A sensitive and high‐throughput LC‐MS/MS method for inhibition assay of seven major cytochrome P450s in human liver microsomes using an in vitro cocktail of probe substrates

A sensitive and high‐throughput LC‐MS/MS method was established and validated for the simultaneous quantification of seven probe substrate‐derived metabolites (cocktail assay) for assessing the in vitro inhibition of cytochrome P450 (CYP) enzymes in pooled human liver microsomes. The metabolites acetaminophen (CYP1A2), hydroxy‐bupropion (CYP2B6), n‐desethyl‐amodiaquine (CYP2C8), 4′‐hydroxy‐diclofenac (CYP2C9), 4′‐hydroxy‐mephenytoin (CYP2C19), dextrorphan (CYP2D6) and 1′‐hydroxy‐midazolam (CYP3A4/5), together with the internal standard verapamil, were eluted on an Agilent 1200 series liquid chromatograph in <7 min. All metabolites were detected by an Agilent 6410B tandem mass spectrometer. The concentration of each probe substrate was selected by substrate inhibition assay that reduced potential substrate interactions. CYP inhibition of seven well‐known inhibitors was confirmed by comparing a single probe substrate assay with cocktail assay. The IC₅₀ values of these inhibitors determined on this cocktail assay were highly correlated (R² > 0.99 for each individual probe substrate) with those on single assay. The method was selective and showed good accuracy (85.89–113.35%) and between‐day (RSD <13.95%) and within‐day (RSD <9.90%) precision. The sample incubation extracts were stable at 25 °C for 48 h and after three freeze–thaw cycles. This seven‐CYP inhibition cocktail assay significantly increased the efficiency of accurately assessing compounds’ potential inhibition of the seven major CYPs in drug development settings. Copyright © 2014 John Wiley & Sons, Ltd.     

Development and validation of a sensitive and specific LC–MS/MS cocktail assay for CYP450 enzymes: Application to study the effect of catechin on rat hepatic CYP activity

A sensitive and specific liquid chromatography tandem mass spectrometric (LC–MS/MS) method that enables the simultaneous quantification of probe substrates and metabolites of cytochrome P450 (CYP) enzymes was developed and validated. These substrates (metabolites)—coumarin (7-hydroxycoumarin), tolbutamide (4-hydroxytolbutamide), S-mephenytoin (4-hydroxymephenytoin), dextromethorphan (dextrorphan), and testosterone (6β-hydroxytestosterone)—were utilized as markers for the activities of the major human CYP enzymes CYP2A6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, respectively. Analytes were separated on Kinetex C₁₈ column (2.1 × 50 mm, 5 μm) using a binary gradient mobile phase of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. Metabolites were detected and quantified by MS using multiple reaction monitoring at m/z 163 → 107.2 for 7-hydroxycoumarin, m/z 235 → 150.1 for 4-hydroxymephenytoin, m/z 287 → 171 for 4-hydroxytolbutamide, m/z 258 → 157.1 for dextrorphan, m/z 305 → 269 for 6β-hydroxytestosterone, and m/z 237 → 194 for the internal standard. The assay exhibited good linearity over a range of 10–500 ng/mL with acceptable accuracy and precision criteria. As a proof of concept, the developed cocktail assay was successfully used to examine the potential impact of catechin on the activity of the major rat liver CYP enzymes.     

In vitro interaction cocktail assay for nine major cytochrome P450 enzymes with 13 probe reactions and a single LC/MSMS run: analytical validation and testing with monoclonal anti-CYP antibodies

A sensitive and rugged LC/MSMS method was developed for a comprehensive in vitro metabolic interaction screening assay with N-in-1 approach reported earlier. A cocktail consisting of ten cytochrome P450 (CYP)-selective probe substrates with known kinetic, metabolic and interaction properties in vivo was incubated in a pool of human liver microsomes, and metabolites of melatonin (CYP1A2), coumarin (CYP2A6), bupropion (CYP2B6), amodiaquine (CYP2C8) tolbutamide (CYP2C9), omeprazole (CYP2C19 and CYP3A4), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1), midazolam (CYP3A4) and testosterone (CYP3A4) were simultaneously analysed with a single LC/MSMS run. Altogether, 13 metabolites and internal standard phenacetin were analysed in multiple reaction mode. Polarity switching mode was utilized to acquire negative ion mode electrospray data for hydroxychlorzoxazone and positive ionization data for the rest of the analytes. Fast gradient elution was applied, giving total injection cycle of 8 min. The method was modified for two different LC/MSMS systems, and was validated for linear range, detection limit, accuracy and precision for each metabolite. In addition, cocktail inhibition system was further tested using monoclonal anti-CYP antibodies as inhibitors for each probe reaction.     

High-throughput screening of inhibitory potential of nine cytochrome P450 enzymes in vitro using liquid chromatography/tandem mass spectrometry

The early detection of potential drug-drug interactions is an important issue of drug discovery that has led to the development of high-throughput screening (HTS) methods for potential drug interactions. We developed a HTS method for potential interactions of inhibitory drugs for nine human P450 enzymes using cocktail incubation and tandem mass spectrometry in vitro. This new method involves incubation of two cocktail doses and single cassette analysis. The two cocktail doses in vitro were developed to minimize solvent effects and mutual drug interactions among substrates: cocktail A was composed of phenacetin for CYP1A2, coumarin for CYP2A6, paclitaxel for CYP2C8, S-mephenytoin for CYP2C19, dextromethorphan for CYP2D6, and midazolam for CYP3A4; and cocktail B was composed of three substrates including bupropion for CYP2B6, tolbutamide for CYP2C9, and chlorzoxazone for CYP2E1. In the incubation study of these cocktails, the reaction mixtures were pooled and simultaneously analyzed using liquid chromatography/tandem mass spectrometry employing a fast gradient. The method was validated by comparing the inhibition data obtained from the incubation of each individual probe substrate alone with data from the new method. The IC50 value of each inhibitor in the cocktail agreed well with that of the individual probe drug as well as with values previously reported in the literature. As a HTS method for potential interactions of the inhibition of these nine P450 enzymes, this new method will be useful in the drug discovery process and for the mechanistic understanding of drug interactions.     

Design, synthesis and evaluation of furanocoumarin monomers as inhibitors of CYP3A4

A number of furanocoumarins isolated from grapefruit juice have been found to inhibit CYP3A4 activity in vitro. In this study, we have designed and synthesised a range of analogues based on bergamottin to investigate the relationship between chemical structure and inhibition of CYP3A4 activity. Studies were performed using human liver microsomes and human intestinal S9 fraction, with testosterone as the marker substrate. With the exception of the coumarin and phenolic furanocoumarin derivatives, which were inactive, the alkyloxy-furanocoumarin analogues were found to inhibit CYP3A4 activity in a dose dependent manner, with observed IC50 values ranging from 0.13 +/- 0.03 to 49.3 +/- 1.9 microM. The unsaturated furan derivatives were found to exhibit time-dependent inhibition, showing a 2-, 4- and 14-fold increase in potency for 6',7'-epoxybergamottin, 6',7'-dihydroxybergamottin and bergamottin, respectively after a preincubation period of ten minutes. Reduction of the furan moiety resulted in an 11-fold decrease in inhibitory potency, suggesting that this functional group is key to the interaction between these compounds and CYP3A4.     

Capillary electrophoresis to assess drug metabolism induced in vitro using single CYP450 enzymes (Supersomes): application to the chiral metabolism of mephenytoin and methadone

Capillary electrophoresis (CE) with multiwavelength absorbance detection is demonstrated to be an effective tool for the assessment of in vitro drug metabolism studies using microsomes containing single human cytochrome P450 enzymes (CYPs) expressed in baculovirus-infected insect cells (Supersomes). Mephenytoin (MEPH), dextromethorphan, diclofenac, caffeine, and methadone (MET) were successfully applied as test substrates for CYP2C19, CYP2D6*1, CYP2C9*1, CYP1A2, and CYP3A4, respectively. For each system, the CE-based assay could be shown to permit the simultaneous analysis of the parent drug and its targeted metabolite. Using a chiral micellar electrokinetic capillary chromatography assay, the aromatic hydroxylation of MEPH catalyzed by CYP2C19 could thereby be confirmed to be highly stereoselective, an aspect that is in agreement with data obtained via urinary analysis after intake of racemic MEPH by extensive metabolizer phenotypes. The MET to 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) conversion was investigated with a chiral zone electrophoresis assay. Incubation of racemic and nonracemic MET with CYP3A4 revealed no stereoselectivity for the transformation to EDDP, whereas no EDDP formation was observed with CYP1A2. CYP2C9 and CYP2C19 provided enhanced formation of R-EDDP and CYP2D6 incubation resulted in the preferential conversion to S-EDDP. Investigations using racemic MET and human liver microsomes revealed a modest stereoselectivity with an R/S EDDP ratio < 1 which is similar to the in vivo findings in urine.     

Effects of vindoline on rat cytochrome P450 isoform activities in vitro

A specific ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC–Q-TOF–MS/MS) method has been described for the simultaneous determination of the metabolites of tacrine, bupropion, diclofenac, dextromethorphan and midazolam, which are the five probe drugs of the five cytochrome P450 (CYP450) isoforms CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A4. The inhibition degree was determined by calculating the IC₅₀. The chromatographic separation was performed on a C₁₈ column with a mobile phase consisting of 0.1% formic acid and acetonitrile. The mass spectrometric analysis was conducted in positive electrospray ionization mode. The IC₅₀ values of CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A were 113.4, 83.78, 22.50, 9.081 and 52.76 μmol L⁻¹, respectively. The in vitro results demonstrated that vindoline could inhibit CYP2D1 activity in rats, and weak inhibitory effect on CYP2C11 and CYP3A, but had no obvious effects on CYP1A2 and CYP2B.     

An evaluation of the CYP2D6 and CYP3A4 inhibition potential of metoprolol metabolites and their contribution to drug–drug and drug–herb interaction by LC‐ESI/MS/MS

The aim of the present study was to evaluate the contribution of metabolites to drug–drug interaction and drug–herb interaction using the inhibition of CYP2D6 and CYP3A4 by metoprolol (MET) and its metabolites. The peak concentrations of unbound plasma concentration of MET, α‐hydroxy metoprolol (HM), O‐desmethyl metoprolol (ODM) and N‐desisopropyl metoprolol (DIM) were 90.37 ± 2.69, 33.32 ± 1.92, 16.93 ± 1.70 and 7.96 ± 0.94 ng/mL, respectively. The metabolites identified, HM and ODM, had a ratio of metabolic area under the concentration–time curve (AUC) to parent AUC of ≥0.25 when either total or unbound concentration of metabolite was considered. In vitro CYP2D6 and CYP3A4 inhibition by MET, HM and ODM study revealed that MET, HM and ODM were not inhibitors of CYP3A4‐catalyzed midazolam metabolism and CYP2D6‐catalyzed dextromethorphan metabolism. However, DIM only met the criteria of >10% of the total drug related material and <25% of the parent using unbound concentrations. If CYP inhibition testing is solely based on metabolite exposure, DIM metabolite would probably not be considered. However, the present study has demonstrated that DIM contributes significantly to in vitro drug–drug interaction. Copyright © 2016 John Wiley & Sons, Ltd.     

One-pot,expeditious and chromatography-free synthesis of new chromeno[4,3-e][1,3]oxazine derivatives catalyzed by reusable TiO2 nanopowder at room temperature

An expeditious, one-pot, pseudo four-component coupling reaction between 3-hydroxy coumarin, formaldehyde, and amine catalyzed by reusable TiO₂ nanopowder in ethanol at room temperature (25–28 °C) under stirring condition to synthesize the chromeno[4,3-e][1,3]oxazine derivatives has been described. A wide range of substrate variation, environmentally benign reaction procedure, easy work-up, chromatography free synthesis, and excellent yields with reusability of the catalyst make the methodology highly effective for the synthesis of chromeno[4,3-e][1,3]oxazine derivatives. To the best of our knowledge, this is the first Letter for the synthesis of chromeno[4,3-e][1,3]oxazines using 3-hydroxy coumarin.     

Validation of higher-throughput high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry assays to conduct cytochrome P450s CYP2D6 and CYP3A4 enzyme inhibition studies in human liver microsomes

In the early stage of drug discovery, thousands of new chemical entities (NCEs) may be screened before a single drug candidate can be identified for development. In order to accelerate the drug discovery process, we have developed higher-throughput enzyme assays to evaluate the inhibition of cytochrome P450 isoforms 2D6 (CYP2D6) and 3A4 (CYP3A4) in human liver microsomes. The assays are based on high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) techniques. The analysis time for each sample was reduced from approximately 20 minutes for the conventional HPLC assay to 30 seconds for the LC/MS/MS assay. For both LC/MS/MS assays, the linearity (r(2) > 0.99), precision (%CV < 15%) and accuracy (% bias <15%) for both inter- and intraday validations were satisfactory. Since the implementation of the LC/MS/MS assays, our sample throughput has increased by over 40-fold.     

Development and Validation of a Novel HPLC Method to Analyse Metabolic Reaction Products Catalysed by the CYP3A2 Isoform: In Vitro Inhibition of CYP3A2 Enzyme Activity by Aspirin (Drugs Often Used Together in COVID-19 Treatment)

Aspirin (also known as acetylsalicylic acid) is a drug intended to treat fever, pain, or inflammation. Treatment of moderate to severe cases of COVID-19 using aspirin along with dexamethasone has gained major attention globally in recent times. Thus, the purpose of this study was to use High-Performance Liquid Chromatography (HPLC) to evaluate the in vitro inhibition of CYP3A2 enzyme activity using aspirin in rat liver microsomes (RLMs). In this study, an efficient and sensitive HPLC method was developed using a reversed phase C18 column (X Bridge 4.6 mm × 150 mm, 3.5 µm) at 243 nm using acetonitrile and water (70:30 v/v). The linearity (r² > 0.999), precision (<15%), accuracy and recovery (80–120%), limit of detection (5.60 µM and 0.06 µM), limit of quantification (16.98 µM and 0.19 µM), and stability of the newly developed method were validated for dexamethasone and 6β-hydroxydexamethasone, respectively, following International Conference on Harmonization (ICH) guidelines. This method was applied in vitro to measure CYP3A2 activity. The results showed that aspirin competitively inhibits 6β-hydroxylation (CYP3A2 activity) with an inhibition constant (Ki) = 95.46 µM and the concentration of the inhibitor causing 50% inhibition of original enzyme activity (IC₅₀) = 190.92 µM. This indicated that there is a minimal risk of toxicity when dexamethasone and aspirin are co-administrated and a very low risk of toxicity and drug interaction with drugs that are a substrate for CYP3A2 in healthcare settings.     

Reactions of phenylenedioxytrihalophosphoranes with arylacetylenes: XIII. Reaction of 5-tert-butyl-2,2,2-trihalo-1,3,2λ5-benzodioxaphospholes with acetylenes

Reactions of 5-tert-butyl-2,2,2-trichloro-, 2,2,2-tribromo-5-tert-butyl-, and 2,2-dibromo-5-tert-butyl-2-fluoro-1,3,2λ⁵-benzodioxaphospholes with aryl- and alkylacetylenes lead to quantitative formation of 2-halo-1,2λ⁵-benzoxaphosphinine 2-oxides which may be regarded as phosphorus analogs of natural heterocyclic compounds, coumarin and chromene. The major products (>70%) are 4-aryl-7-tert-butyl-2,6-dichloro-, 4-aryl-2-bromo-7-tert-butyl-, and 4-aryl-7-tert-butyl-2-fluoro-1,2λ⁵-benzoxaphosphinine 2-oxides. Hydrolysis of these compounds and their treatment with amines gives the corresponding 2-hydroxy and 2-amino derivatives, as well as ammonium salts. The structure of some compounds was proved by X-ray analysis.     

Synthesis of Functionalized Diethyl(pyrrolidin-2-yl)phosphonate and Diethyl(5-oxopyrrolidin-2-yl)phosphonate

Short and efficient syntheses of functionalized (pyrrolidin-2-yl)phosphonate and (5-oxopyrrolidin-2-yl)phosphonate have been developed. The synthetic strategy involved the diastereospecific 1,3-dipolar cycloaddition of N-benzyl-C-(diethoxyphosphoryl)nitrone to cis-1,4-dihydroxybut-2-ene and dimethyl maleate, respectively. O,O-Diethyl 3-carbamoyl-4-hydroxy(5-oxopyrrolidin-2-yl)phosphonate was obtained from O,O-diethyl 2-benzyl-4,5-dimethoxycarbonyl(isoxazolidin-3-yl)phosphonate by hydrogenation and subsequent treatment with ammonia, whereas transformation of O,O-diethyl 2-benzyl-4,5-dihydroxymethyl(isoxazolidin-3-yl)phosphonate into O,O-diethyl 3-aminomethyl-4-hydroxy(pyrrolidin-2-yl)phosphonate was accomplished by mesylation followed by hydrogenolysis to undergo intramolecular cyclization and the introduction of amino group via ammonolysis. Stereochemistry of the isoxazolidine cycloadducts, as well as the final functionalized (pyrrolidin-2-yl)- and (5-oxopyrrolidin-2-yl)phosphonates were established based on conformational analyses using vicinal H–H, H–P, and C–P couplings and supported by the observed diagnostic NOESY correlation signals.     

High-throughput cytochrome P450 (CYP) inhibition screening via a cassette probe-dosing strategy. VI. Simultaneous evaluation of inhibition potential of drugs on human hepatic isozymes CYP2A6, 3A4, 2C9, 2D6 and 2E1

The inhibition potential of drugs towards five major human hepatic cytochrome P450 (CYP) isozymes (CYP2A6, 3A4, 2C9, 2D6, and 2E1) was investigated via cassette dosing of the five probe substrates (coumarin, midazolam, tolbutamide, dextromethorphan, and chlorzoxazone) in human liver microsomes using a 96-well plate format. After microsomal incubations had been terminated with formic acid, the five marker metabolites (7-hydroxycoumarin, 1'-hydroxymidazolam, 4-hydroxytolbutamide, dextrorphan, and 6-hydroxychlorzoxazone) were simultaneously quantified using direct injection/online guard cartridge extraction/tandem mass spectrometry (DI-GCE/MS/MS). Several advantages resulted from the use of a short C(18) guard cartridge (4 mm in length) for DI-GCE/MS/MS, including minimal sample preparation, fast online extraction, short analysis time (2.5 min), and minimal source contamination. In addition, this method demonstrated an inter-day accuracy range from -8.7 - 7.4% with a precision less than 8.3% for the quantification of all the marker metabolites. The inhibition assay for the five CYP isozymes was evaluated using their known selective inhibitors via individual and cassette dosing of the probe substrates. The IC(50) values measured via cassette dosing were consistent with those observed via individual dosing, which were all in agreement with the reported values. In addition, the validated assay was used to evaluate the inhibitory potential of 23 generic drugs (randomly selected) towards the five CYP isozymes. The results suggest the integration of the cassette dosing strategy and the DI-GCE/MS/MS method can provide a reliable in vitro approach to screening the inhibitory potential of new chemical entities, with maximal throughput and cost-effectiveness, in support of drug discovery and development.     

Engineering of Human CYP3A Enzymes by Combination of Activating Polymorphic Variants

The use of human cytochrome P450 (CYP) enzymes is increasing for the production of drug metabolites used for drug safety testing and doping analysis. Major challenges are high-priced cofactors, poor stability, and comparatively low activities. We have shown previously that production of specific metabolites in milligrams to gram scale is feasible using human CYPs recombinantly expressed in fission yeast. In this study, we sought to improve the activities of human CYP3A enzymes by genetic engineering. Two side chains (Pro293 and Arg409) of known activating human CYP3A polymorphic variants were??separately or together??introduced into the wild-type forms of each of the three enzymes CYP3A4, CYP3A5, and CYP3A7, respectively. Different effects of the two mutations and their combination on enzyme activity were monitored using both polar and nonpolar substrates. Interestingly, the CYP3A7 double mutant displayed a strong increase in activity with respect to testosterone 6??-hydroxylation (300?% of wild-type activity) and luciferin-6??-pentafluoro-benzyl ether turnover (400?% compared to wild type), while the single mutant CYP3A5^Pro293 showed 370 and 400?% of wild-type activity towards 6??-hydroxylation of testosterone and 16??-hydroxylation of dehydroepiandrosterone, respectively. Overall, six out of seven newly created mutants displayed increased activity with at least one of the tested substrates. These results support the notion that pharmacogenetic knowledge can directly contribute to the improvement of biotechnological processes.     

Characterization of the CYP3A4 Enzyme Inhibition Potential of Selected Flavonoids

Acacetin, apigenin, chrysin, and pinocembrin are flavonoid aglycones found in foods such as parsley, honey, celery, and chamomile tea. Flavonoids can act as substrates and inhibitors of the CYP3A4 enzyme, a heme containing enzyme responsible for the metabolism of one third of drugs on the market. The aim of this study was to investigate the inhibitory effect of selected flavonoids on the CYP3A4 enzyme, the kinetics of inhibition, the possible covalent binding of the inhibitor to the enzyme, and whether flavonoids can act as pseudo-irreversible inhibitors. For the determination of inhibition kinetics, nifedipine oxidation was used as a marker reaction. A hemochromopyridine test was used to assess the possible covalent binding to the heme, and incubation with dialysis was used in order to assess the reversibility of the inhibition. All the tested flavonoids inhibited the CYP3A4 enzyme activity. Chrysin was the most potent inhibitor: IC₅₀ = 2.5 ± 0.6 µM, K_i = 2.4 ± 1.0 µM, k_inact = 0.07 ± 0.01 min⁻¹, k_inact/K_i = 0.03 min⁻¹ µM⁻¹. Chrysin caused the highest reduction of heme (94.5 ± 0.5% residual concentration). None of the tested flavonoids showed pseudo-irreversible inhibition. Although the inactivation of the CYP3A4 enzyme is caused by interaction with heme, inhibitor-heme adducts could not be trapped. These results indicate that flavonoids have the potential to inhibit the CYP3A4 enzyme and interact with other drugs and medications. However, possible food–drug interactions have to be assessed clinically.     

Enantiomerically pure phosphonate analogues of cis- and trans-4-hydroxyprolines

All the enantiomers of O,O-diethyl 4-hydroxypyrrolidinyl-2-phosphonates, phosphonate analogues of cis- and trans-4-hydroxyprolines, have been obtained for the first time. The synthetic strategy involved 1,3-dipolar cycloaddition of (R)- and (S)-N-(1-phenylethyl)-C-(diethoxyphosphoryl)nitrones to allyl alcohol and separation of the corresponding O,O-diethyl 5-(hydroxymethyl)-2-(1-phenylethyl)isoxazolidinyl-3-phosphonates, which were subsequently mesylated and hydrogenated to undergo intramolecular cyclisation. Absolute configurations of the enantiomeric proline phosphonates were established after N- and O-derivatization with (S)-O-methylmandelic acid employing the Trost model.     

Synthesis and investigation of anti-inflammatory and anticonvulsant activities of novel coumarin-diacylated hydrazide derivatives

A number of novel coumarin derivatives synthesized by the reaction of 3-carbonyl chloride coumarin with some substituted aryl acid hydrazides to investigate their anti-inflammatory and anticonvulsant activities. Carrageenan (0.1 ml of 1%, w/v) was injected subplantarly in the right paw of rats to induce an acute model of inflammation. Anti-inflammatory efficacy was evaluated for 5 hours at 3 different dosages 5, 10, 25 mg/kg. After that, the changes in the level of paw edema volumes and percentage inhibition of all groups were observed and the most effective coumarin derivative was found as N'-(2-hyroxybenzoyl)-2-oxo-2H-chromene-3-carbohydrazide. In addition, N’-(2-oxo-2H-chromene-3-carbonyl)nicotinohydrazide, (E)-N’-(3-(4-hydroxyphenyl)acryloyl)-2-oxo-2H-chromene-3-carbohydrazide, and N’-(5-amino-2-hydroxybenzoyl)-2-oxo-2H-chromone-3-carbohydrazide showed their anti-inflammatory effects in a dose-dependent manner. On the other hand, pentylenetetrazole (PTZ, 80 mg/kg, i.p.)-induced seizure model was used to investigate the anticonvulsant activities of six newly synthesized coumarin derivatives in mice. Hybrid compound of salicylic acid hydrazide and 3-carbonyl chloride coumarin (8d) was found the most promising anticonvulsant agent among all treatment groups according to the onset of seizure and survival rate. Moreover, (E)-N'-cinnamoyl-2-oxo-2H-chromene-3-carbohyrazide (8b) and (E)-N'-(3-(4-hyroxyphenyl)acryloyl)-2-oxo-2H-chromene-3-carbohydrazide (8c) has potential anticonvulsant efficiency in low doses (30 mg/kg). The anticonvulsant effect of these coumarin derivatives may be through enhanced GABA-mediated inhibition in the brain.     

Iridium catalysed alkylation of 4-hydroxy coumarin, 4-hydroxy-2-quinolones and quinolin-4(1H)-one with alcohols under solvent free thermal conditions

Ir catalysed alkylation of 4-hydroxy coumarin, 4-hydroxy-2-quinolones and quinolin-4(1H)-one with a range of substituted benzyl and aliphatic alcohols under solvent free thermal conditions afforded the corresponding monoalkylated products in high to excellent yield and in certain cases produced bis-(3,3′-1-methyl-4-hydroxy)methenes.