engleski

Proliposomal encapsulation of quercetin extracts from onion peel

Quercetin and typical flavonoids present in onion peel draw interest due to bioactive properties. They have numerous beneficial effects like anti obesity, antioxidant, anti- inflammatory and anticancer. The aim of this research was to extract quercetin from onion peel and to increase its bioavailability and stability by liposomal encapsulation. Liposomes are made of bilayers of amphiphilic molecules (such as phospholipids) which enable encapsulation both hydrophilic and lipophilic particles. For utilizing quercetin from onion peel, conventional solvent (70% ethanol)extraction was used and the amount of quercetin in this extract was determined by HPLC-PDA. Both quercetin standard and onion peel extract were encapsulated in liposomes, using different ratios between standard/extract and liposomes (1:20 and 1:100), in order to compare their encapsulation efficiency. The greatest encapsulation efficiency was observed for the quercetin standard prepared with liposomes in ratio 1:20 (87.06±1.13%), while encapsulation efficiency of quercetin from onion peel extract, was lower (75.81±2.12%) at the same conditions. The stability of encapsulated quercetin was followed for 30 days using HPLC- PDA. The interactions between quercetin and lipids were characterised by fluorescence polarisation measurements, electronic paramagnetic spectrometry and differential scanning calorimetry. Quercetin caused a small thermal destabilisation of DPPC transition which shows that the molecules interacted mainly with the polar headgroup regions of the bilayer. Onion peel presents a rich source of quercetin which could be employed in the formation of stable functional dosage forms.

proliposomes ; quercetin ; encapsulation ; onion peel

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