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1.
Freddy A. Bernal Dr. Marcel Kaiser Prof. Dr. Bernhard Wünsch Prof. Dr. Thomas J. Schmidt 《ChemMedChem》2020,15(1):68-78
Protozoal infections are still a global health problem, threatening the lives of millions of people around the world, mainly in impoverished tropical and sub-tropical regions. Thus, in view of the lack of efficient therapies and increasing resistances against existing drugs, this study describes the antiprotozoal potential of synthetic cinnamate ester analogues and their structure-activity relationships. In general, Leishmania donovani and Trypanosoma brucei were quite susceptible to the compounds in a structure-dependent manner. Detailed analysis revealed a key role of the substitution pattern on the aromatic ring and a marked effect of the side chain on the activity against these two parasites. The high antileishmanial potency and remarkable selectivity of the nitro-aromatic derivatives suggested them as promising candidates for further studies. On the other hand, the high in vitro potency of catechol-type compounds against T. brucei could not be extrapolated to an in vivo mouse model. 相似文献
2.
3.
燃料甲酯应用研究浅析 总被引:1,自引:0,他引:1
本阐述了分别使用燃料甲酯及柴油时由柴油机以加俐到的示功图,烟度及过量空气系统等的对比结果。经分析认为:当燃料甲酯取代柴油机时,用户可不必对柴油机另作调整,因而十分方便。 相似文献
4.
Ke-Shun Liu 《Journal of the American Oil Chemists' Society》1994,71(11):1179-1187
Theoretically, preparation of fatty acid methyl esters (FAMEs) deals with reversible chemical reactions in a complex system.
Methodologically, there are numerous ways, generally characterized by the type of catalysts used and steps involved. Although
there are more than a half dozen common catalysts, the majority fall into either acidic (HCl, H2SO4 and BF3) or alkaline types (NaOCH3, KOH and NaOH), with each having its own catalytic capability and application limitations. In terms of steps, many conventional
methods, including those officially recognized, consist of drying, digestion, extraction, purification, alkaline hydrolysis,
transmethylation/methylation and postreaction work-up. Although these methods are capable of providing reliable estimates
if some precautions are taken, they are cumbersome, time-consuming and cost-inefficient. A new approach has been to transmethylate
lipidsin situ. Due to its simplicity, high sensitivity, comparable reliability and capability to determine total fatty acids, the method
of direct transmethylation is finding a unique place in lipid determination. Regardless of which method is used, quantitative
methylation requires chemists to take precautions at every step involved, particularly during FAME formation and subsequent
recovery steps. Evidently, there is an urgent need for more systematic studies, guided by the chemical principle of reactions
involved and physicochemical properties of regents and end products, into factors affecting these steps. Hopefully, this will
lead to an improved method, which measures lipid composition in biological materials not only with high accuracy but also
with high efficiency and minimum costs. 相似文献
5.
Robert L. Wolff 《Journal of the American Oil Chemists' Society》1994,71(3):277-283
Twelve commercial samples of French butter, purchased in October–November, and 12 other samples, purchased in May–June, were
analyzed with particular attention to theirtrans-octadecenoic acid contents. The isomeric fatty acids were quantitated by a combination of gas-liquid chromatography (GLC)
of total fatty acids as isopropyl esters on a polar capillary column (CPSil 88) and of silver nitrate-impregnated thin-layer
chromatography followed by GLC of the pooled saturated (used as internal standards) andtrans-octadecenoic acid fractions. Autumn butters contained 3.22±0.44%trans-octadecenoic acids (relative to total fatty acids), whereas those collected during the spring contained 4.28±0.47% (P<0.01). Minimum and maximum values for the two sets of butters were 2.46 (autumn) and 5.10% (spring), respectively. The annual
mean value for thetrans-octadecenoic acid content in all butter samples was 3.8% of total fatty acids (ca. 2% for thetrans-11 18∶1 acid). This value allows calculation of the daily individual intake oftrans-octadecenoic acids from dairy products by populations of member states of the European Economic Community (EEC). It varies
from 0.57 g (Portugal) to 1.66 g (Denmark). The mean value for the twelve countries of the EEC is 1.16 g/person/d, which is
close to data published for the United States. In France, the consumption oftrans octadecenoic acids from dairy fat is higher than that from margarines (ca. 1.5 vs. 1.1 g/person/d). 相似文献
6.
The solubilities of ethyl palmitate, ethyl oleate, ethyl eicosapentaenoate (EPA) and ethyl docosahexaenoate (DHA) in supercritical
carbon dioxide were determined by a continuous flow method. The solubilities of fatty acid ethyl esters increased with pressure
and decreased as the temperature was increased. An empirical equation, similar to Chrastil's equation, was used to describe
the relationship between solute solubility and the density of carbon dioxide. The empirical equation was further used to qualitatively
estimate the separation efficiency of isolating EPA and DHA ethyl esters from fatty acid esters. The operating conditions
yielding high solubility gave fast extraction rate but resulted in low separation efficiency. Experiments were conducted to
separate ethyl EPA and ethyl DHA from a model mixture containing four fatty acid ethyl esters and from esterified squid visceral
oil. The experimental data compared closely with the calculated values. 相似文献
7.
Per Munk Nielsen Jesper Brask Lene Fjerbaek 《European Journal of Lipid Science and Technology》2008,110(8):692-700
It is well documented in the literature that enzymatic processing of oils and fats for biodiesel is technically feasible. However, with very few exceptions, enzyme technology is not currently used in commercial‐scale biodiesel production. This is mainly due to non‐optimized process design and a lack of available cost‐effective enzymes. The technology to re‐use enzymes has typically proven insufficient for the processes to be competitive. However, literature data documenting the productivity of enzymatic biodiesel together with the development of new immobilization technology indicates that enzyme catalysts can become cost effective compared to chemical processing. This work reviews the enzymatic processing of oils and fats into biodiesel with focus on process design and economy. 相似文献
8.
Marta Martinez-Garcia Winnie Dejonghe Lieve Cauwenberghs Miranda Maesen Karolien Vanbroekhoven Yamini Satyawali 《European Journal of Lipid Science and Technology》2021,123(2):2000225
Glucose- and xylose laurate esters are enzymatically synthesized using equimolar substrate concentrations in 2-methyl-2-butanol, comparing free lauric acid with methyl- and vinyl-laurate as acyl donors. All reactions result in ≥70% acyl donor conversions after 72 h but the activated donors are also partially hydrolyzed to lauric acid, highlighting the difficulty in controlling water presence in this particular reaction system. The esterification of xylose generates a complex product profile, with several regioisomers of monoesters and diesters. The esterification of glucose is quite selective, forming mainly the 6-O monoester (≥96%) with a small presence of two diester isomers (4%). Increasing substrate concentration up to 800 millimoles kg−1 results in lower conversion values (down to 58%) but shows that the reaction proceeds successfully even in the presence of high amounts of insoluble glucose. However, the reaction is less selective and the proportion of diester increases, becoming up to 46% (molar fraction) of the final product. Solvent recovery after esterification can be achieved by organic solvent nanofiltration through a polymeric membrane able to retain ≥80% of all reaction substrates and products. Practical Applications: The use of high substrate concentrations during the enzymatic synthesis of sugar ester biosurfactants leads to product titers that are more industrially appealing, without the need to find a solvent that can solubilize all initial substrate. The sustainability of the enzymatic conversion at mild temperatures can be enhanced by recycling of the reaction solvent through organic solvent nanofiltration, an energy efficient alternative to other traditional methods like distillation. 相似文献
9.
Maltose long-chain fatty acid esters (MFAE), esterified at the 6 and 6′ position, were synthesized with stearic, palmitic,
myristic, and oleic groups. Synthesis yields were 15–20% based on initial maltose present, and structural confirmation was
obtained using plasma desorption mass spectrometry and nuclear magnetic resonance spectroscopy. These surfactants have surface
tensions in the range of 34–36 dyn/cm at their critical micelle concentrations (CMC) of approximately 10−5–10−6 mol/L. The increased chain lengths have a marked effect, reducing CMC values for MFAE by approximately three orders of magnitude
over similar carbohydrate-based dodecyl chain sources. Within chain lengths between 14 and 18 carbons, the rate of change
in CMC is significant and decreases with increasing chain length for MFAE. The melting points of MFAE are approximately 40°C,
and the heat capacities range from 1.6 to 1.9 J/g·K. These numbers are comparable to those of sucrose esters, indicating their
applicability in similar uses. However, because MFAE, unlike sucrose, possess an anomeric carbohydrate carbon position, these
surfactants maintain their reducing nature and are susceptible to further derivatization. They are also synthesized from renewable,
economical carbohydrates and lipids and may provide an excellent alternative to pertrochemical-derived products. 相似文献
10.
The Dufour's gland secretion ofXylocopa virginica texana possesses short-term repellency for conspecifics when applied to passion flowers. This secretion contains a number of straight-chain hydrocarbons. The two major components are the methyl esters of palmitic and myristic acid. A mixture of the two esters and two of the available hydrocarbons were as effective as the Dufour's gland extract in eliciting a response in females to the passion flower,Passiflora incarnata, to which the extract was applied.Approved as TA13387 by the Director, Texas Agricultural Experiment Station and conducted in cooperation with the USDA. Supported in part by NSF-DEB-76-03963. 相似文献