N‐Methyl‐Substituted Fluorescent DAG–Indololactone Isomers Exhibit Dramatic Differences in Membrane Interactions and Biological Activity

N‐methyl‐substituted diacylglycerol–indololactones (DAG–indololactones) are newly synthesized effectors of protein kinase C (PKC) isoforms and exhibit substantial selectivity between RasGRP3 and PKCα. We present a comprehensive analysis of membrane interactions and biological activities of several DAG–indololactones. Translocation and binding activity assays underline significant variations between the PKC translocation characteristics affected by the ligands as compared to their binding activities. In parallel, the fluorescent properties of the ligands were employed for analysis of their membrane association profiles. Specifically, we found that a slight change in the linkage to the indole ring resulted in significant differences in membrane binding and association of the DAG–indololactones with lipid bilayers. Our analysis shows that seemingly small structural modifications of the hydrophobic regions of these biomimetic PKC effectors contribute to pronounced modulation of membrane interactions of the ligands.     

The kinetics of enzyme catalyzed synthesis of sterol ester

The production of sterol ester by transesterification of β‐sitosterol with fish oil (TAG) catalyzed by Thermomyces lanuginosus immobilized lipase enzyme with varied reaction parameters such as temperature, substrate molar ratio, concentration of enzyme to deduce the enzyme kinetics for the reaction was investigated. For this transesterification reaction, the kinetic model was derived by using Ping Pong Bi Bi Mechanism. The K_m value from the first plot containing fish oil as substrate was 1.31 ± 0.05, while K_m from the second plot containing β‐sitosterol as substrate was 1.01 ± 0.04; identical V_max (0.213 ± 0.06) values were obtained by keeping one of the substrate concentration constant and varying the other. Practical applications : Deduction of reaction kinetics is an important criterion to ascertain the viability of any chemical process. Enzymatic processes need special attention to set model reaction parameters which could help in optimization or design of the actual process. In the present study we have derived the enzyme kinetics for the production sterol ester, an important nutraceutical, and calculated its K_m and V_max values along with the Arhenius activation energy to establish the viability of the reaction.     

无溶剂法合成蔗糖硬脂酸酯的工艺研究

以乙醇代替有毒的甲醇与硬脂酸在酸催化下进行反应制出了硬脂酸乙酯。以硬脂酸乙酯与蔗糖为原料在催化剂和乳化剂的作用下，进行酯交换反应合成出蔗糖硬脂酸酯。详细考察了该合成反应过程中乳化剂、催化剂用量，反应温度，原料配比，反应时间等因素对蔗糖硬脂酸酯产率的影响，得出了较佳合成工艺条件，即硬脂酸乙酯：蔗糖摩尔比为2．15：1，乳化剂与蔗糖质量比为0．1：1，催化剂与反应物料质量比为0．14：1，反应温度－120℃，压力－4．35kPa,反应时间－3.5h。以蔗糖计，蔗糖酯产率约75．2％。此外，还把蔗糖硬脂酸酯制成易挥发衍生物，建立了分析其组成的气相色谱方法。     

对羟基苯甲酸酯的催化剂研究

综述了固体超强酸TiO2/SO42-,磷钨、硅钨杂多酸及固载杂多酸盐TiSiW12O40/TiO2,浓硫酸(微波常压法),Lewis酸(FeCl3·6H2O,Fe2(SO4)3·xH2O)等几种不同催化剂催化合成对羟基苯甲酸酯的实验结果.分析各种固体催化剂对该酯化反应的催化活性、选择性、重复使用性能及使用范围.     

Variables affecting the yields of methyl esters derived from in situ esterification of rice bran oil

The influence of specific factors on in situ methanolic esterification of rice bran oil (RBO) using sulfuric acid catalyst was investigated. using high-FFA rice bran was found to be the most effective means to increase methyl ester yields. The ester content of the extract increased about 67% when the FFA content of oil was increased from 16.6 to 84.5%. Increasing the reaction time beyond 30 min did not affect yields. Increasing the temperature from 20 to 65°C elevated the FAME yield by about 30%, but increasing the amount of acid catalyst above 5 mL did not enhance yield, and increasing the methanol dose from 200 to 250 mL had a negligible effect.     

Dufour Gland Contents of Ants of the Cataglyphis bicolor Group

The species of desert-dwelling ants of the Cataglyphis bicolor (Hymenoptera: Formicidae) group are difficult to distinguish by morphological features. Analysis of the secretion from the Dufour glands of workers of a number of colonies was undertaken to see if it provided a clear test of species. Linked 6c-ms showed in all samples straight and branched-chain alkanes, linear alkenes, ketones, aldehydes, acetates, and a group of C₂₂ to C₂₈ esters not previously identified in this genus. Contents of the Dufour glands of C. savignyi from Tunisia and Egypt were similar, and comprised straight and branched-chain alkanes, alkenes and small amounts of esters. C. bicolor from Tunisia contained compounds similar to C. savignyi but was distinguished from the latter by larger amounts of the esters. The major compound in the glands of C. viaticus was tridecane, in contrast to the pentadecane of other species. It also contained a branched alkane, 3-methyltridecane as a major component. Branched-chain esters and a wide variety of acetates were also found in this species. C. diehlii had a limited range of compounds, with branched alkanes almost completely absent and high proportions of pentadecene and dodecyl acetate. C. bombycinus, a sympatric species, but recognized as not belonging to the bicolor group by its different mandibular gland substances, was notable in having butanoate esters in its Dufour glands. Despite these differences among species, both the great variability of individuals from a single colony and the among between conspecific colonies make species diagnosis from a few individuals difficult, in contrast with postpharyngeal glands, which, as recently reported, give a clearer indication of species.     

金属钠——乙醇还原酯的机理

本文介绍了一种较为合理的纳在乙醇中还原酯的机理     

Effect of Lactose Monolaurate and High Intensity Ultrasound on Crystallization Behavior of Anhydrous Milk Fat

Crystallization behavior of anhydrous milk fat (AMF) was studied with the addition of 0.025 and 0.05 % lactose monolaurate (LML). The crystallization behavior was studied at low (ΔT = 3 °C) and high supercooling (ΔT = 6 °C). Polarized light microscopy and laser turbidimetry indicated a delay in crystallization on addition of 0.025 % and 0.05 % LML or Tween 20 to AMF. High intensity ultrasound (HIU) was applied to AMF samples with 0.05 % LML and lower supercooling (T _c = 31 °C; ΔT = 3 °C). HIU application in AMF and AMF + 0.05 % LML induced crystallization (p < 0.05) changing the induction time (τ) at 31 °C from 34.20 ± 1.67 min (AMF) and 47.07 ± 1.27 min (AMF + 0.05 % LML) to 23.23 ± 3.26 min (AMF) and 25.00 ± 0.87 min (AMF + 0.05 % LML). Melting enthalpies (ΔH) of AMF were significantly higher (p < 0.05) than the ones observed for AMF + 0.05 % LML when crystallized without HIU, while enthalpy values increased significantly in AMF + 0.05 % LML samples when crystallized with HIU reaching similar values to the ones obtained for AMF without LML. The viscosity of AMF significantly decreased (p < 0.05) on addition of 0.05 % LML and significantly increased on HIU application.     

Analysis of CLA Isomer Distribution in Nutritional Supplements by Single Column Silver-Ion HPLC

Nutritional supplements containing conjugated linoleic acid (CLA) isomers, widely used to improve body composition and inhibit fat storage, should be thoroughly analyzed, as CLA effects are isomer specific. In this research, an improvement of silver-ion high performance liquid chromatography (Ag⁺-HPLC) was obtained by using a single-column instead of the most commonly used multi-columns. To develop the procedure, a standard CLA mixture has been derivatized with different chain length alcohols (from methanol to hexanol). Hexyl CLA showed better separation between CLA isomer pairs, in particular the resolution of the t10,c12: c9,t11 pair increased from 0.3 (methyl esters) to 0.8 (hexyl esters). Therefore, the CLA isomer composition of some commercial CLA products was determined by Ag⁺-HPLC analysis of hexyl esters. The main isomers in all supplements turned out to be c9,t11-CLA and t10,c12-CLA, the most anti-adipogenic isomer. t8,c10- and c11,t13-CLA were not detected. The nutritional supplements were also analyzed by high resolution gas chromatography of methyl esters to evaluate the fatty acid % composition and total CLA % content. The total CLA ranged from 79.4 to 94.4 %, and the t,t isomer from 1.4 to 7.3 %.     

锡卟啉的合成及其绿色催化氧气氧化环己烯

考察催化剂金属锡次卟啉二甲酯催化氧化环己烯的反应性能。探讨了在催化氧化过程中,反应温度、压力、时间、催化剂用量等因素对环己烯转化率和产物选择性的影响,并结合GC-MS在线分析检测。结果表明,当温度100℃、压力0.8 MPa、时间7 h、催化剂用量0.5 mg(7.6×10-4mmol)、环己烯10 mL(98 mmol)的条件下,环己烯的转化率达84%,相应产物2-环己烯-1-醇和2-环己烯-1-酮的总选择性为94%,并对该反应的催化氧化反应机理进行了初步研究。