Improved assay of coenzyme Q10 from liposomes by Tween 80 solubilisation and UV spectrophotometry

The encapsulated coenzyme Q₁₀ (CoQ₁₀) level is an important index in evaluating the quality of CoQ₁₀ liposomes. This study demonstrates a simple method to release encapsulated CoQ₁₀ from liposomal suspension using moderate amounts of the non‐ionic surfactant Tween 80 to form mixed micelles containing phospholipids, Tween 80 and CoQ₁₀. The encapsulated CoQ₁₀ level was detected by means of Tween 80 solubilisation and ultraviolet (UV) spectrophotometry, in which 1 mL of the reducing agent NaBH₄ (7 mg mL^?1) was added. The proposed method had a good linear correlation with ethanol solubilisation and reverse phase high‐performance liquid chromatography (RP‐HPLC) and with ethanol solubilisation and UV spectrophotometry over a CoQ₁₀ concentration range of 2.5–50 µg mL^?1 (R² > 0.999). The average recovery rate of CoQ₁₀ from blank liposomes was estimated as 99.46 ± 1.54%. The difference in results between the organic solvent extraction method and the Tween 80 solubilisation method was not statistically significant (P > 0.05). When the latter method was applied to determine the total and the encapsulated CoQ₁₀ content quantitatively, the relative standard deviation was lower than 5%. Therefore this method has proved to be convenient, sensitive, accurate and reproducible compared with conventional RP‐HPLC analysis and UV spectrophotometry with organic solvent extraction. Copyright © 2006 Society of Chemical Industry     

In vitro and in vivo antioxidant properties of the plant-based supplement greens+™

Dietary antioxidants play an important role against oxidation, an underlying mechanism in the incidence of chronic diseases. Greens+ is a commercially available preparation containing a variety of plant-derived ingredients. The aim of the current study was to evaluate the antioxidant potential of the methanolic extract of greens+ powder using in vitro and in vivo techniques. In vitro studies were conducted using a liposome model system to simulate biological cell membranes. Total antioxidant potential and polyphenol content of the herbal preparation was measured. For in vivo analysis, 10 healthy human subjects consumed either three or six teaspoons of greens+ per day for four weeks. Blood samples were analyzed at baseline and at the conclusion of the treatment period for total antioxidant capacity, polyphenol content, protein, lipid and LDL oxidation, and the level of glutathione peroxidase. Results showed that greens+ supplementation was well tolerated and increased serum antioxidant potential at higher levels of intake in a dose-dependent manner. HPLC analysis showed the presence of quercetin, apigenin, kaempferol and luteolin in the supplement. Plasma analysis indicated the presence of kaempferol only. A statistically significant (p < 0.05) reduction in protein and lipid oxidation was observed. Based on its antioxidant properties, the results suggest that greens+ might play a role in reducing the risk of chronic diseases involving a burden of oxidative damage.     

血红素铁脂质体的制备

目的：制备血红素铁脂质体。方法：采用乙醇注入法及旋转薄膜- 超声法制备,再经过不同孔径的滤膜得到不同粒径的血红素铁脂质体,在原有技术的基础上优化血红素铁脂质体各组分的制备工艺,应用紫外分光光度计测定血红素铁的含量,计算出血红素铁脂质体的包封率,用差示扫描量热法检测血红素铁脂质体各组成物质的相变过程。结果：两种方法都能够得到较为理想的脂质体,血红素铁:胆固醇:卵磷脂质量比范围为(0.1～200):(1～10):(10～100)。结论：所得血红素铁脂质体呈均一大单室型,通过0.8μm 的滤膜后有效粒径为0.804μm,最大包封率36%。     

Formation of biopolymer-coated liposomes by electrostatic deposition of chitosan

ABSTRACT:  The purpose of this study was to prepare stable biopolymer-coated liposome suspensions using an electrostatic deposition method. Liposome suspensions were produced by homogenizing 1% soy lecithin in acetate buffer (0.1 M, pH 3). Cationic chitosan (Mw approximately 200 kDa) solutions were mixed with anionic liposome suspensions ( d approximately 100 and 200 nm), and the effect of phospholipid concentration, chitosan concentration, and liposome size on the properties of the particles formed was determined. The particle size and charge (ζ-potential) were measured using dynamic light scattering and particle electrophoresis. The particle charge changed from –38 mV in the absence of chitosan to +60 mV in the presence of chitosan, indicating complex formation between the anionic liposomes and cationic chitosan molecules. Below a minimum critical chitosan concentration ( c _min), large aggregates were formed that phase separated within minutes, whose origin was attributed to formation of coacervates. On the other hand, above a maximum critical chitosan concentration ( c _max), large flocs were formed that sedimented within hours, whose formation was attributed to depletion flocculation. Minimum and maximum critical chitosan concentrations depended on liposomal concentration and size. At c _min < c < c _max, chitosan-coated liposomes were formed that did not aggregate and were stable to sedimentation. Coated liposomes had better stability to aggregation than uncoated liposomes when stored at ambient temperatures for 45 d. This study indicates that chitosan can be used to form biopolymer-coated liposomes with enhanced stability over uncoated liposomes.     

猪用生长激素(PST)脂质体包封率测定方法的比较

试验对测定包封率的两种方法即凝胶柱分离法和鱼精蛋白凝聚法进行了比较，测得PST脂质体的包封率分别为75．26％、84．58％，PST回收率分别为90．4％和98．22％。因此确定了鱼精蛋白法为试验产品包封率的测定方法。     

维生素A神经酰胺脂质体的初步研究

采用神经酰胺为类脂质材料研制维生素A脂质体,通过提高维生素A的稳定性和透皮吸收以有助于其在化妆品中的应用。筛选优化了维生素A脂质体的制备工艺,通过高效液相色谱对包封率、载药量、粒径及形态结构进行了研究。结果显示,脂质体形态较为圆整,平均粒径为O．171μm,包封率达98．5％,载药量为2．0％。神经酰胺作为类脂质材料制得的维生素A脂质体包封率高,可较好地应用于化妆品中。     

TP-Lips/LZM-CS复合缓释涂膜对美国红鱼鱼片贮藏品质的影响

目的提高复合缓释涂膜对美国红鱼鱼片的保鲜性能,获得具有长效作用的高效保鲜材料。方法将具有缓释作用的茶多酚脂质体(TP-Lips)与溶菌酶(LZM)复合后加入至壳聚糖(CS)涂膜液中,采用流延法制备TP-Lips/LZM-CS复合缓释涂膜。以美国红鱼鱼片的新鲜度为指针,评价复合涂膜的保鲜性能。结果 TP-Lips/LZM-CS复合缓释涂膜可有效抑制鱼肉中微生物的生长,延缓鱼片pH、硫代巴比妥酸(TBA)值的升高和鱼肉质构指标的变化。结论 TP,LZM和CS的复合使用有效地拓宽了抗菌谱,同时,脂质体和涂膜共同组成的缓释体系,使TP和LZM的作用时间更长,TP-Lips/LZM-CS复合涂膜的保鲜性能最优,并能够将4℃下冷藏美国红鱼鱼片的货架期延长至15 d以上。     

Overcoming Biological Barriers in Neuroblastoma Therapy: The Vascular Targeting Approach with Liposomal Drug Nanocarriers

Neuroblastoma is a rare pediatric cancer characterized by a wide clinical behavior and adverse outcome despite aggressive therapies. New approaches based on targeted drug delivery may improve efficacy and decrease toxicity of cancer therapy. Furthermore, nanotechnology offers additional potential developments for cancer imaging, diagnosis, and treatment. Following these lines, in the past years, innovative therapies based on the use of liposomes loaded with anticancer agents and functionalized with peptides capable of recognizing neuroblastoma cells and/or tumor‐associated endothelial cells have been developed. Studies performed in experimental orthotopic models of human neuroblastoma have shown that targeted nanocarriers can be exploited for not only decreasing the systemic toxicity of the encapsulated anticancer drugs, but also increasing their tumor homing properties, enhancing tumor vascular permeability and perfusion (and, consequently, drug penetration), inducing tumor apoptosis, inhibiting angiogenesis, and reducing tumor glucose consumption. Furthermore, peptide‐tagged liposomal formulations are proved to be more efficacious in inhibiting tumor growth and metastatic spreading of neuroblastoma than nontargeted liposomes. These findings, herein reviewed, pave the way for the design of novel targeted liposomal nanocarriers useful for multitargeting treatment of neuroblastoma.