- Aromatic acyl hydrazone derivative and application thereof as NA inhibitor
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The invention relates to an aromatic acyl hydrazone derivative as shown in a structural formula I, pharmaceutically acceptable salt and a pharmaceutical composition thereof, and application of the aromatic acyl hydrazone derivative and the pharmaceutically acceptable salt and the pharmaceutical composition in preparation of an influenza virus neuraminidase inhibitor, wherein R is one of trifluoromethyl, nitryl, 3-methyl-4-nitryl, 3-hydroxyl-4-nitryl, 3-nitryl-4-hydroxyl, hydroxyl, dihydroxyl, dinitryl, 3-methoxy-4-hydroxyl or trihydroxyl; Y is selected from hydroxyl, dihydroxyl, 2-hydroxyl-3-methoxy, 2-hydroxyl-4-methoxy,2-hydroxyl-5-methoxy,2-hydroxyl-6-methoxy,3-hydroxyl-2-methoxy,3-hydroxyl-4-methoxy,3-hydroxyl-5-methoxy,3-hydroxyl-6-methoxy,4-hydroxyl-2-methoxy,4-hydroxyl-3-methoxy,4-hydroxyl-3,5-dimethoxy, trihydroxyl, 4-hydroxyl-3-ethoxy, or 4-hydroxyl-3,5-dimethoxy; w is selected from CH or N; and z is selected from CH or N.
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Paragraph 0039; 0044-0046; 0258-0262
(2020/12/30)
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- Synthesis and antimicrobial activity of piperine analogues containing 1,2,4-triazole ring
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A series 1,2,4-triazole piperine analogues (TP1-TP6) were designed and synthesized. The structures were confirmed using 1H NMR and 13C NMR. Antibacterial study was done using Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative microorganisms (E. coli and Pseudomonas aeruginosa) by disc diffusion method. Compound containing chloro substitution (TP6) showed the highest effect, while compound TP1, TP3, TP4, TP5 showed the moderate activity.
- Kumar, Kottakki Naveen,Amperayani, Karteek Rao,Ummdi, V. Ravi Sankar,Parimi, Uma Devi
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p. 1077 - 1080
(2019/04/05)
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- Structural design, synthesis and substituent effect of hydrazone-N-acylhydrazones reveal potent immunomodulatory agents
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4-(Nitrophenyl)hydrazone derivatives of N-acylhydrazone were synthesized and screened for suppress lymphocyte proliferation and nitrite inhibition in macrophages. Compared to an unsubstituted N-acylhydrazone, active compounds were identified within initial series when hydroxyl, chloride and nitro substituents were employed. Structure-activity relationship was further developed by varying the position of these substituents as well as attaching structurally-related substituents. Changing substituent position revealed a more promising compound series of anti-inflammatory agents. In contrast, an N-methyl group appended to the 4-(nitrophenyl)hydrazone moiety reduced activity. Anti-inflammatory activity of compounds is achieved by modulating IL-1β secretion and prostaglandin E2 synthesis in macrophages and by inhibiting calcineurin phosphatase activity in lymphocytes. Compound SintMed65 was advanced into an acute model of peritonitis in mice, where it inhibited the neutrophil infiltration after being orally administered. In summary, we demonstrated in great details the structural requirements and the underlying mechanism for anti-inflammatory activity of a new family of hydrazone-N-acylhydrazone, which may represent a valuable medicinal chemistry direction for the anti-inflammatory drug development in general.
- Meira, Cássio S.,dos Santos Filho, José Maurício,Sousa, Caroline C.,Anjos, Pamela S.,Cerqueira, Jéssica V.,Dias Neto, Humberto A.,da Silveira, Rafael G.,Russo, Helena M.,Wolfender, Jean-Luc,Queiroz, Emerson F.,Moreira, Diogo R.M.,Soares, Milena B.P.
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p. 1971 - 1985
(2018/03/12)
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- N-(5-Methyl-1,3-Thiazol-2-yl)-2-{[5-((Un)Substituted- Phenyl)1,3,4-Oxadiazol-2-yl]Sulfanyl}acetamides. Unique Biheterocycles as Promising Therapeutic Agents
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An electrophile, 2-bromo-N-(5-methyl-1,3-thiazol-2-yl)acetamide, was synthesized by the reaction of 5-methyl-1,3-thiazol-2-amine and bromoacetyl bromide in an aqueous medium. In a parallel scheme, a series of (un)substituted benzoic acids was converted sequentially into respective esters, acid hydrazides, and then into 1,3,4-oxadiazole heterocyclic cores. The electrophile was coupled with the aforementioned 1,3,4-oxadiazoles to obtain the targeted bi-heterocyles. Structural analysis of the synthesized compounds was performed by IR, EI-MS, 1H NMR, and 13C NMR. The enzyme inhibition study of these molecules was carried out against four enzymes, namely, acetylcholinesterase, butyrylcholinesterase, α-glucosidase, and urease. The interactions of these compounds with respective enzymes were recognized by their in silico study. Moreover, their cytotoxicity was also determined to find out their utility as possible therapeutic agents.
- Abbasi,Ramzan,Aziz-ur-Rehman,Siddiqui,Shah,Hassan,Seo,Ashraf,Mirza,Ismail
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p. 801 - 811
(2019/02/27)
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- S-substituted 3,5-dinitrophenyl 1,3,4-oxadiazole-2-thiols and tetrazole-5-thiols as highly efficient antitubercular agents
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Two new classes of antitubercular agents, namely 5-alkylsulfanyl-1-(3,5-dinitrophenyl)-1H-tetrazoles and 2-alkylsulfanyl-5-(3,5-dinitrophenyl)-1,3,4-oxadiazoles, and their structure-activity relationships are described. These compounds possessed excellent activity against Mycobacterium tuberculosis, including the clinically isolated multidrug (MDR) and extensively drug-resistant (XDR) strains, with no cross resistance with first or second-line anti-TB drugs. The minimum inhibitory concentration (MIC) values of the most promising compounds reached 0.03 μM. Furthermore, these compounds had a highly selective antimycobacterial effect because they were completely inactive against 4 gram positive and 4 gram negative bacteria and eight fungal strains and had low in vitro toxicity for four mammalian cell lines, including hepatic cell lines HepG2 and HuH7. Although the structure-activity relationship study showed that the presence of two nitro groups is highly beneficial for antimycobacterial activity, the analogues with a trifluoromethyl group instead of one of the nitro groups maintained a high antimycobacterial activity, which indicates the possibility for further structural optimization of this class of antitubercular agents.
- Karabanovich, Galina,Něme?ek, Jan,Valá?ková, Lenka,Carazo, Alejandro,Kone?ná, Klára,Stola?íková, Ji?ina,Hrabálek, Alexandr,Pavli?, Oto,Pávek, Petr,Vávrová, Kate?ina,Roh, Jaroslav,Klime?ová, Věra
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p. 369 - 383
(2016/12/22)
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- Design and optimization of N-acylhydrazone pyrimidine derivatives as E. coli PDHc E1 inhibitors: Structure-activity relationship analysis, biological evaluation and molecular docking study
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By targeting the thiamin diphosphate (ThDP) binding site of Escherichia coli (E. coli) pyruvate dehydrogenase multienzyme complex E1 (PDHc E1), a series of novel ‘open-chain’ classes of ThDP analogs A, B, and C with N-acylhydrazone moieties was designed and synthesized to explore their activities against E. coli PHDc E1 in vitro and their inhibitory activity against microbial diseases were further evaluated in vivo. As a result, A1–23 exhibited moderate to potent inhibitory activities against E. coli PDHc E1 (IC50 = 0.15–23.55 μM). The potent inhibitors A13, A14, A15, C2, had strong inhibitory activities with IC50 values of 0.60, 0.15, 0.39 and 0.34 μM against E. coli PDHc E1 and with good enzyme-selective inhibition between microorganisms and mammals. Especially, the most powerful inhibitor A14 could 99.37% control Xanthimonas oryzae pv. Oryzae. Furthermore, the binding features of compound A14 within E. coli PDHc E1 were investigated to provide useful insights for the further construction of new inhibitor by molecular docking, site-directed mutagenesis, and enzymatic assays. The results indicated that A14 had most powerful inhibition against E. coli PDHc E1 due to the establishment of stronger interaction with Glu571, Met194, Glu522, Leu264 and Phe602 at active site of E.coli PDHc E1. It could be used as a lead compound for further optimization, and may have potential as a new microbicide.
- He, Haifeng,Xia, Hongying,Xia, Qin,Ren, Yanliang,He, Hongwu
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p. 5652 - 5661
(2017/10/09)
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- Synthesis, spectral analysis and antibacterial evaluation of 5-substituted-1,3,4-oxadiazol-2-yl 4-(4-methylpiperidin-1-ylsulfonyl)benzyl sulfides
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Owing to valuable biological activities of 1,3,4-oxadiazole, sulfamoyl and piperidine functionalities, some new 1-(4-{[(5-substituted-1,3,4-oxadiazol-2-yl) thio]methyl}benzene sulfonyl)-4-methylpiperidine (6a-o) derivatives have been introduced. The target molecules were synthesized from different aralkyl/aryl carboxylic acids, 1a-o, through a series of steps. First the compounds, 1a-o, were converted to heterocyclic 1,3,4-oxadiazole nucleophiles, 4a-o. Second an electrophile as 1-(4-bromomethylbenzenesulfonyl)-4-methylpiperidine (5) was synthesized from 4-methylpiperidine. Finally the target compounds, 6a-o, were prepared by reacting 4a-o with 5 in DMF and LiH. The final compounds were structurally elucidated by spectral data of IR, 1H-NMR and EI-MS. All the compounds were screened for their antibacterial evaluation and found to exhibit valuable results.
- Aziz-Ur-Rehman,Ahtzaz, Samreen,Abbasi, Muhammad Athar,Siddiqui, Sabahat Zahra,Rasool, Shahid,Ahmad, Irshad
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p. 3370 - 3375
(2017/05/22)
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- Synthesis and pharmacological screening: Sulfa derivatives of 2-pipecoline-bearing 1,3,4-oxadiazole core
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An electrophile, 1-(4-(bromomethylbenzenesulfonyl)-2-methylpiperidine, was synthesized by the reaction of 2-methylpiperidine (2-pipecoline) and 4-bromomethylbenzenesulfonyl chloride in a weak basic medium under pH control. A series of nucleophiles, 5-aryl/aralkyl-1,3,4-oxadiazol-2-thiols, were synthesized from corresponding carboxylic acids in three steps. The title molecules were synthesized by coupling the electrophile to nucleophiles in an aprotic medium using LiH as an activator. The structures of all synthesized compounds were corroborated through IR, 1H NMR, and EI-MS techniques. All the compounds were screened for their pharmacological behavior, particularly, antibacterial and enzyme inhibitory activities. Notably efficient results were obtained against both gram-positive and gram-negative bacterial strains. Regarding enzyme inhibition, compounds were efficient against acetylcholinesterase and butyrylcholinesterase.
- Aziz-ur-Rehman,Arif,Abbasi,Siddiqui,Rasool,Shah
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p. 328 - 339
(2017/07/04)
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- Rational design, synthesis and biological evaluation of 1,3,4-oxadiazole pyrimidine derivatives as novel pyruvate dehydrogenase complex E1 inhibitors
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On the basis of previous study on 2-methylpyrimidine-4-ylamine derivatives I, further synthetic optimization was done to find potent PDHc-E1 inhibitors with antibacterial activity. Three series of novel pyrimidine derivatives 6, 11 and 14 were designed and synthesized as potential Escherichia coli PDHc-E1 inhibitors by introducing 1,3,4-oxadiazole-thioether, 2,4-disubstituted-1,3-thiazole or 1,2,4-triazol-4-amine-thioether moiety into lead structure I, respectively. Most of 6, 11 and 14 exhibited good inhibitory activity against E. coli PHDc-E1 (IC50 0.97-19.21 μM) and obvious inhibitory activity against cyanobacteria (EC50 0.83-9.86 μM). Their inhibitory activities were much higher than that of lead structure I. 11 showed more potent inhibitory activity against both E. coli PDHc-E1 (IC50 50 50 = 0.97 μM) and cyanobacteria (EC50 = 0.83 μM). The possible interactions of the important residues of PDHc-E1 with title compounds were studied by molecular docking, site-directed mutagenesis, and enzymatic assays. The results indicated that 11d had more potent inhibitory activity than that of 14d or I due to its 1,3,4-oxadiazole moiety with more binding position and stronger interaction with Lsy392 and His106 at active site of E. coli PDHc-E1.
- He, Haifeng,Wang, Wei,Zhou, Yuan,Xia, Qin,Ren, Yanliang,Feng, Jiangtao,Peng, Hao,He, Hongwu,Feng, Lingling
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p. 1879 - 1888
(2016/04/05)
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- Synthesis, Characterization and Energetic Properties of 1,3,4-Oxadiazoles
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An efficient cyclization between nitro-substituted benzoic acids and nitro-substituted benzohydrazides affords 1,3,4-oxadiazoles. Facile synthesis and a broad substrate scope produce a range of compounds, some of them with potential as high-energy compounds. Heats of formation (ΔHf) and densities (ρ) were calculated, and heats of decomposition (ΔHd) and combustion (ΔHc) were determined experimentally. The densities of seven of the synthesized compounds were determined by gas pycnometry, and the respective values of detonation velocity (VD), detonation pressure (PD) and specific impulse (ISP) were calculated using the EXPLO5 program. An X-ray structure of 2-(2,4-dinitrophenyl)-5-(3,5-dinitrophenyl)-1,3,4-oxadiazole (4n) revealed the non-planarity of the molecule and afforded a crystal density of 1.698 (at 120 K), close to the pycnometric value of 1.64 at room temperature. Efficient cyclization between nitro-substituted benzohydrazides and nitro-substituted benzoic acids affords energetic 1,3,4-oxadiazoles.
- Wang, Zuoquan,Zhang, Hong,Killian, Benjamin J.,Jabeen, Farukh,Pillai, Girinath G.,Berman, Heather M.,Mathelier, Michael,Sibble, Ashani J.,Yeung, Justin,Zhou, Wenfeng,Steel, Peter J.,Hall, C. Dennis,Katritzky, Alan R.
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p. 5183 - 5188
(2015/08/18)
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- Synthesis and evaluation of some substituted heterocyclic fluconazole analogues as antifungal agents
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A new series of fluconazole analogues of 1-(1H-1,2,4-triazol-1-yl)-2-(2,4- difluoro-phenyl)-3-4-(substituted-heterocyclic ring-1H-1,2,3- triazol-1-yl)-2-propanols (1-10) were designed, synthesized and evaluated as antifungal agents. Preliminary antifungal tests showed that most of the title compounds exhibited moderate activity with broad spectrum against eight human pathogenic fungi in vitro, compounds 1 and 6 had the best antifungal activity against Candida albicans with the value of MIC80 = 0.5 μg/mL respectively.
- Wang, Shudong,Zhang, Lei,Jin, Yongsheng,Tang, Jin Hao,Su, Hua,Yu, Shichong,Ren, Haixiang
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p. 2362 - 2364
(2014/06/09)
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- Kinetic study on nucleophilic displacement reactions of 2-chloro-4-nitrophenyl x-substituted-benzoates with primary amines: Reaction mechanism and origin of the a-effect
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Second-order rate constants for aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (1a-h) have been measured spectrophotometrically in 80 mol % H2O/20 mol % DMSO at 25.0 °C. The Bronsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (1d) with a series of primary amines curves downward, which has been taken as evidence for a stepwise mechanism with a change in rate-determining step (RDS). The Hammett plots for the reactions of 1a-h with hydrazine and glycylglycine are nonlinear while the Yukawa- Tsuno plots exhibit excellent linearity with ρX = 1.22-1.35 and r = 0.57-0.59, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by stabilization of substrates possessing an electron-donating group (EDG) through resonance interactions between the EDG and C=O bond of the substrates. The α-effect exhibited by hydrazine increases as the substituent X changes from a strong EDG to a strong electron-withdrawing group (EWG). It has been concluded that destabilization of hydrazine through the electronic repulsion between the adjacent nonbonding electrons is not solely responsible for the substituent dependent α-effect but stabilization of the transition state is also a plausible origin of the α-effect.
- Um, Tae-Il,Kim, Min-Young,Kim, Tae-Eun,Um, Ik-Hwan
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p. 436 - 440
(2014/03/21)
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- Synthesis, antibacterial and anticancer evaluation of 5-substituted (1,3,4-oxadiazol-2-yl)quinoline
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2-Chloroquinoline-3-carbaldehyde (2) was synthesized via Vilsmeier-Haack method using acetanilide. Phenoxy/naphthalene-1-yl/naphthalen-2-yloxy methyl-1H-benzimidazol-1-yl)acetohydrazide (7a-c) were synthesized using 2-[2-(phenoxy/naphthalen-1-yl/naphthalen-2-yloxy methyl)-1H-benzimidazol-1-yl]acetohydrazide (6a-c). The title compounds 2-chloro-3-{5-[(2-phenoxy/naphthalene-1-yl/naphthalen-2-yloxy methyl-1-H-benzimidazol-1-yl)methyl]-1,3,4-oxadiazol-2-yl}quinolone (8a-c) were prepared using chloramine-T. In the second series, (2-chloroquinolin-3-yl)methylidene]-substituted benzohydrazide (11a-i) were prepared by the reaction of 2-chloroquinoline-3-carbaldehyde (2) and an acid hydrazide (10a-i). The synthesized compounds were characterized by IR, NMR, Mass spectrometry, elemental analysis and screened for their antibacterial (serial dilution technique and disc diffusion method) and anticancer activity by NCI 60 cell screen at a single high dose (10-5 M) on various panel/cell lines. The synthesized compounds (8a, 8c, 12a, 12b, 12c and 12h) were acting as a magic bullet against gram-positive strains of Bacillus cereus MTCC1305, and the compounds (12a, 12c and 12h) were also found to be extremely active against Klebsiella pneumonia NCTC7447. In the in vitro screen on tested cancer cell line, the compound (12d) showed 95.70 growth percent (GP) and highly active on SNB-75 (CNS cancer) and UO-31 (renal cancer) (GP = 53.35 and 64.35, respectively), and the compound (8a) showed 96.86 GP and highly active on SNB-75 (CNS cancer GP 51.27).
- Salahuddin,Mazumder, Avijit,Shaharyar, Mohammad
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p. 2514 - 2528
(2015/02/19)
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- Antimicrobial evaluation of 4-methylsulfanyl benzylidene/3-hydroxy benzylidene hydrazides and QSAR studies
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A series of 4-methylsulfanyl benzylidene/3-hydroxy benzylidene hydrazides (1-20) was synthesized and tested for in vitro antimicrobial activity against S. aureus, B. subtilis, E. coli, C. albicans and A. niger. The results of antimicrobial studies indicated that 3-phenylacrylic acid-(3-hydroxybenzylidene) -hydrazide, 16, was the most effective as it showed both bactericidal and fungicidal properties and other compounds possessed bacteriostatic/fungistatic activity. The multi-target QSAR model demonstrated that the topological parameter, Balaban topological index (J) is effective in describing the antimicrobial activity of synthesized substituted hydrazides. Springer Science+Business Media, LLC 2010.
- Kumar, Davinder,Narang, Rakesh,Judge, Vikramjeet,Kumar, Devinder,Narasimhan, Balasubramanian
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experimental part
p. 382 - 394
(2012/08/27)
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- Synthesis, molecular structure and spectral analysis of ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate: A combined experimental and quantum chemical approach
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A new hydrazone, ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5- dimethyl-1H-pyrrole-2-carboxylate (PDNBAH) has been synthesized and characterized by FT-IR, 1H NMR, UV-visible spectroscopy. All the quantum chemical calculations have been performed by density functional theory (DFT), using B3LYP functional and 6-31G(d,p) as basis set. The calculated and experimental wavenumber analyses confirm the existence of dimer of PDNBAH. The calculated binding energies of dimer using DFT and Bader's atoms in molecules (AIM) theory are -14.32 and -15.41 kcal/mol respectively. The intermolecular hydrogen bond energy of dimer due to the involvement of intermolecular hetero-nuclear double hydrogen bonds (NH?OC) through pyrrolic NH and CO of ester is also calculated to be equal to -12.29 kcal/mol using AIM calculation. The strength and the nature of hydrogen bonding and weak interactions in dimer have been analyzed by AIM theory in detail. The presence of resonance assisted hydrogen bonds (RAHB) has been confirmed by calculated ellipticity parameters using AIM calculation. The calculated thermodynamic parameters show that the reaction is non spontaneous at room temperature. The local reactivity descriptors show that C(13) is most reactive site for nucleophilic attack.
- Singh,Verma, Divya,Kumar, Amit,Baboo, Vikas
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experimental part
p. 60 - 71
(2012/03/07)
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- Synthesis, antimicrobial evaluation and QSAR studies of 3-ethoxy-4-hydroxybenzylidene/4-nitrobenzylidene hydrazides
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A series of 3-ethoxy-4-hydroxybenzylidene/4-nitrobenzylidene hydrazides (1-20) was synthesized and tested for in vitro antimicrobial activity. The results of antimicrobial studies indicated that the compounds having dinitro, methoxy, hydroxy and nitro substituents on phenyl ring of the aromatic acids were most active ones. The QSAR investigation indicated the importance of the topological parameter, third order molecular connectivity index ( 3χ) in describing the antimicrobial activity of synthesized hydrazides.
- Kumar, Davinder,Kapoor, Archana,Thangadurai, Ananda,Kumar, Pradeep,Narasimhan, Balasubramanian
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experimental part
p. 1293 - 1296
(2012/01/07)
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- Benzylidene/2-chlorobenzylidene hydrazides: Synthesis, antimicrobial activity, QSAR studies and antiviral evaluation
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A series of benzylidene hydrazides (1-20) was synthesized and tested, in vitro, for antibacterial, antifungal and antiviral activities. The microbial screening results indicated that compounds having chloro and nitro substituents were the most active ones. The antiviral evaluation depicted that compounds 9 and 19 were active against Vesicular stomatitis virus (VSV) in HeLa cell cultures. QSAR investigations indicated that the multi-target QSAR model was effective in describing the antimicrobial (antibacterial and antifungal) activity over the one-target QSAR models. Further the mt-QSAR model indicated that the topological parameters, second order molecular connectivity index (2χ) and third order Kier's alpha shape index (κα3) are effective in describing the antimicrobial activity of synthesized hydrazides.
- Kumar, Davinder,Judge, Vikramjeet,Narang, Rakesh,Sangwan, Sonia,De Clercq, Erik,Balzarini, Jan,Narasimhan, Balasubramanian
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experimental part
p. 2806 - 2816
(2010/08/20)
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- Synthesis and antitubercular activities of substituted benzoic acid N′-(substituted benzylidene/furan-2-ylmethylene)-N-(pyridine-3-carbonyl)- hydrazides
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A series of benzoic acid hydrazones and its nicotinyl derivatives (1-10) were prepared and evaluated for their antitubercular activity towards a strain of Mycobacterium tuberculosis (MTB). The structures of newly synthesized compounds were confirmed by infrared (IR) and 1H-nuclear magnetic resonance (NMR) spectral data and elemental analysis. The in vitro antitubercular activity of synthesized compounds against MTB was carried out in Middlebrook 7H11agar medium supplemented with OADC by agar dilution method. The antitubercular activity results indicated that nicotinic acid N-(3,5-dinitro-benzoyl)-N′-(4-methoxy-benzylidene)-hydrazide (1) is the most potent among the synthesized compounds with MIC of 3.5 × 10 -3 μM.
- Kumar, Pradeep,Narasimhan, Balasubramanian,Yogeeswari, Perumal,Sriram, Dharmarajan
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experimental part
p. 6085 - 6089
(2011/01/12)
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- Hansch analysis of substituted benzoic acid benzylidene/furan-2-yl-methylene hydrazides as antimicrobial agents
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A series of substituted hydrazide derivatives have been synthesized and screened for their in vitro antimicrobial activities against five representative microorganisms. The results of antimicrobial study indicated that the presence of electron withdrawing groups on the benzoic acid moiety improved antimicrobial activity. Further, the presence of heterocyclic ring furan does not improve the antimicrobial activity of substituted hydrazides. To understand the relationship between physicochemical parameters and antimicrobial activity of substituted hydrazide derivatives, QSAR investigation was performed by the development of one-target and multi-target models. The multi-target model was found to be effective in describing the antimicrobial activity of substituted hydrazides in comparison to the one-target models. Further, it indicated the importance of the topological parameter, valence third order molecular connectivity index (3χv) and the electronic parameter, energy of highest occupied molecular orbital (HOMO) in describing the antimicrobial activity of substituted hydrazides.
- Kumar, Pradeep,Narasimhan, Balasubramanian,Sharma, Deepika,Judge, Vikramjeet,Narang, Rakesh
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experimental part
p. 1853 - 1863
(2009/09/30)
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- An unusual ground-state stabilization effect and origins of the α- effect in aminolyses of Y-substituted phenyl X-substituted benzoates
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Second-order rate constants have been measured spectrophotometrically for the reactions of X-C6H4CO2C6H4-Y with a series of primary amines in H2O containing 20 mol% DMSO at 25.0 ± 0.1°C. The reactivity increases as the substituent (X and Y) becomes a stronger electron-withdrawing group. The σ+ constants give better Hammett correlation than σ constants for the reactions of 4-nitrophenyl X-substituted benzoates with glycylglycine (glygly) and hydrazine (NH2NH2), indicating that the ground-state stabilization effect is unusually significant on the reaction rates. The reactions of X-C6H4CO2C6H4-Y with glygly and NH2NH2 appear to proceed through the same mechanism, but the degree of leaving-group departure and the negative charge developed in the acyl moiety at the rate-determining TS is considered to be more significant for the glygly system than the NH2NH2 system based on β(1g) and ρ(x) values. The magnitude of the α-effect is observed to be not always dependent on the β(nuc) value but dependent on the electronic nature of the substituent X and Y, i.e., an electron-donating substituent increases the α-effect, while an electron-withdrawing one decreases the α-effect. The present study has led to the conclusion that the ground-state effect is important for the reaction rates but it is not solely responsible for the α-effect, and the intramolecular H-bonding interactions (4) are proposed for the cause of the increasing or decreasing α-effect trends observed in the present system.
- Um, Ik-Hwan,Chung, Eun-Kyung,Lee, So-Mi
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p. 729 - 737
(2007/10/03)
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- BIPOSITIVE METAL COMPLEXES OF N1-(4-CHLOROPHENYL)-N4-(3,5-DINITROBENZOYL) THIOSEMICARBAZIDE
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Polymeric coordination complexes of the type (ML.2H2O)n, where M(II)=Mn, Fe, Ni, Cu or Zn and L=N1-(4-chlorophenyl)-N4-(3,5-dinitrobenzoyl)thiosemicarbazide have been synthesised and characterised by microanalytical, I.R., magnetic, D.R.S. and thermal analysis.The IR spectra indicate tetradentate ligand coordination through the enolic oxygen, thioenolic sulphur and the nitrogen atom of the C=N group.The metal ion is the bridging unit between the donor sites of the ligand molecule, and it is likely that a polymeric chain grows through consecutive ligand-metal links.
- Dwivedi, D.K.,Agarwala, B.V.,Dey, A.K.
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p. 431 - 436
(2007/10/02)
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- Pyrazine aldimine compounds as antimicrobial agents
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The instant invention is directed to a pyrazine compound represented by the formula STR1 wherein Z is --NH--, --NHSO2 --, --NHCO-- or --S--, Ar is a phenyl ring substituted by 1 or 2 substituents selected from the group consisting of halo, lower alkyl, lower alkoxy or nitro, and n is 0 or 1.
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