The isolation and structure determination of cryptomisrine,a novel indolo[3,2-b]quinoline dimeric alkaloid from cryptolepis sanguinolenta

The isolation and structure determination of cryptomisrine, a novel indolo[3,2-b]quinoline dimeric alkaloid obtained from extracts of the roots of the Ghanaian medicinal plant Cryptolepis sanguinolenta is reported. The structure determination was made via a consideration of the spectral data, including uv, ir, nmr, and mass spectra. In particular, one-dimensional proton/carbon nmr, one-dimensional nOe difference nmr, and a series of homonuclear (COSY) and inverse-detected heteronuclear two-dimensional (HMQC, HMBC) experiments were utilized, as well as high resolution FABMS. Cryptomisrine is most unusual in that its two monomeric parts apparently exist in such a C₂ symmetric environment that only one set of proton and carbon nmr resonances are observed. Cryptomisrine is the first example of a dimeric indolo-[3,2-b]quinoline alkaloid to have been isolated from nature.     

Elucidation of the structure of quindolinone,a minor alkaloid of cryptolepis sanguinolenta: Submilligram 1H-13c and 1H-15N heteronuclear shift correlation experiments using micro inverse-detection

Elucidation of minor natural product structures has been significantly augmented by inverse-detection; further improvement has been afforded by the development of micro inverse-detection probes. We report here the elucidation of the structure of a new alkaloid, quindolinone (5H, 10H-indolo[3,2-b]quinolin-11-one), from the West African plant Cryptolepis sanguinolenta. All nmr data for this minor, preparative hplc-isolated alkaloid, including ¹H-¹⁵N one? bond heteronuclear shift correlation (HMQC) data, were recorded on an 800 μg sample of the alkaloid dissolved in 140 μl of 100% d₆-DMSO using a 400 MHz spectrometer.     

An examination of intermolecular and intramolecular hydrogen bonding in biomolecules by AM1 and MNDO/M semiempirical molecular orbital studies

The recent NMDO/M modification and parameterization of the MNDO molecular orbital method has been used to analyze intermolecular hydrogen bonding between amino acids and water, and intramolecular hydrogen bonding in monosaccharides. The results have been compared to AM1 calculations on the same systems. The MNDO/M calculations gave values which were similar to ab initio calculations with respect to the intermolecular interactions, but yielded significantly poorer results for the intramolecular interactions. The AM1 procedure performed better on the intramolecular interactions than the MNDO/M procedure, but frequently provided unfavorable three-centered hydrogen bonding geometries for the intermolecular interactions.     

The kinetics of the crystallization of barium chromate in presence of polyphosphate and phosphonates

Summary The inhibiting effect of polyphosphate and phosphonates on the crystallization of barium chromate for both seeded and unseeded systems has been investigated using the changes in ionic conductivity of the lattice ions in supersaturated solutions containing stoichiometric concentrations of barium and chromate at 298 K. The inhibitors studied are sodium tripolyphosphate (STP), ethylenediaminetetramethylenephosphonic acid (ENTMP), and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP). The effect of these inhibitors on the growth of crystals has been studied at several inhibitor concentrations. The influence of these additives on barium chromate crystallization could be interpreted in terms of aLangmuir type adsorption isotherm. The crystallization retarding effect due to inhibitors is in the orderHEDP>STP>ENTMP. The inhibitors studied can be used as effective compounds for scale formation control.Deceased     

Aliphatic Liquid Crystals with Positive Dielectric Anisotropy

Cyanothyl-subsituted cylohexyl cyclohexanoates, bi(cyclohexanes) and phenyl cyclohexanes were synthisized. Their mesmorphic behaviour is compared to that of the corresponding cyano derivatives. (Cyanoethyl)cyclohexyl cyclohenxanoates show mesmorphic properties in contrast to the corresponding cyano derivative. Separation of the cyano substituent from the rigid core of an anisotropic aliphatic compound by methylene groups enhances the thermodynamic stability of the mesophase. In aromatic compound, the cyanoethyl group leads to lower clearing points. These phenomena are attributed to teh influence of steric effects on the packing density and to the dependence of the clearing point on molecular association.     

Synthesis of 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide

The reaction of methyl 2-bromo-6-(trifluoromethyl)-3-pyridinecarboxylate ( 1 ) with methanesulfonamide gave methyl 2-[(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridine-carboxylate ( 2 ). Alkylation of compound 2 with methyl iodide followed by cyclization of the resulting methyl 2-[methyl(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridinecarboxylate ( 3 ) yielded 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 4 ). The reaction of compound 4 with α,2,4-trichlorotoluene, methyl bromopropionate, methyl iodide, 3-trifluoromethylphenyl isocyanate, phenyl isocyanate and 2,4-dichloro-5-(2-propynyloxy)phenyl isothiocyanate gave, respectively, 4-[(2,4-dichlorophenyl)methoxy]-1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazine 2,2-dioxide ( 5 ), methyl 2-[[1-methyl-2,2-dioxido-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4-yl]oxy]propanoate ( 6 ), 1,3,3-trimethyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 7 ), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N-[3-(trifluoromethyl)phenyl]-1H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide ( 8 ), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N-phenyl-1H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide ( 9 ) and N-[2,4-dichloro-5-(2-propynyloxy)phenyl]-4-hydroxy-1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2] thiazine-3-carboxamide 2,2-dioxide ( 10 ).     

On the preparation of substituted 4H- 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

The reaction of benzoyl isothiocyanates and methoxycarbonyl isothiocyanate with 4-amino-4,5-dihydro-3-(methylthio)-1,2,4-triazin-5-ones in acetonitrile gave several substituted 4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones VIa-h instead of the expected thioureas. In addition, benzoyl isothiocyanate reacted with 4-amino-3-(methylthio)-5-(trifluoromethyl)-4H-1,2,4-triazole to give the benzoyl thiourea IX and with 4-amino-3-mercapto-5-(trifluoromethyl)-4H-1,2,4-triazole to give the bicyclic compound N-[3-(trifluoromethyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazol-6-yl]benzamide IX .     

Nile Red and Nile Blue: Applications and Syntheses of Structural Analogues

Nile red and Nile blue are highly fluorescent and photostable organic dyes from the benzo[a]phenoxazine family. They have been used as histological stains for imaging lysosomes and lipids in vitro. The dyes’ high quantum yields and solvent‐dependent optical properties make them ideal scaffolds for the development of pH probes and local polarity indicators. Reviews of the literature in this area are scarce with only one review ever published in 2006. It has been 10 years since and the field has evolved. This review aims to expand upon topics covered by the previous reviewers and to report on recent advances in the literature. As authors, we hope to convey a sense of scope and to spark renewed interest in this useful niche of dye chemistry.     

Cyanine Dyes Containing Quinoline Moieties: History,Synthesis, Optical Properties,and Applications

Cyanine dyes carrying quinoline moieties are an important class of organic molecules that are of great interest for applications in many fields like medicine, pharmacology, and engineering. Despite their exceptional properties, such as stability, high molar extinction coefficients, and high pH-sensitivity, this class of dyes has been less analyzed and reviewed in the last few decades. Therefore, this review article focuses on discussing the history of quinoline compounds, various synthetic routes to prepare quinolinium salts and symmetrical and asymmetrical mono-, di-, tri-, penta- and heptamethine cyanine dyes, containing quinoline moieties, together with their optical properties and applications as photosensitizers in photodynamic therapy, probes in biomolecules for labeling of nucleic acids, as well as imaging agents.     

High-Performance Thin-Layer Chromatographic Method for the Estimation of Benzyl Isothiocyanate in Salvadora persica Root Extract and Dental Care Herbal Products

JPC – Journal of Planar Chromatography – Modern TLC - A novel, simple, and sensitive high-performance thin-layer chromatography (HPTLC) method has been successfully developed and...