Search

Twelve new lanostane triterpenoids, astraeusins A–L ( 1 – 12 ), together with six known compounds, were isolated from the food mushroom Astraeus odoratus . Their structures were elucidated by spectroscopic analysis and chemical correlations. Antibacterial and cytotoxic activities of these lanostanoids were evaluated. [ABSTRACT FROM AUTHOR]

New series of organotin(IV) complexes and Schiff bases derived from amino acids have been designed and synthesized from condensation of 1H-indole-2,3-dione, 5-chloro-1H-indole-2,3-dione, and α-amino acids (phenylalanine, isoleucine, and glycine). All compounds are characterized by elemental analyses, molar conductance measurements, and molecular weight determinations. Bonding of these complexes is discussed in terms of their UV-visible, infrared, and nuclear magnetic resonance (¹H, 13C, and 119Sn NMR) spectral studies. The results suggest that Schiff bases behave as monobasic bidentate ligands and coordinate with dibutyltin(IV) in octahedral geometry according to the general formula [Bu2Sn(L)2]. Elemental analyses and NMR spectral data of the ligands with their dibutyltin(IV) complexes agree with their proposed distorted octahedral structures. Few representative compounds are tested for their in vitro antibacterial activity against Gram-positive (B. cereus, Staphylococcus spp.) and Gramnegative (E. coli, Klebsiella spp.) bacteria. The results show that the dibutyltin complexes are more reactive with respect to their corresponding Schiff base ligands. [ABSTRACT FROM AUTHOR]

Abstract: Five carbazole alkaloids, clausenawallines G–K (1–5), along with 12 known alkaloids (6–17) were isolated from the twigs of Clausena wallichii. Their structures were established using spectroscopic methods and the antibacterial activity of compounds 1–5 was evaluated. [Copyright &y& Elsevier]

Abstract: A series of new Monensin A dimers linked by diurethane moiety were synthesised and their molecular structures were studied using ESI-MS, FT-IR, 1H and 13C NMR and PM5 methods. The results showed that the compounds form a pseudo-cyclic structure stabilized by three intramolecular hydrogen bonds and the sodium cation was coordinated by five oxygen atoms of polyether skeleton of Monensin moiety. The NMR and FT-IR data of complexes of Monensin urethane sodium salts demonstrated that within the pseudo-cyclic structure the carbonyl oxygen atom of the urethane group did not coordinate the sodium cation. Monensin urethanes were tested in vitro for the activity against Gram-positive and Gram-negative bacteria and fungi as well as against a series of clinical isolates of Staphylococcus: methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA). The most active compound against MRSA and MSSA was 1,4-phenylene diurethane of Monensin with MIC 10.4–41.4μmol/L). [Copyright &y& Elsevier]

The dimeric complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) with two new symmetrical ON-NO donor bis bidentate (tetradentate) azo dye ligands, LH2 = 4,4'-bis(4'-hydroxyquinolinolinylazo)diphenylsulphone, and L'H2 = 4,4'-bis(acetoacetanilideazo)diphenylsulphone have been synthesized. The metal complexes have been characterised by elemental analytical, conductance, magnetic susceptibility, IR, electronic spectra, ESR, NMR, thermogravimetry, X-ray diffraction (powder pattern) spectra, and molecular modelling studies. The Co(II) and Ni(II) complexes are found to be octahedral, Cu(II) complexes are distorted octahedral, and a tetrahedral stereochemistry has been assigned to Zn(II), Cd(II), and Hg(II) complexes. The thermogravimetric study indicates that compounds are quite stable. The energy optimized structures are proposed using the semiempirical ZINDO/1 quantum mechanical calculations. The potential antibacterial study of the ligands and some metal complexes has been made with one gram positive bacteria Staphylococcus aureus and one gram negative bacteria E. coli which gives encouraging results. Both the Co(II) complexes are found to possess monoclinic crystal system. [ABSTRACT FROM AUTHOR]

The increasing resistance of bacteria and fungi to currently available antibiotics is a major concern worldwide, leading to enormous efforts to develop new antibiotics with new modes of actions. Antibacterial peptide CM4 (ABP-CM4) is a small cationic peptide with broad-spectrum activities against bacteria, fungi, and tumor cells, which may possibly be used as a promising candidate for a new antibiotic. For pharmaceutical applications, a large quantity of antimicrobial peptides needs to be produced economically. In this communication, the progress in the structural characteristics, heterologous production, and biological evaluation of ABP-CM4 are reviewed. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of the new 4-(4-acetyl-5- substituted -4, 5-dihydro-1,3,4-oxodiazol-2-yl)methoxy)-2H-chromen-2-ones derivatives 5 was accomplished by the use of 4-hydroxycoumarine as a starting material. The structures of the compounds were confirmed by analytical UV, IR, 1H, 13C-NMR, NOESY and HMBC NMR spectra to elucidate the different positions of protons and carbons. All the compounds exhibited one quasireversible redox process. The UV absorption spectra of the obtained compounds showed strong absorption bands between 264 and 291nm assigned to π-π * transitions of the oxadiazole group. All the newly synthesized compounds were screened for their antibacterial and antioxidant activities. Antimicrobial studies revealed that compounds 5a and 5b showed significant antibacterial activity against Escherichia coli and Pseudomonas Aeruginosa 27853. Furthermore these compounds showed antioxidant activities of different extents with respect to individual compounds as well as to the antioxidant methods. The compounds 5a-d was found to be the most active antioxidant in the series then Trolox, which makes the investigated complexes promising a new class of antibacterial compounds. [Copyright &y& Elsevier]

Chemical fractionation of a southern Australian marine sponge, Trachycladus laevispirulifer, yielded 9-(5′-deoxy-5′-thio-β-d-xylofuranosyl)adenine disulfide as the first recorded natural occurrence of a nucleoside disulfide, and only the second of a xylo-nucleoside. Structure elucidation of the disulfide was achieved by detailed spectroscopic analysis and comparison to synthetic model compounds. The antibacterial, antifungal, and anticancer properties of the disulfide are documented and the literature surrounding natural and synthetic thionucleosides is reviewed. [ABSTRACT FROM AUTHOR]

Abstract: 2,6-Diacetylpyridine bis(benzenesulfonohydrazide) Schiff bases (L1, L2 and L3) and their Cu(II) complexes of the general formula [CuL·H2O] were synthesized and characterized by various spectroscopic techniques. The crystal structure of [CuL3·(py)]·py was investigated by single crystal X-ray structure analysis. The Cu(II) cation has near square pyramidal, penta-coordinate geometry. The binegatively charged tetradentate Schiff base is asymmetrically coordinated to the Cu(II) ion via the pyridine N atom, the azomethine N atom, the sulfonyl O atom and the deprotonated hydrazine N atom. There is a pyridine molecule apically coordinated to the Cu(II) ion. All the Schiff bases and their copper(II) complexes were screened by the disc diffusion method against multi-drug resistant (MDR) gram-negative and gram-positive bacteria. The minimum inhibitory concentration (MIC) values were also determined. These results show that the antibacterial activity of the Schiff bases against Methicillin-resistant Staphylococcus aureus (MRSA) is enhanced when they are chelated with the copper(II) ion. [Copyright &y& Elsevier]

Abstract  The compound 5-bromonicotinic acid [1-(4-chlorophenyl)methylidene]hydrazide monohydrate methanol solvate, derived from the condensation reaction of 5-bromonicotinic acid hydrazide with 4-chlorobenzaldehyde in a methanol solution, was synthesized and characterized by elemental analysis, IR spectrum, 1H NMR and X-ray single crystal determination. The compound crystallizes in the triclinic space group P − 1 with unit cell dimensions a = 6.9360(14) Å, b = 10.070(2) Å, c = 12.267(3) Å, α = 84.39(3)°, β = 86.10(3)°, γ = 80.50(3)°, V = 839.8(3) Ǻ3, Z = 2, R 1 = 0.0724, and wR 2 = 0.1720. X-ray structure determination reveals that the compound has a trans configuration with respect to the C=N double bond or C–N single bond. In the crystal structure, molecules are linked through intermolecular O–H···N, O–H···O, and C–H···O hydrogen bonds, forming layers parallel to the ab plane. The preliminary biological tests show that the compound has excellent antibacterial activity. Index Abstract  The compound 5-bromonicotinic acid [1-(4-chlorophenyl)methylidene]hydrazide monohydrate methanol solvate, derived from the condensation reaction of 5-bromonicotinic acid hydrazide with 4-chlorobenzaldehyde in a methanol solution, was synthesized and characterized by elemental analysis, IR spectrum, 1H NMR and X-ray single crystal determination. The molecule of the compound has a trans configuration with respect to the C=N double bond or C–N single bond. In the crystal structure, molecules are linked through intermolecular O–H···N, O–H···O, and C–H···O hydrogen bonds, forming layers parallel to the ab plane. The preliminary biological tests show that the compound has excellent antibacterial activity. [ABSTRACT FROM AUTHOR]