Difuzija polifenolnih jedinjenja iz mikročestica dobijenih različitim tehnikama inkapsulacije
Diffusion of polyphenols from microparticles obtained from different encapsulation techniques
Author
Pravilović, Radoslava N.
Mentor
Bugarski, Branko
Committee members
Bošković-Vragolović, Nevenka
Pjanović, Rada

Đorđević, Verica
Nedović, Viktor

Metadata
Show full item recordAbstract
Sistemi za kontrolisano otpuštanje aktivnih supstanci predstavljaju istraživačku
oblast koja se intenzivno proučava zbog niza prednosti koje ovi sistemi pružaju i
mogućeg unapređenja dosadašnjih, tradicionalnih formi lekova.
Vodeni ekstrakt biljke majčine dušice je inkapsuliran u alginatne čestice, kao i
alginat-hitozan i alginat-inulin čestice elektrostatičkom ekstruzijom. Pored hidrogel
čestica, ispitivane su i suve i liofilisane forme.
Takođe, fosfolipidne mikročestice (lipozomi) su se pokazale potencijalno pogodnim
nosačima polifenolnih jedinjenja u sistemima ovog tipa.
Eksperimenti su izvedeni korišćenjem Franz–ove difuzione ćelije, u kojima je
praćena difuzija polifenola iz: čajnog ekstrakta, alginatnih čestica, alginat-hitozan,
alginat-inulin čestica, disperzije konvencionalnih lipozoma, disperzije lipozoma
modifikovanih Span-om 20, Span-om 40,Tween-om 20 i disperzije lipozoma
modifikovanih Tween-om 60. Obradom eksperimentalnih rezultata određeni su
koeficijenti difuzije za svak...i od sistema, kao i odgovarajući difuzioni otpori.
Dobijene alginatne čestice su bile veličine oko 730 μm, dok su lipozomi bili u
opsegu od 350 do 900 nm. Stepen inkapsulacije za alginante čestice je bio visok, preko
90 %. Osim toga, analiza je pokazala da postupak inkapsulacije nije degradirao
polifenolna jedinjenja, jer je ukupan sadržaj antioksidanasa ostao nepromenjen.
Odsustvo hemijskih interakcija između ekstrakta čaja i alginata je dokazano i FTIR
analizom.
Jedan od predmeta ovog rada je ispitivanje uticaja sastava membrane lipozoma na
brzinu oslobađanja inkapsuliranih polifenola. Eksperimentalna ispitivanja treba da
pokažu kako modifikacija membrane lipozoma utiče na prenos mase, u odosu na
konvencionalne lipozome. Lipozomi su modifikovani površinski aktivnim materijama
Span 20, Span 40, Tween 20 i Tween 60.
Takođe, na osnovu dobijenih rezultata se može zaključiti da se inkapsulacijom
polifenola u fosfolipidne mikročestice – lipozome, značajno usporava njihova difuzija, a
da se modifikacijom membrane može postići dodatno usporavanje prenosa mase, što
zavisi od strukture molekula kojim se modifikacija vrši. Molekuli Tween-a 20 su se
pokazali uspešnijim modifikatorima membrane lipozoma od molekula Tween-a 60.
Otpor koji membrana modifikovana Tween-om 20 pruža difuziji polifenola je veći i
dovodi do 4.93 puta sporije difuzije u odnosu na sistem sa neinkapsuliranim
polifenolima...
Polyphenols are compound which are widely studied because of their antioxidative
and potential therapeutic properties. Systems for the controlled release of drugs offer a
number of benefits comparing with traditional forms of medicines and because of that
these systems are widely researched.
Encapsulation of Thymus serpyllum L. aqueous extract within Ca-alginate beads was
studied in order to produce dosage formulations containing polyphenolic compounds.
Electrostatic extrusion was applied for encapsulation of thyme aqueous extract in
alginate gel beads. In addition to hydrogel beads, heat-dried and freeze-dried forms of
beads were examined.
The obtained beads with approximately 2 mg g-1 of gallic acid equivalents
encapsulated in 0.015 g ml-1 of alginate were uniformly sized spheres of about 730 μm.
Encapsulation efficiency varied in the range 80-98 % depending on the encapsulation
method. Besides, the analysis reveals that the encapsulation process and the material
used did not degrade... the bioactive compounds, as the total antioxidant content remained
unchanged. This was verified by the FTIR analysis proving the absence of chemical
interactions between extract compounds and alginate. Addition of a filler substance such
as sucrose and inulin in the dried product reduced its collapse and roundness distortion
during drying process.
Also, the objective of this paper is to investigate the possibility of using liposomes
as carriers of polyphenols and influence the membrane composition on the release rate
of encapsulated polyphenols.
Experiments show how the membrane modification affects the mass transfer
comparing to a conventional liposomes. Liposomes were modified with surfactants
Span 20, Span 40, Tween 20 and Tween 60, and thyme tea extract was used as a source
of polyphenols.
The diffusion of polyphenols from thyme extract, dispersion of conventional
liposomes and liposomes modified with Span 20, Span 40, Tween 20 and Tween 60 was
studied using Franz diffusion cell. From the experimental data diffusion coefficients
were determined for each of the systems, as well as the corresponding diffusion resistances...