Simple and efficient synthesis of benzofuran derivatives from tyrosol

A convenient strategy for the preparation of compounds bearing the benzofuran skeleton starting from tyrosol, a phenol largely present in olive oil production waste, with no biological importance, is reported. A bromination/methoxylation sequence, already described for the synthetic transformation of naturally occurring compounds, was exploited. Depending on the solvent used for the methoxylation reaction together with the presence of a 4-phenol moiety respect to the side chain, benzodihydrofurans or a benzofurans derivative can be obtained.     

Metal-organic framework-templated synthesis of magnetic nanoporous carbon as an efficient absorbent for enrichment of phenylurea herbicides

Nanoporous carbon with a high specific surface area and unique porous structure represents an attractive material as an adsorbent in analytical chemistry. In this study, a magnetic nanoporous carbon (MNC) was fabricated by direct carbonization of Co-based metal-organic framework in nitrogen atmosphere without using any additional carbon precursors. The MNC was used as an effective magnetic adsorbent for the extraction and enrichment of some phenylurea herbicides (monuron, isoproturon, diuron and buturon) in grape and bitter gourd samples prior to their determination by high performance liquid chromatography with ultraviolet detection. Several important experimental parameters that could influence the extraction efficiency were investigated and optimized. Under the optimum conditions, a good linearity was achieved in the concentration range of 1.0–100.0 ng g⁻¹ for monuron, diuron and buturon and 1.5–100.0 ng g⁻¹ for isoproturon with the correlation coefficients (r) larger than 0.9964. The limits of detection (S/N = 3) of the method were in the range from 0.17 to 0.46 ng g⁻¹. The results indicated that the MNC material was stable and efficient adsorbent for the magnetic solid-phase extraction of phenylurea herbicides and would have a great application potential for the extraction and preconcentration of more organic pollutants from real samples.     

Immunoaffinity-based extraction of phenylurea herbicides using mixed antibodies against isoproturon and chlortoluron

Summary The analysis of several phenylurea herbicides in different waters is described using an immunoaffinity column clean-up and determination by high performance liquid chromatography. The pesticides were selectively retained on a solid phase extraction column containing antibodies to chlortoluron and to isoproturon immobilised onto silica. Selected phenylureas were eluted using a simple phosphate buffered saline/ethanol mixture at low pH. The immunoaffinity approach gave extracts free of interfering substances and allowed detection limits comparable to those required for pesticides in water in the European Community. The proposed method was successfully applied to the determination of chlortoluron, isoproturon, linuron and chlorbromuron in tap and river water. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

Isoguanosine derivatives from the Northeastern Atlantic sponge Clathria (Microciona) strepsitoxa

After a chemical screening of subtidal sponges from the Northeastern Atlantic, Clathria (Microciona) strepsitoxa (Poecilosclerida: Microcionidae) was selected for deeper investigation. This first chemical study led to the identification of two new 8-oxoisoguanosine derivatives. The structure elucidation was performed after extensive analyses of spectroscopic (1D and 2D NMR) and HR-ESIMS data and no significant antimicrobial or cytotoxic activity was detected.     

Simultaneous HPLC determination of phenylurea herbicides and their corresponding anilines in water after on-line preconcentration

On-line preconcentration on a short C₁₈ column, prior to HPLC with UV and electrochemical detection, has been used for determination of some phenylurea herbicides and their possible degradation products, substituted anilines, in water samples. With electrochemical detection the detection limit at a signal-to-noise ratio of 3 was 5 ppt for 4-chloroaniline and 4-bromoaniline and 7 ppt for 3,4-dichloroaniline; with UV detection the detection limit was ca 300 ppt for all analytes.     

Isolation, synthesis and structures of cytotoxic ginsenoside derivatives

Four known ginsenosides: ginsenoside-Rb1 (1), Rb3 (2), Rd (3) and Re (4) were isolated from the methanolic extract of the traditional Chinese medicine Panax ginseng C. A. Meyer. Further enzyme reactions and chemical modifications led us to obtain ginsenoside-M1 (5) and synthesize three novel mono-esters of ginsenoside-M1, ginsenoside-DM1 (6), PM1 (7) and SM1 (8) 30 - 50% of yield via a facile and green synthetic strategy. The structures were elucidated on the basis of extensive 1D- and 2DNMR, as well as high resolution ESI-TOF mass spectroscopic analyses. The isolated and synthetic compounds were tested in an anti-tumor bioassay, and compounds 5-8 showed considerable cytotoxicity (SRB) against several human cancer cell lines (breast cancer MCF-7, skin melanoma SK-MEL-2 and human ovarian carcinoma B16), but moderate effects on lung carcinoma COR-L23. The other ginsenosides showed no effects.     

Analysis of the cyanolichen Lichina pygmaea metabolites using in situ DART‐MS: from detection to thermochemistry of mycosporine serinol

Direct Analysis in Real Time DART‐HRMS is here first applied to the detection of molecules from a lichen, Lichina pygmaea. The aim was to propose an innovative method of in situ detection of lichen secondary metabolites using the possibilities of elemental composition determination available when a DART source is interfaced with a TOF analyzer. Three kinds of samples have been submitted to DART ionization, i.e. an intact thallus, a powder obtained from the crushed lichen and an aqueous extract. In situ analysis of crushed lichen, yields an extensive chemical profile, comparable to what is obtained from the aqueous extract, comprising both major polar metabolites described in literature along with some other signals that could correspond to potentially unknown metabolites. One of the detected secondary metabolites, mycosporine serinol, underwent a dehydration reaction prior to its transfer in the gas‐phase by DART ionization. The consideration of the thermal transfers involved in the DART ionization process and the possibility to record time‐dependent mass spectra through the use of the TOF analyzer allowed establishing Arrhenius plots of this water molecule loss to obtain associated thermodynamic quantities. The low values of corresponding activation enthalpy ( of the order of 25 kJ mol^?1) enabled formulating some assumption regarding a possible role of such metabolites in the lichen. Copyright © 2015 John Wiley & Sons, Ltd.     

Evaluation of new selective molecularly imprinted polymers prepared by precipitation polymerisation for the extraction of phenylurea herbicides

Three different molecularly imprinted polymers (MIPs) have been prepared by precipitation polymerisation using linuron (LIN) or isoproturon (IPN) (phenylurea herbicides) as templates and methacrylic acid (MAA) or trifluormethacrylic acid (TFMAA) as functional monomers. The ability of the different polymers to selectively rebind not only the template but also other phenylurea herbicides has been evaluated. In parallel, the influence of the different templates and functional monomers used during polymers synthesis on the performance of the obtained MIPs was also studied through different rebinding experiments. The experimental binding isotherms were fitted to the Langmuir-Freundlich isotherm allowing to describe the kind of binding sites present in the imprinted polymers under study. It was concluded that TFMAA-based polymer using IPN as template presents the best properties to be used as a selective sorbent for the extraction of phenylurea herbicides.     

Isolation,analysis, and synthesis of ephedrine and its derivatives

A review is given of methods for the isolation, quantitative determination, and modification of the ephedrine alkaloids, and advances in this field of natural compound chemistry are discussed.Institute of Organic Synthesis and Coal Chemistry of the Kazakh SSR Academy of Sciences, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 307–319, May–June, 1989.     

Determination of phenylurea and triazine herbicides in milk by microwave assisted ionic liquid microextraction high-performance liquid chromatography

The determination of phenylurea and triazine herbicides in milk based on microwave assisted ionic liquid microextraction (MAILME) coupled with high-performance liquid chromatographic separation was described. The experimental parameters of the MAILE, including type and amount of ionic liquid, microwave extraction power, extraction time and salt concentration in sample, were evaluated by a univariate method and orthogonal screening. When 60 μL of [C₆MIM][PF₆] was used as extraction solvent the target compounds can be isolated from the 4 mL of milk. The MAILME is quick (7 min) and simple. The detection limits for isoproturon, monolinuron, linuron, propazine, prometryne, terbutryn and trietazine are 0.46, 0.78, 1.00, 1.21, 1.96, 0.84 and 1.28 μg L⁻¹, respectively. The proposed method was applied to the analysis of milk samples and the recoveries of the analytes ranged from 88.4 to 117.9% and relative standard deviations were lower than7.43%.     

Three antibacterial naphthoquinone analogues from cultured mycobiont of lichen Astrothelium sp.

<正>A new naphthoquinone compound named 7-hydroxyl-8-methoxyltrypethelone 3 together with two known compounds trypethelone 1 and trypethelone methyl ether 2 was isolated from cultured mycobiont of Astrothelium sp.The structures were elucidated by 1D and 2D NMR spectroscopic analysis as well as comparison with those reported in literatures.Compound 1 displayed significant antibacterial activity against Bacillus subtilis(ATCC 6633),and showed modest antibacterial activity against Staphylococcus aureus col(MRSA)(CGMCC 1.2465),while compounds 2 and 3 showed modest antibacterial activity against Enterococcus faecalis 850E(CGMCC 1.2135) and S.aureus col(MRSA)(CGMCC 1.2465).     

Design,modification, and bio-evaluation of salazinic acid derivatives

Data on synthesized derivatives of salazinic acid are scarce, with existing reports addressing only derivative hexaacetyl salazinic acid. This study investigated a set of novel potential antidiabetic agents. Analogs of salazinic acid were designed and synthesized using bromination, nucleophilic addition, Friedel-Crafts alkylation, and esterification. Ten synthetic compounds were prepared and structurally elucidated, including eight new compounds (1a-1c, 2a, 3a, 3b, 4a, 4b) and two known analogs. Under bromination, salazinic acid (1) enabled the following reaction chain: oxidation, decarboxylation, and substitution. This yielded products 1a-1c, which were found to have unprecedented scaffolds. Parmosidone F (5) was prepared from 1 with orsellinic acid via Friedel-Crafts alkylation, confirming a previously reported biosynthesis route. These analogs were evaluated for enzyme inhibition of α-glucosidase, and all showed more potent activity than that of acarbose, a positive control (IC₅₀ 332 μM), with IC₅₀ values in the range 9.32–39.96 μM. An in silico molecular docking model confirmed that, in terms of enzyme inhibition, the compounds ranked as follows: 3b > 4b > 4a > 1c > 2a > 1b > 1a > 3a. The kinetics of enzyme inhibition showed 4a and 5 to be a non-competitive-type and mixed-type inhibitors, respectively.     

Analysis of phenylurea and propanil herbicides by solid-phase microextraction and liquid chromatography combined with post-column photochemically induced fluorimetry derivatization and fluorescence detection

This study examines the application of solid-phase microextraction coupled with high performance liquid chromatography combined with post-column photochemically induced fluorimetry derivatization and fluorescence detection (SPME-HPLC-PIF-FD) for the determination of four phenylurea herbicides (monolinuron, diuron, linuron and neburon) and propanil in groundwater. Direct immersion (DI) SPME was applied using a 60 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber for the extraction of the pesticides from groundwater samples. An AQUASIL C₁₈ column (150 mm × 4.6 mm i.d., 5 μm) was used for separation and determination in HPLC. The method was evaluated with respect to the limits of detection (LODs) and the limits of quantification (LOQs) according to IUPAC. The limits of detection varied between 0.019 μg L⁻¹ and 0.034 μg L⁻¹. Limits of quantification ranged between 0.051 μg L⁻¹ and 0.088 μg L⁻¹. These values meet the recommended limits for individual pesticides in groundwater (0.1 μg L⁻¹) established by the EU. Recoveries ranged between 86% and 105% and relative standard deviation values between 2% and 8%.     

Chemical constituents of the lichen Usnea baileyi (Stirt.) Zahlbr

Investigation of the chemical constituents of the lichen Usnea baileyi (Stirt.) Zahlbr led to the isolation of a new dimeric xanthone, bailexanthone (1), and a novel depsidone, bailesidone (2), along with twenty-five known metabolites (3–27). Their structures were established by means of extensive spectroscopic analysis and comparison with data reported in the literatures. Compound 1 derives from secalonic acid scaffold with C-8/8′ reduction and compound 2 represents the first example of menegazziaic acid derivative with an unprecedented B-ring moiety. Two new compounds 1–2 were evaluated for their cytotoxic activities against A549 (human lung carcinoma) and HT29 (human colorectal adenocarcinoma) cell lines. All of them showed weak or no activity against two cell lines.     

Isolation of the chitin from crustaceans of the Aral Sea and the synthesis of derivatives of it

The isolation of chitin and the synthesis of chitosan and of the Na salt of carboxymethylchitosan from a testaceous crustacean of the Aral Sea — the shrimp Palaemon elegans — have been carried out for the first time.Institute of the Chemistry and Physics of Polymers, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 44 26 61. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 600–602, July–August, 1995. Original article submitted October 18, 1994.     

Isolation and synthesis of glutamine and glutarimide derivatives fromCroton humilis

Extract ofCroton humilis L. were shown to contain N - [N - (2 - methylpropanoyl) -l - glutaminoyl] - 2 - phenylethylamine, N - [N - 2R - methylbutanoyl) -l - glutaminoyl] - 2 - phenylethylamine, 2 - [N- (2 - methylpropanoyl)] - N - phenylethylglutarimide and 2 - [N- (2R - methylbutanoyl)] - N - phenylethylglutarimide. Structural proof was based on acid degradation, spectral studies as well as the synthesis of N - [N- (2- methylpropanoyl) -l - glutaminoyl] - 2 - phenylethylamine and 2 - [N - (2 - methylpropanoyl] - N - phenylethylglutarimide.     

<Emphasis Type="Italic">Parmelia sulcata</Emphasis> lichen transplants positioning towards wind direction (Part I): precipitation volumes,total element deposition and lichen element content

Parmelia sulcata transplants were used in three different exposure systems, focused on three different influxes: free influx, horizontal influx and vertical influx. The total element deposition and the precipitation volumes were found to be positively correlated for Fe and Ni only. The element contents in lichen transplants and in total element deposition showed significant correlations for Ca, Fe and Mn in the free influx system and for Na, Ni and V in the horizontal influx system. No significant positive correlations were found for the vertical influx. The results indicate that, apart from response rates, the transplant positioning systems may have effects on element-specific net accumulation.