Effects of Enzymatic Pretreatment of Seeds on the Physicochemical Properties,Bioactive Compounds,and Antioxidant Activity of Pomegranate Seed Oil

Enzymatic pretreatment of seeds is a novel approach that enhances the health benefits of the extracted oil. The study investigated the influence of the enzymatic pretreatment of seeds on the quality of oil from different pomegranate cultivars. The quality of the ultrasound-assisted (and ethanol-extracted) oil was studied, with respect to the refractive index (RI), yellowness index (YI), conjugated dienes (K232), peroxide value (PV) ρ-anisidine value (AV), total oxidation value (TOTOX), total carotenoid content (TCC), total phenolic compounds (TPC), fatty acid composition, phytosterol composition, ferric reducing antioxidant power (FRAP), and 2.2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging capacity. The seeds of three different pomegranate cultivars (‘Wonderful’, ‘Herskawitz’, and ‘Acco’) were digested with an equal mixture of Pectinex Ultra SPL, Flavourzyme 100 L, and cellulase crude enzymes, at a concentration, pH, temperature, and time of 1.7%, 4.5, 40 °C, and 5 h, respectively. Enzymatic pretreatment of PS increased oil yield, PV, TPC, TCC, and DPPH radical scavenging capacity, but decreased the YI. The levels of K232, AV and TOTOX, fatty acids, phytosterols, RI, and FRAP, were not significantly affected by enzymatic pretreatment of PS. Principal component analysis (PCA) established that oil extracted from the ‘Acco’ seed after enzymatic pretreatment had higher yield, TPC, TCC, and DPPH radical scavenging capacity. Therefore, enzyme-pretreated ‘Acco’ pomegranate fruit seed is a source of quality seed oil with excellent antioxidant properties.     

The Influence of Molecular Host Lattices on Electronic Properties of Orbitally (Near-) Degenerate Transition Metal Complexes

Transition metal complexes often have low-lying excited electronic states and, as a consequence, tend to be electronically labile, i.e., their electronic properties exhibit pronounced sensitivity to external perturbations. Often drastic changes in various spectroscopic properties indicating substantial electronic rearrangements can be induced be relatively weak intermolecular forces as provided by nonpolar solvents or solid molecular host lattices. This behaviour can be explained by crossing of potential surfaces in the vicinity of the absolute minimum. Many physical properties of a given orbitally (near-) degenerate system depend strongly on the relative magnitude of some characteristic parameters determining the shape of the ground Born-Oppenheimer potential surface(s), e.g. barrier height versus zero-point energy, distance between minima versus zero-point amplitude, energy difference between minima, etc. Typical examples are systems exhibiting Jahn-Teller activity, spin-crossover, mixed valence, exchange coupling and other types of electronic near-degeneracies. In paramagnetic systems changes in the electronic wavefunction can be most conveniently detected and analyzed by using EPR. spectroscopy. In paramagnetic sandwich complexes we studied two types of orbital degeneracies: Jahn-Teller degeneracies (d⁷-systems such as Co (cp)₂, Ni(cp) and Fe (cp) (bz), low-spin d⁵-systems such as Mn (cp)₂) and low-spin/high-spin equilibria (d⁵-systems such as Mn (cp)₂). By diluting these complexes and ring-substituted derivatives in a large variety of diamagnetic host systems we have been able to control the ⁶A/²E equilibrium of Mn (cp)₂ by influencing the metal-to-ring distance and by changing the degree of ring alkylation; similarly we have been able to vary the relative weights of the two electronic states contributing to the two-fold degenerate electronic ground state of d⁵- and d⁷-systems to a large degree by variation of the local asymmetric fields offered by the lattice sites of the host systems. For comparison the electronic ground state properties of octahedral Cu(II) complexes with CuN₆ CuO₆ chromophores, of V (CO)₆ and tetrahedral VCl₄ were also studied by EPR. between 4K and room temperature in several host systems. Characteristic differences in the details of the temperature and host dependence of the EPR. spectra in all these electronically labile systems can be explained in terms of differences in the vibronic coupling type (E ? e vs. T ? e, t), the strength of linear and/or quadratic JT-coupling and the effects produced by spin-orbit coupling.     

A facile microwave-assisted palladium-catalyzed cyanation of aryl chlorides

We report an efficient method for the preparation of aryl nitriles from aryl chlorides under either microwave assisted or thermal conditions. A catalyst system comprising tris(dibenzylidene acetone)dipalladium (Pd₂(dba)₃) and 2-(2′,6′-dimethoxybiphenyl)dicyclohexylphosphine (S-Phos) is shown to effectively promote cyanation of various aryl chlorides with Zn(CN)₂ as the cyanide source.     

Excited-state symmetry and reorientation dynamics of perylenes in liquid solutions: time-resolved fluorescence depolarization studies using one- and two-photon excitation

The excited-state symmetry and molecular reorientation of perylene, 1,7-diazaperylene, and 2,5,8,11-tetra- tert-butylperylene have been studied by different fluorescence depolarization experiments. The first excited electronic singlet state was reached through one-photon excitation (OPE) and two-photon excitation (TPE). A 400 and 800 nm femtosecond laser pulse was used for this purpose, and data were collected by means of the time-correlated single-photon counting technique. It is found that the rotational correlation times for each perylene derivative are very similar in the OPE and TPE depolarization experiments. For the determination of the two-photon absorption tensor, a recently described theoretical model has been applied (Ryderfors et al. J. Phys. Chem. A 2007, 111, 11531). It was found that the two-photon process can be described by a 2 x 2 absorption tensor for which the components are solvent dependent and exhibit mixed vibronic character. In the dipole approximation this is compatible with a parity-forbidden two-photon absorption into the first excited singlet state.     

Photochemically and thermally tunable planar defects in colloidal photonic crystals

We report a bottom-up synthesis of a photochemically and thermally active azobenzene-based polyelectrolyte multilayer (PEM) planar defect embedded in a colloidal photonic crystal (CPC). Both photoisomerization and thermal cycling lead to a precise tuning of an intragap transmitting state induced by the PEM structural defect.     

Asymptotic cones of finitely presented groups

Let G be a connected semisimple Lie group with at least one absolutely simple factor S such that and let Γ be a uniform lattice in G.

(a)

If CH holds, then Γ has a unique asymptotic cone up to homeomorphism.

(b)

If CH fails, then Γ has 2^2ω asymptotic cones up to homeomorphism.

     

Thermally-Induced Extrusion of Sulfur Dioxide from Allyl Alkyl Sulfones. Use of the Rearrangement for the Synthesis of Dihydrojasmone

For some time we have been interested in the mechanistic and potential synthetic applications of the thermal transformation illustrated in equation (1)^1.     

Radical Localization in a Series of Symmetric NiII Complexes with Oxidized Salen Ligands

Square‐planar nickel(II) complexes of salen ligands, N,N′‐bis(3‐tert‐butyl‐(5R)‐salicylidene)‐1,2‐cyclohexanediamine), in which R=tert‐butyl ( 1 ), OMe ( 2 ), and NMe₂ ( 3 ), were prepared and the electronic structure of the one‐electron‐oxidized species [ 1 – 3 ]^+. was investigated in solution. Cyclic voltammograms of [ 1 – 3 ] showed two quasi‐reversible redox waves that were assigned to the oxidation of the phenolate moieties to phenoxyl radicals. From the difference between the first and second redox potentials, the trend of electronic delocalization 1 ^+.> 2 ^+.> 3 ^+. was obtained. The cations [ 1 – 3 ]^+. exhibited isotropic g tensors of 2.045, 2.023, and 2.005, respectively, reflecting a lower metal character of the singly occupied molecular orbital (SOMO) for systems that involve strongly electron‐donating substituents. Pulsed‐EPR spectroscopy showed a single population of equivalent imino nitrogen atoms for 1 ^+., whereas two distinct populations were observed for 2 ^+.. The resonance Raman spectra of 2 ^+. and 3 ^+. displayed the ν_8a band of the phenoxyl radicals at 1612 cm^?1, as well as the ν_8a bands of the phenolates. In contrast, the Raman spectrum of 1 ^+. exhibited the ν_8a band at 1602 cm^?1, without any evidence of the phenolate peak. Previous work showed an intense near‐infrared (NIR) electronic transition for 1 ^+. (Δν_1/2=660 cm^?1, ε=21 700 M ^?1 cm^?1), indicating that the electron hole is fully delocalized over the ligand. The broader and moderately intense NIR transition of 2 ^+. (Δν_1/2=1250 cm^?1, ε=12 800 M ^?1 cm^?1) suggests a certain degree of ligand‐radical localization, whereas the very broad NIR transition of 3 ^+. (Δν_1/2=8630 cm^?1, ε=2550 M ^?1 cm^?1) indicates significant localization of the ligand radical on a single ring. Therefore, 1 ^+. is a Class III mixed‐valence complex, 2 ^+. is Class II/III borderline complex, and 3 ^+. is a Class II complex according to the Robin–Day classification method. By employing the Coulomb‐attenuated method (CAM‐B3LYP) we were able to predict the electron‐hole localization and NIR transitions in the series, and show that the energy match between the redox‐active ligand and the metal d orbitals is crucial for delocalization of the radical SOMO.