An efficient synthesis of the phytoestrogen 8-prenylnaringenin from isoxanthohumol with magnesium iodide etherate

Xanthohumol was isolated from supercritical carbon dioxide-spent hop and transformed into isoxanthohumol. The demethylation of isoxanthohumol with the best yield 93% occurred when MgI₂ etherate in anhydrous THF was applied. Salts such as MgBr₂, MgCl₂, CaI₂, Mg(OAc)₂, Mg(OMe)₂ were also investigated. A convenient method for the xanthohumol isolation from supercritical carbon dioxide-spent hop is also described.     

Mechanisms of air oxidation of ethoxylated surfactants--computational estimations of energies and reaction behaviors

Pathways for formation of previously observed autoxidation products of ethoxylated surfactants have been studied by DFT (B3LYP). In addition to the established radical-chain reaction, several mechanistic possibilities for intramolecular fragmentation of the intermediate radicals have been characterized concerning reaction barriers and energies of transition states. The results can rationalize the formation of previously observed autoxidation products, including several, which have been implicated as strongly allergenic.     

Photochemical stability of poly(vinyl pyrrolidone) in the presence of collagen

The photochemical stability of poly(vinyl pyrrolidone) (PVP) in the presence of 1%, 3% and 5% of collagen has been studied by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TG) and derivative thermogravimetry (DTG). Surface properties have been studied by contact angle measurements. PVP samples and samples containing 1%, 3% and 5% of collagen were irradiated with UV light of wavelength λ = 254 nm in air for up to 24 h. The amount of gel created during UV irradiation was estimated.PVP in the presence of 1%, 3% and 5% of collagen is less stable both thermally and photochemically. Collagen enhances photochemical processes leading to crosslinking of PVP. The contact angle measurements and values of surface free energy showed that the wettability of PVP films was changed by the addition of collagen and by UV irradiation. The increase of polarity of samples indicates an efficient photooxidation on the surface upon UV irradiation.     

New structural types and different oxidation levels in the family of Mn6-oxime single-molecule magnets

The synthesis and magnetic properties of three new members of a family of salicyaldoxime based [Mn6] single-molecule magnets possessing new structural types, core topologies and Mn oxidation state distributions are reported. The isostructural complexes [MnIII6O2(R-sao)6(X)2(EtOH)6] (R = Et, X = Br (1); R = Me, X = I (2)) exhibit single-molecule magnet behaviour with spin Hamiltonian parameters S = 12, g = 1.98 and D = -0.36 cm(-1) in both cases. The hexametallic cluster [MnIII4MnIV2O2(OMe)(4-)(Et-sao)6(MeOH)2].MeOH (3.MeOH) possesses a planar rod-like topology and a mixed valent [MnIV4MnIII2] core, which is unprecedented in this family of [Mn6] SMMs.     

Analysis of chemical shift changes reveals the binding modes of isoindolinone inhibitors of the MDM2-p53 interaction

In this study we present a method for defining the binding modes of a set of structurally related isoindolinone inhibitors of the MDM2-p53 interaction. This approach derives the location and orientation of isoindolinone binding, based on an analysis of the patterns of magnitude and direction of chemical shift perturbations for a series of inhibitors of the MDM2-p53 interaction. The MDM2-p53 complex is an attractive target for therapeutic intervention in cancer cells with intact tumor suppressor p53, as it offers the possibility of releasing p53 by blocking the MDM2-p53 binding site with a small molecule antagonist to promote apoptosis. Isoindolinones are a novel class of MDM2-antagonists of moderate affinity, which still require the development of more potent candidates for clinical applications. As the applicability of conventional structural methods to this system is limited by a number of fundamental factors, the exploitation of the information contained in chemical shift perturbations has offered a useful route to obtaining structural information to guide the development of more potent compounds. For a set of 12 structurally related isoindolinones, the data suggests 4 different orientations of binding, caused by subtle changes in the chemical structure of the inhibitors.     

Synthesis and anticancer activity evaluation of 3-(4-oxo-2-thioxothiazolidin-5-yl)-1H-indole-carboxylic acids derivatives

Abstract

A mild and efficient method for the synthesis of 1-oxo-9H-thiopyrano[3,4-b]indole-3-carboxylic acids and dimerized 3-(4-carboxy-1H-3-indolyl)-2-propenoic acids via alkaline hydrolysis of 3-(rhodanin-5-yl)-1H-indole-2-carboxylic acids derivatives was elaborated. Anticancer activity screening in NCI60-cell lines assay allowed identification of 5-fluoro-3-(4-oxo-2-thioxothiazolidin-5-ylidenemethyl)-1H-indole-2-carboxylic acid methyl ester 2a with significant antimitotic activity at micromolar and submicromolar concentrations.     

New oxacalix[4]arene carboxylate detects viologen in protic media

ABSTRACT

We demonstrate that Ullman fragment-coupling can be used to synthesise an oxacalix[4]arene monocarboxylic acid, which provides easy access to its water-soluble carboxylato derivatives. Crystallographic and computational data suggest that the new carboxyl-substituted oxacalix[4]arene adopts a 1,3-alternate conformation both in the solid-state and in methanol solution. Its water-soluble tetrabutylammonium derivate can detect the herbicide paraquat at neutral pH in aqueous media (K _a = 111 ± 3 M^–1) and in methanol (K _a = 2020 ± 70 M^–1).     

Impregnated silica-based layers in thin layer chromatography

Abstract

Impregnated thin-layer chromatography (TLC) layers based on silica gel are presented. Impregnating agents such as metal cations, inorganic ions, chelating agents, chiral selectors, surfactants, ion-pairing reagents, and ionic liquids are discussed. The role of impregnated TLC layers in medicinal chemistry is highlighted. The historical overview of TLC separations on physically coated layers is given and some future prospects ahead of this technique are discussed.     

Variation in essential oil content and composition of Ridolfia segetum Moris based on 30-hour prolonged fractionated extraction procedure

Abstract

A comprehensive study on essential oil samples extracted from Ridolfia segetum Moris (Apiaceae) collected in Tarquinia (Italy) is reported. In this study, a 30-hour, fractionated, steam distillation procedure for essential oil preparation was applied. The gas chromatographic-mass spectrometry analysis showed monoterpene o-cymene and phenylpropanoid dill-apiol as the major essential oil’s constituents revealing a new chemotype dependent on extraction duration. Great impact of the duration of the distillation process on chemical profile of essential oil was observed; prolonged distillation gives chemically more diverse essential oil samples. Preliminary microbiological evaluations of the essential oils samples revealed some activity, although not high, against Candida albicans.     

Surface antimicrobial modification of polyamide by poly(hexamethylene guanidine) hydrochloride

Antimicrobial polyamide (PA) received much attention for the demand of packaging and biomedical fields. In this paper, an antimicrobial PA6 membrane was prepared via a surface chemical reaction. A highly effective antibacterial component (PHMG‐E) with terminal epoxy group was firstly synthesized via a reaction between polyhexamethylene guanidine hydrochloride (PHMG) and ethylene glycol diglycidyl ether (EGDE). Then, PHMG‐E was bonded on the surface of PA6 membrane with secondary amine reduced by borane‐tetrahydrofuran (BH₃‐THF). The antimicrobial rates of surface‐modified PA6 membrane (PA6‐PHMG) against Escherichia coli and Staphylococcus aureus were both higher than 99.99%, and the PHMG was non‐leaching due to the chemical bonding. The hydrophilicity of antibacterial PA6 membrane was also significantly improved and the mechanical performance became better.