Chemical composition and antibacterial activity of Tussilago farfara (L.) essential oil from Quebec,Canada

Abstract

The chemical composition of Tussilago farfara L. essential oil from the Saguenay-Lac-St-Jean region of Quebec, Canada was analyzed by gas chromatography–flame ionisation detector (GC-FID) and gas chromatography–mass spectrometry (GC-MS), and the antibacterial activity of the oil was tested against Escherichia coli and Staphylococcus aureus. Forty-five (45) compounds were identified from the GC profile. The main components were 1-nonene (40.1%), α-phellandrene (26.0%) and ρ-cymene (6.6%). The essential oil demonstrated antibacterial activity against E. coli (MIC₅₀ = 468 µg·mL^?1; MIC₉₀ = 6869 µg·mL^?1) and S. aureus (MIC₅₀ = 368 µg·mL^?1; MIC₉₀ = 773 µg·mL^?1). Dodecanoic acid was found to be active against both bacteria having a MIC₅₀ and MIC₉₀ of 16.4 µg·mL^?1 and 95 µg·mL^?1, respectively for E. coli and a MIC₅₀ and MIC₉₀ of 9.8 µg·mL^?1 and 27.3 µg·mL^?1, respectively for S. aureus. In addition, 1-decene and (E)-cyclodecene were also found to be active against E. coli.     

A bidirectional access to novel thiadiazine hybrid molecules by double multicomponent reactions

In an attempt to further exploit multicomponent reactions in the field of hybrid heterocyclic molecules, we describe a bidirectional approach for the synthesis of novel 1,3,5-thiadiazine-peptides molecules. The process relies on the execution of two Ugi reactions between dicarboxy-functionalized 1,3,5-thiadiazine with different amines and isocyanides. An alternative strategy relying on a sequential multicomponent macrocyclization procedure was also developed to afford thiadiazine peptide-like macrocycles. Both methods showed great chemical efficiency and versatility.     

Protein structure and dynamics in ionic liquids. Insights from molecular dynamics simulation studies

We present in this work the first molecular simulation study of an enzyme, the serine protease cutinase from Fusarium solani pisi, in two ionic liquids (ILs): 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1-butyl-3-methylimidazolium nitrate ([BMIM][NO(3)]). We tested different water contents in these ILs at room temperature (298 K) and high temperature (343 K), and we observe that the enzyme structure is highly dependent on the amount of water present in the IL media. We show that the enzyme is preferentially stabilized in [BMIM][PF6] at 5-10% (w/w) (weight of water over protein) water content at room temperature. [BMIM][PF6] renders a more nativelike enzyme structure at the same water content of 5-10% (w/w) as previously found for hexane, and the system displays a similar bell-shape-like dependence with the water content in the IL media. [BMIM][PF6] is shown to increase significantly the protein thermostability at high temperatures, especially at low hydration. Our analysis indicates that the enzyme is less stabilized in [BMIM][NO(3)] relative to [BMIM][PF6] at both temperatures, most likely due to the strong affinity of the [NO(3)]- anion toward the protein main chain. These findings are in accordance with the experimental knowledge for these two ionic liquids. We also show that these ILs "strip off" most of the water from the enzyme surface in a degree similar to that found for polar organic solvents such as acetonitrile, and that the remaining waters at the enzyme surface are organized in many small clusters.     

Single crystalline commensurate metallic assemblages of pi-slabs and CdI2-type layers: synthesis and properties of beta-(EDT-TTF-I2)2[Pb5/6 square 1/6I2](3) and beta-(EDT-TTF-I2)2[Pb2/3+xAg1/3-2x square xI2]3, x = 0.05

The ability of I...I van der Waals interactions to direct the self-assembly of slabs of the radical cation of ethylenedithio-1,2-diiodo-tetrathiafulvalene, EDT-TTF-I(2), and polymeric lead iodide covalent anionic layers is demonstrated by the synthesis of single crystals of beta-(EDT-TTF-I(2))(2)(.+)[(Pb(5/6) square (1/6)I(2))(1/3-)](3), triclinic, P-1, a = 7.7818(8), b = 7.9760(8), c = 19.9668(2) A, alpha = 82.409(12), beta = 85.964(12), gamma = 61.621(11) degrees, V = 1080.76(19) A(3), R1, wR2 = 0.0459, 0.0947; and beta-(EDT-TTF-I(2))(2)(.+)[(Pb(2/3+x)Ag(1/3-2x)square(x)I(2))(1/3-)](3), x approximately 0.05, triclinic, P-1, a = 7.7744(8), b = 7.9193(8), c = 19.834(2) A, alpha = 87.189(12), beta = 83.534(12), gamma = 61.602(11) degrees, V = 1067.4(2) A(3), R1, wR2 = 0.0508, 0.0997. The state-of-the-art, combined microprobe and structural analysis of the metal site vacancies and occupancies patterns reveal a commensurate organic-inorganic interface and point out the importance of halogen.halogen van der Waals interactions to future studies aiming at directing interface topologies. The electronic structure, room-temperature metallic character and metal-insulator transition at ca. 70 K of the two-dimensional organic slabs are retained upon alloying of the inorganic sublattice with monocations. The room-temperature conductivity of the metallic lead-silver alloy is 2 orders of magnitude larger than that of beta-(EDT-TTF-I(2))(2)(.+)[(Pb(5/6) square (1/6)I(2))(1/3-)](3). This calls for the study of materials with diverse alloying patterns with metal cations of different nature and charge.     

Spin correlations and a mesoscopic structure in Ni-Mn-Ga

The mesoscopic structures of the Heusler alloys Ni_49.1Mn_29.4Ga_21.5 and Ni₂MnGa are studied by small-angle polarized neutron scattering in the temperature range 15 < T < 400 K. The characteristic temperatures of phase transformations (ferromagnetic, martensitic, and premartensitic transformations) and the characteristic sizes of mesoscopic inhomogeneities in them have been determined. Differences in the spin dynamics of these phases and magnetic-nuclear interference upon neutron scattering have been revealed. The evolutions of the mesoscopic structures in the nonstoichiometric and stoichiometric alloys are found to be substantially different.     

Change of sign in the pyroelectric coefficient of KDP at 15.3 K

Low temperature measurements of the charge released (or absorbed) by prepolarized crystalline samples of ferroelectric potasium dihydrogen phosphate clearly indicate that just above 3 K the samples absorb charge, (i.e. the spontaneous polarization increases slightly). After passing through a maximum, the samples begin to release charge at 15.3 K, implying a change of sign in the pyroelectric coefficient, a behavior which had been only observed previously in a few non-ferroelectric or polycrystalline pyroelectric materials.     

Trifluoromethyl radical triggered radical cyclization of N-benzoyl ynamides leading to isoindolinones

Science China Chemistry - Under photocatalytic reductive conditions, trifluoromethyl radical addition onto an ynamide followed by cyclization on a benzoyl moiety produces diverse isoindolinone...     

Structural properties of some heteroaryl amines. Crystallographic studies on 2-N-(2,4,6-trinitrophenyl)-pyridineamine(I),-4-methylthiazoleamine(II), and-pyrimidineamine(III)

Crystallographic properties of the title compounds are reported and inter- and intra-molecular interactions of the amino group are discussed and related to spectroscopic data. The geometry of the nitrogroups and of the 2-aminoheterocyclic moiety indicate that classical conjugation theory cannot explain the UV/vis spectra. The red shift observed on substituting H by a Me on the 2-amino group is interpreted in terms of internal charge-transfer.     

Triplet-state monitoring by fluorescence correlation spectroscopy

The effects of high excitation intensities in fluorescence correlation spectroscopy (FCS) in terms of saturation and triplet-state build-up have been studied for the case of Rh6G in aqueous solution. It was found that FCS provides a powerful means for the determination of intersystem crossing and triplet-state depopulation rates of fluorophores in solution.This is a peer-reviewed conference proceeding article from the Third Conference on Methods and Applications of Fluorescence Spectroscopy, Prague, Czech Republic, October 18–21, 1993.