- Lipid-core nanocapsules restrained the indomethacin ethyl ester hydrolysis in the gastrointestinal lumen and wall acting as mucoadhesive reservoirs
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The aim of this work was to investigate if the indomethacin ethyl ester (IndOEt) released from lipid-core nanocapsules (NC) is converted into indomethacin (IndOH) in the intestine lumen, intestine wall or after the particles reach the blood stream. NC-IndOEt had monomodal size distribution (242 nm; PDI 0.2) and zeta potential of -11 mV. The everted rat gut sac model showed IndOEt passage of 0.16 μmol m-2 through the serosal fluid (30 min). From 15 to 120 min, the IndOEt concentrations in the tissue increased from 6.13 to 27.47 μmol m-2. No IndOH was formed ex vivo. A fluorescent-NC formulation was used to determine the copolymer bioadhesion (0.012 μmol m-2). After NC-IndOEt oral administration to rats, IndOEt and IndOH were detected in the gastrointestinal tract (contents and tissues). In the tissues, the IndOEt concentrations decreased from 459 to 5 μg g-1 after scrapping, demonstrating the NC mucoadhesion. In plasma (peripheric and portal vein), in spleen and liver, exclusively IndOH was detected. In conclusion, after oral dosing of NC-IndOEt, IndOEt is converted into IndOH in the intestinal lumen and wall before reaching the blood stream. The complexity of a living system was not predicted by the ex vivo gut sac model.
- Cattani, Vitória Berg,Fiel, Luana Almeida,J?ger, Alessandro,J?ger, Eliézer,Colomé, Letícia Marques,Uchoa, Flavia,Stefani, Valter,Costa, Teresa Dalla,Guterres, Sivia Stanis?uaski,Pohlmann, Adriana Raffin
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Read Online
- Green Esterification of Carboxylic Acids Promoted by tert-Butyl Nitrite
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In this work, the green esterification of carboxylic acids promoted by tert-butyl nitrite has been well developed. This transformation is compatible with a broad range of substrates and exhibits excellent functional group tolerance. Various drugs and substituted amino acids are applicable to this reaction under near neutral conditions, with good to excellent yields.
- Cheng, Xionglve,Jiang, Gangzhong,Li, Xingxing,Tao, Suyan,Wan, Xiaobing,Zhao, Yanwei,Zheng, Yonggao
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supporting information
p. 2713 - 2718
(2021/06/25)
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- Effects of steric hindrance and electron density of ester prodrugs on controlling the metabolic activation by human carboxylesterase
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Carboxylesterase (CES) plays an important role in the hydrolysis metabolism of ester–type drugs and prodrugs. In this study, we investigated the change in the hydrolysis rate of hCE1 by focusing on the steric hindrance of the ester structure and the elect
- Takahashi, Masato,Hirota, Ibuki,Nakano, Tomoyuki,Kotani, Tomoyuki,Takani, Daisuke,Shiratori, Kana,Choi, Yura,Haba, Masami,Hosokawa, Masakiyo
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- Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations
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Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non-explosive and non-toxic, and should find broad utility as a replacement for diazomethane.
- Svec, Riley L.,Hergenrother, Paul J.
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supporting information
p. 1857 - 1862
(2019/12/27)
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- Cross-Coupling of Chloro(hetero)arenes with Thiolates Employing a Ni(0)-Precatalyst
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A general and efficient Ni-catalyzed coupling of challenging aryl chlorides and in situ generated aliphatic and aromatic thiolates is described. The employed on-cycle, air-stable defined Ni precatalysts allow for transformation of a broad scope of substrates. A variety of functional groups and heterocyclic motifs as well as structurally varied thiols are tolerated at unprecedented moderate catalyst loadings and reaction temperatures. Depending on reaction conditions, aryl thiols can selectively undergo C-S or C-C couplings.
- Gehrtz, Paul H.,Geiger, Valentin,Schmidt, Tanno,Sr?an, Laura,Fleischer, Ivana
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supporting information
p. 50 - 55
(2019/01/11)
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- Myoglobin-Catalyzed C?H Functionalization of Unprotected Indoles
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Functionalized indoles are recurrent motifs in bioactive natural products and pharmaceuticals. While transition metal-catalyzed carbene transfer has provided an attractive route to afford C3-functionalized indoles, these protocols are viable only in the presence of N-protected indoles, owing to competition from the more facile N?H insertion reaction. Herein, a biocatalytic strategy for enabling the direct C?H functionalization of unprotected indoles is reported. Engineered variants of myoglobin provide efficient biocatalysts for this reaction, which has no precedents in the biological world, enabling the transformation of a broad range of indoles in the presence of ethyl α-diazoacetate to give the corresponding C3-functionalized derivatives in high conversion yields and excellent chemoselectivity. This strategy could be exploited to develop a concise chemoenzymatic route to afford the nonsteroidal anti-inflammatory drug indomethacin.
- Vargas, David A.,Tinoco, Antonio,Tyagi, Vikas,Fasan, Rudi
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supporting information
p. 9911 - 9915
(2018/07/31)
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- Fundamental studies and development of nickel-catalyzed trifluoromethylthiolation of aryl chlorides: Active catalytic species and key roles of ligand and traceless MeCN additive revealed
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A catalytic protocol to convert aryl and heteroaryl chlorides to the corresponding trifluoromethyl sulfides is reported herein. It relies on a relatively inexpensive Ni(cod)2/dppf (cod = 1,5-cyclooctadiene; dppf = 1,1′-bis(diphenylphosphino)ferrocene) catalyst system and the readily accessible coupling reagent (Me4N)SCF3. Our computational and experimental mechanistic data are consistent with a Ni(0)/Ni(II) cycle and inconsistent with Ni(I) as the reactive species. The relevant intermediates were prepared, characterized by X-ray crystallography, and tested for their catalytic competence. This revealed that a monomeric tricoordinate Ni(I) complex is favored for dppf and Cl whose role was unambiguously assigned as being an off-cycle catalyst deactivation product. Only bidentate ligands with wide bite angles (e.g., dppf) are effective. These bulky ligands render the catalyst resting state as [(P-P)Ni(cod)]. The latter is more reactive than Ni(P-P)2, which was found to be the resting state for ligands with smaller bite angles and suffers from an initial high-energy dissociation of one ligand prior to oxidative addition, rendering the system unreactive. The key to effective catalysis is hence the presence of a labile auxiliary ligand in the catalyst resting state. For more challenging substrates, high conversions were achieved via the employment of MeCN as a traceless additive. Mechanistic data suggest that its beneficial role lies in decreasing the energetic span, therefore accelerating product formation. Finally, the methodology has been applied to synthetic targets of pharmaceutical relevance.
- Yin, Guoyin,Kalvet, Indrek,Englert, Ulli,Schoenebeck, Franziska
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supporting information
p. 4164 - 4172
(2015/04/14)
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- Synthesis of indoles through Rh(III)-catalyzed C-H cross-coupling with allyl carbonates
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A practical Rh-catalyzed reaction was developed to achieve 2-alkyl-substituted indole synthesis. The reaction can tolerate a variety of synthetically important functional groups. The indole products can also be transformed into other important skeletons. Two bioactive compounds, that is indomethacin and pravadoline were prepared using the new method.
- Gong, Tian-Jun,Cheng, Wan-Min,Su, Wei,Xiao, Bin,Fu, Yao
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supporting information
p. 1859 - 1862
(2014/03/21)
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- An algorithm to determine the mechanism of drug distribution in lipid-core nanocapsule formulations
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Aqueous solutions of lipid-core nanocapsules are interesting drug delivery systems for passive drug targeting. In this study, we hypothesized that the drug distribution mechanisms in lipid-core nanocapsule formulations could be categorized into six different types. To experimentally determine the type of drug distribution in these formulations, we proposed the use of an algorithm as an innovative strategy. The approach is shown to be a valuable tool to optimize and select formulations intended for drug delivery. The best physico-chemical parameter in terms of predicting the type of distribution was the log D value. In conclusion, the use of the algorithm developed in this study represents a simple and rapid approach through which it was possible to experimentally determine the drug distribution in colloidal formulations for eight drug models.
- Oliveira, Catiuscia P.,Venturini, Cristina G.,Donida, Bruna,Poletto, Fernanda S.,Guterres, Silvia S.,Pohlmann, Adriana R.
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p. 1141 - 1150
(2013/03/28)
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- Accidental discovery of a 'longer-range' vinylogous Pummerer-type lactonization: Formation of sulindac sulfide lactone from sulindac
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Unexpected formation of sulindac sulfide lactone occurred when sulindac was treated with oxalyl chloride and triethylamine. Structurally analogous sulindac sulfide and indomethacin did not undergo such lactonization under similar reaction conditions. We b
- Halder, Somnath,Satyam, Apparao
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experimental part
p. 1179 - 1182
(2011/03/21)
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- Converting cox inhibition compounds that are not COX-2 selective inhibitors to derivatives that are COX-2 selective inhibitors
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A method of altering specificity of cyclooxygenase-inhibiting compounds that have a COOH moiety by changing the various COOH containing compounds, such as indomethacin, into ester derivatives or into secondary amide derivatives.
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- Profiling indomethacin impurities using high-performance liquid chromatography and nuclear magnetic resonance
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The anti-inflammatory drug indomethacin was investigated regarding new related impurities. Therefore, related substances 2-9 were prepared by independent synthesis and physicochemically characterized. To determine indomethacin and its related substances, a new HPLC-UV method was developed and validated. Indomethacin and its impurities were eluted on a C18 column with a mobile phase consisting of methanol and an aqueous solution of 0.2% phosphoric acid at a flow rate of 1.5 ml/min and were quantified by UV detection at 320 nm. Overall, the HPLC-UV method was simple and reliable for the detection of eight impurities in indomethacin. In addition to the HPLC-UV method, 1H nuclear magnetic resonance (NMR) was used to investigate indomethacin regarding impurities. For that purpose, related substances 2-9 were systematically added to indomethacin and investigated. The NMR method was found to be very useful for the identification of impurities in bulk substance without prior separation. Both HPLC-UV and NMR were used to analyze 38 batches of indomethacin available on the European market. The outcome was that 42% of the batches did not meet the compendial requirements although they met the specifications of current compendial methods. Some batches contained the previously undescribed impurity 8, while other batches contained by-products from two distinct synthetic routes. The methods presented herein are important contributions to the ongoing efforts to reduce impurities and therefore the risk of adverse side-effects in drugs that are no longer under patent protection.
- Hess,Teubert,Ortwein,Eger
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p. 301 - 311
(2007/10/03)
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- Ester and amide derivatives of the nonsteroidal antiinflammatory drug, indomethacin, as selective cyclooxygenase-2 inhibitors
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Recent studies from our laboratory have shown that derivatization of the carboxylate moiety in substrate analogue inhibitors, such as 5,8,11,14- eicosatetraynoic acid, and in nonsteroidal antiinflammatory drugs (NSAIDs), such as indomethacin and meclofenamic acid, results in the generation of potent and selective cyclooxygenase-2 (COX-2) inhibitors (Kalgutkar et al. Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 925-930). This paper summarizes details of the structure-activity studies involved in the transformation of the arylacetic acid NSAID, indomethacin, into a COX-2-selective inhibitor. Many of the structurally diverse indomethacin esters and amides inhibited purified human COX-2 with IC50 values in the low-nanomolar range but did not inhibit ovine COX-1 activity at concentrations as high as 66 μM. Primary and secondary amide analogues of indomethacin were more potent as COX-2 inhibitors than the corresponding tertiary amides. Replacement of the 4- chlorobenzoyl group in indomethacin esters or amides with the 4-bromobenzyl functionality or hydrogen afforded inactive compounds. Likewise, exchanging the 2-methyl group on the indole ring in the ester and amide series with a hydrogen also generated inactive compounds. Inhibition kinetics revealed that indomethacin amides behave as slow, tight-binding inhibitors of COX-2 and that selectivity is a function of the time-dependent step. Conversion of indomethacin into ester and amide derivatives provides a facile strategy for generating highly selective COX-2 inhibitors and eliminating the gastrointestinal side effects of the parent compound.
- Kalgutkar, Amit S.,Marnett, Alan B.,Crews, Brenda C.,Remmel, Rory P.,Marnett, Lawrence J.
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p. 2860 - 2870
(2007/10/03)
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- Cyclic amide derivatives as potential prodrugs II: N- hydroxymethylsuccinimide- / isatin esters of some NSAIDs as prodrugs with an improved therapeutic index
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Ester prodrugs of aspirin la, ibuprofen 1b, naproxen 1c and indomethacin 1d were synthesized using N-Hydroxymethylsuccinimide (HMSI) 3 and N- hydroxymethylisatin (HMIS) 4 as promoieties to reduce their gastrointestinal toxicity and improve bioavailability. Additionally, the kinetics of hydrolysis of the synthesized prodrugs 5a-d and 6a-d were studied at 37°C in non-enzymatic simulated gastric fluid (SGF; hydrochloric acid buffer pH = 1.2); 0.02 M phosphate buffer (pH = 7.4); 80% human plasma and 10% rat liver homogenate. The results indicate higher chemical stability of the ester prodrugs in non-enzymatic SGF (t(1/2) ? 6.5-18.6 h) and rapid conversion to the parent drugs in 80% human plasma (t(1/2) ? 11.4-235 min) as well as in 10% rat liver homogenates (t(1/2) ? 12.0-90.0 min). As a general pattern, the HMSI esters 5a-d revealed higher chemical stability than the corresponding HMIS analogues 6a-d. The pH-rate profile of 5c and 6a indicated maximum stability of the former at pH = 1.2-8.0 and of the latter at pH = 1.2-4.0. The distribution coefficient (D7.4) values of the prodrugs 5a-d, 6a-d and the parent drugs 1a-d in an n-octanol/phosphate buffer (pH =7.4) system indicated enhanced lipophilic properties of the prodrugs. Furthermore, the HMIS ester prodrugs 6a-d are more lipophilic than the corresponding HMSI derivatives 5a-d. In vivo ulcerogenicity studies using scanning electron microscopy on stomach specimens of rats treated with an oral dose for 4 d revealed that the synthesized ester prodrugs are significantly less irritating to gastric mucosa than the parent drugs. These results suggested HMSI and/or HMIS esters possess good potential as prodrugs with an improved therapeutic index for oral delivery of NSAIDs.
- Mahfouz, Nadia M.,Omar, Farghaly A.,Aboul-Fadl, Tarek
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p. 551 - 562
(2007/10/03)
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- Rigid analogs of indomethacin
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10 Chloro 2 methoxy 5 methyl 7 H pyrrolo [3,2,1 de]phenanthrid 7 one 4 acetic acid and its deschloro analog were synthesized as rigid analogs of indomethacin. The chloro analog was found to be inactive in a standard in vivo guinea pig uv erythema assay.
- Olson,Wheeler,Wells
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p. 167 - 171
(2007/10/08)
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