基于非靶向代谢组技术研究不同发酵温度酱油中代谢产物差异

目的 基于非靶向代谢组学研究不同发酵温度(25、30、35、40℃)酱油中代谢产物差异。方法 采用超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)检测不同发酵温度的酱油样品的代谢物,通过主成分分析(principal component analysis,PCA)、正交偏最小二乘判别分析法(orthogonal partial least square-discriminant analysis,OPLS-DA)等统计学分析,筛选不同温度发酵酱油的差异代谢物。结果 4种不同发酵温度酱油样品共鉴定出14类266个代谢物。其中,25℃下发酵酱油中氨基酸和有机酸类化合物的含量最高,而35℃发酵酱油的中氨基酸、脂肪酸类和生物碱化合物的相对含量最高。通过OPLS-DA分析研究,鉴定出了37种显著差异代谢物质(变量投影重要性>1),包括有氨基酸9种,糖类和有机酸各5种,生物碱和脂肪酸各4种,芳香类化合物3种,香豆素类、胺类和酚类各2种,黄酮类1种。结论 该研究明...     

Influence of the hydrophilic moiety of anionic and nonionic surfactants on their aerobic biodegradation in seawater

The extent and kinetics of the primary biodegradation have been characterized for the most commonly-used surfactants, employing four homologues with the same alkyl chain: dodecyl ethoxy sulfate (C₁₂AES), sodium dodecyl sulfate (SDS), dodecyl alcohol ethoxylate (C₁₂AEO) and dodecyl benzenesulfonate (C₁₂LAS). A brief acclimatization period has been required to enable an effective degradation of C₁₂LAS and C₁₂AES to take place, but this lag phase has not been detected for SDS and C₁₂AEO. Primary biodegradation percentages at the end of these experiments were higher than 99%, showing a fast degradation rate in all cases (average half-life lower than 2 days). The secondary biodegradation of C₁₂LAS was also monitored. C₁₂LAS external isomers, which are predominant, are preferentially degraded by successive β-oxidations, generating significant amounts of external even isomers of sulfophenylcarboxylic acid (SPC) (mainly 2,3ΦC_4,6SPCs). In ontrast, internal isomers are converted into internal odd isomers of SPC (mostly 4,5ΦC_5,7SPCs) by ω-oxidation followed by α-oxidation and/or β-oxidations.     

Influence of pH-dependent sorption and transformation on simulated pesticide leaching

The leaching of a substance is influenced by its physico-chemical characteristics as well as environmental conditions. In spatially distributed modelling the influence of soil properties on the half-life and the sorption constant of the substance might become important and can be taken into account. The GeoPEARL model includes options to account for sorption and transformation being dependent on soil characteristics.Using some of these options in calculations for a herbicide with both sorption and transformation dependent on the pH of the soil, the calculated leaching from an application in spring appeared to be higher than anticipated from calculations according to the so-called paired parameter approach, in which the leaching is assessed for pairs of sorption and transformation parameters at regular pH intervals. The reason for the higher leaching was that the most critical leaching conditions were not covered by the selected pH values. A ‘paired approach’ might however be useful as a first tier assessment of the leaching potential. The maximum leaching is expected with the highest DegT₅₀/K_om ratio, which might be obtained from plotting this ratio against the characteristic soil property.The leaching potential of the parent was more important for the leaching of the metabolite than the leaching potential of the metabolite itself. This should be accounted for in the evaluation procedure.     

Synthesis of Dihydrodiol Metabolites of Naphtho[8,1,2- GHI ]Chrysene and Dibenzo[ C,MNO ]Chrysene

Syntheses of naphtho[8,1,2- ghi ]chrysene (naphtho[1,2- e ]pyrene, N[ e ]P) 1 , dibenzo[ c,mno ]chrysene (naphtho[1,2- a ]pyrene, N[ a ]P) 2 and their dihydrodiol metabolites are described. The hydrocarbons N[ e ]P 1 and N[ a ]P 2 and their fjord region dihydrodiols 12 and 19 were synthesized using a Suzuki cross-coupling reaction followed by the appropriate manipulation of the functional groups. The K-region cis dihydrodiols of N[ e ]P-4,5-diol 20 , N[ a ]P-4,5-diol 23 , N[ a ]P-7,8-diol 24 were obtained by OsO 4 oxidation. The cis diols thus obtained were first converted to the corresponding quinones with pyridinium chlorochromate and, finally, to the desired trans dihydrodiols 22 , 27 , and 28 by NaBH 4 reduction. The mixture of trans N[ a ]P-4,5- and 7,8-dihydrodiols was separated by high-performance liquid chromatography.     

Proanthocyanidin metabolites associated with dietary fibre from in vitro colonic fermentation and proanthocyanidin metabolites in human plasma

Proanthocyanidins (PAs) or condensed tannins, a major group of dietary polyphenols, are oligomers and polymers of flavan‐3‐ol and flavan‐3, 4‐diols widely distributed in plant foods. Most literature data on PAs' metabolic fate deal with PAs that can be extracted from the food matrix by aqueous‐organic solvents ( extractable proanthocyanidins). However, there are no data on colonic fermentation of non‐extractable proanthocyanidins (NEPAs), which arrive almost intact to the colon, mostly associated to dietary fibre (DF). The aim of the present work was to examine colonic fermentation of NEPAs associated with DF, using a model of in vitro small intestine digestion and colonic fermentation. Two NEPA‐rich materials obtained from carob pod (Ceratonia siliqua L. proanthocyanidin) and red grapes (grape antioxidant dietary fibre) were used as test samples. The colonic fermentation of these two products released hydroxyphenylacetic acid, hydroxyphenylvaleric acid and two isomers of hydroxyphenylpropionic acid, detected by HPLC‐ESI‐MS/MS. Differences between the two products indicate that DF may enhance the yield of metabolites. In addition, the main NEPA metabolite in human plasma was 3,4‐dihydroxyphenyl acetic acid. The presence in human plasma of the same metabolites as were detected after in vitro colonic fermentation of NEPAs suggests that dietary NEPAs would undergo colonic fermentation releasing absorbable metabolites with potential healthy effects.     

利用生物废料的固体发酵生产增值产品

生物废料中含有多种高价值的可再利用物质,例如可溶性糖和纤维等。在固体发酵中,这些废料可以作为支持底物参与反应,生产工业相关代谢产物,从而创造较大的经济价值,同时降低废料对环境的污染。本文综述了通过固体发酵技术,再生利用生物废料生产香料、有机物、聚合物、酶和抗生素等增值产品的研究进展,从而为该项技术的生产应用提供理论依据。     

生物试样中安定、利眠宁、舒宁药物及其代谢降解物的GC/MS分析

本文描述了生物试样中安定、利眠宁、舒宁药物及其代谢降解产物,二苯甲酮类、N-去甲安定、脱氧利眠宁、喹唑啉类衍生物的GC/MS分析法,讨论了热解和水解过程。安定、利眠宁、舒宁的检测灵敏度可达15ng。     

超高效液相色谱-串联质谱法测定动物源性食品中硝基咪唑类药物及其代谢物的残留量的研究

目的建立超高效液相色谱-串联质谱法测定动物源性食品中硝基咪唑类药物及其代谢物的分析方法。方法试样经三氯乙酸溶液提取, MCX固相萃取小柱净化, 5%的甲醇水(V/V)溶液复溶。电喷雾正离子模式电离,多反应监测模式检测,基质匹配内标法定量。结果硝基咪唑及其代谢物在0.25～50 ng/mL范围内线性关系良好,相关系数均大于0.9915,加标回收率为73.5%～120.4%;相对标准偏差在2.4%～13.4%之间,定量限为0.1～0.5μg/kg。结论本方法简便、灵敏,适用于动物源性食品中硝基咪唑类药物及其代谢物残留的定性、定量分析。     

Identification of nobiletin metabolites in mouse urine

Nobiletin, a major component of citrus polymethoxyflavones, has many potential significant health benefits. While the biological activities of nobiletin have been widely reported, its in vitro and in vivo metabolic fate has been rarely studied. To explore the biotransformation mechanism of nobiletin we conducted an investigation into its metabolic profile in mouse urine, by various analytical techniques. Due to sample amount limitations for isolating and characterizing an individual metabolite, two possible nobiletin metabolites were prepared in a similar multi-step organic synthetic route: 3'-hydroxy-5,6,7,8,4'-pentamethoxyflavone (3'-demethylnobiletin) and 4'-hydroxy-5,6,7,8,3'-pentamethoxyflavone (4'-demethylnobiletin). Normal phase (silica gel) and C(18) reverse phase chromatography, as well as liquid chromatography-mass spectrometry-mass spectrometry, were employed in the separation of 3'-demethylnobiletin and 4'-demethylnobiletin, however, without success due to the structural similarities of these mono-demethylated nobiletins. Using a chiral packed column eluted under supercritical fluid chromatography (SFC) conditions, a clear separation was achieved. Thus, by comparing the SFC profiles of metabolite mixtures with the synthesized standard compounds, the major nobiletin metabolite of mouse urine is identified as 4'-demethylnobiletin, whereas 3'-demethylnobiletin is a minor metabolite. In this study, the concentration of 4'-demethylnobiletin in mouse urine is 28.9 microg/mL.