RESUMO
Oxidized pterins, efficient photosensitizers under UVA irradiation, accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder. Soybean phosphatidylcholine (SoyPC) liposomes were employed as model membranes to investigate if pterin (Ptr), the parent compound of oxidized pterins, is able to photoinduced lipid peroxidation. Size exclusion chromatography and dialysis experiments showed that Ptr is not encapsulated inside the liposomes and the lipid membrane is permeable to this compound. The formation of conjugated dienes and trienes, upon UVA irradiation, was followed by absorption at 234 and 270 nm, respectively. The photoproducts were characterized by mass spectrometry and oxygenation of SoyPC was demonstrated. In addition, analysis of MS/MS spectra suggested the formation hydroperoxides. Finally, the biological implications of the findings are discussed.
Assuntos
Peróxidos Lipídicos/química , Lipossomos/química , Fosfatidilcolinas/química , Fármacos Fotossensibilizantes/química , Pterinas/química , Peroxidação de Lipídeos/efeitos da radiação , Lipossomos/efeitos da radiação , Permeabilidade , Glycine max/química , Raios UltravioletaRESUMO
In Antarctica microorganisms are exposed to several conditions that trigger the generation of reactive oxygen species, such as high UV radiation. Under these conditions they must have an important antioxidant defense system in order to prevent oxidative damage. One of these defenses are pigments which are part of the non-enzymatic antioxidant mechanisms. In this work we focused on the antioxidant capacity of pigments from an Antarctic microorganism belonging to Pedobacter genus. This microorganism produces different types of pigments which belong to the carotenoids group. The antioxidant capacity of a mix of pigments was analyzed by three different methods: 1,1-diphenyl-2-picrylhydrazyl, ROS detection and oxygen electrode. The results obtained from these approaches indicate that the mix of pigments has a strong antioxidant capacity. The oxidative damage induced by UVB exposure to liposomes was also analyzed. Intercalated pigments within the liposomes improved its resistance to lipid peroxidation. Based on the analysis carried out along this research we conclude that the antioxidant properties of the mix of pigments protect this bacterium against oxidative damage. These properties make this mix of pigments a powerful antioxidant mixture with potential biotechnological applications.
Assuntos
Antioxidantes/metabolismo , Pedobacter/metabolismo , Pigmentos Biológicos/metabolismo , Regiões Antárticas , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Peroxidação de Lipídeos , Lipossomos/efeitos da radiação , Dados de Sequência Molecular , Estresse Oxidativo , Pedobacter/classificação , Pedobacter/genética , Pedobacter/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Raios UltravioletaRESUMO
It is desirable and challenging to prevent E-resveratrol (E-RSV) from photoisomerizing to its Z-configuration to preserve its biological and pharmacological activities. The aim of this research was to evaluate the photostability of E-RSV-loaded supramolecular structures and the skin penetration profile of chemically and physically stable nanoestructured formulations. Different supramolecular structures were developed to act as carriers for E-RSV, that is, liposomes, polymeric lipid-core nanocapsules and nanospheres and solid lipid nanoparticles. The degrees of photostability of these formulations were compared with that of an ethanolic solution of E-RSV. The skin penetration profiles of the stable formulations were obtained using vertical diffusion cells (protected from light and under UVA radiation) with porcine skin as the membrane, followed by tape stripping and separation of the viable epidermis and dermis in a heated water bath. Photoisomerization was significantly delayed by the association of resveratrol with the nanocarriers independently of the supramolecular structure. Liposomes were the particles capable of maintaining E-RSV concentration for the longest time. On the other hand, E-RSV-loaded liposomes reduced in size showing low physical stability under UVA radiation. In the dark, the skin penetration profiles were very similar, but under UVA radiation the E-RSV-loaded nanocarriers showed increasing amounts in the total epidermis.
Assuntos
Derme/metabolismo , Epiderme/metabolismo , Lipossomos/química , Nanocápsulas/química , Nanopartículas/química , Estilbenos/metabolismo , Estilbenos/efeitos da radiação , Administração Cutânea , Animais , Permeabilidade da Membrana Celular , Cromatografia Líquida de Alta Pressão , Cultura em Câmaras de Difusão , Estabilidade de Medicamentos , Etanol , Cinética , Lipossomos/efeitos da radiação , Lipossomos/ultraestrutura , Microscopia Eletrônica de Transmissão , Nanocápsulas/efeitos da radiação , Nanocápsulas/ultraestrutura , Nanopartículas/efeitos da radiação , Nanopartículas/ultraestrutura , Tamanho da Partícula , Fotólise , Resveratrol , Estilbenos/química , Suínos , Raios UltravioletaRESUMO
Membrane-modification effects, induced by ultraviolet (UV) irradiation in diacetylenic liposomes, were analyzed upon contact with cells, biological membranes, and proteins. Liposomes formulated with mixtures of unsaturated 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine and saturated 1,2-dimyristoyl-sn-glycero-3-phosphocholine, in a 1:1 molar ratio, were compared with those that were UV-irradiated and analyzed in several aspects. Membrane polymerization inherence on size stability was studied as well as its impact on mitochondrial and microsomal membrane peroxidation induction, hemolytic activity, and cell viability. Moreover, in order to gain insight about the possible irradiation effect on interfacial membrane properties, interaction with bovine serum albumin (BSA), lysozyme (Lyso), and apolipoprotein (apoA-I) was studied. Improved size stability was found for polymerized liposomes after a period of 30 days at 4°C. In addition, membrane irradiation had no marked effect on cell viability, hemolysis, or induction of microsomal and mitochondrial membrane peroxidation. Interfacial membrane characteristics were found to be altered after polymerization, since a differential protein binding for polymerized or nonpolymerized membranes was observed for BSA and Lyso, but not for apoA-I. The substantial contribution of this work is the finding that even when maintaining the same lipid composition, changes induced by UV irradiation are sufficient to increase size stability and establish differences in protein binding, in particular, reducing the amount of bound Lyso and BSA, without increasing formulation cytotoxicity. This work aimed at showing that the usage of diacetylenic lipids and UV modification of membrane interfacial properties should be strategies to be taken into consideration when designing new delivery systems.
Assuntos
Bicamadas Lipídicas/química , Bicamadas Lipídicas/farmacologia , Lipossomos/química , Lipossomos/farmacologia , Polimerização/efeitos da radiação , Ligação Proteica/efeitos da radiação , Animais , Apolipoproteína A-I/metabolismo , Bovinos , Linhagem Celular Transformada , Sobrevivência Celular/efeitos dos fármacos , Dimiristoilfosfatidilcolina/química , Di-Inos/química , Eritrócitos/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Bicamadas Lipídicas/metabolismo , Bicamadas Lipídicas/efeitos da radiação , Peroxidação de Lipídeos/efeitos dos fármacos , Lipossomos/metabolismo , Lipossomos/efeitos da radiação , Lipossomos/ultraestrutura , Camundongos , Microscopia Eletrônica de Varredura , Muramidase/metabolismo , Tamanho da Partícula , Fosfatidilcolinas/química , Albumina Sérica/metabolismo , Raios UltravioletaRESUMO
The antioxidant activity of catechin monomers and procyanidin (dimers to hexamers) fractions purified from cocoa was studied in two in vitro systems: liposomes and human LDL. Liposome oxidation (evaluated as formation of 2-thiobarbituric acid reactive substances) was initiated with 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH), 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN), iron/ascorbate, or UV-C; LDL oxidation (evaluated as formation of conjugated dienes) was initiated with Cu(2+) or AAPH. Catechin monomers and procyanidin fractions inhibited both liposome and LDL oxidation. Monomers, dimers, and trimers fractions were the most effective antioxidants when liposome oxidation was initiated in the aqueous phase. When oxidation was initiated in the lipid domains, higher molecular weight procyanidins were the most effective. All fractions significantly inhibited Cu-mediated LDL oxidation; no significant effect of procyanidin molecular weight was observed. The hexamer fraction was the least effective with respect to preventing AAPH initiated LDL oxidation. Results reported herein give further evidence on the influence of the oligomer chain length on the antioxidant protection by procyanidins.