Chemical Composition,Biological Activities and In Silico Analysis of Essential Oils of Three Endemic Prangos Species from Turkey

In this study, the essential oils (EOs) obtained from three endemic Prangos species from Turkey (P. heyniae, P. meliocarpoides var. meliocarpoides, and P. uechtritzii) were studied for their chemical composition and biological activities. β-Bisabolenal (12.2%) and caryophyllene oxide (7.9%) were the principal components of P. heyniae EO, while P. meliocarpoides EO contained sabinene (16.7%) and p-cymene (13.2%), and P. uechtritzii EO contained p-cymene (24.6%) and caryophyllene oxide (19.6%), as the most abundant components. With regard to their antioxidant activity, all the EOs were found to possess free radical scavenging potential demonstrated in both DPPH and ABTS assays (0.43–1.74 mg TE/g and 24.18–92.99 mg TE/g, respectively). Additionally, while no inhibitory activity was displayed by P. meliocarpoides and P. uechtritzii EOs against both cholinesterases (acetyl- and butyryl-cholinesterases). Moreover, all the EOs were found to act as inhibitors of tyrosinase (46.34–69.56 mg KAE/g). Molecular docking revealed elemol and α-bisabolol to have the most effective binding affinity with tyrosinase and amylase. Altogether, this study unveiled some interesting biological activities of these EOs, especially as natural antioxidants and tyrosinase inhibitors and hence offers stimulating prospects of them in the development of anti-hyperpigmentation topical formulations.     

Highly sintered nickel oxide: surface morphology and FTIR investigation of CO adsorbed at low temperature

The monolayer of CO molecules adsorbed at low temperature on highly sintered nickel oxide, gives rise to a very symmetric IR absorption band at 2136 cm⁻¹ (θ_max) with a full-width at half-maximum (FWHM) of 3.7 cm⁻¹. This band shifts to higher frequenc upon decreasing the coverage, reaching the 2152 cm⁻¹ value for θ→0. The observed shift is due to changes in the lateral interactions (dynamic and static) among the adsorbed molecules. The observed spectral simplicity implies that most of the adsorbed CO molecules occupy crystallographically identical sites with a similar environment. Moreover, the remarkably small half-width indicates that inhomogeneous broadening effects, due to surface defects, are very small and that NiO microcrystals behave as single crystals. The morphology of microcrystals has been studied by SEM, AFM and HRTEM techniques: it was concluded that the surface termination of the sample is mainly represented by the (100) and (111) faces.     

Homogeneous immunoassay of atrazine in water by terbium-entrapping liposomes as fluorescent markers

Atrazine (Atr) was conjugated to mastoparan (Mast) cytolytic peptide; Mast-Atr derivative was used as cytolytic agent on liposomes trapping Tb/citrate complex. This was applied in a time-resolved fluoroimmunoassay for detection of Atr in water. The cytolytic activity was read by means of time-resolved fluorescence after adding an excess of dipicolinic acid (DPA). Tb/citrate-entrapping liposomes are easy to prepare, and the assay is carried out in a short incubation time and in a range between 10 pg and 100 ng. The procedure was applied to analyse samples taken from Adda River and from irrigation ditches in an agricultural area around the town of Lodi. Recovery in samples spiked with two different Atr concentrations was between 95 and 105%.     

A partial least squares regression study with antioxidant flavonoid compounds

The quantitative structure-activity relationship of a set of 19 flavonoid compounds presenting antioxidant activity was studied by means of PLS (Partial Least Squares) regression. The optimization of the structures and calculation of electronic properties were done by using the semiempirical method AM1. A reliable model (r ²=0.806 and q ²=0.730) was obtained and from this model it was possible to consider some aspects of the structure of the flavonoid compounds studied that are related with their free radical scavenging ability. The quality of the PLS model obtained in this work indicates that it can be used in order to design new flavonoid compounds that present ability to scavenge free radicals.     

Iron(III) complexes with benzoxazole derivatives

Summary Iron(III) complexes of the general formula Fe(L)_nX₃·mH₂O, where L=benzoxazole(benzox), 2-methylbenzoxazole(2-Mebenzox), 2, 5-dimethylbenzoxazole(2, 5-diMebenzox); n=2, 3, 4, 6; X=Cl, Br, NO₃ or ClO₄; m=0, 1, 2, 5, have been prepared and studied by chemical analysis, magnetic moments, i.r., electronic, Mössbauer spectra and molar conductivity values.The oxazoles are N_ring bonded and the complexes are hexacoordinate in the solid state with exception of the five-coordinate Fe(2, 5-diMebenzox)₂Br₃.     

Stereoselective synthesis of enynes by nickel-catalyzed cross-coupling of divinylic chalcogenides with alkynes

(Z,Z)- and (E,E)-divinylic selenides and telurides undergo direct coupling with terminal alkynes in the presence of a nickel/CuI catalyst at room temperature to give (Z)- and (E)-enyne systems in good yields and with complete retention of configuration.     

SERS studies of the adsorption of guanine derivatives on gold colloidal nanoparticles

Surface enhanced Raman scattering spectra of guanine, guanosine and 2'-deoxyguanosine adsorbed on gold colloidal nanoparticles were obtained. From the striking similarity of the SERS spectra of these compounds, it can be evidenced that guanosine and 2'-deoxyguanosine adsorb on gold nanoparticles through the guanine moiety. The molecular sites involved in the interaction with the gold surface are the same for the 3 compounds: the oxygen of the carbonilic group and the N(7) atom. Guanine, guanosine and 2'-deoxyguanosine adsorb on the gold substrates with a tilted orientation with respect to the metal surface. SERS data were interpreted taking into account density functional theoretical (DFT) calculations of guanine.     

Electrospray mass spectrometry in the differentiation of some isomeric trimethylfurocoumarins

Electrospray mass spectrometry (ES-MS) was successfully employed for the structural differentiation of six isomeric trimethylfurocoumarins of possible pharmaceutical interest. Two different approaches were employed. The first was based on MS(n) experiments of MH(+) ions. Although the product ion spectra of MH(+) of the isomers are very similar, the MS(3) spectra of the collisionally generated [MH[bond]CO](+) ions show some characteristic differences. The second approach was based on complexation of the molecules with Li(+), Na(+) and K(+) using ESI-MS of sample solutions containing alkali ions in a 100:1 molar ratio with respect to the analyte. Significant differences were observed in complex production yields, and these were related to the dimension of the alkali ion and to the steric availability of chelating groups in the different isomers.     

Conformation of three tetrahydropyridinyl oxime cognition activators

The conformational features of three tetrahydropyridinyl oxime cognition activators 1-(1-methyl-1,2,5,6-tetrahydro-3-pyridinyl)ethanone oxime·HCl (I), 1-(1-methyl-1,2,3,6-tetrahydro-4-pyridinyl)ethanone oxime·HCl (II), and 1-(1,2,5,6-tetrahydro-3-pyridinyl)ethanone O-methyloxime HCl(III) were analyzed by X-ray diffraction and the quantum mechanical semiempirical PM3 methods. Results indicate that in the solid state the drugs exhibit anti-syn isomerism, with the substituent at the oxime oxygen atomanti oriented in respect to C=N. This arrangement also represents a low-energy situationin vacuo, as confirmed at the PM3 level, although another low-energy conformation (clinal-anti) could be of significance in the conformational energetics of the drugs.