Glucosinolate Amperometric Bienzyme Biosensor Based on Carbon Nanotubes‐Gold Nanoparticles Composite Electrodes

A novel electrochemical biosensor design for glucosinolate determination involving bulk‐incorporation of the enzymes glucose oxidase and myrosinase into a colloidal gold ‐ multiwalled carbon nanotubes composite electrode using Teflon as binder is reported. Myrosinase catalyzes the hydrolysis of glucosinolate forming glucose, which is enzymatically oxidized. The generated hydrogen peroxide was electrochemically detected without mediator at the nanostructured composite electrode at E=+0.5 V vs. Ag/AgCl. Under the optimized conditions, the bienzyme MYR/GOx‐Au_coll‐MWCNT‐Teflon exhibited improved analytical characteristics for the glucosinolate sinigrin with respect to a biosensor constructed without gold nanoparticles, i.e. a MYR/GOx‐MWCNT‐Teflon electrode, as well as with respect to other glucosinolate biosensor designs reported in the literature. The biosensor exhibits good repeatability of the amperometric measurements and good interassay reproducibility. Furthermore, the biosensor exhibited a high selectivity with respect to various potential interferents. The usefulness of the biosensor was evaluated by the determination of glucosinolate in Brussel sprout seeds.     

近红外光谱技术在检测转基因油菜籽中芥酸和硫甙上的应用研究

随着转基因食品的迅速发展,人们越来越关心其食用安全性。以转基因油菜及其亲本为实验材料,借助于近红外光谱仪对转基因油菜及其亲本中的芥酸和硫甙进行了测定分析：扫描区间为12 000～4 000 cm-1,分辨率为4 cm-1,扫描次数为64次。结果显示近红外检测样品的结果与通用方法结果相近,说明通过扫描光谱加上数学和计算机软件分析,非常准确、方便的测定了转基因油菜中的芥酸和硫甙。结果表明,转基因油菜中的芥酸含量明显高于亲本中的含量,芥酸含量是非转基因亲本1.5～2.0倍;硫甙含量也表现出芥酸相同的规律,转基因油菜中显著高于其相应亲本,是亲本含量的1.3～1.51倍以上。所以,在转基因作物的育种过程中,在改善个别性状的同时,如何保持其他优良性状应当引起重视。     

Bioinformatic analysis of molecular network of glucosinolate biosynthesis

Glucosinolates constitute a major group of secondary metabolites in Arabidopsis, which play an important role in plant interaction with pathogens and insects. Advances in glucosinolate research have defined the biosynthetic pathways. However, cross-talk and interaction between glucosinolate pathway and other molecular pathways are largely unknown. Here three bioinformatics tools were used to explore novel components and pathway connections in glucosinolate network. Although none of the software tools were prefect to predict glucosinolate genes, combination of results generated by all the tools led to successful prediction of all known glucosinolate genes. This approach was used to predict new genes in glucosinolate network. A total of 330 genes were found with high potential to relate to glucosinolate biosynthesis. Among them 64 genes were selected to construct glucosinolate network because their individual connection to at least one known glucosinolate gene was predicted by all the software tools. Microarray data of candidate gene mutants were used for validation of the results. The mutants of nine genes predicted by glucosinolate seed genes all exhibited changes in the expression of glucosinolate genes. Four of the genes have been well-known to functionally interact with glucosinolate biosynthesis. These results indicate that the approach we took provides a powerful way to reveal new players in glucosinolate networks. Creation of an in silico network of glucosinolate biosynthesis will allow the generation of many testable hypotheses and ultimately enable predictive biology.     

An improved procedure for the preparation of β-thiohydroximates for glucosinolate synthesis

A novel and simple method is described for the synthesis of β-thiohydroximates from oximes and 2,3,4,6-tetra-O-acetyl-1-thio-β-d-glucopyranose, which are key intermediates in the synthesis of glucosinolates. The procedure involves the in situ formation of an oximyl chloride from the oxime, using inexpensive bleach, which is then reacted directly under basic conditions with the thioglucopyranose.     

New artificial standards for the HPLC analysis of natural glucosinolates

The separation of new, artificial, non-sulfated glucosinolates and desulfated natural glucosinolates on different apolar (C8, TMS, phenyl) or weakly polar (CN) bonded stationary phases by gradient elution has shown that apolar or weakly polar bonded silica-based adsorbents, in addition to the C8 phase chosen for the standard procedure, can be used with benefit for the analysis of glucosinolate mixtures. The use of new artificial glucosinolates, not present in cruciferae, as internal standards for the standard HPLC method for the determination of the main glucosinolate composition and content of rapeseed is discussed. The main factors influencing the retention and selectivity toward several natural and artificial non-sulfated glucosinolates for different chromatographic systems have been studied, and for additional information the retention data have been analyzed statistically by factor analysis. The first results from this study show that the mechanism of the HPLC retention of glucosinolates is the sum of only two methematically independent physico-chemical phenomena. The first is associated with the hydrophobicity of compounds. A better understanding of the chromatographic behavior of glucosinolates has made it possible to investigate the synthesis of new, artificial standard glucosinolates with the intention of providing an ideal standard for every kind of analysis. It also supplies a tool to enable laboratories to choose the best chromatographic system for a particular selectivity problem.     

Retention of some glucosinolates in anion exchange chromatography. Part I: Qualitative study on a silica-trialkylammonium exchanger

Summary The retention and separation of glucosinolates, as organic anions, were studied on a silica-based strong anion exchanger under isocratic elution conditions. All glucosinolates carry the same functional ionic group (-OSO ₃ ^– ), however they do not have the same retention in anion exchange chromatography. The plots of capacity factors of organic anions versus the reciprocal of eluent ion concentration show good linearity. From the slope and y-intercept data the major retention mechanisms are interpreted as ion exchange and reversed-phase interactions. The effects of nature and concentration of the eluent ion and the influence of organic modifier addition to the aqueous buffered mobile phase are also investigated. Direct and indirect UV detection were used.Our results open the way for the development of new systems for intact glucosinolate analysis which are easier to use than the present ion-pairing chromatographic method.     

A simple O-sulfated thiohydroximate molecule to be the first micromolar range myrosinase inhibitor

New non-hydrolyzable analogues of glucosinolates have been prepared. Myrosinase inhibition was observed with modified aglycon moieties, even bulky phenothiazine analogue 6 gave reasonable inhibition. The simplest structure 8 derived from dimethylaminoethanethiol has shown to be the most potent inhibitor with an IC₅₀ of 3.32 μM.     

油菜叶片中硫甙总量与分量的HPLC测定

硫甙是一类含硫次生代谢产物,广泛存在于芸薹属植物。油菜中常见的硫甙成分有近20种,研究表明,油菜籽硫甙含量降低后,其植株抗性也明显下降,油菜种子、茎、叶的硫甙含量受不同基因型控制[1]。油菜种子中硫甙含量及组分的检测技术已有很多报道[2-6],李培武等[5-7]建立了胶束电动     

Investigation of electron beam irradiation effects on anti-nutritional factors, chemical composition and digestion kinetics of whole cottonseed, soybean and canola seeds

This study was completed to determine effects of electron beam (EB) irradiation at doses of 15, 30 and 45 kGy on anti-nutritional factors, ruminal degradation and in vitro crude protein (CP) digestibility of whole cottonseed (WCS), soybean (SB) and canola seeds (CS). EB-irradiation eliminated completely (P<0.001) phytic acid of WCS, SB and CS at a dose of 30 kGy. EB-irradiation decreased linearly (P<0.001) the total glucosinolate content of CS. Trypsin inhibitor activity of 15, 30 and 45 kGy EB-irradiated SB was decreased by 19, 73 and 88%, respectively. Free gossypol content of WCS was reduced linearly (P<0.001) by irradiation. EB-irradiation increased linearly (P<0.001) CP digestibility of feeds. In conclusion, EB-irradiation was an effective processing method for improving the nutritive value of WCS, SB and CS.