Moyano M A, Segall A
Cátedra de Control de Calidad de Medicamentos, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina.
J Cosmet Sci. 2011 Jul-Aug;62(4):405-15.
Skin becomes thin, dry, pale, and finely wrinkled with age. Retinoids are a large class of compounds that are important in modern therapy for dermatological treatment of wrinkled skin. Of the retinoids, retinol and vitamin A palmitate are thought to induce thickening of the epidermis and to be effective for treatment of skin diseases. Accordingly, α-lipoic acid or the reduced form, dihydrolipoate, are potent scavengers of hydroxyl radicals, superoxide radicals, peroxyl radicals, singlet oxygen, and nitric oxide with anti-inflammatory properties (1). Cosmetic ingredient stability prediction relies on kinetic quantitative chemical analysis of active components at different temperatures. Vitamin A palmitate and α-lipoic acid, are known to be unstable to light or heat (2). The aims of this study were to evaluate the stability of α-lipoic acid and vitamin A palmitate in the presence of vitamin E (acetate) and other antioxidants in lipophilic/hydrophilic medium (O/W emulsions) at pH 3.0, 5.0, and 7.0. The formulations that were investigated contained 0.12% (w/w) vitamin A palmitate, 0.4% (w/w) vitamin E acetate, and 0.5 % α-lipoic acid (formulation A), supplemented with ascorbyl palmitate, magnesium ascorbyl phosphate, and vitamin C (formulation B) or with butylhydroxytoluene (BHT, formulation C) or ascorbyl palmitate (formulation D). The chemical analyses of α-lipoic acid and vitamin A palmitate were carried out by HPLC. Formulations C and D at pH 7.0 were selected as the most stable for these components. The purpose of this paper is the selection of the most stable formulations for their application in in vivo studies.
随着年龄增长，皮肤会变薄、干燥、苍白且出现细纹。维甲酸是一大类化合物，在现代治疗皱纹皮肤的皮肤科治疗中很重要。在维甲酸中，视黄醇和维生素A棕榈酸酯被认为可诱导表皮增厚，对皮肤病治疗有效。因此，α-硫辛酸或其还原形式二氢硫辛酸是羟基自由基、超氧自由基、过氧自由基、单线态氧和一氧化氮的有效清除剂，具有抗炎特性(1)。化妆品成分稳定性预测依赖于不同温度下活性成分的动力学定量化学分析。已知维生素A棕榈酸酯和α-硫辛酸对光或热不稳定(2)。本研究的目的是评估在pH值为3.0、5.0和7.0的亲脂性/亲水性介质（水包油乳液）中，α-硫辛酸和维生素A棕榈酸酯在维生素E（醋酸酯）和其他抗氧化剂存在下的稳定性。所研究的配方含有0.12%（w/w）维生素A棕榈酸酯、0.4%（w/w）维生素E醋酸酯和0.5%α-硫辛酸（配方A），补充了棕榈酰维生素C、抗坏血酸磷酸镁和维生素C（配方B）或丁基羟基甲苯（BHT，配方C）或棕榈酰维生素C（配方D）。通过高效液相色谱法对α-硫辛酸和维生素A棕榈酸酯进行化学分析。pH值为7.0的配方C和配方D被选为这些成分最稳定的配方。本文的目的是选择最稳定的配方用于体内研究。
