Molecules

100 KiB

Open AccessArticle

A Simple and Efficient Approach to the Synthesis of Endo and Exo Bicyclo[6.1.0]nona-3,5-diene-9-carboxaldehyde

by Mehdi Ghandi and Gholamreza Mashayekhi

Molecules 2007, 12(10), 2427-2433; https://doi.org/10.3390/12102427 - 30 Oct 2007

Cited by 2 | Viewed by 7031

Monobromination of 1,5-cyclooctadiene, followed by cyclopropanation with ethyl diazoacetate, led to the formation of endo and exo ethyl 4,5-dibromobicyclo[6.1.0]nonane-9-carboxylates 3a and 3b. Bis-dehydrobromination of 3a and 3b using 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) afforded the endo and exo ethyl bicyclo[6.1.0]nona-3,5-diene-9-carboxylates 4a and 4b. Reduction of these [...] Read more.

Monobromination of 1,5-cyclooctadiene, followed by cyclopropanation with ethyl diazoacetate, led to the formation of endo and exo ethyl 4,5-dibromobicyclo[6.1.0]nonane-9-carboxylates 3a and 3b. Bis-dehydrobromination of 3a and 3b using 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) afforded the endo and exo ethyl bicyclo[6.1.0]nona-3,5-diene-9-carboxylates 4a and 4b. Reduction of these compounds to the corresponding alcohols 5a and 5b and subsequent oxidation with pyridinium chlorochromate (PCC) resulted in the formation of the target compounds endo and exo bicyclo[6.1.0]nona-3,5-diene-9-carboxaldehydes 6a and 6b. Full article

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161 KiB

Open AccessArticle

Antibacterial Activity of Some 3-(Arylideneamino)-2-phenylquinazoline-4(3H)-ones: Synthesis and Preliminary QSAR Studies

by Ashis Kumar Nanda, Subarna Ganguli and Ranadhir Chakraborty

Molecules 2007, 12(10), 2413-2426; https://doi.org/10.3390/12102413 - 30 Oct 2007

Cited by 105 | Viewed by 10697

Abstract

Synthesis of ten 3-(arylideneamino)-2-phenylquinazoline-4(3H)-ones is reported. All the compounds contained a common phenyl group at the 2-position, while the substituents on the arylideneamino group were varied. The compounds were investigated for their antimicrobial activity against both Gram-positive (Staphylococcus aureus 6571 and Bacillus [...] Read more.

Synthesis of ten 3-(arylideneamino)-2-phenylquinazoline-4(3H)-ones is reported. All the compounds contained a common phenyl group at the 2-position, while the substituents on the arylideneamino group were varied. The compounds were investigated for their antimicrobial activity against both Gram-positive (Staphylococcus aureus 6571 and Bacillus subtilis) and Gram-negative bacteria (Escherichia coli K12 and Shigella dysenteriae 6) using a turbidometric assay method. It was found that the incorporation of the 3-arylideneamino substituent enhanced the anti-bacterial activity of the quinazolone system. The preliminary QSAR studies were done using some computer derived property descriptors, calculated values of partition coefficients as well as usual Hammett’s sigma constants and the substituent’s molar refractivity. Full article

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167 KiB

Open AccessArticle

Bioreversible Derivatives of Phenol. 2. Reactivity of Carbonate Esters with Fatty Acid-like Structures Towards Hydrolysis in Aqueous Solutions

by Jesper Ostergaard and Claus Larsen

Molecules 2007, 12(10), 2396-2412; https://doi.org/10.3390/12102396 - 30 Oct 2007

Cited by 25 | Viewed by 19350

Abstract

A series of model phenol carbonate ester prodrugs encompassing derivatives with fatty acid-like structures were synthesized and their stability as a function of pH (range 0.4 – 12.5) at 37°C in aqueous buffer solutions investigated. The hydrolysis rates in aqueous solutions differed widely, [...] Read more.

A series of model phenol carbonate ester prodrugs encompassing derivatives with fatty acid-like structures were synthesized and their stability as a function of pH (range 0.4 – 12.5) at 37°C in aqueous buffer solutions investigated. The hydrolysis rates in aqueous solutions differed widely, depending on the selected pro-moieties (alkyl and aryl substituents). The observed reactivity differences could be rationalized by the inductive and steric properties of the substituent groups when taking into account that the mechanism of hydrolysis may change when the type of pro-moiety is altered, e.g. n-alkyl vs. t-butyl. Hydrolysis of the phenolic carbonate ester 2-(phenoxycarbonyloxy)-acetic acid was increased due to intramolecular catalysis, as compared to the derivatives synthesized from ω-hydroxy carboxylic acids with longer alkyl chains. The carbonate esters appear to be less reactive towards specific acid and base catalyzed hydrolysis than phenyl acetate. The results underline that it is unrealistic to expect that phenolic carbonate ester prodrugs can be utilized in ready to use aqueous formulations. The stability of the carbonate ester derivatives with fatty acid-like structures, expected to interact with the plasma protein human serum albumin, proved sufficient for further in vitro and in vivo evaluation of the potential of utilizing HSA binding in combination with the prodrug approach for optimization of drug pharmacokinetics. Full article

(This article belongs to the Special Issue Prodrugs)

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118 KiB

Open AccessArticle

Bioreversible Derivatives of Phenol. 1. The Role of Human Serum Albumin as Related to the Stability and Binding Properties of Carbonate Esters with Fatty Acid-like Structures in Aqueous Solution and Biological Media

by Jesper Ostergaard and Claus Larsen

Molecules 2007, 12(10), 2380-2395; https://doi.org/10.3390/12102380 - 30 Oct 2007

Cited by 12 | Viewed by 11930

Abstract

With the overall objective of assessing the potential of utilizing plasma protein binding interactions in combination with the prodrug approach for improving the pharmacokinetics of drug substances, a series of model carbonate ester prodrugs of phenol, encompassing derivatives with fatty acid-like structures, were [...] Read more.

With the overall objective of assessing the potential of utilizing plasma protein binding interactions in combination with the prodrug approach for improving the pharmacokinetics of drug substances, a series of model carbonate ester prodrugs of phenol, encompassing derivatives with fatty acid-like structures, were characterized in vitro. Stability of the derivatives was studied in aqueous solution, human serum albumin solution, human plasma, and rat liver homogenate at 37°C. Stability of the derivatives in aqueous solution varied widely, with half-lives ranging from 31 to 1.7 × 10⁴ min at pH 7.4 and 37°C. The carbonate esters were subject to catalysis by plasma esterases except for the t-butyl and acetic acid derivatives, which were stabilized in both human plasma and human serum albumin solutions relative to buffer. In most cases, however, hydrolysis was accelerated in the presence of human serum albumin indicating that the derivatives interacted with the protein, a finding which was confirmed using the p-nitrophenyl acetate kinetic assay. Different human serum albumin binding properties of the phenol model prodrugs with fatty acid-like structure and neutral carbonate esters were observed. In the context of utilizing plasma protein binding in combination with the prodrug approach for optimizing drug pharmacokinetics, the esterase-like properties of human serum albumin towards the carbonate esters potentially allowing the protein to act as a catalyst of parent compound regenerations is interesting. Full article

(This article belongs to the Special Issue Prodrugs)

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107 KiB

Open AccessArticle

Synthesis of Novel N-(4-Ethoxyphenyl) Azetidin-2-ones and Their Oxidative N-Deprotection by Ceric Ammonium Nitrate

by Aliasghar Jarrahpour and Maaroof Zarei

Molecules 2007, 12(10), 2364-2379; https://doi.org/10.3390/12102364 - 25 Oct 2007

Cited by 47 | Viewed by 13901

Abstract

It is shown that the N-(p-ethoxyphenyl) group on β-lactams can be oxidatively removed by ceric ammonium nitrate in good yield. Fourteen new N-(p-ethoxyphenyl)-2-azetidinones 8a-n were synthesized through standard [2+2] ketene-imine cycloadditions (Staudinger reaction). Treatment of these compounds [...] Read more.

It is shown that the N-(p-ethoxyphenyl) group on β-lactams can be oxidatively removed by ceric ammonium nitrate in good yield. Fourteen new N-(p-ethoxyphenyl)-2-azetidinones 8a-n were synthesized through standard [2+2] ketene-imine cycloadditions (Staudinger reaction). Treatment of these compounds with ceric ammonium nitrate yielded the N-dearylated 2-azetidinones 9a-n in good to excellent yields. The effects of solvent, molar equiv of CAN and different temperatures have been investigated and optimum conditions were established. Full article

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107 KiB

Open AccessArticle

Synthesis, Chemical Characterization and Biological Screening for Cytotoxicity and Antitumor Activity of Organotin (IV) Derivatives of 3,4-Methylenedioxy 6-nitrophenylpropenoic Acid

by Muhammad Sheeraz Ahmad, Mukhtiar Hussain, Muhammad Hanif, Saqib Ali and Bushra Mirza

Molecules 2007, 12(10), 2348-2363; https://doi.org/10.3390/12102348 - 25 Oct 2007

Cited by 70 | Viewed by 10508

Abstract

A series of mono-, di- and triorganotin compounds with general formulae [RSnL₂Cl], R = Bu (compound 3), [R₂SnL₂], where R = Me, Et, Bu, Oct (compounds 1, 2, 4 and 6) and [R₃SnL], where R [...] Read more.

A series of mono-, di- and triorganotin compounds with general formulae [RSnL₂Cl], R = Bu (compound 3), [R₂SnL₂], where R = Me, Et, Bu, Oct (compounds 1, 2, 4 and 6) and [R₃SnL], where R = Bu, Cy and Ph (compounds 5, 7 and 8) and where L = 3,4-methylenedioxy-6-nitrophenylpropenoic acid have been prepared and characterized by elemental analysis, multinuclear (¹H-, ¹³C- and ¹¹⁹Sn-) NMR and mass spectrometry. The ligand and its respective organotin complexes were screened for cytotoxicity using the brine shrimp lethality assay and for antitumor activity using the crown gall tumor inhibition (potato disc) assay. The bioassay results support the conclusion that the biological activities of these synthetic compounds are in the following order: [RSnL₂Cl] < [R₂SnL₂] < [R₃SnL]. Full article

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65 KiB

Open AccessCommunication

Preparation of Benzalkonium Salts Differing in the Length of a Side Alkyl Chain

by Kamil Kuca, Jan Marek, Petr Stodulka, Kamil Musilek, Petra Hanusova, Martina Hrabinova and Daniel Jun

Molecules 2007, 12(10), 2341-2347; https://doi.org/10.3390/12102341 - 24 Oct 2007

Cited by 21 | Viewed by 13516

Abstract

Benzalkonium salts are widely used as disinfectants, biocides and detergents,among a variety of other applications. The cationic surface-activity of these saltsdetermines their potential to act as a biocide on both target and non-target organisms. Inthis study, a quick synthesis of a complete set [...] Read more.

Benzalkonium salts are widely used as disinfectants, biocides and detergents,among a variety of other applications. The cationic surface-activity of these saltsdetermines their potential to act as a biocide on both target and non-target organisms. Inthis study, a quick synthesis of a complete set of the benzalkonium salts differing in thelength of an alkylating chain (from C₂ to C₂₀) is described. Moreover, their ¹H-NMR, HPLC-MS, TLC and HPLC analysis were recorded. Full article

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138 KiB

Open AccessArticle

Electrochemical Behavior and Antioxidant and Prooxidant Activity of Natural Phenolics

by Aleksandra Simić, Dragan Manojlović, Dejan Šegan and Marija Todorović

Molecules 2007, 12(10), 2327-2340; https://doi.org/10.3390/12102327 - 24 Oct 2007

Cited by 298 | Viewed by 16481

Abstract

We have investigated the electrochemical oxidation of a number natural phenolics (salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, protocatechuic acid, o-coumaric acid, m-coumaric acid, p-coumaric acid, caffeic acid, quercetin and rutin) using cyclic voltammetry. The antioxidant properties of these [...] Read more.

We have investigated the electrochemical oxidation of a number natural phenolics (salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, protocatechuic acid, o-coumaric acid, m-coumaric acid, p-coumaric acid, caffeic acid, quercetin and rutin) using cyclic voltammetry. The antioxidant properties of these compounds were also studied. A structural analysis of the tested phenolics suggests that multiple OH substitution and conjugation are important determinants of the free radical scavenging activity and electrochemical behavior. Compounds with low oxidation potentials (Epa lower than 0.45) showed antioxidant activity, whereas compounds with high Epa values (>0.45) act as prooxidants. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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1277 KiB

Open AccessArticle

Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

by Patrick Garidel, Annegret Hildebrand, Katja Knauf and Alfred Blume

Molecules 2007, 12(10), 2292-2326; https://doi.org/10.3390/12102292 - 23 Oct 2007

Cited by 114 | Viewed by 15912

Abstract

The two main steps of the membranolytic activity of detergents: 1) the partitioning of detergent molecules in the membrane and 2) the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC) and sodium deoxycholate (NaDC) [...] Read more.

The two main steps of the membranolytic activity of detergents: 1) the partitioning of detergent molecules in the membrane and 2) the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC) and sodium deoxycholate (NaDC) with biological phospholipid model membranes are considered. The membranolytic activity is analysed as a function of the hydrophobicity of the bile salt, ionic strength, temperature, membrane phase properties, membrane surface charge and composition of the acyl chains of the lipids. The results are derived from calorimetric measurements (ITC, isothermal titration calorimetry). A thermodynamic model is described, taking into consideration electrostatic interactions, which is used for the calculation of the partition coefficient as well as to derive the complete thermodynamic parameters describing the interaction of detergents with biological membranes (change in enthalpy, change in free energy, change in entropy etc). The solubilisation properties are described in a so-called vesicle-to-micelle phase transition diagram. The obtained results are supplemented and confirmed by data obtained from other biophysical techniques (DSC differential scanning calorimetry, DLS dynamic light scattering, SANS small angle neutron scattering). Full article

(This article belongs to the Special Issue Bile Acids)

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50 KiB

Open AccessCommunication

A Novel Flavonoid C-glycoside from Sphaeranthus indicus L. (Family Compositae)

by Bhuwan B. Mishra, S. B. Yadav, Rakesh K. Singh and Vyasji Tripathi

Molecules 2007, 12(10), 2288-2291; https://doi.org/10.3390/12102288 - 20 Oct 2007

Cited by 25 | Viewed by 9943

Abstract

A novel flavonoid C-glycoside, 5-hydroxy-7-methoxy-6-C-glycosylflavone (1), was isolated from the aerial part of Sphaeranthus indicus. Its structure was elucidated by spectroscopic methods. Full article

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155 KiB

Open AccessArticle

Relative Stereochemistry of a Diterpene from Salvia cinnabarina

by Angela Bisio, Bruno Pagano, Alessia Romussi, Olga Bruno, Nunziatina De Tommasi, Giovanni Romussi and Carlo Andrea Mattia

Molecules 2007, 12(10), 2279-2287; https://doi.org/10.3390/12102279 - 10 Oct 2007

Cited by 14 | Viewed by 9048

Abstract

The relative stereochemistry of 3,4-secoisopimara-4(18),7,15-triene-3-oic acid, a diterpenoid with antispasmodic, hypotensive and antibacterial activities isolated from Salvia cinnabarina, was determined by an X-ray diffraction analysis of a single crystal of a suitable crystalline derivative. Full article

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19 KiB

Open AccessEditorial

Notice of Dual Publication: Madkour *, H.M.F.; Mahmoud, M.R.; Nassar, M.H.; Habashy, M.M. Behaviour of Some Activated Nitriles Toward Barbituric Acid, Thiobarbituric Acid and 3-Methyl-1-Phenylpyrazol-5-one. Molecules 2000, 5, 746-755

by Shu-Kun Lin

Molecules 2007, 12(10), 2277-2278; https://doi.org/10.3390/12102277 - 3 Oct 2007

Cited by 1 | Viewed by 4897

Abstract

We have been notified that this paper has also been published almost verbatim in another scientific journal [1].[...] Full article

124 KiB

Open AccessCommunication

A New Sesquiterpene Glycoside from the Aerial Parts of Saussurea triangulata

by Min Cheol Yang, Sung Min Kim, Kyu Ha Lee, Ki Hyun Kim and Kang Ro Lee

Molecules 2007, 12(10), 2270-2276; https://doi.org/10.3390/12102270 - 2 Oct 2007

Cited by 10 | Viewed by 8327

Abstract

Column chromatographic separation of a MeOH extract of the aerial parts of Saussurea triangulata led to the isolation of a new sesquiterpene glycoside 6, together with three quinic acid derivatives, two phenolics, two sesquiterpene glycosides and two flavonoids. The new compound 6 was [...] Read more.

Column chromatographic separation of a MeOH extract of the aerial parts of Saussurea triangulata led to the isolation of a new sesquiterpene glycoside 6, together with three quinic acid derivatives, two phenolics, two sesquiterpene glycosides and two flavonoids. The new compound 6 was identified as amarantholidol A glycoside by spectroscopic and chemical methods. Full article

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Molecules, Volume 12, Issue 10 (October 2007) – 13 articles , Pages 2270-2433

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