Sulfoxide Metabolites Research Articles

Antigiardial and antiamebic activities of fexinidazole and its metabolites: new drug leads for giardiasis and amebiasis.

The intestinal parasites Giardia lamblia and Entamoeba histolytica are major causes of morbidity and mortality associated with diarrheal diseases. Metronidazole is the most common drug used to treat giardiasis and amebiasis. Despite its efficacy, treatment failures in giardiasis occur in up to 5%-40% of cases. Potential resistance of E. histolytica to metronidazole is an increasing concern. Therefore, it is critical to search for more effective drugs to treat giardiasis and amebiasis. We identified antigiardial and antiamebic activities of the rediscovered nitroimidazole compound, fexinidazole, and its sulfone and sulfoxide metabolites. Fexinidazole is equally active against E. histolytica and G. lamblia trophozoites, and both metabolites were 3- to 18-fold more active than the parent drug. Fexinidazole and its metabolites were also active against a metronidazole-resistant strain of G. lamblia. G. lamblia and E. histolytica cell extracts exhibited decreased residual nitroreductase activity when metabolites were used as substrates, indicating nitroreductase may be central to the mechanism of action of fexinidazole. In a cell invasion model, fexinidazole and its metabolites significantly reduced the invasiveness of E. histolytica trophozoites through basement membrane matrix. A q.d. oral dose of fexinidazole and its metabolites at 10 mg/kg for 3 days reduced G. lamblia infection significantly in mice compared to control. The newly discovered antigiardial and antiamebic activities of fexinidazole, combined with its FDA-approval and inclusion in the WHO Model List of Essential Medicines for the treatment of human African trypanosomiasis, offer decreased risk and a shortened development timeline toward clinical use of fexinidazole for treatment of giardiasis or amebiasis.

In silico studies and in vitro microsomal metabolism of potent MetAP2 inhibitor and in vivo tumor suppressor for prostate cancer: A thioether-triazole hybrid

Background/aim: The in-vitro microsomal metabolism of (S)-3-((2,4,6-trimethylphenyl)thio)-4-(4-fluorophenyl)-5-(1-(6-methoxynaphtalene-2-yl)ethyl)-4H-1,2,4-triazole (SGK636), an anticancer drug candidate was studied using pig microsomal preparations fortified with NADPH to identify the potential S-oxidation and S-dealkylation metabolites.
 Materials and methods: In the present study, the sulfoxide metabolite was synthesized, purified and characterized by chromatographic and spectroscopic methods. SGK636, the S-oxidation and S-dealkylation metabolites were then separated by a reversed phase LC-MS, with UV detection and with an HP-TLC system. The results from the in-vitro microsomal metabolic experiments showed that SGK636 produced the corresponding S-oxidation metabolite (sulfoxide) which was observed by LC-MS, LC-MS/MS and HP-TLC with the identical Rt and Rfx100 values and UV/MS spectra in comparison with the authentic compounds, but no any S-dealkylation metabolite was detected.
 Results: The present results were proved with molecular docking and molecular dynamic studies. Since sulfoxidation process can be reversible and it may partly explain the low amount of sulfoxide metabolite in our experiment, we also incubated the sulphoxide. No conversion back to the substrate (SGK636) was observed, but it produced the corresponding sulphone metabolite. In order to establish if SGK636 is autooxidized, the substrate was also incubated in buffer under standard incubation conditions, but no any autooxidation was observed into the corresponding sulfoxide. We also did a stability work for SGK636-SO (sulfoxide) in buffer to see any possible autooxidation to sulphone or reduction back to SGK636. No conversion was observed in either way. The substrate seems to be stable to metabolic reactions and to autooxidation which could be an advantage in terms of its pharmacological activity.
 Conclusion: The present metabolic and study indicates that SGK 636 underwent S-oxidation. In order to identify the responsible oxydative enzyme, molecular docking and molecular dynamic studies were performed. CYP3A4 was found to be responsible enzyme for S-oxidation.

Reactivity and binding mode of disulfiram, its metabolites, and derivatives in SARS-CoV-2 PLpro: insights from computational chemistry studies.

The papain-like protease (PLpro) from SARS-CoV-2 is an important target for the development of antivirals against COVID-19. The safe drug disulfiram (DSF) presents antiviral activity inhibiting PLpro in vitro, and it is under clinical trial studies, indicating to be a promising anti-COVID-19 drug. In this work, we aimed to understand the mechanism of PLpro inhibition by DSF and verify if DSF metabolites and derivatives could be potential inhibitors too. Molecular docking, DFT, and ADMET techniques were applied. The carbamoylation of the active site cysteine residue by DSF metabolite (DETC-MeSO) is kinetically and thermodynamically favorable (ΔG‡ = 3.15 and ΔG = − 12.10 kcal mol-1, respectively). Our results strongly suggest that the sulfoxide metabolites from DSF are promising covalent inhibitors of PLpro and should be tested in in vitro and in vivo assays to confirm their antiviral action.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00894-022-05341-2.

Development of molecularly imprinted polymer for the selective recognition of the weakly interacting fenamiphos molecule

The possible manufacture of Molecularly Imprinted Polymers (MIPs) under the conditions of weak interaction between the functional monomer and template molecule is addressed with the help of the case of the Fenamiphos organophosphorus insecticide. The choice of the functional monomer is addressed by investigating MIPs prepared by the surface imprinting technique using three very different types of monomers (methacrylic acid, 4-vinylpyridine and 2–(methacryloyloxyethyl)trimethylammonium chloride), a solid silica support grafted with 3-mercaptopropyltrimethoxysilane on its surface; ethylene glycol dimethacrylate as the cross-linker and acetonitrile as solvent. The prepared materials were characterized by IR, solid state 13C NMR, TGA, DLS, BET and TEM. Their performance as adsorbents were evaluated by modeling their experimental adsorption isotherms using the Langmuir–Volmer model. All MIPs show similar adsorbent performance although the functional monomers were quite different and the interactions with fenamiphos were weak. The latter were assessed by 1H and 31P NMR experiments in DMSO‑d6 solution. The adsorption process presented weakly exothermic and endothermic behavior onto molecular imprints and non-specific sites respectively. The selectivity for adsorption of fenamiphos with respect to its sulfone and sulfoxide metabolites was quite high.

A comparative study of the effect of phenothiazine derivatives and their S-oxides on cholinesterase investigated by a new kinetic spectrophotometric method

Aim. To develop a new kinetic spectrophotometric method for determining acetylcholinesterase (AChE) inhibitors – phenothiazine antipsychotic drugs (PhT) and their sulfoxide metabolites (S-oxides) without adding an exogenous catalyst to obtain a chromogenic agent.Materials and methods. The bases of S-oxides of promethazine (PMZ), chlorpromazine (CPM) and thioridazine (THZ) were obtained by oxidizing the corresponding PhT hydrochlorides with diperoxyadipic acid. The structure of the S-oxides of the corresponding PhT synthesized was proven by melting points, spectral characteristics (1H NMR and IR methods) and oscillopolarography results. 1H NMR spectra were recorded on a Varian XL-200 spectrometer. IR spectra were recorded within the range of 4000-400 cm–1 on a SPECORD M-80 spectrometer (Zeiss, Jena, Germany). To register polarograms, a “PO 03 CLA” oscillopolarograph with a three-electrode cell was used. The purity of S-oxides was determined by the high-performance liquid chromatography method on a Zorbax SB, C-18 (250 × 4.6) mm column. Measurements of absorbance of solutions were performed in a 1 cm cuvette on an Evolution 60S UV-Visible Thermo-Scientific Spectrophotometer (USA) (λ = 358 nm).Results and discussion. Acetylcholine (ACh) was found to mimic the activity of peroxidase; based on it, a spectrophotometric system containing ACh–H2O2–p-Ph for a sensitive and selective assessment of the AChE activity and determination of its inhibitors was developed. According to the plots of inhibition efficiency vs inhibitors concentration, the inhibiting ability of chlorpromazine, promethazine and thioridazine and their S-oxides was determined. The IC50 values of CPM, PMZ and THZ and their metabolites in relation to the AChE activity were estimated as 11 ng mL−1 (CPM) and 1.8 ng mL−1 (CPM S-oxide), 17 ng mL−1 (PMZ) and 2.5 ng mL−1 (PMZ S-oxide) and 27 ng mL−1 (THZ 2S,5S-dioxide). The results obtained indicate that S-oxides of the corresponding PhT are selective and potent inhibitors of AChE. The values of the inhibition efficiency obtained for S-oxides of PhT derivatives were an order of magnitude lower than those of the corresponding PhT derivatives.Conclusions. The spectrophotometric method proposed without the addition of other exogenous catalysts holds promise for the on-site determination of PhT antipsychotics and can be additionally used for sensory applications in areas related to environmental protection and food safety, as well as in the chemical-toxicological analysis.

Ways to Improve Insights into Clindamycin Pharmacology and Pharmacokinetics Tailored to Practice.

Given the increase in bacterial resistance and the decrease in the development of new antibiotics, the appropriate use of old antimicrobials has become even more compulsory. Clindamycin is a lincosamide antibiotic approved for adults and children as a drug of choice for systemic treatment of staphylococcal, streptococcal, and gram-positive anaerobic bacterial infections. Because of its profile and high bioavailability, it is commonly used as part of an oral multimodal alternative for prolonged parenteral antibiotic regimens, e.g., to treat bone and joint or prosthesis-related infections. Clindamycin is also frequently used for (surgical) prophylaxis in the event of beta-lactam allergy. Special populations (pediatrics, pregnant women) have altered cytochrome P450 (CYP)3A4 activity. As clindamycin is metabolized by the CYP3A4/5 enzymes to bioactive N-demethyl and sulfoxide metabolites, knowledge of the potential relevance of the drug’s metabolites and disposition in special populations is of interest. Furthermore, drug–drug interactions derived from CYP3A4 inducers and inhibitors, and the data on the impact of the disease state on the CYP system, are still limited. This narrative review provides a detailed survey of the currently available literature on pharmacology and pharmacokinetics and identifies knowledge gaps (special patient population, drug–drug, and drug–disease interactions) to describe a research strategy for precision medicine.

Neutrophil Myeloperoxidase-Mediated N-Demethylation of Quetiapine Leads to N-Desalkylquetiapine, a Pharmacologically Active Cytochrome P450 Metabolite

The atypical antipsychotic drugs, quetiapine and clozapine, are associated with idiosyncratic drug reactions (such as agranulocytosis or neutropenia) that are thought to involve reactive metabolites. Neutrophil myeloperoxidase (MPO) metabolism of quetiapine is not well-studied, but is metabolized by cytochrome P450. Based on structural similarity to clozapine, we hypothesized that quetiapine can be metabolized by MPO and that there is overlap between cytochrome P450 and MPO metabolism of quetiapine. The interaction of quetiapine and clozapine with MPO and MPO chlorination activity was studied using UV-vis spectrophotometry. The metabolites were characterized using liquid chromatography-mass spectrometry (LC-MS), and electron paramagnetic resonance (EPR) spectroscopy was used for detecting drug-catalyzed glutathione oxidation. In the presence of quetiapine, MPO compound II accumulated for about 7.5 min, whereas in the presence of clozapine, MPO compound II was not observed as it was rapidly reduced back to the resting state. Increasing quetiapine concentrations resulted in a decrease in MPO chlorination activity, while the opposite result was found in the case of clozapine. UV-vis spectral studies showed no change when quetiapine was oxidized in the absence and presence of chloride anion (Cl-, to catalyze chlorination reactions). Significant changes, however, were observed in the same assay with clozapine, where Cl- appeared to hinder the rate of clozapine metabolism. The MPO-catalyzed hydroxylated and dealkylated metabolites of quetiapine and hydroxylated metabolites of clozapine were observed from the LC-MS analyses, particularly when Cl- was included in the reaction. In addition, hydroxylated, dealkylated, and a proposed sulfoxide metabolite of quetiapine were also observed in the reaction catalyzed by human microsomes/NADPH. Lastly, compared to quetiapine, clozapine metabolism by MPO/H2O2 and glutathione produced more glutathionyl radicals using EPR spin trapping. In conclusion, MPO/H2O2/Cl- was shown to metabolize quetiapine to S-oxidation and P450-like dealkylation products, and quetiapine metabolites were generally less reactive than clozapine.

52500 Characterization of a Series of 1,4-diaryl-pyrazolo-pyridinones as Anti-Leishmanial Agents

ABSTRACT IMPACT: The first-line chemotherapies used to treat leishmaniasis are highly toxic intravenous antimonials yet drug resistance has begun to develop, causing the use of oral treatment options with high price tags; there is a strong need for new, safe, and effective chemotherapeutic agents to treat leishmaniasis. OBJECTIVES/GOALS: This study was conducted in order to identify novel chemical compounds that exhibit anti-leishmanial activity and to further characterize their efficacy and toxicity in in vitro and in vivo systems in the hopes of future chemotherapeutic developments. METHODS/STUDY POPULATION: A total of 28 unique 1,4-diaryl-pyrazolo-pyridinone (1,4-DAPP) compounds were synthesized and anti-leishmanial efficacy and host cell toxicity were determined using L. donovani mCherry-expressing amastigotes and THP-1 macrophages. Additional pharmacokinetic analyses of a potent 1,4-DAPP compound were conducted, revealing a potential metabolite structure. A select group of the novel compounds were screened in a cutaneous leishmaniasis (CL) murine model using L. major mCherry-expressing parasites and female Balb/C mice. The treatment consisted of 10 intralesional injections of compound over a period of 4 weeks, while lesion growth was monitored via fluorescence and manual measurements. RESULTS/ANTICIPATED RESULTS: Four experimental compounds had IC50 values less than 5 micromolar, providing similar anti-leishmanial activity to Miltefosine. Compound 9279817 had a clearance almost twice the rate of normal hepatic blood flow and had a relatively high volumes of distribution, indicating this compound is rapidly cleared and distributes into tissues. In vitro rat liver microsome assays suggest a rapid metabolism of 9279817 and MS/MS results suggest this metabolite is most likely formed via oxidation of the sulfur on the lower aryl ring. This sulfoxide metabolite has similar efficacy as the parent compound and does not exhibit toxicity in vitro. Three of the experimental compounds behaved similarly to the antimony positive control in the murine CL model. DISCUSSION/SIGNIFICANCE OF FINDINGS: This study revealed a novel structural class of compounds that have anti-leishmanial activity. Experiments show compounds with similar efficacy to Miltefosine while having significantly less cytotoxicity, suggesting that the 1,4-DAPP structural class could be further developed as a potential chemotherapeutic.

A combined in vitro in-silico approach to predict the oral bioavailability of borderline BCS Class II/IV weak base albendazole and its main metabolite albendazole sulfoxide

The aim of this study was to use a combined in vitro-in silico approach to develop a physiologically based pharmacokinetic model (PBPK) that predicts the bioavailability of albendazole (ABZ), a BCS class II/IV lipophilic weak base, and simulates its main metabolite albendazole sulphoxide (ABZSO) after oral administration of the current marketed dose of 400 mg in the fasted state. In vitro data was collected from solubility and dissolution tests performed with biorelevant media and transfer tests were carried out to evaluate the supersaturation and precipitation characteristics of ABZ upon gastric emptying. These in vitro results were used as biopharmaceutical inputs together with ABZ physicochemical properties including also permeability and in vitro metabolism data and information gathered from different clinical trials reported in the literature, were used to enable PBPK models to be developed using GastroPlus™ (version 9.7). As expected for this weak base with pKa = 3.6, ABZ exhibited a pronounced pH dependent solubility, with the solubility and extent of dissolution being greater at gastric pH and dropping significantly in the intestinal environment suggesting supersaturation and precipitation upon gastric emptying, which was confirmed by the transfer model experiments. PBPK models were set up for heathy volunteers using a full PBPK modeling approach and by implementing dynamic fluid volumes in the ACAT gut physiology in GastroPlus™. When coupling in vitro data (solubility values, dissolution rate and precipitation rate constant, etc.) for ABZ and with fitted values for the Vdss and liver systemic clearance of the sulfoxide metabolite to the PBPK model, the simulated profiles successfully predicated plasma concentrations of ABZ at 400 mg dose and simulated ABZSO at different ABZ dose levels and with different study populations, indicating the usefulness of combing in vitro biorelevant tools with PBPK modeling for the accurate prediction of ABZ bioavailability. The results obtained in this study also helped confirm that ABZ behaves as a BCS class IV compound.

Abstract 3019: Non-linear absorption pharmacokinetics (PK) of the ATR inhibitor AZD6738 in mice

Abstract Introduction: AZD6738 is an inhibitor of the apical kinase Ataxia telangiectasia and Rad-3 related (ATR) and can block induction of DNA damage response signaling cascades that are initiated by ATR following chemotherapy or radiation cancer treatment. AZD6738 is in clinical development and also being used preclinically to mechanistically probe ATR signaling. Currently, little is known about AZD6738 PK, including bioavailability, and tissue distribution, and this information is valuable in both clinical and preclinical settings. Here we describe the intravenous (IV) and oral (PO) PK of AZD6738 in mice. Methods: Single doses of AZD6738 (IV 10 mg/kg, PO 2.0, 7.5, 20, or 75 mg/kg) were administered to female Balb/c mice. Mice were euthanized from 5 min to 24 h after dosing and plasma and tissues were collected and analyzed by an LC-MS/MS assay modified to include a sulfoxide and sulfone metabolite semiquantitatively. PK parameters and PO bioavailability were determined non-compartmentally (NCA) and compartmentally (CA). Dose linearity was assessed using naively pooled data and statistical comparison of dose normalized Cmax and AUC. ADAPT5 software was used to develop a CA model. Extraction ratio (EH) was calculated from IV administered mice to discern the contribution of hepatic first-pass metabolism to observed bioavailability. Results: IV data was best described by a two-compartment linear model. Negligible differences were observed between PO half-life at any dose (95.3 to 116 min) compared to the IV half-life (104 min). Increases in PO dose resulted in greater than proportional increases in exposure with statistical differences observed for dose-normalized Cmax and AUC. Concordantly, the bioavailability increased as dose increased, ranging from an F of 31.3% at 2.0 mg/kg to 81.3% at 75 mg/kg. A decrease in Tmax was also observed as dose increased, with a Tmax of 60 min at 2.0 mg/kg and 15 min at all other PO doses. As PO dose increased, decreases in sulfoxide dose-normalized AUC metabolic ratios were observed. A two-compartment model with an absorption compartment containing a saturable component capturing both efflux and first-pass metabolism was developed that adequately described the data with non-linear bioavailability. An empirical Emax fit to bioavailability as a function of dose determined the maximum bioavailability (Emax) to be 87.6% (95%CI 66.7-114%) and Km to be 3.99 (95% CI 1.06-11.3). Comparison of the EH of IV administered mice to the observed 2 mg/kg bioavailability determined ~50% passes the gut wall. Conclusion:AZD6738 was observed to display saturable intestinal efflux/first-pass metabolism resulting in dose-dependent bioavailability. Increased PO doses yield greater than proportional increases in exposure in mice. Presence of non-linear absorption PK in humans is conjecture. Funding: TL1TR001858, R50CA211241, P30CA047904 and American Foundation for Pharmaceutical Education, PA DoH Tobacco grant. Citation Format: Brian F. Kiesel, Jianxia Guo, Christopher J. Bakkenist, Jan H. Beumer. Non-linear absorption pharmacokinetics (PK) of the ATR inhibitor AZD6738 in mice [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3019.

In vitro inhibition of the hepatic S-oxygenation of the anthelmintic albendazole by the natural monoterpene thymol in sheep

Combinations of bioactive phytochemicals with synthetic compounds have been suggested as promissory tools for the improvement of nematode control in livestock. Bioactive phytochemicals may interfere with the activity of drug-metabolizing enzymes and delay the metabolic conversion of anthelmintics into less potent metabolites.This research assessed the effect of the monoterpene thymol (TML) on the in vitro hepatic metabolism of the anthelmintic albendazole (ABZ) in sheep.Liver microsomes from four (4) Texel lambs were incubated with ABZ (50 µM) in absence or in presence of TML (0.05–10 mM).The concentration of TML producing a 50% decrease in ABZ S-oxygenation (IC50) was 13.5 mM. The FMO-dependent S-oxygenation of ABZ was markedly inhibited by the monoterpene (54.1 ± 11.6%, p < .01). In agreement with this observation, TML produced a marked inhibition of benzydamine (BZ) N-oxidase, a specific FMO activity.The CYP-dependent production of the sulfoxide metabolite (ABZSO) was less affected, being 25.3 ± 17.5 lower (p < .05) in presence of TML. Additionally, TML completely abolished the specific CYP1A1-dependent enzyme activity 7-ethoxyresorufin O-deethylase.Overall, the results presented here show that, in addition to its own anthelmintic affect, TML may potentiate ABZ anthelmintic activity by preventing its metabolic conversion into a less active metabolite.

Assessment of the pharmacological interactions between the nematodicidal fenbendazole and the flukicidal triclabendazole: In vitro studies with bovine liver microsomes and slices.

Parasitic diseases have a significant impact on livestock production. Nematodicidal drugs, such as fenbendazole (FBZ) or its oxidized metabolite oxfendazole (OFZ), can be used along with the trematodicidal triclabendazole (TCBZ), to broaden the spectrum of anthelmintic activity. However, co-exposure to these compounds could lead to drug-drug (D-D) interactions and eventually alter the clinical profile of each active principle. The aim of this study was to assess the presence of such interactions by means of two in vitro models, namely bovine liver microsomal fractions and bovine precision-cut liver slices (PCLSs). To this end, an in vitro assessment involving incubation of FBZ and TCBZ or a combination of FBZ and TCBZ was carried out. Results with microsomal fractions showed a 78.4% reduction (p=.002) in the rate of OFZ production upon co-incubation, whereas the sulfoxide metabolite of TCBZ (TCBZSO) exhibited a decreasing tendency. With PCLS, OFZ accumulation in the incubation medium increased 1.8-fold upon co-incubation, whereas TCBZSO accumulation decreased by 28%. The accumulation of FBZ and OFZ in the liver tissue increased upon 2-hr co-incubation, from 2.1±1.5 to 18.2±6.1 (p=.0009) and from 0.4±0.1 to 1.3±0.3nmol (p=.0005), respectively. These results confirm the presence of D-D interactions between FBZ and TCBZ. Further studies are needed to determine the extent of involvement of drug-metabolizing enzymes and membrane transporters in interactions between compounds largely used in livestock production systems.

Oxidation of Selected Phenothiazine Drugs During Sample Preparation: Effects of Varying Extraction Conditions on the Extent of Oxidation.

Characterization of degradation products formed from selected phenothiazine drugs during standard solid-phase extraction (SPE) approaches is described. An analytical method for promethazine (PMZ), chlorpromazine (CPZ) and their respective N-desmethyl and sulfoxide metabolites in biological samples (bone tissue extract and blood) by ultra performance liquid chromatography-photodiode array detection, using mixed-mode SPE for basic drugs was developed. When ethyl acetate:isopropanol:ammonium hydroxide (80:17:3) was used as the elution solvent during method development, extraneous peaks were observed that were absent in the negative controls. Analysis of extracts of PMZ and CPZ individually showed extraneous peaks, including peaks with retention time and UV spectra suggesting the formation of the sulfoxide metabolites, amongst others. Analytes were then extracted individually and analyzed by ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The results confirmed the oxidation of PMZ to its sulfoxide and N-oxide metabolites and oxidation of CPZ to its sulfoxide metabolite. Oxidation was also observed in analysis of whole blood, and thus was not specific to bone tissue extract. To determine if extraction with minimal oxidation was possible, extractions using SPE with a different elution solvent system (dichloromethane:isopropanol:ammonium hydroxide) and filtration/pass through extraction (FPTE) with and without evaporation were evaluated. The results demonstrated that the sample preparation method highly influenced the extent of oxidation. FPTE without an evaporation step was the only method that did not measurably induce analyte oxidation.

CYP-Mediated Sulfoximine Deimination of AZD6738.

In hepatic S9 and human liver microsomes (HLMs) the sulfoximine moiety of the ATR inhibitor AZD6738 is metabolized to its corresponding sulfoxide (AZ8982) and sulfone (AZ0002). The initial deimination to AZ8982 is nominally a reductive reaction, but in HLMs it required both NADPH and oxygen and also was inhibited by 1-aminobenzotriazole at a concentration of 1 mM. Studies conducted in a panel of 11 members of the cytochrome P450 (P450) family (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 CYP2J2, CYP3A4, and CYP3A5) confirmed that deimination was an oxidative process that was mediated largely by CYP2C8 with some CYP2J2 involvement, whereas the subsequent oxidation to sulfone was carried out largely by CYP2J2, CYP3A4, and CYP3A5. There was no measureable metabolism in flavin-containing monooxygenase (FMO) enzymes FMO3, FMO5 or NADPH cytochrome C reductase. Studies using Silensomes, a commercially available HLM in which specific members of the P450 family have been inhibited by selective mechanism-based inhibitors, showed that when CYP2C8 was inhibited, the rate of deimination was reduced by 95%, suggesting that CYP2J2 is only playing a minor role in HLMs. When CYP3A4 was inhibited, the rate increased by 58% due to the inhibition of the subsequent sulfone formation. Correlation studies conducted in HLM samples from different individuals confirmed the role of CYP2C8 in the deimination over CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A. Hence, although nominally a reduction, the deimination of AZD6738 to its sulfoxide metabolite AZ8982 is an oxidation mediated by CYP2C8, and this metabolite is subsequently oxidized to the sulfone (AZ0002) largely by CYP3A.

The sodium salt of the enantiomers of ricobendazole: Preparation, solubility and chiroptical properties

Albendazole (ABZ) is a sulfanyl-benzimidazole anthelmintic drug used worldwide in the treatment and prevention of parasitic diseases in animals and humans. Following oral administration, ABZ is rapidly oxidized into the pharmacologically active chiral sulfoxide metabolite known as ricobendazole (RBZ). As its achiral precursor, RBZ shows very low intestinal absorption due to its poor solubility in water (0.06mgmL−1). To the best of our knowledge, there is no known example in human medicine of a water-soluble salt form of racemic or enantiomerically pure RBZ.In the present study, we describe in detail the preparation of the sodium (Na) salt of the enantiomers of RBZ through a two-step process: i) the multi-milligram resolution of RBZ by HPLC on the amylose-based Chiralpak IG chiral stationary phase under polar organic mode; ii) the salification of the isolated enantiomers of RBZ by reaction with sodium hydroxide solution. The spectroscopic and chiroptical properties of the RBZ-Na enantiomers were determined. Due to their unique solubility in 0.01M phosphate buffer at physiological pH (14.49mgmL−1) and the high sample throughput obtained on semipreparative separation of the non-salified form, it is potentially possible to develop new anthelmintic enantiopure formulations with improved pharmacokinetic properties and lower toxicity.

Dissipation behavior of phorate and its toxic metabolites in the sandy clay loam soil of a tropical sugarcane ecosystem using a single-step sample preparation method and GC-MS

The dissipation of phorate in the sandy clay loam soil of tropical sugarcane ecosystem was studied by employing a single-step sample preparation method and gas chromatography with mass spectrometry. The limit of quantification of the method was 0.01 μg/g. The recoveries of phorate, phorate sulfoxide, phorate sulfone, and phorate oxon were in the range 94.00-98.46% with relative standard deviations of 1.51-3.56% at three levels of fortification between 0.01 and 0.1 μg/g. The Half-life of phorate and the total residues, which include phorate, phorate sulfoxide and phorate sulfone, was 5.5 and 19.8 days, respectively at the recommended dose of insecticide. Phorate rapidly oxidized into its sulfoxide metabolite in the sandy clay loam soil. Phorate sulfoxide alone accounted for more than 20% of the total residues within 2 h post-application and it was more than 50% on the fifth day after treatment irrespective of the doses applied. Phorate sulfoxide and phorate sulfone reached below the detectable level on 105 and 135 days after treatment, respectively as against 45 days after treatment for phorate residues at the recommended dose. Thus, the reasonably prolonged efficacy of phorate against soil pests may be attributed to longer persistence of its more toxic sulfoxide and sulfone metabolites.

Quetiapine Carboxylic Acid and Quetiapine Sulfoxide Prevalence in Patient Urine.

Treatment adherence is often an issue with mental health patients. For those prescribed quetiapine (Seroquel®), the low levels of parent drug and plasma metabolite(s) (e.g., 7-hydroxyquetiapine) typically used in urine drug monitoring can result in false negatives with concomitant unfavorable impacts on patient care. Literature review coupled with liquid chromatography/time-of-flight mass spectrometry analysis of patient positive urine samples indicated the presence of quetiapine carboxylic acid and quetiapine sulfoxide as significant urinary metabolites of quetiapine. Analysis of these two metabolites determined that they are abundant in the urine of quetiapine patients and can result in apparent adherence rates that are improved relative to those determined using only quetiapine and 7-hydroxyquetiapine. For example, analysis of a random set of 114 patients who were prescribed quetiapine exhibited an apparent adherence rate of 47% using the quetiapine carboxylic acid and quetiapine sulfoxide metabolites. Traditional metabolite testing with quetiapine and 7-hydroxyquetiapine yielded apparent adherence rates of ~31% while all four analytes resulted in apparent adherence of 48%. The prevalence of these metabolites suggests that quetiapine urine drug testing would be more consistent with prescriptions when they are included in the analysis.

Two anti-angiogenic TKI-PET tracers, [11C]axitinib and [11C]nintedanib: Radiosynthesis, in vivo metabolism and initial biodistribution studies in rodents

IntroductionTyrosine kinase inhibitors (TKIs) are very attractive targeted drugs, although a large portion of patients remains unresponsive. PET imaging with EGFR targeting TKIs ([11C]erlotinib and [18F]afatinib) showed promise in identifying treatment sensitive tumors. The aim of this study was to synthesize two anti-angiogenic TKI tracers, [11C]axitinib and [11C]nintedanib, and to evaluate their potential for PET. MethodsFollowing successful tracer synthesis, biodistribution studies in VU-SCC-OE and FaDu xenograft bearing mice were performed. Furthermore, tracer stability studies in mice were performed employing (radio-)HPLC and LC–MS/MS techniques. For [11C]nintedanib an LC–MS/MS method was developed to detect the primary carboxylic acid metabolite, resulting from methylester cleavage, in plasma and tumors, because this metabolite is postulated to be important for nintedanib efficacy. LC–MS/MS was also explored to assess the metabolic fate of [11C]axitinib in vivo, since axitinib has an isomerizable double bond. Results[11C]axitinib and [11C]nintedanib were successfully synthesized with 10.5±2.6% and 25.6±3.3% radiochemical yield (corrected for decay), respectively. Biodistribution studies only demonstrated tumor uptake of [11C]nintedanib in FaDu xenografts of 1.66±0.02% ID/g at 60min p.i. In vivo stability analysis of [11C]axitinib at 45min p.i. revealed the formation of predominantly non-polar metabolites (36.6±6.8% vs 47.1±8.4% of parent tracer and 16.3±2.1% of polar metabolites), while for [11C]nintedanib mostly polar metabolites were found (70.9±4.1 vs 26.7±3.9% of parent tracer and only 2.4±1.6 of a non-polar metabolites). No isomerization of [11C]axtinib was observed in vivo; however, a sulfoxide metabolite could be detected using LC–MS/MS. For [11C]nintedanib, LC–MS/MS revealed formation of the reported primary carboxylic acid metabolite when in vitro plasma incubations were performed, with large differences in plasmas from different species. In vivo metabolite analysis, however, did not demonstrate the presence of the carboxylic acid in plasma or tumor tissue. ConclusionsReliable syntheses of [11C]axitinib and [11C]nintedanib were successfully developed. Tumor uptake was observed for [11C]nintedanib, albeit modest. The metabolic profiles of the tracers suggest that rapid metabolism is partly responsible for the modest tumor targeting observed.

Abstract B74: Dietary reprogramming of the metabolome of the laying hen: Prevention and suppression of ovarian cancer

Abstract Ovarian cancer is the most lethal gynecological malignancy among women in the US and causes 14,600 deaths annually. Unfortunately, despite intensive research towards detection and treatment of ovarian cancer, long term survival has only fractionally improved. Lack of a model animal, early detection, and curative chemotherapy has hampered progress in the fight against ovarian cancer. The laying hen is proving to be a robust model of spontaneous ovarian cancer that mimics human disease. Nutritive intervention with flaxseed, high in omega 3 polyunsaturated fatty acids (PUFA), has shown promise for reducing severity and incidence of ovarian cancer, by reprogramming cellular metabolism, ameliorating inflammatory pathways in comparison with a diet high in omega 6 PUFA, such as corn oil. We have demonstrated that omega 3 fatty acids and phytoestrogens lignans has greatly reduced cancer incidence and severity in the laying hen by targeting inflammatory pathways. Another finding from our flaxseed feeding study, is that the overall wellbeing of the hens was also improved by the diet. Mortality was significantly reduced and the lean body mass of the hens was improved and maintained. The objective of this study was to determine if 6 different diets consisting of: control meal, defatted flax meal, whole flax seed, corn oil, fish oil, and flax oil affect the plasma metabolomics profile compared to a control diet, hence contributing to their anti and pro-carcinogenic effects on ovarian cancer. Old, cancer prone hens were fed a diet for one year, after 6 months, blood was collected through wing vein, plasma was prepared. Samples were snap frozen within 5 minutes or less of collection. Plasma was subjected to one-carbon base metabolomics analysis at UT Southwestern by Ralph DeBerardinis and Zeping Hu. Discovery based metabolomic analysis results indicate that a host of differences among 125 metabolites were found. 63% of the variability in the metabolites can be accounted for by the 6 diets. The analysis indicates that there are suites of metabolites associated with the different dietary treatments. Principal component analysis and hierarchal clustering revealed within the flax fed group urea, hypoxanthine adenosine, and myo-inositol metabolites increased compared to the control diet. This could be indicative of a protective effect. Conversely, homoserine, lysine, methionine, and sulfoxide were decreased in the flax diet compared to the control diet. Hens fed a corn oil diet gave rise to an increase in homoserine, lysine, methionine sulfoxide metabolites compared to the control diets, which has been associated with systemic oxidative stress. Also with the corn oil diet, a decrease in the concentration of urea, hypoxanthine, adenosine, and myo-inositol metabolites was observed, compared to the control diet. Interestingly, it has been previously reported that a reduction in these metabolites has been observed from patients with non-Hodgkin Lymphomas. The changes in the concentration of metabolites are suspected to be the result of the diet-driven alterations in surrogate cancer endpoints. To further map observable changes in the metabolic profile of tumor metabolism, analysis of tissue level metabolites will be assessed next with emphasis on malignant tissue versus normal tissues within the respective diets. [Supported by NIH AT004085, AT005295] Citation Format: Stephanie M. Eastwood, Lacey Gibson, Dale Buchanan Hales. Dietary reprogramming of the metabolome of the laying hen: Prevention and suppression of ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr B74.

Abstract 1665: Design, synthesis, biological evaluation of cyclopenta[d]pyrimidines as antitubulin agents and discovery of N-(4-methylthiophenyl) and N-(4-dimethylaminophenyl) substituted N,2-dimethyl-cyclopenta[d]pyrimidines as long acting and poten

Abstract Compounds that bind to the colchicine site of microtubules have promising antitumor potential. Some of these agents also possess the ability to overcome multiple drug resistance mechanisms, including those mediated by the expression of P-glycoprotein (Pgp) or expression of the tubulin β-III isotype. We have reported that compounds 1 and 2 were potent antiproliferative agents that bind to the colchicine site of tubulin. The previous structure-activity relationship studies of cyclopenta[d]pyrimidine based antitubulin agents demonstrated the importance of the para-methoxyphenyl moiety for antiproliferative activity. However, the literature suggests that the major metabolism of the methoxyphenyl moiety was likely O-demethylation. In order to increase the potency and in vivo stability of 1, we focused our attention on the variation of the para-methoxy aniline moiety. Compound 3 with a 4′-methylthiophenyl substitution was designed to decrease potential metabolic demethylation. This S-methyl analog was a potent inhibitor of proliferation with an IC50 of 4.6 ± 0.5 nM in MDA-MB-435 cells. The possible sulfoxide metabolite, 4 was synthesized and had an IC50 = 7.9 ± 0.5 nM. Each of these depolymerized microtubules. In addition, the 4′-dimethylamino moiety compound 5 also demonstrated potent antitubulin and antiproliferative activity (MDA-MB-435: IC50 = 8.2 ± 0.6 nM). The possible N-demethylated metabolite of 5, para-methylamino 6 was also a highly potent antiproliferative agent (MDA-MB-435: IC50 = 20 ± 1.9 nM). The parent compounds 3 and 5, as well as their probable metabolites 4 and 6, inhibited the binding of [3H]colchicine to tubulin, which showed that these compounds bind to the colchicine site. The potent antiproliferative activities of the parent compounds and the potential metabolites of compounds 3 and 5 suggest the utility of 3 and 5 as long acting, potent antimitotic agents. Finally, the in vivo efficacy of the S-methyl analog 2 was demonstrated against MDA-MB-435 triple negative breast cancer murine xenograft model, indicating the potential utility of these analogs as antitumor agents. Citation Format: Aleem Gangjee, Weiguo Xiang, Susan L. Mooberry, Ernest Hamel. Design, synthesis, biological evaluation of cyclopenta[d]pyrimidines as antitubulin agents and discovery of N-(4-methylthiophenyl) and N-(4-dimethylaminophenyl) substituted N,2-dimethyl-cyclopenta[d]pyrimidines as long acting and poten [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1665. doi:10.1158/1538-7445.AM2015-1665