Chemistry and Physics of Lipids最新文献

Liposomes, in addition to providing greater efficacy to antibiotics, decrease toxicity and increase selectivity. This work has as main objectives the sensitization of the need to solve bacterial resistance to antibiotics, addressing the potential of antibiotics carried by liposome. In the preparation of the liposomes, the lipids dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylserine (DPPS), and cholesterol (COL) with > 99% purity were used. The Staphylococcus aureus strains used were SA-1199B, which expresses the NorA gene encoding the NorA efflux protein, which expels hydrophilic fluoroquinolones and other drugs intercalating DNA dyes, and the wild strain SA-1199. The liposomes associated with antibiotics in the wild type of strain SA-1199 and the carrier strain of pump 1199B, had a better representation of growth inhibition than the wild type strain SA-1199. Given the potential for inhibition of efflux pump seen in the results, we highlight the creation of new drugs or alteration of existing drugs. They are not recognized by the efflux pumps and removed from the target cell.

6-Gingerol (Gn) is an active compound derived from ginger which possesses various biological activities. The therapeutic applications of Gn are limited due to its hydrophobic nature. To ease its administration, one of the nano-emulsion methods, liposome was selected to encapsulate Gn. Response Surface Methodology (RSM) was used to optimize liposome ratio. 97.2% entrapment efficiency was achieved at the ratio of 1:20:2 (Drug: Lipid: Cholesterol). The optimized liposome attained size below 200 d nm, spherical shape, negative surface charge and showed sustain release upon physical characterization methods such as FESEM, DLS, Zeta potential, Drug release. The signature FTIR peaks of both free Gn and free liposome (FL) were also observed in Lipo-Gn peak. Lipo-Gn showed significant cytotoxic effect on A549 cells (IC50 160.5 ± 0.74 µM/ml) as well as inhibits the cell migration. DAPI staining showed higher apoptotic nuclear morphological change in the cells treated with Lipo-Gn, and also Lipo-Gn increased the apoptotic percentage in A549 as 39.89 and 70.32 for 12 and 24 h respectively which were significantly more than free Gn. Moreover, the formulation of Lipo-Gn showed significant cell cycle arrest at the G2/M phase compared with free Gn (28.9% and 34.9% in Free Gn vs. 42.7% and 50.1% in Lipo -Gn for 12 and 24 h respectively). Lipo-Gn have been assessed in NSCLC induced BALB/c mice and showed significantly improved pharmacological properties compared to those of free Gn. Thus, Lipo-Gn may be considered for its widening applications against lung cancer.

The use of deuterium-incorporated bioactive compounds is an efficient method for tracing their metabolic fate and for quantitative analysis by mass spectrometry without complicated HPLC separation even if their amounts are extremely small. Plant sphingolipids and their metabolites, which have C4, 8-olefins on a common backbone as a sphingoid base, show unique and fascinating bioactivities compared to those of sphingolipids in mammals. However, the functional and metabolic mechanisms of exogenous plant sphingolipids have not been elucidated due to the difficulty in distinguishing exogenous sphingolipids from endogenous sphingolipids having the same polarity and same molecular weight by mass spectrometric analysis. Their roles might be elucidated by the use of deuterated probes with original biological and physicochemical properties. In this study, we designed (2S,3R,4E,8Z)-2-aminooctadeca-4,8-diene-17,17,18,18,18-d₅-1,3-diol (penta-deuterium-labeled 4E, 8Z-sphingadienine) as a tracer for exogenous metabolic studies. In addition, the sphingadienine was confirmed to be metabolized in HEK293 cells and showed distinct peaks in mass spectrometric analysis.

Malaria is one of the most challenging parasitic infectious diseases in tropical and subtropical regions all over the world. The increasing drug resistance of plasmodium falciparum even makes the treatment procedure of malaria challenging and more problematic. Therefore, it is essential to develop new antimalarial drugs for effective treatments. In this study, the encapsulated amphotericin B (Constantinides et al.) in DSPC/DSPE-PEG2000 micelles was investigated as an antimalarial drug against P. falciparum 3D7 strain. The mean particle size, morphological and microstructural properties of drug-free and drug-loaded micelles prepared with amphotericin B were determined through DLS, FESEM, and TEM analysis. The synthesized phospholipid micelles containing AmB drug with a mean diameter of 115 nm and a polydispersity index of 0.331. The TEM and SEM studies indicate the uniform and homogeneous morphology of the micelles. Drug encapsulation efficiency is 88.3%. The slow release of the micellar system shows the maximum drug release of 75.67% within 24 h. This in vitro study was conducted on P. falciparum 3D7 to investigate the interactions between AmB micelles and P. falciparum parasites using different drug ratios. According to the findings, the IC₅₀ of free AmB is 4.834 µg/ml, while the nano-diameter AmB has a significantly lower IC₅₀ of 2.394 µg/ml. The results of this study suggest that the drug-loaded phospholipid micelles have significantly higher bioactivity and greater plasmodial properties compared to the direct application of AmB against P. falciparum. Moreover, according to the results of this study, the encapsulated AmB drugs are promising nanostructures for malaria treatment. Therefore the nanoencapsulation AmB showed promising application for malaria treatment.

Lipids play a central role within the cell. They not only encompass it but are also engaged in many processes such as cellular transport and energy production. Despite ongoing advances in experimental studies, computer simulations are a viable method to trace their behavior at the atomic level and on an elusive time scale. In molecular modeling studies, the quality of the obtained results is associated with the considered force field and its parameters. In the present work, the authors have investigated the procedure of partial charges fitting on the example of a triacetin molecule, containing chemical moieties present in the glycerol backbone. The goal of the study was to validate assigned partial charges based on the quality of the torsion profiles using optimally assigned torsional coefficients and reproduction of the condensed phase properties of triacetin. We applied various approaches and noticed a significant improvement in the parameterization of triacetin compared to the original one. The results showed that it is important to take into account the intermolecular interactions in the partial charges fitting procedure to obtain good quality validation results.

Silibinin (SIL) is a neuroprotective and amyloid aggregate inhibitor that showed therapeutic applications in preclinical studies of Alzheimer’s disease (AD). Due to poor aqueous solubility free SIL is unable to reach the brain after oral administration. Therefore SIL was encapsulated in nano-liquid crystals (NLCs) to increase payload in brain using glyceryl monooleate (GMO). The NLCs were prepared through the emulsification and probe sonication method. The optimization of SIL-NLCs was done using Box-Behnken design (BBD). BBD investigated the effect of independent variable such as GMO weight, pluronics-127 (PF-127) concentration, and sonication time on critical quality attributes such as particle size and percentage drug loading (%DL) for enhancement of drug availability at targeted site. The particle size of SIL-NLCs optimized by BBD was found to be 113.2 ± 3.3 nm particle size and 8.02 ± 0.4% DL. The FTIR and DSC characterization of SIL-NLCs showed SIL is dispersed in the GMO matrix in the amorphous form. TEM analysis confirmed the cubical and crystal-like shape of the NLCs having particle size less than 150 nm. After single oral gavage of a 30 mg/kg dosage of SIL in Wistar rats, the pharmacokinetic investigations revealed that the amount of SIL available in plasma of animals administered with NLCs showed AUC_0-∞ = 19.61 µg mL⁻¹ h compared to free SIL group having AUC_0-∞ = 6.72 µg mL⁻¹ h (P > 0.005). Brain uptake studies showed SIL-NLCs treated groups have 2.25 µg/g availability of SIL compared to 10.02 µg/g for the free SIL group. The outcomes of this investigation are promising in terms of potential use of SIL-NLCs in further studies as well as using SIL for the treatment of AD.

Three oxysterols (7β-hydroxycholesterol; 7β-OH, 7-ketocholesterol; 7-K and 25-hydroxycholesterol, 25-OH) differing in the site of oxidation (ring system versus chain) and kind of polar group (hydroxyl versus carbonyl) were studied in lipid raft environment using the Langmuir monolayer technique complemented with theoretical calculations. Experiments were performed for the unmodified raft system, composed of sphingomyelin (SM) and cholesterol (Chol), and in the next step the raft was modified by the incorporation of oxysterol in different proportions. In the examined three-component system (Chol:SM:oxysterol), apart from interactions between the lipid raft components, the affinity of Chol to its oxidized derivatives also plays an important role. 25-OH was found to enhance interactions between SM and Chol and thus stabilize the raft, contrary to 7β-OH and 7-K, which exerted the fluidizing effect as well as the destabilization of the raft. Different action of oxysterols on model raft was observed. 7β-OH and 7-K, which are highly potent inducers of cell death caused raft destabilization, while 25-OH, which is the least toxic of the investigated oxysterols, was found to stabilize the raft.

Curcumin has been incorporated for the development of new products with applicability in food, pharmaceutical and cosmetic fields in Asia, due to the traits of anti-oxidation and anti-inflammatory. In the application of food engineering, high-pressure processing (HPP) can destroy non-covalent bonds and use as a method to inactivate bacteria for extending the perseveration of food. Thus, this study focuses on a novel approach for the microencapsulation of curcumin by the combination of ethanol injection and HPP at the room temperature for stabilizing pure curcumin in aqueous solutions and in liposome. The results revealed that the most optimal curcumin-liposome was prepared by HPP at operational pressure of 200 MPa within 5 mins holding time to obtain the minimum particle size of 281.9 nm, encapsulation efficiency of 87.25% and polydispersity index (PDI) of 0.23. Particle size could reduce to nanoscale (70.65 nm) after 0.5% addition of Tween 80, but the encapsulation efficiency spontaneously decreased to 45.05%. It is an option to produce liposome with nanosize and uniform distribution for the consideration of high drug delivery. Conclusively, HPP process could not only effectively decrease particle size and PDI of liposome but also efficiently sterilize bacteria around concentration of 10³ CFU/g.

Background

Non-alcoholic fatty liver disease (NAFLD) is considered to be the leading cause of liver pathologies worldwide. Accurate diagnosis and staging of NAFLD is of utmost prognostic importance. Herein, we propose the application of multiparametric MRI in whole-body fat imaging that may serve in obesity and NAFLD diagnosis as we established based on an experimental preclinical model of high-calorie diet-induced NAFLD rats.

Methods and results

Sprague Dawley male rats randomly divided into control and high-fat diet (HFD) groups to develop NAFLD were used in the experiments. After 12 weeks of the feeding the animals were subjected to MRI modalities based on the Dixon mode and DWI following T2-weighted imaging. Moreover, serum TAG, liver histopathological examination and liver fatty acids analysis (GC-MS) were also performed.

The qualitative analysis of DWI images revelated the decrease of signals in the liver of rats subjected to HFD. The statistical analysis of signals from the water- and fat-separated voxels on Dixon images also showed the increase of the fat tissue along with the decrease of water molecules in the liver parenchyma of obese animals. The quantitative analysis of Dixon images allowed to estimate the statistically significant changes of whole-body fat profiles in both normal and obese rats. Histological analysis of the liver tissues, serum TAG and fatty acids profile in the livers confirmed the changes in the fat profile as demonstrated in MRI studies.

Conclusions

The MRI-based modalities such as DWI and Dixon method provide both qualitative and quantitative data on the whole-body fat distribution and adipose tissues in the liver parenchyma of obese rats. The results show that MRI is a promising and reliable method and has potential to be used as a non-invasive translational biomarker in NAFLD.

Cell membranes are the first barriers for drug binding and key for the action of photosensitizers (PS). Herein, we report on the incorporation of the PS hypericin into Langmuir monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) to represent eukaryotic cell membranes, and 1,2-dioleoyl-sn-glycero-3-phospho(1’-rac-glycerol) (DOPG) to mimic bacterial membranes. Surface pressure (π) vs mean molecular area (Å) isotherms showed a high degree of interaction (binding, penetration and relative solubilization) of hypericin into DPPC and DOPC monolayers. On the other hand, electrostatic repulsions govern the interactions with DOPG and DOPS, favoring hypericin self-aggregation, as visualized by Brewster angle microscopy (BAM). Indeed, the larger domains in BAM were consistent with the greater expansion of DOPG monolayers with incorporated hypericin, owing to stronger electrostatic repulsions. In contrast to DPPC, light-irradiation of DOPC monolayers containing hypericin induced loss of material due to hydrocarbon chain cleavage triggered by contact-dependent reactions between triplet excited state of hypericin and chain unsaturations. The mild effects noted for both irradiated DOPS and DOPG monolayers are attributed to hypericin self-aggregation, which may have decreased the singlet oxygen quantum yield (Φ¹O₂) via self-quenching, despite the increased instability induced in the monolayers.