Asiaticoside is a compound extracted from traditional Chinese medicine Centella asiatica, and mainly used in wound healing and scar repair in clinical, with notable efficacy. However, its poor transdermal absorption and short action time restrict its wide application. In this experiment, the reserve-phase-extrusion-lyophilization method was conducted to prepare the lyophilized asiaticoside-loaded flexible nanoliposomes (LAFL). Its characteristics including electron microscope structure, particle size, Zeta potential, entrapment rate, drug-loading rate, stability and drug release were determined with the intelligent transdermal absorption instrument. LAFL were white spheroids, with pH, particle size and zeta potential of 7. 03, 70. 14 nm and - 36. 5 mV, respectively. The average entrapment rate of the 3 batch samples were 31. 43% , and the average asiaticoside content in 1 mg lyophilized simple was 0. 134 mg. The results indicated that LAFL have good physicochemical properties and pharmaceutical characteristics, with an improved transdermal performance.
Animals ; Liposomes ; chemistry ; Nanoparticles ; chemistry ; Triterpenes ; chemistry

To prepare composite phospholipid liposomes containing total alkaloids of Strychnos nux-vomica with hydrogenated soybean phosphatidylcholine (HSPC) and 1, 2-dipalmitoyl-sn-glycero-3-phosphacholine (DPPC), and compare with normal DPPC thermosensitive liposomes for thermosensitive release property. Total alkaloids were extracted from S. nux-vomica with the impregnation method and further purified. Liposomes containing total alkaloids, thermosensitive liposomes and conventional thermosensitive liposomes without thermosensitive release property were prepared by ammonium sulfate transmembrane gradients and stealth liposome technique. Their encapsulation efficiency (EE), grain size, zeta potential and drug release behavior were compared. Their EEs and zeta potentials were almost identical; but the grain sizes of composite phospholipid liposomes and thermosensitive liposomes were significantly smaller than conventional liposomes. After comparing release behaviors of the three liposomes at 37, 43 degrees C, we found that the release of composite phospholipid liposomes was significantly lower than that of thermosensitive liposomes at 37 degrees C, but higher than that of thermosensitive liposomes at 43 degrees C. Meanwhile, conventional liposomes, with a very high phase-transition temperature, showed only slight release behavior at both temperatures. The study results showed that composite phospholipid liposomes had a better thermosensitive release behavior when the dosage of lysophosphatidic was reduced by 2. 5 times.
Alkaloids ; chemistry ; Liposomes ; chemistry ; Phospholipids ; chemistry ; Strychnos nux-vomica ; chemistry

AIMTo establish a spectrophotometric method for measurement of the sizes of liposomes for evaluating physical stability of liposomes.

METHODSThe sterically stabilized liposomes (SLs) were prepared by ethanol injection method and extrusion method. The mean cumulant diameters (D) of the vesicles were determined by electron microscopy and dynamic light scattering. On the basis of Rayleigh-Gans-Debye theory, the absorbance at 436 nm per unit lipid concentration (A436 nm/Cp) was measured as a function of vesicle diameter.

RESULTSlog(A436 nm/Cp) was closely related to logD (r2 > or = 0.93, n = 5).

CONCLUSIONThe absorbance of liposomes reflect their relative sizes and can be used to evaluate physical stability of liposomes.

Liposomes ; chemistry ; Particle Size ; Spectrophotometry ; methods

OBJECTIVETo characterize the property of uricase loaded in uricase-catalase liposomes (BUCLPs) prepared using borate buffer.

METHODSBUCLPs were prepared using reverse-phase evaporation, and the physicochemical properties of uricase in the prepared BUCLPs were examined.

RESULTSThe optimal temperature of BUCLP and URI was 40 degrees celsius, their optimal pH values were 8.0 and 8.5, and their Michaelis-Menten constants were 14.207 µmol/L and 13.623 µmol/L, respectively. Fluorescence intensity of nanoliposome-loaded uricase-catalase that bound to FITC was higher than that of uricase-catalase binding directly with FITC; the fluorescence intensity of BUCLP was higher than that of free uricase-catalase at 280 nm.

CONCLUSIONUricase activity is enhanced after loading in uricase and catalase liposomes.

Borates ; Catalase ; Liposomes ; Nanoparticles ; chemistry ; Temperature ; Urate Oxidase ; chemistry

OBJECTIVETo study the formulation and preparation of ampelopsin liposomes and evaluate their quality.

METHODThe liposomes were prepared by a film-ultrasonic dispersion technique. Served as quota with the entrapment ratio and appearance and diameter of the liposomes, the optimal formulation and preparation were selected by means of an uniform design test. The appearance of liposomes was observed by micrography. The diameter and electric charge of surface were determined by granularity mensuration instrument. The entrapment ratio and the leakage rate of ampelopsin liposome were determined by means of dialyze. The content of ampelopsin was determined by UV.

RESULTThe result of electron micrography and the size distribution showed that the liposomes were similar to spherical small unilamellar vesicles. The mean diameter was (258.2 +/- 51.2) nm and the electric charge of surface is 19.0 mV. The entrapment ratio of ampelopsin liposomes was 62. 3% and the lecithoid oxidative rate was 0.83% (n = 3).

CONCLUSIONThe selected formulation and preparation of ampelopsin liposomes is efficient and practicable.

Flavonoids ; chemistry ; Liposomes ; chemical synthesis ; chemistry ; Microscopy, Electron

OBJECTIVETo prepare the novel liposomes composed of hydrogenated soybean phosphatidylcholine (HSPC) and soybean phosphatidylcholine (SPC) containing the total alkaloids from seed of Strychnos nux-vomica, and to compare the pharmaceutical properties of the novel liposomes with the corresponding HSPC or SPC liposomes.

METHODThe total alkaloids were extracted from seeds of S. nux-vomica. and further purified. Novel liposomes containing the total alkaloids were prepared by ammonium sulfate transmembrane gradients and stealth liposome technique. Pharmaceutical properties such as encapsulation efficiency (EE), size, zeta potential and drug release profile of novel liposomes and corresponding HSPC or SPC liposomes were compared intensively.

RESULTFor novel liposomes, HSPC-SPC (1:3) was the best ratio which has the highest EE. At the drug/lipid weight ratio of 1:6, the EE of novel, SPC and HSPC liposomes were (73.6 +/- 2.9)%, (62.9 +/- 1.8)% and (54.7 +/- 1.0)% (n = 3), respectively. Compared with the corresponding SPC or HSPC liposomes, the size of novel liposomes was obviously decreased but the zeta potential was not different. The results of drug release showed that the novel liposomes were more stable than the SPC liposomes in the presence of rat plasma

CONCLUSIONTaken together, high encapsulation efficiency improved stability in blood, and relative low price of phospholipids of the novel liposomes, indicate that the novel liposomes may act as promising carriers for anti-tumor traditional Chinese medicine.

Alkaloids ; chemistry ; Animals ; Drug Carriers ; chemistry ; Liposomes ; chemistry ; Rats ; Seeds ; chemistry ; Strychnos nux-vomica ; chemistry

Polyethylene glycol (PEG) lipid derivatives could increase the stability of liposomes in vivo and in vitro and prolong the circulation time of liposomes in vivo. However, the chemical bond between PEG and lipid was so stable that liposomes modified with traditional PEG-lipid derivatives could not release their contents at targeted tissue immediately and the pharmacodynamic effect was reduced. The concept of cleavable PEG-lipid was raised in recent years and these PEG-lipid derivatives could break under physiological or pathological condition. The cleavable PEG-lipid derivatives could prolong the circulation time of liposomes, and after arriving at targeted location, PEG fragment had cleaved from the surface of liposomes, so liposomes could bind with pathological cells and release contents into cells. Removal of the protective polymer layer is necessary once the liposome close to the tumour to allow to fuse and release drug. Attempts have been made to increase the circulation time and reconstitute the cellular affinity of liposomes by incorporating PEG-lipid derivatives. This review focused on the kinds of cleavable PEG-lipid derivatives, types of cleavage, the application feature to liposomes and the advantages and localizations.
Cholesterol ; analogs & derivatives ; chemistry ; Drug Delivery Systems ; methods ; Humans ; Liposomes ; chemistry ; Phosphatidylethanolamines ; chemistry ; Polyethylene Glycols ; chemistry

OBJECTIVETo optimize the formulation of long-circulating solid lipid nanoparticles (LSLN) carrying ginkgolides A and B (GAB) extracted from traditional Chinese medicinal herbs.

METHODSGAB-LSLN was prepared by high pressure homogenization. The effects of such factors as the contents of glycerol monostearate, soybean lecithin and Myrj 59 on the mean diameter, entrapment efficiency and drug loading were investigated using central composite design and response surface method. The data were analyzed using multi-linear equation and second-order polynomial equation for selecting the optimal conditions for LSLN preparation.

RESULTSThe method of second-order polynomial equation was superior to multi-linear equation method in view of the multiple correlation coefficients. Under the optimal conditions, the mean diameter, entrapment efficiency, and drug loading of the GAB-LSLN were 169.5 nm, 92.3% and 5.1%, respectively.

CONCLUSIONThe optimized process for GAB-LSLN preparation is stable, feasible and allows high inclusion rate in the large-scale production of GAB-LSLN.

Delayed-Action Preparations ; chemical synthesis ; chemistry ; Drug Compounding ; methods ; Ginkgolides ; chemistry ; Lactones ; chemistry ; Liposomes ; Nanoparticles ; chemistry

Polyethylene glycol (PEG) is extensively used to increasing the in vivo and in vitro stability of liposomes. However, PEGylated liposomes also produce some negative effects with further research, such as low cellular uptake, poor "endosomal escape" of pH sensitive liposome (PSL) and accelerated blood clearance (ABC) phenomenon, and this situation is referred as the "PEG dilemma". "PEG dilemma" posed severe challenges for the targeted delivery of PEGylated liposomes-loaded anticancer drugs, effective intracellular release of PEGylated PSL-encapsulated gene and protein drugs, and repeated administration of PEGylated liposomes. Therefore, it is urgent to solve the "PEG dilemma". This review focused on the definition, classification of "PEG dilemma", and discussed several possible approaches to overcome "PEG dilemma".
Antineoplastic Agents ; chemistry ; Drug Carriers ; chemistry ; Liposomes ; chemistry ; Polyethylene Glycols ; chemistry

OBJECTIVETo discuss the feasibility of preparing gypenosides liposomes with sphingomyelin and cholesterol, and optimize the preparation process and prescription.

METHODGypenosides liposomes were prepared with sphingomyelin and cholesterol. The entrapment efficiency was determined by the protamine precipitation method. The entrapment efficiency was taken as the evaluation index to screen out the optimum preparation process for the new-type gypenosides liposomes. The preparation process was optimized by the orthogonal design. The new-type gypenosides liposomes were characterized by grain size, potential and atomic force microscope (AFM).

RESULTEthanol injection was the optimum process to prepare gypenosides liposome with sphingomyelin and cholesterol as follow: the ratio of gypenosides to sphingomyelin was 1: 10, the ratio of sphingomyelin to cholesterol was 4: 1, the pH of PBS buffer solution was 7.0, the hydration temperature was 45 degrees C, the entrapment efficiency was 79.06%, particle size was 191.4 nm, the Zeta potential was -33.16 mV, and the morphology were round under AFM.

CONCLUSIONIt was feasible to prepare gypenosides liposome with sphingomyelin and cholesterol. The gypenosides liposomes prepared by the optimum preparation process were good in morphology, particle size and reproducibility.

Cholesterol ; chemistry ; Drug Carriers ; chemistry ; Drug Compounding ; methods ; Gynostemma ; chemistry ; Liposomes ; chemistry ; Particle Size ; Plant Extracts ; chemistry ; Sphingomyelins ; chemistry