage drug release at 2 (Y2), 4 (Y4) and 8 h (Y8). The developed rafts were evaluated by their physical and chemical properties. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to study the chemical interaction and thermal behaviour of drug with polymers. Alginate and pectin contents of R9 formulation were 99.28% and 97.29%, respectively, and acid neutralization capacity was 8.0. R9 formulation showed longer duration of neutralization and nature of raft was absorbent. The raft of R9 formulation showed 98.94% release of PSS at 8 h in simulated gastric fluid. Fourier transform infrared spectroscopy showed no chemical interaction and differential scanning calorimetry indicated endothermic peaks at 250 °C for pantoprazole sodium sesquihydrate. tmax for the test and reference formulations were 8 ± 2.345 h and 8 ± 2.305 h, respectively. Cmax of test and reference formulations were 46.026 ± 0.567 µg/mL and 43.026 ± 0.567 µg/mL, respectively. AUC(0-t) of the test and reference formulations were 472.115 ± 3.467 µg × h/mL and 456.105 ± 2.017 µg × h/mL, respectively. Raft forming system successfully delivered the drug in controlled manner and improved the bioavailability of drugs.

Doubly charged trimeric cluster ions: effective in mutual chiral recognition of tadalafil and three proton pump inhibitors.

Mutual chiral recognition of four stereoisomers of tadalafil and three pairs of enantiomers of proton pump inhibitors (PPIs) including pantoprazole, lansoprazole, and omeprazole, as well as quantitative analysis of enantiomeric excess is achieved on the basis of the competitive fragmentation of doubly charged trimeric NiII cluster ions. Compared with a singly charged trimeric cluster ion, a doubly charged trimeric cluster ion was proved efficient in the recognition of chiral drugs with one or multiple chiral centers, due to its rich fragmentation ions. Upon collision-induced dissociation (CID), the cluster ion [NiII(PPIs)(tadalafil)2]2+ yielded two diagnostic ions [tadalafil + H]+ and [tadalafil - benzo[d][1,3]dixoloe]+ through electrospray ionization quadrupole time-of-flight mass spectrometry. The abundance ratio of the two fragment ions relied mainly on the configuration of PPIs and tadalafil, and therefore the chiral selectivity (Rchiral) of one enantiomer relative to the others is different. The chiral recognition of all four stereoisomers of tadalafil was achieved by using S configuration PPIs as references, and S-omeprazole showed the best selectivity. The Rchiral values for R,R/S,S, R,S/S,R, R,R/R,S and R,R/S,R-tadalafils were 1.47, 1.17, 2.37, and 2.10, respectively. In a reciprocal process, the Rchiral was 1.36 and 1.31 for R/S-pantoprazole and R/S-lansoprazole, respectively, by using R,R-tadalafil as a reference. Although omeprazole is a racemic drug, it can also be discriminated with S-omeprazole. Calibration curves were constructed with favorable correlation coefficients (r2 > 0.991) by relating the ln(Rchiral) values to the isomeric composition in a mixture. The sensitivity of the methodology allows mixtures to be analyzed for the enantiomeric excess (ee) by recording the ratios of fragment ion abundances in a mass spectrum. The sensitivity of the methodology allowed the determination of enantiomeric impurities of 5% molar composition in individual compounds present in mixtures; the diastereoisomeric impurity of R,R-tadalafil could be quantified even at 1%. We believe that the developed method not only has scientific significance in qualitative and quantitative chiral analyses of tadalafil and PPIs, but also provides great opportunity for enabling the discrimination on a wide range of chiral drugs.

Elucidation of antimicrobial activity and mechanism of action by N-substituted carbazole derivatives.

Compounds belonging to a carbazole series have been identified as potent fungal plasma membrane proton adenosine triphophatase (H+-ATPase) inhibitors with a broad spectrum of antifungal activity. The carbazole compounds inhibit the adenosine triphosphate (ATP) hydrolysis activity of the essential fungal H+-ATPase, thereby functionally inhibiting the extrusion of protons and extracellular acidification, processes that are responsible for maintaining high plasma membrane potential. The compound class binds to and inhibits the H+-ATPase within minutes, leading to fungal death after 1-3h of compound exposure in vitro. The tested compounds are not selective for the fungal H+-ATPase, exhibiting an overlap of inhibitory activity with the mammalian protein family of P-type ATPases; the sarco(endo)plasmic reticulum calcium ATPase (Ca2+-ATPase) and the sodium potassium ATPase (Na+,K+-ATPase). The ion transport in the P-type ATPases is energized by the conversion of ATP to adenosine diphosphate (ADP) and phosphate and a general inhibitory mechanism mediated by the carbazole derivative could therefore be blocking of the active site. However, biochemical studies show that increased concentrations of ATP do not change the inhibitory activity of the carbazoles suggesting they act as allosteric inhibitors. Furthermore decreased levels of intracellular ATP would suggest that the compounds inhibit the H+-ATPase indirectly, but Candida albicans cells exposed to potent H+-ATPase-inhibitory carbazoles result in increased levels of intracellular ATP, indicating direct inhibition of H+-ATPase.

Repurposing of Proton Pump Inhibitors as first identified small molecule inhibitors of endo-ß-N-acetylglucosaminidase (ENGase) for the treatment of NGLY1 deficiency, a rare genetic disease.

N-Glycanase deficiency, or NGLY1 deficiency, is an extremely rare human genetic disease. N-Glycanase, encoded by the gene NGLY1, is an important enzyme involved in protein deglycosylation of misfolded proteins. Deglycosylation of misfolded proteins precedes the endoplasmic reticulum (ER)-associated degradation (ERAD) process. NGLY1 patients produce little or no N-glycanase (Ngly1), and the symptoms include global developmental delay, frequent seizures, complex hyperkinetic movement disorder, difficulty in swallowing/aspiration, liver dysfunction, and a lack of tears. Unfortunately, there has not been any therapeutic option available for this rare disease so far. Recently, a proposed molecular mechanism for NGLY1 deficiency suggested that endo-ß-N-acetylglucosaminidase (ENGase) inhibitors may be promising therapeutics for NGLY1 patients. Herein, we performed structure-based virtual screening utilizing FDA-approved drug database on this ENGase target to enable repurposing of existing drugs. Several Proton Pump Inhibitors (PPIs), a series of substituted 1H-benzo [d] imidazole, and 1H-imidazo [4,5-b] pyridines, among other scaffolds, have been identified as potent ENGase inhibitors. An electrophoretic mobility shift assay was employed to assess the inhibition of ENGase activity by these PPIs. Our efforts led to the discovery of Rabeprazole Sodium as the most promising hit with an IC50 of 4.47±0.44µM. This is the first report that describes the discovery of small molecule ENGase inhibitors, which can potentially be used for the treatment of human NGLY1 deficiency.

Design, synthesis of novel furan appended benzothiazepine derivatives and in vitro biological evaluation as potent VRV-PL-8a and H+/K+ ATPase inhibitors.

A series of new of furan derivatised [1,4] benzothiazepine analogues were synthesized starting from 1-(furan-2-yl)ethanone. 1-(Furan-2-yl)ethanone was converted into chalcones by its reaction with various aromatic aldehydes, then were reacted with 2-aminobenzenethiol in acidic conditions to obtain the title compounds in good yields. The synthesized new compounds were characterized by 1H NMR, 13C NMR, Mass spectral studies and elemental analyses. All the new compounds were evaluated for their in vitro VRV-PL-8a and H+/K+ ATPase inhibitor properties. Preliminary studies revealed that, some molecules amongst the designed series showed promising VRV-PL-8a and H+/K+ ATPase inhibitor properties. Further, rigid body docking studies were performed to understand possible docking sites of the molecules on the target proteins and the mode of binding. This finding presents a promising series of lead molecules that can serve as prototypes for the treatment of inflammatory related disorder that can mitigate the ulcer inducing side effect shown by other NSAIDs.