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Liposomes encapsulating catechins: a biophysical approach for skin cancer therapy
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Resumo(s)
Every year, a large number of skin cancer cases caused by a prolonged ultraviolet
radiation exposure, are diagnosed around the world. Epigallocatechin–3–
gallate (EGCG) derived from green tea leaves, display protective effect against
oxidative stress which reduce the risk of contracting skin cancer. However, frequently,
the antioxidant and anti–inflammatory activities of EGCG in are compromised
because this molecule is extremely unstable and rapidly degraded in
physiological conditions. Considering these issues, the main goal of this thesis
was developed a stable liposomal nanocarrier for topical/transdermal delivery of
EGCG, firstly, to increase its bioavailability and, secondly, to offer an desirable
skin protection against harmful effects of UV radiation. Primarily, the molecular
mechanisms between EGCG and different phospholipids were studied using
Langmuir experiments, revealling the affinity and localization of EGCG on each
lipidic membrane, which according to the results depends on the molecular organization
of lipidic monolayer (functional groups anchored at headgroup) and of
the degree of protonation of EGCG. EGCG establishes electrostatic and hydrogenbonding
interactions with zwitterionic (DMPC, DPPC) and anionic (DPPG and
DPPS) phospholipids, which condense the monolayers and alter the membrane’s
potential and compressibility. Regarding the irradiation experiments, the results
indicated that EGCG efficiently slows down the oxidant events in monolayers and
in lipid bilayers, which were produced by blue and ultraviolet radiation exposure,
respectively. Lastly, the nanofibers meshes containing EGCG-loaded liposomes
are biocompatible, support human fibroblasts adhesion and scavenge the oxidant
species generated by UV radiation, which guarantees a higher cell survival.
Descrição
Palavras-chave
skin cancer oxidative stress EGCG liposomes wound healing