Development of a High-Performance Thin-Layer Chromatography Method for the Quantification of Alkyl Glycerolipids and Alkenyl Glycerolipids from Shark and Chimera Oils and Tissues

Ether lipids are composed of alkyl lipids with an ether bond at the sn-1 position of a glycerol backbone and alkenyl lipids, which possess a vinyl ether bond at the sn-1 position of the glycerol. These ether glycerolipids are present either as polar glycerophospholipids or neutral glycerolipids. Before studying the biological role of molecular species of ether glycerolipids, there is a need to separate and quantify total alkyl and alkenyl glycerolipids from biological samples in order to determine any variation depending on tissue or physiopathological conditions. Here, we detail the development of the first high-performance thin-layer chromatography method for the quantification of total alkyl and alkenyl glycerolipids thanks to the separation of their corresponding alkyl and alkenyl glycerols. This method starts with a reduction of all lipids after extraction, resulting in the reduction of neutral and polar ether glycerolipids into alkyl and alkenyl glycerols, followed by an appropriate purification and, finally, the linearly ascending development of alkyl and alkenyl glycerols on high-performance thin-layer chromatography plates, staining, carbonization and densitometric analysis. Calibration curves were obtained with commercial alkyl and alkenyl glycerol standards, enabling the quantification of alkyl and alkenyl glycerols in samples and thus directly obtaining the quantity of alkyl and alkenyl lipids present in the samples. Interestingly, we found a differential quantity of these lipids in shark liver oil compared to chimera. We quantified alkyl and alkenyl glycerolipids in periprostatic adipose tissues from human prostate cancer and showed the feasibility of this method in other biological matrices (muscle, tumor).     

Production of bactericidal substances by a marine vibrio isolated from cultures of the scallop Argopecten purpuratus

A marine vibrio (strain C33) having inhibitory effects on the growth of the pathogen Vibrio anguillarum-VAR was isolated from seawater used in mass culture of the north-Chilean scallop Argopecten purpuratus. This bacterial isolate demonstrated broad inhibitory activity on several bacterial strains, including some pathogenic vibrios. Ethyl acetate extracts of extracellular products of strain C33 were separated by thin layer chromatography (TLC), and three fractions thus obtained were found to have antimicrobial activity when tested using microplate bioassays. One of the fractions (A2) having marked antimicrobial activity, was further purified using TLC and analyzed by IR spectrophotometry and NMR'H and was characterized on a preliminary basis as an aliphatic hydroxyl ether. This compound demonstrated bacteriostatic activity against the important marine pathogens Vibrio parahaemolyticus and V. splendidus, and as discussed in the paper, may be useful in developing natural strategies for the control of pathogens in mass cultures of Argopecten purpuratus and possibly other molluscs affected by these bacteria.     

海水养殖贝类中多溴联苯醚的浓度特征

[目的]研究乐清湾海水养殖贝类中多溴联苯醚(PBDEs)的浓度特征.[方法]以乐清湾海域为例,研究了3个采样点(青屿、七一塘、八一塘)9个贝类样品,采用气相色谱-质谱-化学离子源检测方法对PBDEs的39种同系物在海水养殖贝类(泥蚶、蛤蜊、蛏子)的含量进行了检测.并对该海域中泥蚶和沉积物中PBDEs含量做定量分析.[结果]泥钳、蛤蜊、蛏子样品中∑PBDEs的含量分别为1 349.3～2288.9、1378.2～2927.9和1 509.8 ～3057.8 ng/kg(干重).贝类中PBDEs的浓度为1.35 ～3.06 ng/g(干重),平均值为2.01ng/g(干重),3个站位总PBDEs的浓度从高到低排列是青屿、七一塘、八一塘.该海域泥蚶和沉积物中PBDEs的含量具有很好的相关性.[结论]与国内外其他海域相比,台州沿海养殖环境沉积物中PBDEs的污染程度较轻.     

八氯二丙醚在不同茶树品种上的残留消解研究

采用气相色谱（GC—ECD）分析方法,研究了八氯二丙醚（S421）在碧香早、槠叶齐、群体品种等3种不同茶树上的消解动态和最终残留。茶叶样品用水-丙酮-正己烷（2：2：3．V／V）提取,离心后合并提取液在40℃水浴中吹至近干,加入1mL正己烷,浓硫酸磺化后取上清液供GC—ECD检测,外标法定量。结果表明,S421在碧香早、槠叶齐、群体品种上的丰衰期分别为5．18d,4．44d和3．83d。在茶叶上施用S4216000倍液3次．距末次施药后30d采样测定春秋两季茶叶中S421的残留量低于欧盟制订的S421在茶叶中的MRL值0．01mg·kg^-1。茶叶品种、生长期、采摘期和气温可能影响S421在茶叶上的消解。     

八氯二丙醚的杀虫活性研究

观察八氯二丙醚对卫生害虫的杀虫活性。以八氯二丙醚为有效成分制成喷射剂和蚊香,在实验室内观察这2种剂型对蚊蝇和蟑螂的杀灭效果,同时对增效醚和增效胺以相同的方法进行比较。对八氯二丙醚以乙醇制成喷射剂,浓度在0.5%～1.5%时,对淡色库蚊的KT50在15.70～5.28min,24h死亡率在34.8%～73.2%;浓度在1.0%～1.5%时,对家蝇的KT50在15.75～11.63min,24h死亡率在10.7%～22.0%;浓度在1.5%时,对德国小蠊的KT50在18.30min,72h死亡率在15.0%;而增效醚和增效胺几乎无杀虫活性。以八氯二丙醚制成盘式蚊香,含量在0.5%～1.0%时,对淡色库蚊的KT50在6.9～10.3min,24h死亡率在76.0%～100%;而增效醚和增效胺无杀虫活性。表明八氯二丙醚对蚊蝇和蟑螂具有一定的杀虫活性。     

对氯苯乙酮肟醚衍生物的合成及生物活性

为寻找高活性的新农药化合物,通过2-取代氨基-1-对氯苯乙酮-1-肟与卤代烃反应,设计并合成了35个对氯苯乙酮肟醚衍生物,其结构均经核磁共振氢谱和元素分析确证。初步的生物活性测定结果表明,该类化合物具有一定的杀虫、抑菌及除草活性,其中 C9、C12 在500 mg/L时对蚜虫Aphis craccivaora的致死率达到100%; C10、C12、C15和C23 在1 000 mg/L时对朱砂叶螨Tetranychus cinabarinus的致死率达到100%; C29、C30和C31 在500 mg/L时对黄瓜白粉病菌Sphaerotheca fuligineas的抑制率达到95%以上; C29、C30、C33和C35 在100 mg/L时对马唐Digitaria sanguinalis的抑制率达到90%以上。     

甲基叔丁基醚胁迫对水稻幼苗生长和抗氧化酶类活性的影响

通过营养液培养试验,研究了外源甲基叔丁基醚(MTBE)污染胁迫对水稻幼苗生长及抗氧化酶类活性的影响。结果表明:在0~500 mg/L范围内,水稻幼苗未产生明显的毒害作用。MTBE胁迫浓度低于5 mg/L时,幼苗生长并不受影响。在高浓度下(50 mg/L和500 mg/L),水稻幼苗生长受到不同程度的抑制。与对照相比株高降低59.1%,根鲜重减少29.2%,茎叶鲜重减少20.6%,叶绿素含量下降29.4%,叶绿素a和叶绿素b含量分别降低22.0%和55.7%,叶绿素a/b值由对照的2.98增加到5.37,与对照相比达到极显著水平(P<0.01)。MTBE胁迫影响水稻幼苗抗氧化酶的活性,MTBE浓度低于5 mg/L时,水稻幼苗SOD活性比对照降低,脂质过氧化物MDA也相应降低。MTBE处理浓度提高到500 mg/L时,SOD活性比对照提高27.4%。在50 mg/L MTBE浓度下,MDA含量累积出现峰值,继续增大胁迫浓度,MDA含量逐渐降低。叶片SOD和POD活性在MTBE浓度低于5 mg/L时,没有明显变化,更高浓度的MTBE处理则诱导酶活性升高,表明氧化胁迫程度增加。但当MTBE浓度达到500 mg/L时,由于过多的H2O2或MTBE积累引起CAT和POD酶活性下降。综合生物量变化及抗氧化酶的响应结果,认为水稻幼苗具有一定的抵御MTBE伤害的应答防御系统。     

Hydration Mechanism of Cellulose Ether Modified Cement Pastes Under Rapid Water Loss

With foamed concrete as the absorbing substrate, under rapid water loss, the hydration mechanism of cellulose ether modified thin layer cement pastes was studied. The cement pastes were divided into three layers from surface to interface. Each layer cement paste of 6 h, 12 h, 1 d and 3 d ages was analyzed by using water loss speed, moisture content, XRD, FTIR and TG DSC DTG. The results show that cement pastes of different layers quickly lose water when hydration time is less than 6 hours and characteristic diffraction peaks of Ca(OH)2 are detected only in the second and third layer. The water loss speed significantly decreases when hydration time is more than 12 h and characteristic diffraction peaks of Ca(OH)2 are detected in every layer. The content of Ca(OH)2 increases continuously from the first layer cement paste to the third layer cement paste and aggregation state of ［SiO4］4- in C S H gel changes. The intensity of diffraction and vibration peaks of Ca(OH)2 within cement pastes increases as hydration time prolongs.     

Synthesis and α-glucosidase inhibitory mechanisms of bis(2,3-dibromo-4,5-dihydroxybenzyl) ether, a potential marine bromophenol α-glucosidase inhibitor

Bis(2,3-dibromo-4,5-dihydroxybenzyl) ether (BDDE), derived from the marine algae, is a potential α-glucosidase inhibitor for type 2 diabetes treatment. In the present study, a synthetic route was established as a valid approach to obtain BDDE. Fluorescence spectra, circular dichroism spectra and molecular docking methods were employed to elucidate the inhibitory mechanisms of BDDE against α-glucosidase. The results showed that BDDE could be prepared effectively and efficiently with the established synthetic methods. Synthetic BDDE bound with α-glucosidase and induced minor conformational changes of the enzyme. The docking results indicated the interaction between BDDE and α-glucosidase was driven by both hydrophobic forces and hydrogen bonds. The docked BDDE molecule was completely buried in the α-glucosidase binding pocket with part of the molecule reaching the catalytic center and overlapping with the position of glucose, and the rest of the molecule extending towards protein surface. This study provides useful information for the understanding of the BDDE-α-glucosidase interaction and for the development of novel α-glucosidase inhibitors.