Formulation, characterization and in vitro bioaccessibility evaluation of mixed soy lecithin-based squalene liposome-encapsulated quercetin with added phytosterols
Liposomes, resembling biomembranes, are effective delivery systems for lipid bioactive compounds but face instability from various stressors. Understanding the impact of incorporated materials on membrane integrity is crucial. Squalene (SQ) conjugation to phospholipids enhances lipophilicity, whi...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/113801/1/113801%28UPM%20A%29.pdf |
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| Summary: | Liposomes, resembling biomembranes, are effective delivery systems for lipid
bioactive compounds but face instability from various stressors. Understanding the
impact of incorporated materials on membrane integrity is crucial. Squalene (SQ)
conjugation to phospholipids enhances lipophilicity, while cholesterol (CH), β-
sitosterol (βS), and stigmasterol (ST) modify membrane properties. However,
quercetin's (QU) insolubility hampers absorption, necessitating novel nanovesicles for
solubilization.
In the first part of the study, the effect of membrane composition and concentrations
on the degradation of mixed soy lecithin (ML)-based liposomes was investigated.
Liposomes were prepared using SQ, CH, and Tween 80 (TW80) to increase bilayer
deformability. Liposome batches were prepared with and without SQ, and their zeta
potential, particle size, and antioxidant activity against UV-induced ROS generation
were evaluated. Results showed SQ association reduced size without extra energy
input and improved stability and antioxidant activity. Additionally, different lipid
compositions significantly influenced physical and chemical characteristics.
The second part focused on enhancing the photostability, integrity, and antioxidant
capacity of ML-based liposomes by adjusting the formulation within the membrane.
QU encapsulation in ML-based liposomes and the concentration-dependent solubility
of QU were investigated. A combination of βS and ST was used to modulate ML
bilayers, maintaining liposome function. Encapsulation efficiency measurements
revealed effective QU encapsulation using specific concentrations of βS and ST. The
presence and type of phytosterols affected membrane integration characteristics and
photostability.
In the subsequent part, the effects of environmental conditions on liposome stability
and antioxidant capacity were evaluated. Liposomes stored at 4°C for 8 weeks showed
decreased stability over time, but remained stable for the first 6 weeks. Differential
scanning calorimetry results showed desirable interaction with liposome membrane
models. X-ray diffraction patterns revealed variations in lattice distortion and
structural disorder upon changing membrane composition.
Finally, the in vitro bio-accessibility of QU-loaded ML-based liposomes was
examined. Different membrane stabilizers influenced QU bio-accessibility,
correlating with entrapment efficacy. The phase transition temperature in liposomes
changed with the addition of stabilizers, indicating enhanced membrane stability. This
highlights the potential of well-designed ML-based liposomes to increase the stability
and bio-accessibility of lipophilic bioactives like QU.
In conclusion, the presence of different lipid compositions significantly influenced the
physicochemical characteristics of the liposomes, including entrapment efficacy and
photodamage transformation. |
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