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Chemistry and Physics of Lipids

William M Penny, Christopher P Palmer
Understanding how stereochemistry affects interactions with cell membranes is important for effective drug development. Chirality has been shown to greatly effect pharmaceutical distribution and metabolism within the cell. However it has been thought that interactions with, and passive diffusion through, the membrane are not stereochemically selective. Various studies have produced conflicting results regarding whether interactions with lipid bilayers are or can be stereoselective. In the current work, stereoselective interactions between a pair of atropisomers, R-(+)/(S)-(-) 1,1'-Bi-2-naphthol, and sphingomyelin nanodisc bilayers, are demonstrated...
May 10, 2018: Chemistry and Physics of Lipids
Pavan Walvekar, Ramesh Gannimani, Sanjeev Rambharose, Chunderika Mocktar, Thirumala Govender
No abstract text is available yet for this article.
May 3, 2018: Chemistry and Physics of Lipids
Huina Ruan, Lujing Xu, Shan Hong, Songbai Liu
A general highly efficient solvent-free esterification of phytosterols with edible magnesium oxide and Span-60 emulsifier catalyst system has been developed. The edible emulsifier dramatically promotes the catalyzing activity of the metal oxide in the reaction. The loading of the magnesium oxide is as low as 0.1 wt% to phytosterols and far lower than the known ones. As demonstrated by the results of scanning electro-microscopy (SEM), the synergistic effect of emulsifier and magnesium oxide presumably results from elimination of nano-scale interfacial barrier between phytosterols and fatty acids and facilitation of mass transfer of reaction agents...
May 1, 2018: Chemistry and Physics of Lipids
Marjut Vähäheikkilä, Tapio Peltomaa, Tomasz Róg, Mario Vazdar, Sanja Pöyry, Ilpo Vattulainen
Cardiolipins have multiple vital functions within biological cell membranes, most notably in the energy metabolism associated with the inner mitochondrial membrane. Considering their essential role, peroxidation of cardiolipins may plausibly have significant effects, as peroxidation is known to alter the functionality of lipid molecules. We used atomistic molecular dynamics simulations to study how peroxidation of cardiolipin affects the properties of the inner mitochondrial membrane. To this end, we explored what happens when varying fractions of fatty acid chains of cardiolipin are replaced by its four different oxidized products in systems modeling the inner mitochondrial membrane...
April 30, 2018: Chemistry and Physics of Lipids
Zoran Arsov, Emilio J González-Ramírez, Felix M Goñi, Stephanie Tristram-Nagle, John F Nagle
Despite the biological significance of sphingomyelins (SMs), there is far less structural information available for SMs compared to glycerophospholipids. Considerable confusion exists in the literature regarding even the phase behavior of SM bilayers. This work studies both palmitoyl (PSM) and egg sphingomyelin (ESM) in the temperature regime from 3 °C to 55 °C using X-ray diffraction and X-ray diffuse scattering on hydrated, oriented thick bilayer stacks. We observe clear evidence for a ripple phase for ESM in a large temperature range from 3 °C to the main phase transition temperature (TM ) of ∼38 °C...
April 21, 2018: Chemistry and Physics of Lipids
Daniel J Mayo, Indra D Sahu, Gary A Lorigan
Aligned CW-EPR membrane protein samples provide additional topology interactions that are absent from conventional randomly dispersed samples. These samples are aptly suited to studying antimicrobial peptides because of their dynamic peripheral topology. In this study, four consecutive substitutions of the model antimicrobial peptide magainin 2 were synthesized and labeled with the rigid TOAC spin label. The results revealed the helical tilts to be 66° ± 5°, 76° ± 5°, 70° ± 5°, and 72° ± 5° for the TOAC substitutions H7, S8, A9, and K10 respectively...
April 21, 2018: Chemistry and Physics of Lipids
Ezequiel N Frigini, J J López Cascales, Rodolfo D Porasso
Extensive Molecular Dynamics simulations have been performed to study the effect of Glyphosate (in their neutral and charged forms, GLYP and GLYP2- , respectively) on fully hydrated DiPalmitoylPhosphatidylCholine (DPPC) lipid bilayer. First, we calculated the free energy profile (using the Umbrella Sampling technique) for both states of charge of glyphosate. The minimum value for the free energy for GLYP is ∼-60 kJ.mol-1 located at z=±1.7 nm (from the lipid bilayer center), and there is almost no maximum at the center of the lipid bilayer...
April 20, 2018: Chemistry and Physics of Lipids
K Talló, V Moner, M De Cabo, M Cócera, O López
Phospholipids and fatty acids are the main building blocks of biological membranes. Oleic acid is a monounsaturated omega-9 fatty acid commonly found in many natural sources. Its characteristic kinked structure grants this molecule with a great number of biological properties. To better understand the role that this kind of fatty acids play into phospholipid membranes, nanostructured systems formed with hydrogenated soy phosphatidylcholine and oleic acid were studied in this work by means of cryo-electron microscopy, dynamic light scattering and differential scanning calorimetry...
April 18, 2018: Chemistry and Physics of Lipids
Katarzyna Dopierała, Marta Skrzypiec
The aim of the present study was to investigate the interfacial behaviour of model biomembranes in the presence of β-carotene (βC). The Langmuir monolayer technique was used to form the mixed lipid film at the air/water interface. Using the surface pressure-area isotherms, the surface potential-area curves and the Brewster angle microscopy the nature of interactions between carotenoid and lipid components of the monolayers was investigated. The results were obtained for complex models of the lipid bilayer composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol (CHOL)...
April 4, 2018: Chemistry and Physics of Lipids
Tamara Lützenburg, Ines Neundorf, Matthias Scholz
Herein, we report the synthesis and characterization of direct carborane-peptide conjugates. Carboranes are non-natural and extremely hydrophobic compounds and turned out to be suitable pharmacophores for diverse biological applications. In this work, we established an efficient procedure for the coupling of carboranes to peptides on solid support. We identified the coupling of carborane-1-carboxylic acids to amino groups to be superior to those with hydroxy- or sulfhydryl-groups. The carborane-peptide conjugates showed remarkably prolonged, and carborane isomer dependent chromatographic retention times...
March 29, 2018: Chemistry and Physics of Lipids
Sarmistha Saha, Ramtej J Verma
Eugenol and its related compounds are major active constituents of essential oils and have been extensively used as food flavoring agents with significant lipid peroxidation inhibition activity, highlighting the importance of understanding detailed molecular mechanisms behind their interactions with lipid bilayer. For this, we studied antioxidant activity of essential oils rich extract of Cinnamomum tamala leaves and molecular dynamics simulations of eugenol, isoeugenol, methyleugenol, acetyleugenol and eugenol oxide in POPC and PLPC lipid bilayers...
March 26, 2018: Chemistry and Physics of Lipids
Enrique Rodriguez-Garcia, Josefina Ruiz-Nava, Sonia Santamaria-Fernandez, Jose Carlos Fernandez-Garcia, Antonio Vargas Candela, Raquel Yahyaoui, Francisco J Tinahones, M Rosa Bernal-Lopez, Ricardo Gomez-Huelgas
OBJECTIVE: There is a lack of consensus when it comes to establishing the biochemical parameters that define metabolically healthy obese (MHO) subjects. Indeed, most studies do not include subjects' lipid profiles. Our objective was to characterize lipoprotein size, particle and subclass concentration using1 H NMR in MHO women after two years of weight loss with a hypocaloric Mediterranean diet and physical exercise. METHODS: 115 non-diabetic women (aged 35-55 years) with a body mass index (BMI) of 30-40 kg/m2 and ≤1 of the following criteria: blood pressure ≥135/85 mmHg, fasting plasma glucose ≥100 mg/dL, HDL cholesterol ≤50 mg/dL and triglycerides ≥150 mg/dL were included...
March 23, 2018: Chemistry and Physics of Lipids
Zane Berzina, Lukasz M Solanko, Ahmed S Mehadi, Maria Louise V Jensen, Frederik W Lund, Maciej Modzel, Maria Szomek, Katarzyna A Solanko, Alice Dupont, Gitte Krogh Nielsen, Christian W Heegaard, Christer S Ejsing, Daniel Wüstner
Niemann-Pick disease type C2 is a lipid storage disorder in which mutations in the NPC2 protein cause accumulation of lipoprotein-derived cholesterol in late endosomes and lysosomes (LE/LYSs). Whether cholesterol delivered by other means to NPC2 deficient cells also accumulates in LE/LYSs is currently unknown. We show that the close cholesterol analog dehydroergosterol (DHE), when delivered to the plasma membrane (PM) accumulates in LE/LYSs of human fibroblasts lacking functional NPC2. We measured two different time scales of sterol diffusion; while DHE rich LE/LYSs moved by slow anomalous diffusion in disease cells (D ∼ 4...
March 23, 2018: Chemistry and Physics of Lipids
Su-Min Han, Jong-Suep Baek, Min-Soo Kim, Sung-Joo Hwang, Cheong-Weon Cho
Liposomes can achieve a controlled release and an improved bioavailability of water- insoluble drug with minimized side effects. Paclitaxel is an efficient anticancer drug for the treatment of various cancers. However, paclitaxel has a solubility of 0.5 mg/L in water and a low bioavailability of 6.5%. Moreover, paclitaxel is a substrate for p-glycoprotein, which shows a decreased accumulation of drug within the cancer cell expressed by a p-glycoprotein. Therefore, the purpose of this study is to prepare a paclitaxel-loaded liposome and evaluate the effect of d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) as an inhibitor of p-glycoprotein on the paclitaxel-loaded liposome...
March 14, 2018: Chemistry and Physics of Lipids
Gopinath Viswanathan, Md Jafurulla, G Aditya Kumar, Tirumalai R Raghunand, Amitabha Chattopadhyay
Mycobacteria are intracellular pathogens that can invade and survive within host macrophages. Mycobacterial infections remain a major cause of mortality and morbidity worldwide, with serious concerns of emergence of multi and extensively drug-resistant tuberculosis. While significant advances have been made in identifying mycobacterial virulence determinants, the detailed molecular mechanism of internalization of mycobacteria into host cells remains poorly understood. Although several studies have highlighted the crucial role of sphingolipids in mycobacterial growth, persistence and establishment of infection, the role of sphingolipids in the entry of mycobacteria into host cells is not known...
March 8, 2018: Chemistry and Physics of Lipids
Georg Hölzl, Christian Sohlenkamp, Miguel Angel Vences-Guzmán, Nicolas Gisch
Amino acid-containing acyloxyacyl lipids are composed of a 3-hydroxy fatty acid amide-bound to the α-amino group of an amino acid. A second fatty acid is ester-linked to the 3-hydroxy group of the first fatty acid. Most commonly, ornithine is the headgroup of these lipids, but glycine, serineglycine, glutamine and lysine have also been described in bacteria. Ornithine lipids (OL) can be synthesized by about 50% of the sequenced bacterial species, and several covalent modifications of its basic structure have been described...
March 7, 2018: Chemistry and Physics of Lipids
Feroz Ahmad, David S Leake
Oxidised low density lipoprotein (LDL) was considered to be important in the pathogenesis of atherosclerosis, but the large clinical trials of antioxidants, including the first one using probucol (the PQRST Trial), failed to show benefit and have cast doubt on the importance of oxidised LDL. We have shown previously that LDL oxidation can be catalysed by iron in the lysosomes of macrophages. The aim of this study was therefore to investigate the effectiveness of antioxidants in preventing LDL oxidation at lysosomal pH and also establish the possible mechanism of oxidation...
March 5, 2018: Chemistry and Physics of Lipids
Lorale J Lalgee, Leonette Cox, Richard A Fairman, Lebert Grierson
A novel series of amphiphilic cobalt-cage derivatives (ACCD), bearing a diaza-crown bridge and varying alkyl chains, facilitate ion transport across biomembrane models via self-aggregation. In this study, compression isotherm analyses and atomic force microscopy (AFM) were used to assess the interactions of these amphiphiles with Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC) in order to elucidate electrostatic and steric contributions to ion transport. The stability and compressibility of DPPC monolayers are disrupted by ACCD molecules with short (C12 ) alkyl chains...
February 27, 2018: Chemistry and Physics of Lipids
Allan Svendsen, Tommy Nylander
No abstract text is available yet for this article.
March 2018: Chemistry and Physics of Lipids
Stefania Mele, Olle Söderman, Helena Ljusberg-Wahrén, Krister Thuresson, Maura Monduzzi, Tommy Nylander
The phase behavior in the oleic acid/sodium oleate/normal saline (0.15M NaCl aqueous solution) system has been determined. For this purpose visual inspection of samples between crossed polarizers, and Small Angle X-ray diffraction was used to identify the various phases and their unit cell dimensions. A rich phase behavior was observed for the ternary system, featuring reverse micellar, micellar cubic, hexagonal, and cubic phases, and large regions with lamellar phases. As expected the ratio the 'oleic acid/sodium oleate' determines the pH and as a consequence the phase behavior...
March 2018: Chemistry and Physics of Lipids
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