The effect of supplementation of a white clover or perennial ryegrass diet with grape seed extract on indole and skatole metabolism and the sensory characteristics of lamb

Condensed tannin in the form of a grape seed extract (GSE) was dosed to weaned wether lambs fed white clover (WC) or perennial ryegrass (PRG) over a 9‐week period to determine whether the ‘pastoral’ flavour and odour of meat could be altered. The concentrations of the pastoral flavour compounds indole and skatole were determined in the rumen fluid, blood plasma and intermuscular fat. The odour and flavour of fat and meat from the slaughtered lambs was assessed by a trained panel. The rumen fluid and blood plasma concentrations of indole and skatole were higher in those lambs fed WC compared to PRG (P < 0.05) and the overall meat flavour intensity was greater when feeding WC (P < 0.01). The observed concentration of indole and skatole in the fat between WC and PRG feeding treatments was not statistically different. Power analysis indicated that increasing the number of lambs per treatment group from 20 to 65 would result in a higher fat skatole concentration (P < 0.05) being detected in lambs fed WC compared to PRG. Dosing with GSE gave a small reduction in skatole concentration in the rumen fluid and reduced plasma concentration of indole and skatole (P < 0.001). Odour and flavour scores of the fat and meat samples were not particularly high however, dosing with GSE lowered the overall and sweet odour and the sheepy, camphor, faecal and barnyard flavour (P < 0.05). Although the plasma concentration of indole and skatole suggests that GSE reduced indole and skatole formation, the intermittent supply of the GSE to the rumen environment was not sufficient to reduce their concentration in the fat. Hence, the small difference in the scores for pastoral odour and flavour attributes associated with GSE treatment may arise from other unknown factors. From a primary investigation, there was no difference in the concentration of indole and skatole in fat samples collected from carcasses before and after chilling. Further investigations into meat pastoral flavour are warranted through feeding condensed tannin‐containing forages. Copyright © 2007 Society of Chemical Industry     

多功能针式过滤器-高效液相色谱法快速检测豆芽中的吲哚乙酸

基于Qu ECh ERS原理,该研究建立了多功能针式过滤器-高效液相色谱法快速检测豆芽中的吲哚乙酸。样品经1%乙酸乙腈和1 g氯化钠、2 g硫酸镁提取,多功能针式过滤器快速净化后,采用ZORBAX SB-C₁₈(4.6×250 mm,5μm)为色谱柱,以乙腈和0.1%甲酸溶液为流动相,梯度洗脱,流速1.0 mL/min,柱温:35℃,检测波长:267 nm,对提取净化液中吲哚乙酸含量进行高效液相色谱检测。吲哚乙酸在豆芽基质中基质效应较小,故使用纯溶剂配制的标准曲线进行定量。结果显示,吲哚乙酸在0.05~10.0 mg/L范围内线性关系良好,相关系数为0.9999。在0.1~5.0mg/kg的加标水平范围内得到的平均回收率为80.6%~105.3%,相对标准偏差(RSD)是2.3%~4.6%。检出限为0.03μg/kg,定量下限为0.1μg/kg。该方法操作简单、准确可靠,适用于豆芽中吲哚乙酸残留量的快速检测。     

Engineered RebH Halogenase Variants Demonstrating a Specificity Switch from Tryptophan towards Novel Indole Compounds

Activating industrially important aromatic hydrocarbons by installing halogen atoms is extremely important in organic synthesis and often improves the pharmacological properties of drug molecules. To this end, tryptophan halogenase enzymes are potentially valuable tools for regioselective halogenation of arenes, including various industrially important indole derivatives and similar scaffolds. Although endogenous enzymes show reasonable substrate scope towards indole compounds, their efficacy can often be improved by engineering. Using a structure-guided semi-rational mutagenesis approach, we have developed two RebH variants with expanded biocatalytic repertoires that can efficiently halogenate several novel indole substrates and produce important pharmaceutical intermediates. Interestingly, the engineered enzymes are completely inactive towards their natural substrate tryptophan in spite of their high tolerance to various functional groups in the indole ring. Computational modelling and molecular dynamics simulations provide mechanistic insights into the role of gatekeeper residues in the substrate binding site and the dramatic switch in substrate specificity when these are mutated.     

微波辅助纳米TiO2紫外光催化降解吲哚研究

难降解有机污染物的处理是目前环保技术研究的一大热点.此类污染物可生化性差,常规的处理技术难以去除,微波与紫外光的协同作用可以大大提高光催化剂的活性.以吲哚为研究对象,研究了微波辅助紫外光催化降解工艺条件及影响因素,研究结果表明,在7种不同的体系中降解吲哚,降解效果依次为:UV相似文献   

浆态体系中吲哚对NiMo/g-Al2O3加氢脱硫性能的影响

以二苯并噻吩为模型化合物,在浆态反应釜中考察了吲哚对NiMo/g-Al2O3催化剂加氢脱硫性能的影响. 用微库仑仪、气相色谱-质谱联用仪对反应中的样品进行含硫量和组分分析,并对反应前后的催化剂进行性能表征. 结果表明,加入吲哚在一定程度上提高了活化阶段的反应速率,但显著降低了活化后的反应速率,导致加氢脱硫总体活性显著下降,脱硫率由70%降到约58%. 反应前后催化剂表面形貌和活性相晶体结构均无明显变化,但比表面积有所增加. 加入吲哚导致催化剂孔径减小约12%,积碳量增加约50%. 组分分析表明,加入吲哚后反应中生成的环己基苯显著减少,加氢路径受到抑制.     

CH3COOH/ZnCl2低共熔溶剂脱除模拟油中氮化物

通过加热乙酸（CH3COOH）和氯化锌（ZnCl2）的混合物制备了CH3COOH-ZnCl2低共熔溶剂,采用傅里叶变换红外光谱、核磁共振氢谱对其进行了表征,并以喹啉及吲哚模拟油为原料考察其脱氮性能。结果表明：在CH3COOH和ZnCl2摩尔比为 10:1、萃取时间为25 min、油剂质量比为5:1、萃取温度为30 ℃的条件下,喹啉和吲哚的脱除率分别为98.57%和93.73%,且该低共熔溶剂在回收3次之后,喹啉模拟油和吲哚模拟油的脱氮率仍分别能达到70%以上。此外,对该萃取脱氮体系的脱氮机理进行了探讨。     

吲哚及其衍生物合成的研究进展

吲哚及其衍生物是重要的精细化工原料和化工产品,评述了吲哚及其衍生物的化学合成方法.     

Intramolecular Photochemical Cross‐Coupling Reactions of 3‐Acyl‐2‐haloindoles and 2‐Chloropyrrole‐3‐carbaldehydes with Substituted Benzenes

Highly efficient syntheses of indolo[2,1‐a]isoquinolines, indolo[2,1‐a][2]benzazepines, pyrrolo[2,1‐a]isoquinolines and pyrrolo[1,2‐a]benzazepines in excellent yields have been achieved by the intramolecular photochemical cross‐coupling reactions of 3‐acyl‐2‐halo‐N‐(ω‐arylalkyl)indoles and 2‐chloro‐N‐(ω‐arylalkyl)pyrrole‐3‐carbaldehydes in acetone. A new heterocyclic ring system – pyrrolo[1,2‐d][1,4]benzoxazepine – has also been constructed for the first time in this work by the photocyclization of 2‐chloro‐N‐(2‐phenoxyethyl)pyrrole‐3‐carbaldehyde.     

Extractive denitrogenization of liquid model fuel using polyethylene glycol methyl ether 350

In the present study, we studied the effectiveness of the water-soluble polymer polyethylene glycol methyl ether 350 (PEG ME-350) on the extraction of nitrogen-containing heterocyclic compounds—quinoline and indole—from n-hexane. The dependences of the quantitative characteristics of the extraction of N-compounds on the contact time of the phases, the content of PEG ME-350 in the n-hexane–water system, the initial concentration of nitrogen-containing heterocyclic compounds in the organic phase, and the volumetric ratio of the phases were obtained. It has been established that PEG ME-350 is an effective extractant in the process of stepwise extraction of quinoline and indole, and the mechanisms of their extraction have also been proposed and proven. The results can be further used in the purification of light hydrocarbon fractions from nitrogen-containing heterocyclic compounds.