Archaeosomes as carriers for antioxidants: a preliminary study of characteristics and stability

ANA GONZALEZ PAREDES; MARCOS ZARU; ME NADER-MACIAS; ANNA MARIA FADDA; MERCEDES MONTEOLIVA SANCHEZ

Patras, Grecia

Workshop; Nanomedicine, Nanoparticcules for Drug Delivery; 2008

Galeno¢¥¢¥s Network

Introduction: Antioxidants are pharmacologically active compounds with a wide potential use, both for human and animal applications. Previous studies were performed to identify and purify those present in higher concentrations in olive mill waste. Also, the extraction of lipids from Halobacterium salinarum for archaeosome preparation was standardized in our laboratory. Objectives: To evaluate the capability of archaeosomes to incorporate phenolic compounds obtained from two-phase olive mill waste (TPOMW). Conventional liposomes made with phosphatidylcholine mixtures were prepared as control. Methods: Antioxidant material from TPOMW was extracted with methanol, dried in a rotavapor and resuspended in water. Multilamellar vesicles (MLVs) were prepared according to the film hydration method. Sonicated small unilamellar vesicles (SUVs) were produced from MLV dispersions by sonication in ice bath. Phenolic compounds loaded vesicles were characterized by dynamic laser scattering for mean size distribution and Z potential; by TEM for vesicle morphology and by colorimetric assays for phenolic compounds concentration and entrapment efficiency (E%). In vitro skin permeation studies were performed by using newborn pig skin and vertical Franz diffusion cells.   Results: The phenolic extracts from TPOMW showed a satisfactory antioxidant activity during the extraction process. Archaeosomes, vesicles prepared with polar ether lipids extracted from Archaea, are thermostable and resistant to oxidation, as well as to chemical and enzymatic hydrolysis. Several archaeosomal formulations were prepared and characterized. Formulations containing lipid/cholesterol in 1:0.5 molar ratio showed the highest stability during 90 days of storage at 4¢ªC. Therefore, they were selected for further studies. Archaeosomes showed Z potential values more negative than those of traditional liposomes, while encapsulation efficiency was quite similar in both vesicular systems. In vitro skin permeation studies are still in progress, but preliminary results showed that phenolic compounds accumulate in the outermost skin layers, while no permeation occurred.   Conclusions: Preliminary results obtained in this work seem to indicate that archaeosomes may be  promising carriers for topical drug delivery.