Cytotoxicity of constituents from Mexican propolis against a panel of six different cancer cell lines

The cytotoxicity of 39 compounds, including eighteen flavonoids (flavanones, 1-10; flavones, 11-17; flavanol, 18), sixteen phenolic acid derivatives (aromatic acids, 19-24; aldehyde, 25; esters, 26-34) and five glycerides (35-39), isolated from Mexican propolis, were evaluated against a panel of six different cancer cell lines; murine colon 26-L5 carcinoma, murine B16-BL6 melanoma, murine Lewis lung carcinoma, human lung A549 adenocarcinoma, human cervix HeLa adenocarcinoma and human HT-1080 fibrosarcoma. A phenylpropanoid-substituted flavanol, (2R,3S)-8-[4-phenylprop-2-en-1-one]-4',7-dihydroxy-3',5-dimethoxyflavan-3-ol (18), showed the most potent cytotoxicity against A549 cells (IC50, 6.2 microM) and HT-1080 cells (IC50, 3.9 microM), stronger than those of the clinically used anticancer drug, 5-fluorouracil (IC50, 7.5 microM and 5.4 microM, respectively). Based on the observed results, the structure-activity relationships are discussed.     

Conformational control in a bipyridine linked π-conjugated oligomer: cation mediated helix unfolding and refolding

A chiral π-conjugated oligomer having alternate bipyridine and carbazole moieties connected through acetylinic bonds undergoes helical folding in chloroform-acetonitrile (40/60, v/v) as evident by fluorescence and circular dichroism changes. In the presence of transition metal cations such as Zn(2+) defolding of the helical conformation occurs. Upon decomplexation of the cation with EDTA, the helical conformation is regained.     

Benzopentalenonaphthalenones from the intramolecular capture of a merocyanine derived from a naphthopyran

Novel, highly coloured benzopentalenonaphthalenones result from a cascade process initiated by the thermally-induced ring-opening of diarylmethanol substituted 2H-naphtho[1,2-b]pyrans in the presence of acid.     

Multifunctional ZrO2 nanoparticles and ZrO2-SiO2 nanorods for improved MALDI-MS analysis of cyclodextrins, peptides, and phosphoproteins

Multifunctional ZrO₂ nanoparticles (NPs) and ZrO₂-SiO₂ nanorods (NRs) have been successfully applied as the matrices for cyclodextrins and as affinity probes for enrichment of peptides (leucine-enkephalin, methionine-enkephalin and thiopeptide), phosphopeptides (from tryptic digestion products of β-casein) and phosphoproteins from complex samples (urine and milk) in atmospheric pressure matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and MALDI time-of-flight (TOF) MS. The results show that the ZrO₂ NPs and ZrO₂-SiO₂ NRs can interact with target molecules (cyclodextrins, peptides, and proteins), and the signal intensities of the analytes were significantly improved in MALDI-MS. The maximum signal intensities of the peptides were obtained at pH 4.5 using ZrO₂ NPs and ZrO₂-SiO₂ NRs as affinity probes. The limits of detection of the peptides were found to be 75-105 fmol for atmospheric pressure MALDI-MS and those of the cyclodextrins and β-casein were found to be 7.5-20 and 115-125 fmol, respectively, for MALDI-TOF-MS. In addition, these nanomaterials can be applied as the matrices for the analysis of cyclodextrins in urine samples by MALDI-TOF-MS. ZrO₂ NPs and ZrO₂-SiO₂ NRs efficiently served as electrostatic probes for peptide mixtures and milk proteins because 2–11 times signal enhancement can be achieved compared with use of conventional organic matrices. Moreover, we have successfully demonstrated that the ZrO₂ NPs can be effectively applied for enrichment of phosphopeptides from tryptic digestion of β-casein. Comparing ZrO₂ NPs with ZrO₂-SiO₂ NRs, we found that ZrO₂ NPs exhibited better affinity towards phosphopeptides than ZrO₂-SiO₂ NRs. Furthermore, the ZrO₂ and ZrO₂-SiO₂ nanomaterials could be used to concentrate trace amounts of peptides/proteins from aqueous solutions without tedious washing procedures. This approach is a simple, straightforward, separation-and washing-free approach for MALDI-MS analysis of cyclodextrins, peptides, proteins, and tryptic digestion products of phosphoproteins.      

1,3-Dipolar cycloaddition of nitrile oxides to (R)-1-(1-phenylethyl)-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones: synthesis and antimycobacterial evaluation of novel enantiomerically pure di- and trispiroheterocycles

Enantiomerically pure (R)-(1-phenylethyl)-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones were synthesized for the first time, and their 1,3-dipolar cycloaddition with nitrile oxides affording di- and trispiroheterocycles regio- and stereoselectively in moderate yields was investigated. These compounds were evaluated against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug-resistant M. tuberculosis (MDR-TB). Among the compounds screened, the dispiroheterocycle, namely, (5R,6R,10S)-3,9-bis(4-chlorophenyl)-10-(2,4-dichlorophenyl)-14-[(E)-(2,4-dichlorophenyl)methylidene]-12-[(R)-1-phenylethyl]-1,4,7-trioxa-2,8,12-tri-azadispiro[4.0.4.4]tetradeca-2,8-diene 5m was found to possess the maximum activity with MIC of 0.49 μM against MTB, being 9.6 and 15.6 times more potent than ciprofloxacin and ethambutol, respectively. Against MDR-TB, 5m displayed maximum activity with an MIC of 0.49 μM, with it thus being more active than rifampicin, isoniazid, ciprofloxacin and ethambutol by 7.8, 23, 77 and 124 times, respectively.     

Chiral N-phosphonyl imine chemistry:asymmetric additions of glycine enolate to diphenyl diamine-based phosphonyl imines

Diphenyl diamine-based phosphonyl imines attached by the N-isopropyl group in the auxiliary have been synthesized in good yields under convenient reaction conditions.These new chiral N-phosphonyl imines can react with glycine enolate smoothly to give chiral α-β diamino esters in good yields(72%-90%) and up to excellent diastereoselectivity(>99:1 dr).By treatment with HBr,the chiral auxiliary can be readily removed.The absolute structure has been unambiguously determined by converting a product to a known sa...     

Mono- and di-substituted urea derivatives of cyclodiphosphazane: [ClP(μ-NBu)2PN(Me)CON(H)Me] and [Me(H)NCON(Me)P(μ-NBu)]2

The reaction of cis-[ClP(μ-N^tBu)]₂ with N,N′-dimethylurea leads to the formation of both mono- and di-substituted derivatives [ClP(μ-N^tBu)₂P(NMeCON(H)Me)] and [(μ-N^tBu)P(NMeCON(H)Me)]₂, instead of monomeric, dimeric or higher oligomeric macrocycles. The structure of [ClP(μ-N^tBu)₂P(NMeCON(H)Me)] shows rare non-bonded P?Cl and intermolecular hydrogen bonding interactions leading to a 2D-sheet like structure.     

Iodine assisted palladium catalyzed ring opening of bicyclic hydrazines with organoboronic acids: stereoselective synthesis of functionalized cyclopentenes and alkylidene cyclopentenes

A novel reactivity of organoboronic acids with bicyclic hydrazines leading to the stereoselective formation of trans-vicinal disubstituted cyclopentenes in good to excellent yield is discussed. The reaction of cyclopentadiene and fulvene derived azabicyclic alkenes with organoboronic acids afforded the trans-3,4-disubstituted cyclopentenes and alkylidene cyclopentenes in good to excellent yields. The products, having a broad range of substituents, are important intermediates in the synthesis of a number of pharmaceutically important molecules.     

Optical,magnetic and photocatalytic properties of magnetically separable Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>-doped ZnO and pristine ZnO nanospheres

This work focussed on the optical, magnetic and photocatalytic properties of sol–gel-synthesized Fe₃O₄-doped ZnO nanospheres and was compared with pristine ZnO nanospheres. The crystalline phase of Fe₃O₄-doped ZnO nanospheres was studied with X-ray diffraction analysis and was well matched with standard pattern. Surface morphology was studied with HR-SEM images and EDAX spectrum. Furthermore, elemental mapping analysis was carried out to confirm the presence of Fe₃O₄ phase in Fe₃O₄-doped ZnO nanospheres. FT-Raman spectral studies show that a strong intense peak at 670 cm^?1 indicates the presence of Fe₃O₄ in Fe₃O₄-doped ZnO nanospheres. The mean crystallite size of Fe₃O₄-doped ZnO nanospheres was 34 nm as calculated by Debye–Scherrer’s formula which confirmed with HR-TEM image. The SAED pattern shows the presence of (100), (101), (102) and (202) of ZnO phase and (400) of Fe₃O₄ phase, confirming the crystalline nature of Fe₃O₄-doped ZnO nanospheres. The vibrating sample magnetometer (VSM) result shows that Fe₃O₄-doped ZnO nanospheres possess superparamagnetic nature and the composite nanospheres are magnetically separable. The optical properties have been studied by diffuse reflectance spectroscopy and time-resolved photoluminescence spectra. Implantation of Fe₃O₄ in ZnO nanospheres modifies the UV absorption edge, and it displays near-band gap emission and deep-level emission. The photocatalytic activity of Fe₃O₄-doped ZnO nanospheres studied against rhodamine B dye is found higher than that of pristine ZnO nanospheres which shows that Fe₃O₄-doped ZnO nanospheres are a promising photocatalyst.     

Rhodium‐Catalyzed Oxidative Benzannulation of N‐Pivaloylanilines with Internal Alkynes through Dual C−H Bond Activation: Synthesis of Highly Substituted Naphthalenes

An efficient method was developed for the synthesis of highly substituted naphthalenes through rhodium‐catalyzed oxidative benzannulation of N‐pivaloylanilines with internal alkynes. The benzannulation reaction proceeded smoothly through dual C?H bond activation to produce the corresponding highly substituted naphthalene products in satisfactory to good yields.