Ester prodrugs of a potent analgesic, morphine-6-sulfate: syntheses, spectroscopic and physicochemical properties

The aim of this work is to develop 3-acyl prodrugs of the potent analgesic morphine-6-sulfate (M6S). These are expected to have higher potency and/or exhibit longer duration of analgesic action than the parent compound. M6S and the prodrugs were synthesized, then purified either by recrystallization or by semi-preparative HPLC and the structures confirmed by mass spectrometry, IR spectrophotometry and by detailed 1- and 2-D NMR studies. The lipophilicities of the compounds were assessed by a combination of shake-flask, group contribution and HPLC retention methods. The octanol-buffer partition coefficient could only be obtained directly for 3-heptanoylmorphine-6-sulfate, using the shake-flask method. The partition coefficients (P) for the remaining prodrugs were estimated from known methylene group contributions. A good linear relationship between log P and the HPLC log capacity factors was demonstrated. Hydrolysis of the 3-acetyl prodrug, as a representative of the group, was found to occur relatively slowly in buffers (pH range 6.15-8.01), with a small buffer catalysis contribution. The rates of enzymatic hydrolysis of the 3-acyl group in 10% rat blood and in 10% rat brain homogenate were investigated. The prodrugs followed apparent first order hydrolysis kinetics, with a significantly faster hydrolysis rate found in 10% rat brain homogenate than in 10% rat blood for all compounds. (C) 1998 Elsevier Science B.V. All rights reserved.

Investigation of the antinociceptive efficacy and relative potency of extended duration injectable 3-acylmorphine-6-sulfate prodrugs in rats

This investigation was designed to examine the antinociceptive activity in rats of 3-O-acyl prodrugs of M6S relative to the parent drug, after intravenous and intramuscular injection, using the tail flick latency test of antinociception. M6S, 3-acetylmorphine-6-sulfate (3AcM6S), 3-propionylmorphine-6-sulfate (3PrM6S), 3-butanoylmorphine-6-sulfate (3BuM6S) and 3-heptanoylmorphine-6-sulfate (3HpM6S) were administered by the IV route in a dose of 4.10 mu mol/kg. Relatively high levels of antinociception (>40% Maximum Possible Effect) were achieved following administration of M6S, 3AcM6S and 3PrM6S, whereas insignificant antinociception (<20%MPE) was achieved following administration of 3BuM6S or 3HpM6S. Although the mean duration of action for 3AcM6S (6 h) was longer than for M6S or 3PrM6S (4 h), the mean area (+/- S.E.M.) under the degree of antinociception versus time curve (AUG) for 3AcM6S (151.6 +/- 6.9%MPE h) was not significantly different (p <0.05) from that for M6S (120.8 +/- 32.7%MPE h) or for 3PrM6S (106.0 +/- 21.3%MPE h). The mean ED50 (range) doses for M6S, 3AcM6S and 3PrM6S were calculated to be 4.16 (3.61-4.48), 4.32 (3.55-5.09) and 4.54 (4.21-4.79) mu mol/kg, respectively. Preliminary studies were conducted on potential long-acting formulations containing 8 x ED50 doses of M6S and the 3-acetyl and 3-propionyl esters suspended in soybean oil. These showed that 3PrM6S gave a greater AUC (mean + S.E.M.) (1087.4 +/- 97.4%MPE h) and longer duration of action (20 h) than did M6S (613.1 +/- 155.9%MPE h; 10 h duration) or 3AcM6S (379.3 + 114.2%MPE h: 8 h duration). Further studies are needed to more fully investigate these findings. (C) 1998 Elsevier Science B.V. All rights reserved.

LC-MSn analysis of the cis isomers of chlorogenic acids

The behaviour of cis isomers of selected mono- and di-acyl chlorogenic acids produced by UV-irradiation has been investigated by LC-MSn. cis Isomers fragment identically to the more common trans isomers. cis-5-Acyl chlorogenic acids are more hydrophobic and elute later than their mono- or di-trans counterparts whereas the reverse is true for cis-3-acyl and cis-4-acyl chlorogenic acids. The cis isomers of 1,3-dicaffeoylquinic acid, the only I-acyl chlorogenic acid investigated, are also more hydrophobic than the di-trans isomer. Coffee leaves had a proportionately greater content of cis isomers relative to trans isomers compared with coffee beans suggesting that UV-irradiation in vivo may also cause geometric isomerisation. (c) 2007 Elsevier Ltd. All rights reserved.

Quinolizine-2,4-diones by reversible dimerisation 2-pyridylketenes

Quinolizine-2,4-diones 11 are obtained by ash vacuum thermolysis (FVT) of 3-acyl-1,2,3-triazolo[1,5-a]pyridines 7. The reaction takes place via methyl- and phenyl(2-pyridyl)ketenes 10, which are directly observable by infrared spectroscopy in low temperature matrices. FVT of 11 regenerates the ketenes 10.

Diversity in Catalytic Reactions of Propargylic Diazoesters

Abstract Title of Document: Diversity in Catalytic Reactions of Propargylic Diazoesters Huang Qiu, Doctor of Philosophy, 2016 Directed By: Professor Michael P. Doyle, Department of Chemistry and Biochemistry Propargylic aryldiazoesters, which possess multiple reactive functional groups in a single molecule, were expected to undergo divergent reaction pathways as a function of catalysts. A variety of transition metal complexes including rhodium(II), palladium(II), silver(I), mercury(II), copper(I and II), and cationic gold (I) complexes have been examined to be effective in the catalytic domino reactions of propargylic aryldiazoesters. An unexpected Lewis acid catalyzed pathway was also discovered by using FeCl3 as the catalyst. Under the catalysis of selected gold catalysts, propargylic aryldiazoesters exist in equilibrium with 1-aryl-1,2-dien-1-yl diazoacetate allenes that are rapidly formed at room temperature through 1,3-acyloxy migration. The newly formed allenes further undergo a metal-free rearrangement in which the terminal nitrogen of the diazo functional group adds to the central carbon of the allene initiating a sequence of bond forming reactions resulting in the production of 1,5-dihydro-4H-pyrazol-4-ones in good yields. These 1,5-dihydro-4H-pyrazol-4-ones undergo intramolecular 1,3-acyl migration to form an equilibrium mixture or quantitatively transfer the acyl group to an external nucleophile with formation of 4-hydroxypyrazoles. In the presence of a pyridine-N-oxide, both E- and Z-1,3-dienyl aryldiazoacetates are formed in high combined yields by Au(I)-catalyzed rearrangement of propargyl arylyldiazoacetates at short reaction times. Under thermal reactions the E-isomers form the products from intramolecular [4+2]-cycloaddition with H‡298 = 15.6 kcal/mol and S‡298= -27.3 cal/ (mol•degree). The Z-isomer is inert to [4+2]-cycloaddition under these conditions. The Hammett relationships from aryl-substituted diazo esters ( = +0.89) and aryl-substituted dienes ( = -1.65) are consistent with the dipolar nature of this transformation. An unexpected reaction for the synthesis of seven-membered conjugated 1,4-diketones from propargylic diazoesters with unsaturated imines was disclosed. To undergo this process vinyl gold carbene intermediates generated by 1,2-acyloxy migration of propargylic aryldiazoesters undergo a formal [4+3]-cycloaddition, and the resulting aryldiazoesters tethered dihydroazepines undergo an intricate metal-free process to form observed seven-membered conjugated 1,4-diketones with moderate to high yields.

Acyl-CoA synthetase 3 promotes lipid droplet biogenesis in ER microdomains.

Control of lipid droplet (LD) nucleation and copy number are critical, yet poorly understood, processes. We use model peptides that shift from the endoplasmic reticulum (ER) to LDs in response to fatty acids to characterize the initial steps of LD formation occurring in lipid-starved cells. Initially, arriving lipids are rapidly packed in LDs that are resistant to starvation (pre-LDs). Pre-LDs are restricted ER microdomains with a stable core of neutral lipids. Subsequently, a first round of"emerging" LDs is nucleated, providing additional lipid storage capacity. Finally, in proportion to lipid concentration, new rounds of LDs progressively assemble. Confocal microscopy and electron tomography suggest that emerging LDs are nucleated in a limited number of ER microdomains after a synchronized stepwise process of protein gathering, lipid packaging, and recognition by Plin3 and Plin2. A comparative analysis demonstrates that the acyl-CoA synthetase 3 is recruited early to the assembly sites, where it is required for efficient LD nucleation and lipid storage.

Acyl-CoA synthetase 3 promotes lipid droplet biogenesis in ER microdomains.

Control of lipid droplet (LD) nucleation and copy number are critical, yet poorly understood, processes. We use model peptides that shift from the endoplasmic reticulum (ER) to LDs in response to fatty acids to characterize the initial steps of LD formation occurring in lipid-starved cells. Initially, arriving lipids are rapidly packed in LDs that are resistant to starvation (pre-LDs). Pre-LDs are restricted ER microdomains with a stable core of neutral lipids. Subsequently, a first round of"emerging" LDs is nucleated, providing additional lipid storage capacity. Finally, in proportion to lipid concentration, new rounds of LDs progressively assemble. Confocal microscopy and electron tomography suggest that emerging LDs are nucleated in a limited number of ER microdomains after a synchronized stepwise process of protein gathering, lipid packaging, and recognition by Plin3 and Plin2. A comparative analysis demonstrates that the acyl-CoA synthetase 3 is recruited early to the assembly sites, where it is required for efficient LD nucleation and lipid storage.

Novel electroluminescent devices containing Eu(3+)-(2-acyl-1,3-indandionate) complexes with TPPO ligand

Fabrication and electroluminescent properties of devices containing europium complexes of general formula [Eu(ACIND)(3)(TPPO)(2)], where ACIND, 2-acyl-1,3-indandionate ligands: and TPPO, triphenylphosphine oxide. as emitter layers are discussed. The double-layer devices based on these complexes present the following configurations: device 1: ITO/TPD/[Eu(AlND)(3)(TPPO)(2)]/Al: device 2: ITO/TPD/[Eu(ISOV-IND)(3)(TPPO)(2)]/Al and device 3: ITO/TPD/[Eu(BIND)(3)(TPPO)(2)]/Al, where AlND, 2-acetyl-1,3-indandionate; ISOVIND, 2-isovaleryl-1,3-indandionate; and BIND, 2-benzoyl-1,3-indandionate, respectively. These devices exhibited photo and electroluminescent emissions. An important characteristic presented by devices is that their electroluminescent (EL) spectra, in the region of (5)D(0) -> (7)F(J) (J = 0, 1, 2, 3 and 4) transitions of Eu(3+) ion, show profiles that are different from photoluminescent (PL) ones. In addition to narrow bands arising from intraconfigurational-4f(6) transitions, devices 1 and 2 also exhibited a broad band with maximum at around 500 nm which is assigned to electrophosphorescence from the indandionate ligands. On the other hand, EL spectra of device 3 present only narrow bands from (5)D(0) -> (7)F(J) transitions. [Eu(ACIND)(3)(TPPO)(2)] complexes are promising candidates to prepare efficient organic light-emitting devices (OLEDs) when compared with those containing Eu(3+)-complexes of aliphatic beta-diketonate anions. (C) 2009 Elsevier B.V. All rights reserved.

Study of the 3-Hydroxy Eicosanoyl-Coenzyme A Dehydratase and (E)-2,3 Enoyl-Coenzyme A Reductase Involved in Acyl-Coenzyme A Elongation in Etiolated Leek Seedlings1

(R,S)-[1-14C]3-Hydroxy eicosanoyl-coenzyme A (CoA) has been chemically synthesized to study the 3-hydroxy acyl-CoA dehydratase involved in the acyl-CoA elongase of etiolated leek (Allium porrum L.) seedling microsomes. 3-Hydroxy eicosanoyl-CoA (3-OH C20:0-CoA) dehydration led to the formation of (E)-2,3 eicosanoyl-CoA, which has been characterized. Our kinetic studies have determined the optimal conditions of the dehydration and also resolved the stereospecificity requirement of the dehydratase for (R)-3-OH C20:0-CoA. Isotopic dilution experiments showed that 3-hydroxy acyl-CoA dehydratase had a marked preference for (R)-3-OH C20:0-CoA. Moreover, the very-long-chain synthesis using (R)-3-OH C20:0-CoA isomer and [2-14C]malonyl-CoA was higher than that using the (S) isomer, whatever the malonyl-CoA and the 3-OH C20:0-CoA concentrations. We have also used [1-14C]3-OH C20:0-CoA to investigate the reductant requirement of the enoyl-CoA reductase of the acyl-CoA elongase complex. In the presence of NADPH, [1-14C]3-OH C20:0-CoA conversion was stimulated. Aside from the product of dehydration, i.e. (E)-2,3 eicosanoyl-CoA, we detected eicosanoyl-CoA resulting from the reduction of (E)-2,3 eicosanoyl-CoA. When we replaced NADPH with NADH, the eicosanoyl-CoA was 8- to 10-fold less abundant. Finally, in the presence of malonyl-CoA and NADPH or NADH, [1-14C]3-OH C20:0-CoA led to the synthesis of very-long-chain fatty acids. This synthesis was measured using [1-14C]3-OH C20:0-CoA and malonyl-CoA or (E)-2,3 eicosanoyl-CoA and [2-14C]malonyl-CoA. In both conditions and in the presence of NADPH, the acyl-CoA elongation activity was about 60 nmol mg−1 h−1, which is the highest ever reported for a plant system.

Long-Chain Acyl-Homoserine Lactones from Methylobacterium mesophilicum: Synthesis and Absolute Configuration

The acyl-homoserine lactones (acyl-HSLs) produced by Methylobacterium mesophilicum isolated from orange trees infected with the citrus variegated chlorosis (CVC) disease have been studied, revealing the occurrence of six long-chain acyl-HSLs, i.e., the saturated homologues (S)-N-dodecanoyl (1) and (S)-N-tetradecanoyl-HSL (5), the uncommon odd-chain N-tridecanoyl-HSL (3), the new natural product (S)-N-(2E)-dodecenoyl-HSL (2), and the rare unsaturated homologues (S)-N-(7Z)-tetradecenoyl (4) and (S)-N-(2E,7Z)-tetradecadienyl-HSL (6). The absolute configurations of all HSLs were determined as 3S. Compounds 2 and 6 were synthesized for the first time. Antimicrobial assays with synthetic acyl-HSLs against Gram-positive bacterial endophytes co-isolated with M. mesophilicum from CVC-infected trees revealed low or no antibacterial activity.

Molecular Modeling Suggests Cruzain Specificity for Peptide Primaquine Prodrugs

Chagas` disease, infection caused by the protozoan Trypanosoma cruzi, is an important, social and medical ailment in the Latin America. This disease is endemic in 21 countries, mostly Latin America countries, with more than 300,000 new cases every year and about 16-18 million infected people. Current therapy is not effective in the chronic phase of the disease. Thus, new and better drugs are urgently needed. In this sense, the in vitro activity of primaquine (PQ) was reported. Based on this, peptide prodrugs of primaquine containing dipeptides - lysine-arginine (LysArg), phenylalanine-alanine (PheAla) and phenylalanine-arginine (PheArg) -- as carriers, were designed to be selectively cleaved by cruzain, a specific cysteine protease of T. cruzi. The prodrugs have shown to be active against tripomastigote forms according to this order: LysArg-PQ> PheAla-PQ> PheArg-PQ. The molecular mechanism of action considered a probable nucleophilic attack of the catalytic residue of cruzain (Cys25) on the respective prodrug amide carbonyl carbon, releasing PQ. In order to test this hypothesis, molecular modeling studies were performed, physicochemical parameters and stereoelectronic features calculated by using the AM1 semi-empirical method suggest that the amide carbonyl carbon is favorable for cleavage, where the LysArg showed the most electronic reactive and sterically disposable, leading to the prodrug release and action. In addition, the docking study indicates the occurrence of specific interactions between prodrugs and the pockets S1 and S2 of cruzain through the dipeptides carriers, being the distance between cruzain Cys25 and the amide carbonyl group related to the biological activity of the prodrugs.

Molecular modeling as a promising tool to study dendrimer prodrugs delivery

Molecular modeling methodologies were applied to perform preliminary studies concerning the release of active agents from potentially antichagasic and antileishmanial dendrimer prodrugs. The dendrimer was designed having myo-inositol as a core, L-malic acid as a spacer group, and hydroxymethylnitrofurazone (NFOH), 3-hydroxyflavone or quercetin, as active compounds. Each dendrimer presented a particular behavior concerning to the following investigated properties: spatial hindrance, map of electrostatic potential (MEP), and the lowest unoccupied molecular orbital energy (E(LUMO)). Additionally, the findings suggested that the carbonyl group next to the active agent seems to be the most promising ester breaking point. (C) 2009 Elsevier B.V. All rights reserved.

Hepatic structure-pharmacokinetic relationships: The hepatic disposition and metabolite kinetics of a homologous series of O-acyl derivatives of salicylic acid

1 The hepatic disposition and metabolite kinetics of a homologous series of O-acyl (acetyl, propionyl, butanoyl, pentanoyl, hexanoyl and octanoyl) esters of salicylic acid (C2SA, C3SA, C4SA, C5SA, C6SA and C8SA, respectively) was determined using a single-pass, in-sills rat liver preparation. 2 The hepatic venous outflow profiles for the parent esters and the generated metabolite, salicylic acid (SA) were analysed by HPLC. Non-parametric moments analysis was used to determine the area under the curve (AUC'), mean transit time (MTT) and normalized variance (CV2) for the parent esters and generated SA. 3 Pregenerated SA ([C-14]-salicylic acid) was injected into each liver with the parent ester to determine its distribution characteristics. 4 The overall recovery of ester plus metabolite was 89% of the ester dose injected and independent of the ester carbon number, suggesting that ester extraction was due to hepatic metabolism to salicylic acid. 5 The metabolite AUC' value increased directly with the lipophilicity of the parent ester (from 0.12 for C2SA to 0.95 for C8SA). By contrast, the parent AUC' decreased with the lipophilicity (from 0.85 for C2SA to zero for C8SA). The metabolite MTT value also showed a trend to increase with the lipophilicity of the parent ester (from 15.72 s for C3SA to 61.97 s for C8SA). However, the parent MTT value shows no significant change across the series. 6 The two-compartment dispersion model was used to derive the kinetic parameters for parent ester, pregenerated SA and generated SA. Consequently, these parameters were used to estimate the values of AUG', MITT and CV2 for the parent ester and metabolite. The moments values obtained using the two-compartment dispersion model show similar trends to the corresponding moments values obtained from the outflow profiles using a non-parametric approach. 7 The more lipophilic aspirin analogues are more confined to the portal circulation after oral administration than aspirin due to their more extensive hepatic elimination avoiding systemic prostacyclin inhibition. Given that aspirin's selectivity as an anti-thrombotic agent has been postulated to be due to selective anti-platelet effects in the portal circulation, the more lipophilic and highly extracted analogues are potentially more selective anti-thrombotic agents than aspirin.

Synthesis of (Z)-1-Organylthiobut-1-en-3-ynes: Hydrothiolation of Symmetrical and Unsymmetrical Buta-1,3-diynes

Hydrothiolation of 1-organylbuta-1,3-diynes and 1,4-diorganylbuta-1,3-diynes with the sodium organylthiolate anions, which were generated in situ by reacting diphenyl and dibutyl disulfide with NaBH(4) in ethanol, results in the regio-, stereo-, and chemoselective formation of (Z)-1-organylthio-4-organylbut-1-en-3-ynes and (Z)-1-organylthio-1,4-diorganylbut-1-en-3-ynes, respectively.

Dipeptidyl peptidase IV is a target for covalent adduct formation with the acyl glucuronide metabolite of the anti-inflammatory drug zomepirac

The nonsteroidal anti-inflammatory drug zomepirac (ZP) is metabolised to a chemically reactive acyl glucuronide conjugate (ZAG) which can form covalent adducts with proteins. In vivo, such adducts could initiate immune or toxic responses. In rats given ZP, the major band detected in liver homogenates by immunoblotting with a polyclonal ZP antiserum was at 110 kDa. This adduct was identified as ZP-modified dipeptidyl peptidase IV (DPP IV) by immunoblotting using the polyclonal ZP antiserum and monoclonal DPP IV antibodies OX-61 and 236.3. In vitro, ZAG, but not ZP itself, covalently modified recombinant human and rat DPP IV. Both monoclonal antibodies recognized DPP IV in livers from ZP- and vehicle-dosed rats. Confirmation that the 110 kDa bands which were immunoreactive with the ZP and DPP IV antibodies represented the same molecule was obtained from a rat liver extract reciprocally immunodepleted of antigens reactive with these two antibodies. Furthermore, immunoprecipitations with OX-61 antibody followed by immunolotting with ZP antiserum, and the reciprocal experiment, showed that both these antibodies recognised the same 110 kDa molecule in extracts of ZP-dosed rat liver. The results verify that DPP IV is one of the protein targets for covalent modification during hepatic transport and biliary excretion of ZAG in rats. (C) 2001 Elsevier Science Inc. All rights reserved.