Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, 90610-000, Porto Alegre, RS, Brazil.
J Biomed Nanotechnol. 2011 Aug;7(4):598-607. doi: 10.1166/jbn.2011.1318.
Lipoic acid is a widely studied substance, whose therapeutic effects are related to its antioxidant activity. Our objective was to develop lipoic acid-loaded lipid-core nanocapsules and evaluate their in vitro antioxidant effect against lipid peroxidation induced by ascorbyl free radicals, using soybean lecithin liposomes as the substrate. The nanocapsule suspensions were prepared by interfacial deposition of poly(epsilon-caprolactone) and characterized by particle size and polydispersion index (photon correlation spectroscopy), zeta potencial (eletrophoretic mobility), drug content and encapsulation efficiency (HPLC). The extent of lipid peroxidation was determined (TBARS). The nanostrucutures presented mean diameters of between 191 and 349 nm, zeta potential values from -14.1 +/- 4.5 to -10.4 +/- 0.6, and high lipoic acid encapsulation. A significant increase in the antioxidant activity of lipoic acid was achieved through nanoencapsulation or by increasing its concentration in the formulation. The protection results ranged from 48.9 +/- 3.4 to 57.4 +/- 9.1% for lipoic acid-loaded lipid-core nanocapsules. The lipoic acid release from nanostrucutures significantly decreased with increasing polymer concentration. Also, it was observed an increasing in the antioxidant activity as the lipoic acid release time decreased. The co-encapsulation of lipoic acid with melatonin in lipid-core nanocapsules did not improve the protection against lipid peroxidation. The results obtained demonstrate the optimal concentrations of polymer and lipoic acid in the formulations in terms of enhancing the antioxidant activity. Furthermore, by the strategy applied, it was verified that nanoencapsulation is an efficient alternative to increase the antioxidant effect of lipoic acid, representing a potential approach for therapeutic applications.
硫辛酸是一种广泛研究的物质，其治疗效果与其抗氧化活性有关。我们的目的是开发负载硫辛酸的脂质核纳米胶囊，并评估其对抗坏血酸自由基诱导的脂质过氧化的体外抗氧化作用，以大豆卵磷脂脂质体为底物。纳米胶囊混悬液通过界面沉积聚己内酯制备，并通过粒径和多分散指数（光相关光谱法）、zeta 电位（电泳迁移率）、药物含量和包封效率（HPLC）进行表征。脂质过氧化程度用 TBARS 法测定。纳米结构的平均粒径为 191 至 349nm，zeta 电位值为-14.1 ± 4.5 至-10.4 ± 0.6，并且硫辛酸包封率高。纳米封装或增加制剂中硫辛酸的浓度均可显著提高硫辛酸的抗氧化活性。负载硫辛酸的脂质核纳米胶囊的保护效果范围为 48.9 ± 3.4%至 57.4 ± 9.1%。随着聚合物浓度的增加，纳米结构中硫辛酸的释放显著减少。此外，随着硫辛酸释放时间的延长，抗氧化活性逐渐增加。将硫辛酸与褪黑素共包封在脂质核纳米胶囊中并没有提高对脂质过氧化的保护作用。研究结果表明，在提高抗氧化活性方面，制剂中聚合物和硫辛酸的最佳浓度是最佳的。此外，通过应用的策略，验证了纳米封装是提高硫辛酸抗氧化效果的有效方法，代表了治疗应用的一种潜在方法。
