Chemical composition and in vitro activity of plant extracts from Ferula communis and Dittrichia viscosa against postharvest fungi

F. communis and D. viscosa are perennial Mediterranean weeds that have been used for different therapeutic purposes in traditional pharmacopeia. Plant extracts were obtained from air dried D. viscosa young shoots (DvA) and F. communis aerial part (FcA) and roots (FcR) with n-hexane. The chemical compositions of the extracts were analyzed by HPLC-DAD, LC-MS (ESI) and LC-Q-TOF techniques. Two sesquiterpene lactones (inuviscolide, tomentosin) and three sesquiterpene acids (costic acid, hydroxycostic acid, ilicic acid) were identified from the D. viscosa extract, while in F. communis extracts three daucane sesquiterpenes (acetoxyferutinin, oxojaeskeanadioyl anisate, fertidin) and one coumarin (ferulenol) derivates were found. Biological activities of plant extracts were studied in in vitro experiments on the colonies and conidia of Botryotinia fuckeliana, Penicillium digitatum, P. expansum, Monilinia laxa, M. fructigena and Aspergillus spp. Extracts showed varying degree of antifungal activities on colony growth and conidia germination. The extract from FcA showed the least effect, while DvA extract had the strongest fungitoxic effects. FcR extract presented a fungitoxic effect on the colony growth, but it was not able to inhibit the conidia germination. These distinctions can be attributed to the differences in chemical composition of plant extracts.     

Tandem hollow-fiber flow field-flow fractionation

Reinjection of one ore more collected fractions of eluted samples is recognized as a useful procedure in analytical separation techniques, among which field-flow fractionation (FFF), to improve the actual separation of complex samples. Hollow-fiber flow FFF (HF5) is a micro-channel subset of flow FFF (F4), which has recently reached a performance comparable to that of standard, flat-channel F4. To further improve HF5 of complex protein samples, we present a new device and method for in-line, reinjection HF5 that we call tandem HF5 (HF5/HF5). HF5 is ideally suited for tandem operation because (1) small channel volume and low operation flow rates allow reducing dilution and volume of the collected fractions, and (2) the relaxation/focusing step that takes place between the 1st and 2nd run (refocusing) allows reestablishing the volume and concentration of the sample plug before the 2nd elution. HF5/HF5 proves particularly effective in the case of oligomeric proteins since it allows collecting and reinjecting the bands that correspond to each separated oligomeric form. This provides information on the dynamic equilibria between the different oligomers. For HF5/HF5 operations, a modified, prototype HF5 instrumentation is presented which includes a "trap" constituted of a four-port, two-way valve positioned downstream the UV detector and a collection loop. The effect of refocusing conditions on HF5/HF5 performance is investigated by varying refocusing time. With a complex protein samples such as blood serum, HF5/HF5 can improve detectability of the low abundance components since overloading effects due to high-abundance components are reduced. This is shown for serum lipoproteins: while after the 1st run high density lipoproteins (HDLs) are not separated from high-abundance serum proteins, after the 2nd run it is shown possible to separate the HDL subclasses.     

Determination of wine aroma compounds by dehydration followed by GC/MS

A new extraction method for the analysis of the volatile fraction of white and red wines has been developed and validated. A dehydration step with MgSO4 separated an aroma compounds-rich alcoholic-glycerine layer. Spiked samples showed good recoveries in the range between 75 and 120% with CVmax% of 17, except for 2-phenylethanol and y-butyrolactone for which recoveries in red wines were under 60%, and for monoethylsuccinate, where recoveries averaged 50 and 60% in white and red wines, respectively. Method repeatability and intermediate precision showed good CVmax% with minimum and maximum values between 7.7 and 24, and between 18.7 and 25.0, respectively. The average determination coefficients were greater than 0.99 with CVmax% of 13. The instrumental LOD and LOQ were, in all cases, under 0.05 mg/L, except for 2,3 butanediol (0.20 mg/L). Overall, the presence of wine matrix affected aroma compounds responses in GC/MS analysis. These observations indicate that the use of a matrix-matched calibration curve is mandatory to obtain reliable quantitative data.     

Synthesis of analogues of ochratoxin A

Four analogues of ochratoxin A (OTA) differing for the aminoacidic moiety were synthesised using ochratoxin α (OTα) as the starting material. The condensation reaction between protected amino acids and OTα, carried out in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC???HCl) and N-hydroxybenzotriazole (HOBt) as coupling agents, followed by deprotection and PTLC purification afforded OTA alanine, leucine, serine and tryptophane analogues in satisfactory yields (33-47%, based on OTα).     

Experimental study on the retention of silica particles in gravitational field-flow fractionation effects of the mobile phase composition

Effects of mobile phase composition can play an effective role in modulating the retention of particles in gravitational field-flow fractionation (GFFF), the simplest and cheapest among field-flow fractionation (FFF) techniques. In the framework of an optimized procedure for the GFFF characterization of particulate systems, an experimental approach to the effects of the mobile phase composition on the retention of silica particles retention is presented. The role of the ionic strength and the presence of surfactant are emphasized, with special regards to the shape of the particles. Moreover, the first experimental evidence of potential-barrier GFFF is reported.     

Dioxomolybdenum(VI) Complexes with New Enantiomerically Pure Amino Diol Ligands

(R)-Phenylglycinol is shown to be an efficient building block for the synthesis of chiral amino diols in pure diastereomeric form by epoxide ring-opening reactions. The reaction with rac-trans-stilbene oxide gives [HOCH(2)-(R)-PhCH]NH[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-HNO(2)H(2)] in 32% yield, which can be methylated at nitrogen to give enantiomerically pure [HOCH(2)-(R)-PhCH]NCH(3)[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-MeNO(2)H(2)]. These amino diol ligands have been used to prepare chiral dioxomolybdenyl complexes of the formula N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) (1) and N(R)-2(R)-3(R)-4(S)-(MeNO(2))MoO(2) (2). The absolute configuration at each stereocenter in the Mo(VI) complexes has been established by (1)H NOESY spectroscopy. The configuration determined for 1 has been confirmed by an X-ray analysis. Crystal data: orthorhombic P2(1)2(1)2(1), a =7.620(3), b = 13.589(2), c = 20.339(3) ?, Z = 4, R = 0.0336. The structure consists of a polymeric chain of N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) molecules connected through unsymmetrical Mo=O --> Mo bridges. Each metal center is coordinated in a distorted octahedral geometry by a cis dioxo unit and by two trans alkoxo atoms. The coordination polyhedron is completed by a nitrogen atom and by a bridging oxo oxygen atom from an adjacent molecule. Compound 2 catalyzes the oxidation of PPh(3) to OPPh(3) by DMSO through a mechanism that involves the intermediacy of a Mo(IV) species.     

Side-chain liquid crystalline polyesters for optical information storage

Azobenzene side-chain liquid crystalline polyester structures suitable for permanent optical storage are described. The synthesis and characterization of the polyesters together with differential scanning calorimetry and X-ray investigations are discussed. Optical anisotropic investigations and holographic storage in one particular polyester are described in detail and polarized Fourier transform infrared spectroscopic data complementing the optical data are presented. Optical and atomic force microscope investigations point to a laser-induced aggregation as responsible for permanent optical storage.     

[Re5(μ-H)4(CO)20]− and [Re5(μ-H)5(CO)20], Two Isolobal Analogues of Cyclopentane

The first five-membered rings of metal atoms connected by M–M or M-H-M bonds only have been obtained by a Re₂+Re₃ condensation in which a polyhydride acts as a bridging bidentate ligand toward a coordinatively unsaturated fragment (see scheme below). In spite of the octahedral coordination of the Re centers, the Re₅ rings display conformations (twisted and envelope) comparable with those observed for organic five-membered rings of tetrahedral carbon atoms.     

Hydrido-Carbonyl Rhenium Clusters with a Square Geometry of the Metal Core. Synthesis and X-Ray Characterization of the Novel [Re4(μ-H)3(CO)16]− Anion

Three and tetranuclear ring clusters have been obtained by treatment of [Re₂(CO)₈(THF)₂] with carbonyl-rhenates containing two terminal hydrides. The reaction with [ReH₂(CO)₄]^- provided a selective route to the previously known [Re₃(-H)₂(CO)₁₂]^- triangular cluster anion 1. The reaction with [Re₂H₂(-H)(CO)₈]^- gave the novel [Re₄(-H)₃(CO)₁₆]^- anion 2, containing a rare example of a puckered-square metal cluster. Protonation of 1 is known to afford the neutral [Re₃(-H)₃(CO)₁₂] species 3. Analogously the reaction of 2 with a strong acid afforded the previously known square metal clusters [Re₄(-H)₄(CO)₁₆] 4. The reaction could not be reversed by treatment with bases. Photolysis of 4 gave the unsaturated complex [Re₂(-H)₂(CO)₈] 5: this is the reverse of the dimerization reaction, that in THF at room temperature produces 4 from 5. Thermal treatment (reflux in cyclohexane for 24 h) left 4 almost unchanged. A single crystal X-ray analysis of [NEt₄]2 showed a s/e/s/s (e=eclipsed, s=staggered) conformation of the Re(CO)₄ units, leading to a puckered geometry of the ring, at variance with the square-planar geometry of 4 (all eclipsed). Two of the three hydrides of 2 have been located as bridging the Re–Re edges from inside the metal ring, as previously observed in 4. Density functional computations indicated a puckered conformation as the most stable for both 2 and 4, with very low activation energies for ring inversion (6.6 and 2.2 kcal·mol^-1, respectively), but ruled out solid state fluxionality for 4, whose observed planar geometry must be attributed to packing stabilization.     

Hydrogenation of Quinoline by Rhodium Catalysts Modified with the Tripodal Polyphosphine Ligand MeC(CH2PPh2)3

As part of our modelling studies of the hydrodenitrogenation of N‐heterocycles contained in raw oil materials, we investigated the selective hydrogenation of quinoline to 1,2,3,4‐tetrahydroquinoline by rhodium catalysts modified with the tripodal polyphosphane ligand MeC(CH₂PPh₂)₃. Experiments in standard autoclaves and in high‐pressure sapphire NMR tubes, kinetic and isotope labelling studies, and independent reactions with isolated compounds have contributed to the elucidation of the catalytic mechanism as well as identification of the electronic requisites of the metal catalyst for selective and efficient hydrogenation.