Phenolic constituents of licorice. III. Structures of glicoricone and licofuranone, and inhibitory effects of licorice constituents on monoamine oxidase

Two new phenolic compounds, glicoricone (3) and licofuranone (4), were isolated from a species of licorice brought from the northwestern region of China, and their structures were assigned. Among the twelve licorice constituents examined for the inhibition of monoamine oxidase (MAO), six compounds, 3, 4, genistein (6), licopyranocoumarin (7), licocoumarone (14) and glycyrrhisoflavone (15), inhibited the enzyme with the IC50 (concentration required for 50% inhibition of the enzyme activity) values of 6.0 x 10(-5)-1.4 x 10(-4) M. Glycyrrhizin (1) also inhibited MAO with the IC50 value of 1.6 x 10(-4) M.     

Meso-tetrakis[o-(N-methyl)pyridinium]porphyrin ensembles with axially coordinated cyclodextrin-penetrating phenethylimidazole: reversible dioxygen-binding in aqueous DMF solution

alpha-Cyclodextrin (alpha CD)-penetrating 2-methyl-1-phenethylimidazole coordinates to the zinc(II) and iron(II) complexes of meso-tetrakis[o-(N-methyl)pyridinium] porphyrinate, giving non-covalently linked alpha CD-porphyrin ensembles; the iron(II) complex can reversibly bind and release dioxygen in aqueous DMF solution.     

Excited states of phosphorescent platinum(II) complexes containing N wedge C wedge N-coordinating tridentate ligands: spectroscopic investigations and time-dependent density functional theory calculations

The absorption and emission spectra of the Pt(II) complexes containing N wedge C wedge N-coordinating tridentate ligands, platinum(II) 1,3-di(2-pyridyl)benzene chloride [Pt(dpb)Cl] and platinum(II) 3,5-di(2-pyridyl)toluene chloride [Pt(dpt)Cl], together with their corresponding free ligands, 1,3-di(2-pyridyl)benzene (dpbH) and 3,5-di(2-pyridyl)toluene (dptH), have been analyzed by density functional theory (DFT) for the ground state and time-dependent DFT (TDDFT) for the excited states. T(1)(A(1)) and S(1)(B(2)) of the complexes (in C(2)(v) symmetry) were assigned on the basis of the calculated excitation energies as well as comparison of the experimental spectroscopic properties and the calculated states' characteristics. The calculated excitation energies for T(1) and S(1) of the complexes as well as those for T(1) of the free ligands were in good agreement with their observed values within 600 cm(-1). The d-pi* characters of the excited states were evaluated from the change in electron densities between the ground and excited states by Mulliken population analysis; values of 25% for T(1) and 32% for S(1) were obtained for both complexes. The calculated values of d-pi* character were found to be consistent with the reported emission lifetimes as well as the observed emission energy shifts from the corresponding free ligands. Most spectroscopic properties of the complexes and the free ligands, which include solvatochromic shift, Stokes shifts, methyl substitution shifts, and emission spectra profiles, were well explained from the calculation results.     

Highly active, immobilized ruthenium catalysts for oxidation of alcohols to aldehydes and ketones. Preparation and use in both batch and flow systems

A novel, highly active immobilized ruthenium catalyst, which can be successfully used in oxidation of alcohols to aldehydes and ketones, has been developed. In contrast to most immobilized catalysts, the Ru catalyst has activity that is higher than that of the original non-immobilized catalyst. In a batch system, the Ru catalyst was recovered and reused several times without loss of activity. The catalyst was also applied to a flow system, in which excellent conversions and yields were demonstrated. No leaching of Ru was observed in both cases.     

Chemical release control: Carbamates of 3-vinylphenyl and 2-methacryloyloxyethyl isocyanates and perfume and herbicide alcohols

Polymerizable carbamates were synthesized from 3-vinylphenyl and 2-methacryloyloxyethyl isocyanates and perfume and herbicide alcohols, such as 2-phenethyl alcohol, citronellol, geraniol, 1-menthol, borneol, and 2-(2,4-dichlorophenoxy)- and 2-(2,4,5-trichlorophenoxy)ethyl alcohols. Copolymerization of these carbamate monomers and N-vinyl-2-pyrrolidone with AIBN in dioxane gave respective copolymers. Hydrolyses of both monomers and copolymers, however, required severe acid conditions, although different chemical structures gave different hydrolytic behaviors.     

Molecular modeling study of species-selective peroxisome proliferator-activated receptor (PPAR) alpha agonist; possible mechanism(s) of human PPARalpha selectivity of an alpha-substituted phenylpropanoic acid derivative (KCL)

In order to investigate the reason why phenylpropanoic acid derivative (KCL), a potent, human peroxisome proliferator-activated receptor (PPAR) alpha-selective agonist, shows this selectivity, we analyzed the binding modes of KCL and a related compound to the ligand-binding domain of human PPARalpha and rat PPARalpha by means of computer-aided molecular modeling. We concluded that the characteristic specificity of KCL is due to a specific hydrophobic contact between the hydrophobic tail part (the 4-trifluoromethyl group) and the key amino acid Ile272 located on the helix three region of the human PPARalpha ligand binding domain. We propose a possible binding mode of KCL with the ligand-binding domain of human PPARalpha. This binding model should offer important insights for further structural design of subtype-selective PPARalpha agonists for the treatment of altered metabolic homeostasis, such as dyslipidemia, obesity, and diabetes.     

The structure of enopeptins A and B, novel depsipeptide antibiotics

The structures of enopeptins A and B, novel depsipeptide antibiotics with 1,3,5,7,9-decapentaene-1,10-dicarboxylic acid and 2-amino-3-hydroxycyclopent-2-enone in a side chain, were determined by chemical and spectroscopic means.     

Chelating behavior of new chelating resins derived from n-(o-hydroxybenzyl)iminodiacetic acid

The chelating behavior of a new resin prepared by polycondensation of N-(o-hydroxybenzyl) iminodiacetic acid (o-HDA) with phenol and formaldehyde, is compared with that of the monomer, with p-HDA resin and p-HDA monomer, and with Chelex-100. The order of chelate stability for the o-HDA resin is Cu(II) > Ni(II) > Zn(II) > Co(II). An unusually high stability of the o-HDA and o-HDA resin iron(III) chelates in acidic solution is attributed to the participation of the o-hydroxyl group in the coordination process.     

Rotational correlation times of adenosine 5′-monophosphate in solution as deduced from 1H and 13C spin-lattice relaxation times

Rotational correlation times (τ_T) of the 5′-AMP molecule deduced from spin-lattice relaxation times (T₁) of different protons in the molecule agree fairly well with each other in the temperature range of 3.5–74°C. The same is true with τ_T values deduced from ¹³CT₁ values. These results indicate that the internal motions are slow as compared to the overall rotation of the 5′-AMP molecule.