Micellar electrokinetic capillary chromatography—Synchronous monitoring of substrate and products in the myrosinase catalysed hydrolysis of glucosinolates

A micellar electrokinetic capillary chromatography (MECC) method has been developed for monitoring the myrosinase catalysed hydrolysis of 2-hydroxy substituted glucosinolates and the simultaneous formation of the corresponding degradation products (oxazolidine-2-thiones (OZTs) and nitriles). Glucosibarin ((2R)-2-hydroxy-2-phenylethylglucosinolate) was chosen as the model glucosinolate owing to the difficulties in determining hydrolysis rates of this type of substrates in traditional UV-assays. The method was afterwards validated with glucobarbarin ((2S)-2-hydroxy-2-phenylethylglucosinolate) and progoitrin ((2R)-2-hydroxybut-3-enylglucosinolate). Aromatic glucosinolates without a 2-hydroxy group in their side chains, such as glucotropaeolin (benzylglucosinolate) and gluconasturtiin (phenethylglucosinolate) were also tested. Formation of the glucosinolate hydrolysis products was monitored simultaneously at 206 nm and 230 nm. This allowed estimation of the extinction coefficient of the OZT derived from glucosibarin, which was found to be 18,000M−1 cm−1 and 12,000M−1 cm−1 at 206 nm and 230 nm, respectively. The developed method has limit of detection of 0.04mM and 0.06mM and limit of quantification of 0.2mM and 0.3mM for the glucosibarin derived OZT and nitrile, respectively. Linearity of the glucosinolate concentration was examined at six concentration levels from 2.5mMto 100mMand at 206 nm a straight line (R2 = 0.9996) was obtained. The number of theoretical plates (N) at the optimal system conditions was 245,000 for the intact glucosibarin, 264,000 for the OZT and 252,000 for the nitrile

Effect of ascorbic acid and glutathione on the production of nitriles by myrosinase

Biofumigation is based on the use of glucosinolate-containing plants for the control of soil-borne pest and diseases. Upon tissue damage, glucosinolates are hydrolyzed by endogenous enzymes (myrosinase) and a range of biologically active compounds are formed. Isothiocyanates (ITCs) are the quantitatively dominating products formed at neutral pH. Most of these compounds are volatile and only sparingly soluble in aqueous systems, and depending on the R-group structure and the presence of nucleophiles, further transformation of ITCs occurs. At lower pH and in the presence of certain molecules able to deliver two redox equivalents, the proportion of nitriles increases at the expense of ITC. The effect of ascorbic acid and glutathione on the production of nitriles at pH 5 was investigated by micellar electrokinetic capillary chromatography (MECC). The presence of 0.25 µmol ascorbic acid increased the production of nitriles although at higher concentrations the proportion of nitriles decreased. Increasing amounts of GSH favored the production of nitriles (40% of the total degradation products were nitriles in the presence of 2 µmol GSH). The oxidation of GSH gives the redox equivalents needed for the liberation of the sulfur from the unstable intermediate of the glucosinolate hydrolysis leading to the formation of the nitrile

Glucosinolate hydrolysis products for weed control

Glucosinolates are allelochemicals present in all Brassica plants. Upon hydrolysis by endogenous enzymes they produce a series of biologically active compounds, such as isothiocyanates and their deriva-tives among others. These compounds have marked fungicidal, nematocidal and herbicidal effects and therefore their use as biodegradable natural products for crop protection has attracted much attention in the last years. A number of these compounds, either individually or in combination, were tested against Sinapis alba and Lollium perenne in Petri dishes bio-assays. C50 values as low as 0.7 and 0.2 mM were obtained. This may open the possibility for using glucosinolate hydrolysis products as herbicides

Glucosinolate types and concentrations in seedlings of different Brassica species used for food

Brassicaceous food crops contain in their tissues different quantities of the glucoside allelochemicals known as glucosinolates (Bellostas et al., 2004; Sørensen, 1990). These compounds are alkyl-N-hydroximine sulphate esters with a β-D-thioglucopyranoside group attached to the hydroximine carbon in Z-configuration relative to the sulphate group (Ettlinger and Kjær, 1968; Kjær, 1960). Glucosinolates are biosynthetically derived from amino acids (Hill et al., 2003) and they occur in all plants of the order Capparales and in some other plants (Bjerg and Sørensen, 1987; Kjær, 1960; Rodman, 1978). These compounds co-occur with myrosinase isoenzymes (Thioglucosidase; EC 3.2.1.147), which catalyze the hydrolysis of the β-D-thioglucopyranoside bond releasing an aglucone that forms a variety of biologically active products with structures defined by the type of glucosinolate and the reaction conditions (Bjergegaard et al., 1994; Buskov et al., 2000a; Buskov et al., 2000b; Buskov et al., 2000c; Palmieri et al., 1998). These breakdown products are chemically very reactive and they have for a long time been related to the pungent odour and flavour typical for Brassicaceous plants. These compounds show a various range of biological activities that goes from antinutritional (Bjerg et al., 1989; Hansen et al., 1997), to fungicidal, nematicidal and bactericidal (Brown and Morra, 1997; Buskov et al., 2002; Kirkegaard and Sarwar, 1998). In the last years, interest in their anticarcinogenic properties has increased and research has mainly focused on the effect of the isothiocyanates present in sprouts of certain Brassica food crops, especially broccoli (Zhang et al., 1992; Zhang, 2004). These isothiocyanates have been related to the increase in the activity of the Phase 2 enzymes, which is related to detoxification of xenobiotica and protection against cancer (Bonnesen et al., 1999). They have also been related to an increased antioxidative metabolism by induction of the scavenging of oxygen radicals, which may contribute to a decreased risk of coronary diseases (Wu et al., 2004). Given the biological effects of Brassica crops used for food, it was considered of interest to investigate the glucosinolate profile during early development of the Brassica plant in order to be able to determine the stages at which the desired biologically active compounds are present. It would also allow determining the presence of other potentially active compounds as well as to allow better understanding the metabolic changes occurring during germination and early growth. Five B. oleracea used for food (white cabbage, red cabbage, broccoli, cauliflower and savoy cabbage) and two B. napus (a low and a high-glucosinolate rapeseeds) were used in the present experiments. The content of glucosinolates in seeds, seedlings and the individual parts of grown plants was followed from germination to one-month growth. Samples were taken at one, two, three, four, seven, 14, 21 and 28 days and plants were separated into cotyledons, leaves, epicotyle and roots. Glucosinolates were isolated and their concentration determined by HPLC following standard procedures developed at our laboratory

Baseline 2000 Background Report: The Status of Integrated Coastal Management as an International Practice (Second Iteration)

The Coastal Zone Canada 2000 Conference occurred in Saint John, New Brunswick from September 17 to 22. All of the 600 registrants received a canvas packet that included four separately bound publications: the final conference program, the tradeshow program, Canadian Synopsis (a table of ICM efforts in Canada), and Baseline 2000. The Coastal Zone Canada Association organized and administered the Conference as they had done for three previous Canadian based international CZ conferences (Victoria, British Columbia in 1998, Rimouski, Québec in 1996, and Halifax, Nova Scotia in 1994). Two of the fundamental objectives of the Coastal Zone Canada Association (CZCA) and its Coastal Zone Canada (CZC) Conference Series, are that its meetings must build both on previous events and on multi-sectoral, multi-disciplinary, international gatherings that discuss and debate key challenges to integrated coastal management (ICM). The goal is to derive new guidance, tools and motivations to advance its practice. While the CZCA’s first three international conferences have, to a degree, achieved these two objectives and generated products of some value (i.e. CZC ’94 Call for Action; CZC ’96 Rimouski Declarations; CZC \u2798 Tool Kit), progress has been constrained by the absence of a baseline that is clear, coherent, well researched, and based on consensus. The CZCA decided that a baseline paper should be prepared for CZC 2000 to provide an assessment of the existing ‘state of the art’ in the practice of ICM on an international basis. State-of the-art in this context means both the current stage of development of a practice as well as newest or best practices . If this information could be obtained by the project, then a baseline could be established in the year 2000 to enable periodic assessment (such as at biennial conferences) of a number of indicators to determine ICM’s growth, development, success in overcoming challenges, and achievements. Furthermore, the information obtained from Baseline 2000 and the information obtained from the periodic assessments of changes in the ICM’s baseline should improve the efficiency and effectiveness of the practice by providing the abilities to learn from experience, particularly what works, what doesn’t work, and why. Most of Baseline 2000 (or B2K) is directed at the current stage (or status) of development of ICM as an international practice. Newest or best practices can be derived from three of the organizing frameworks proposed by B2K: 1) issues and model approaches and techniques (Section 4), common challenges to ICM (Section 7), and the index of ICM topics (Section 10)

In vitro screening of the effect of three glucosinolate derived nitriles on soil-borne fungi

Glucosinolates are allelochemicals present in all plants of the order Capparales that are hydrolysed by endogenous enzymes (myrosinases) forming a variety of compounds with biological activity. ‘Biofumigation’ is the term used to describe the effect of these compounds on soil-borne pathogens and it has normally been attributed to isothiocyanates. At acidic pH and in the presence of redox co-factors such as glutathione, glucosinolate hydrolysis yields also nitriles, which are more hydrophilic and stable than isothiocyanates. Three nitriles (allyl-, benzyl- and phenethyl cyanide) were tested against soil borne fungi of economic importance: Aphanomyces euteiches var. pisi, Gaeumannomyces graminis var. tritici and Verticillium dahliae. The nitriles were initially tested at 1 mM and four additional concentrations were further tested in order to determine LD50. At 1 mM, allyl cyanide showed in all cases less than 10% inhibition and it did not inhibit fungi growth at higher concentrations. LD50 of benzyl cyanide was 2.5 mM for Verticillium and Aphanomyces, whereas it was as low as 0.5 mM for Gaeumannomyces. LD50 of phenyl ethyl cyanide was 2.5 mM for Verticillium, 1.4 mM Gaeumannomyces and 1.25 mM Aphanomyces. Although nitriles are generally less toxic than ITCs, their role in biofumigation should not be disregarded

The Dynamics of House Prices - International Evidence

‘New’ long run data regarding Norway, the Netherlands, United Kingdom and USA has been collected and will be graphically, statistically and econometrically compiled and analyzed to prove that real house prices in the long run are constant and mean reverting. Co-integration of nominal house prices show that the long run fundamentals of real estate are income, rent and construction costs consistently across markets. In contrast an ECM analysis underscores that house prices in the short run are momentum drive, and house prices can deviate substantially from equilibrium in the SR. This fact is supported by theoretical insight about behaviourism and herding behaviour. Analyzing the empirical evidence of dynamics of house prices and relating it to history shows that the housing markets have become synchronized for the first time in history. The latest boom in house prices have been strong and could have created an international housing bubble. The main reason for the creation of bubbles has been identified as liberalization of credit. Turning points are highly correlated with credit constraints being imposed, but other shocks can initiate the process too: interest rate increases or public regulation. All it takes is a change in sentiment, which will make the short run house prices correct towards equilibrium.house price; real estate; bubble; mean reversion; recession; synchronized; financial crisis; credit crisis;

Metastatic pattern in adenocarcinoma of the lung An autopsy study from a cohort of 137 consecutive patients with complete resection

A cohort of 137 patients with completely resected stage I or II adenocarcinoma of the lung was observed from the time of operation; the metastatic pattern determined at autopsy is described in relation to clinical, histologic, and laboratory variables. The pretreatment variables evaluated were performance status, age, gender, lactate dehydrogenase, stage, degree of differentiation, and histologic subtype of adenocarcinoma of the lung. Patients who survived longer than 30 days after operation were eligible for analysis, and 35 autopsies were performed in this patient group (autopsy rate: 39.8%). The most common intrathoracic metastatic sites were mediastinal lymph nodes (43%), lung (31%), pleura (20%), pericardium (9%), and heart (6%). The most common extrathoracic sites were liver (37%), brain (33%), bones (21%), adrenals (17%), and kidneys (17%). Patients undergoing resection for stage I disease had significantly fewer intrathoracic metastases than patients with stage II disease (p = 0.01). Patients who survived less than 1 year had significantly more extrathoracic metastases than patients who survived for a longer period (p = 0.01). Patients with highly differentiated tumors had fewer extrathoracic metastases than patients with less differentiated tumors. No other statistically significant differences were observed. Overall, patients with stage I adenocarcinoma of the lung had better local control of the disease at autopsy than those with stage 11 disease, but distant metastases are a large problem despite the favorable prognosis of this patient group. The extrathoracic metastatic potential was greatest for less differentiated tumors. An active adjuvant systemic therapy after resection is needed in selected patients with poorly differentiated adenocarcinomas of the lung, even in those with stage I disease

Quantum noise limited interferometric measurement of atomic noise: towards spin squeezing on the Cs clock transition

We investigate theoretically and experimentally a nondestructive interferometric measurement of the state population of an ensemble of laser cooled and trapped atoms. This study is a step towards generation of (pseudo-) spin squeezing of cold atoms targeted at the improvement of the Caesium clock performance beyond the limit set by the quantum projection noise of atoms. We calculate the phase shift and the quantum noise of a near resonant optical probe pulse propagating through a cloud of cold 133Cs atoms. We analyze the figure of merit for a quantum non-demolition (QND) measurement of the collective pseudo-spin and show that it can be expressed simply as a product of the ensemble optical density and the pulse integrated rate of the spontaneous emission caused by the off-resonant probe light. Based on this, we propose a protocol for the sequence of operations required to generate and utilize spin squeezing for the improved atomic clock performance via a QND measurement on the probe light. In the experimental part we demonstrate that the interferometric measurement of the atomic population can reach the sensitivity of the order of N_at^1/2 in a cloud of N_at cold atoms, which is an important benchmark towards the experimental realisation of the theoretically analyzed protocol.Comment: 12 pages and 9 figures, accepted to Physical Review

Editorial

This special issue of Chemical Engineering Research and Design features selected papers from the international conference on Distillation & Absorption held in Friedrichshafenon 14–17 September 2014. The conference was organised byDECHEMA and ProcessNet’s Subject Division on Fluid Separations on behalf of the European Federation of Chemical Engineering (EFCE) and its Working Party on Fluid Separations.The first conference in this series took place in Brighton in the UK in 1960. The conferences are now held every 4 years, last in Eindhoven in 2010, and showcase the newest findings and research in distillation and absorption technology