Khan Hira, Akhtar Naveed, Ali Atif, Khan Haji M Shoaib, Sohail Muhammad, Naeem Muhammad, Nawaz Zarqa
Acta Pol Pharm. 2016 Sep;73(5):1339-1349.
Stability of hydrophilic and lipophilic vitamin C derivatives for quenching synergistic antioxidant activities and to treat oxidative related diseases is a major issue. This study was aimed to encapsulate hydrophilic and lipophilic vitamin C derivatives (ascorbyl palmitate and sodium ascorbyl phosphate) as functional ingredients in a newly formulated multiple emulsion of the W//W type to attain the synergistic antioxidant effects and the resultant system's long term physical and chemical stability. Several multiple emulsions using the same concentration of emulsifiers but different concentrations of ascorbyl palmitate and sodium ascorbyl phosphate were developed. Three finally selected multiple emulsions (ME₁, ME₂ and ME₃) were evaluated for physical stability in terms of rheology, microscopy, conductivity, pH, and organoleptic characteristics under different storage conditions for 3 months. Chemical stability was determined by HPLC on Sykam GmbH HPLC system (Germany), equipped with a variable UV detector. Results showed that at accelerated storage conditions all the three multiple emulsions had shear thinning behavior of varying shear stress with no influence of location of functional ingredients in a carrier system. Conductivity values increased and pH values remained within the skin pH range for 3 months. Microscopic analysis showed an increase in globule size with the passage of time, especially at higher temperatures while decreased at low temperatures. Centrifugation test did not cause phase separation till the 45th day, but little effects after 2 months. Chemical stability analysis by HPLC at the end of 3 months showed that ascorbyl palmitate and sodium ascorbyl phosphate were almost stable in all multiple emulsions with no influence of their location in a carrier system. Multiple emulsions were found a stable carrier for hydrophilic and lipophilic vitamin C derivatives to enhance their desired effects. Considering that many topical formulations contain simple vitamin C it is suggested that present study may contribute to the development of more stable formulations with a combination of vitamin C derivatives to enhance their cosmetic benefits.
亲水性和亲脂性维生素C衍生物在淬灭协同抗氧化活性及治疗氧化相关疾病方面的稳定性是一个主要问题。本研究旨在将亲水性和亲脂性维生素C衍生物（棕榈酸抗坏血酸酯和抗坏血酸钠磷酸酯）作为功能成分包封在新配制的W//W型多重乳液中，以实现协同抗氧化作用以及所得体系的长期物理和化学稳定性。制备了几种使用相同浓度乳化剂但不同浓度棕榈酸抗坏血酸酯和抗坏血酸钠磷酸酯的多重乳液。对最终选定的三种多重乳液（ME₁、ME₂和ME₃）在不同储存条件下进行3个月的流变学、显微镜检查、电导率、pH值和感官特性方面的物理稳定性评估。化学稳定性通过配备可变紫外检测器的德国Sykam GmbH高效液相色谱系统进行高效液相色谱测定。结果表明，在加速储存条件下，所有三种多重乳液均具有不同剪切应力的剪切变稀行为，功能成分在载体体系中的位置对此无影响。电导率值增加，pH值在3个月内保持在皮肤pH范围内。显微镜分析表明，随着时间的推移，液滴尺寸增大，尤其是在较高温度下，而在低温下减小。离心试验在第45天之前未引起相分离，但2个月后影响较小。3个月末通过高效液相色谱进行的化学稳定性分析表明，棕榈酸抗坏血酸酯和抗坏血酸钠磷酸酯在所有多重乳液中几乎稳定，其在载体体系中的位置对此无影响。发现多重乳液是亲水性和亲脂性维生素C衍生物的稳定载体，可增强其预期效果。鉴于许多局部用制剂含有单纯的维生素C，建议本研究可能有助于开发更稳定的含有维生素C衍生物组合的制剂，以增强其美容益处。
