Liposomes and liposomes-alginate systems for controlled release of resveratrol.

Abstract

Resveratrol is in the limelight all over the world as a health-beneficial compound widely investigated as natural antioxidant suitable for prevention of human cardiovascular diseases and inhibition of low-density lipoproteins oxidation. Nonetheless, it is prone to oxidation, poorly soluble in water, poorly bioavailable, and characterized by weak absorption after oral administration and rapid metabolism in vivo. Moreover, the addition of antioxidants to aqueous-based food and pharmaceutical products can be limited due to their troublesome characteristics. Liposomes are well known carriers that may be used to overcome these disadvantages. They can be prepared using only natural components and therefore the new formulations could be quickly implemented. In this doctoral thesis different methods were tested for design of liposomes aimed at effective encapsulation of resveratrol. Liposomes were prepared with a commercial lipid mixture of phospholipids using thin film and proliposome method and further investigated and compared from the aspect of size distribution, surface charge, entrapment efficiency, phase behaviour and stability. Both methods provided high entrapment efficiency (92.9% and 97.4%, respectively), but proliposome method is more convenient for the industrial application. Extrusion and sonication techniques were applied to obtain smaller liposomes of the average diameter between 120 and 270 nm. The sonicated liposomes incorporated resveratrol (44–56%) fewer than extruded vesicles (92–96%). Furthermore, the antioxidative activity of encapsulated resveratrol was examined. The results showed that it was retained upon encapsulation and the antioxidant activity of resveratrol was also confirmed by its 95% inhibition of lipid peroxidation, compared to liposomes without resveratrol exposed to the same conditions...

Resveratrol je prirodni antioksidans koji budi velika interesovanja širom sveta zbog svog pozitivnog dejstva na zdravlje ljudi. Ipak, ovaj antioksidans je izuzetno podložan oksidaciji, slabo rastvoran u vodi, ima malu bioraspoloživost i slabo se apsorbuje nakon oralne administracije. Dodatak resveratrola prehrambenim i farmaceutskim proizvodima na bazi vode problematičan je upravo zbog ovih karakteristika. Jedna vrsta nosači koja može da omoguće prevazilaženje nedostataka koje resveratrol ima su lipozomi. Lipozomi mogu da se pripreme upotrebom prirodnih komponenti pa je stoga njihova primena znatno olakšana. U ovoj doktorskoj disertaciji upoređene su različite metode za pripremu lipozoma sa inkapsuliranim resveratrolom. Za pripremu lipozoma korišćena je komercijalna lipidna smeša, a od metoda primenjene su metoda tankog filma i prolipozomna metoda koje daju velike lipozome. Tako pripremljeni lipozomi ispitani su sa stanovišta raspodele veličina, površinskog naelektrisanja, stepena inkapsulacije, fazne transformacije i stabilnosti. Pokazano je da obe metode obezbeđuju visok procenat inkapsulacije resveratrola (92,9% i 97,4%, respektivno), ali prolipozomna metoda ima prednost nad metodom tankog filma zbog većih mogućnosti za uvećanje razmera proizvodnje. Ekstruzija i sonikacija primenjene su na prethodno formirane velike lipozome kako bi se smanjila njihova veličina i povećala uniformnost. Ipak, sonikacijom dolazi do gubitka resveratrola pa je procenat inkapsulacije između 44 i 56%, dok je kod ekstruzije ovaj procenat i dalje visok (92–96%)...