Department of Pharmaceutical Technology and Biopharmaceutics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120, Halle (Saale), Germany.
Department of Pharmaceutics and Social Pharmacy, School of Pharmacy, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia.
Anal Bioanal Chem. 2018 Aug;410(20):4775-4785. doi: 10.1007/s00216-018-1162-z. Epub 2018 Jun 9.
Ceramides (CERs) are the backbone of the intercellular lipid lamellae of the stratum corneum (SC), the outer layer of the skin. Skin diseases such as atopic dermatitis, psoriasis, and aged skin are characterized by dysfunctional skin barrier and dryness which are associated with reduced levels of CERs. Replenishing the depleted epidermal CERs with exogenous CERs has been shown to have beneficial effects in improving the skin barrier and hydration. The exogenous CERs such as phyto-derived CERs (PhytoCERs) can be delivered deep into the SC using novel topical formulations. This, however, requires investigating the rate and extent of skin permeation of CERs. In this study, an LC/APCI-MS method to detect and quantify PhytoCERs in different layers of the skin has been developed and validated. The method was used to investigate the skin permeation of PhytoCERs using Franz diffusion cells after applying an amphiphilic cream containing PhytoCERs to the surface of ex vivo human skin. As plant-specific CERs are not commercially available, well-characterized CERs isolated from oat (Avena abyssinica) were used as reference standards for the development and validation of the method. The method was linear over the range of 30-1050 ng/mL and sensitive with limit of detection and quantification of 10 and 30 ng/mL, respectively. The method was also selective, accurate, and precise with minimal matrix effect (with mean matrix factor around 100%). Even if more than 85% of oat CERs in the cream remained in the cream after the incubation periods of 30, 100, and 300 min, it was possible to quantify the small quantities of oat CERs distributed across the SC, epidermis, and dermis of the skin indicating the method's sensitivity. Therefore, the method can be used to investigate the skin permeation of oat CERs from the various pharmaceutical and cosmeceutical products without any interference from the skin constituents such as the epidermal lipids. Graphical abstract ᅟ.
神经酰胺（CERs）是皮肤角质层（SC）细胞间脂质层的骨架，角质层是皮肤的外层。特应性皮炎、银屑病和衰老皮肤等皮肤疾病的特征是皮肤屏障功能障碍和干燥，这与 CERs 水平降低有关。用外源性 CERs 补充耗竭的表皮 CERs 已被证明对改善皮肤屏障和保湿具有有益作用。新型局部制剂可将植物源性 CERs（PhytoCERs）等外源性 CERs 递送至 SC 深部。然而，这需要研究 CERs 的皮肤渗透速率和程度。在这项研究中，开发并验证了一种 LC/APCI-MS 方法，用于检测和定量皮肤不同层中的 PhytoCERs。该方法用于研究含有 PhytoCERs 的两性乳膏涂于离体人皮肤表面后 PhytoCERs 的皮肤渗透情况。由于植物特异性 CERs 无法商业化获得，因此使用从燕麦（Avena abyssinica）中分离出的特征明确的 CERs 作为参考标准，用于开发和验证该方法。该方法在 30-1050ng/mL 范围内呈线性，检测限和定量限分别为 10 和 30ng/mL，灵敏度高。该方法还具有选择性、准确性和精密度，基质效应最小（平均基质因子约为 100%）。即使在孵育 30、100 和 300min 后，乳膏中超过 85%的燕麦 CERs 仍留在乳膏中，也能够定量分析分布在 SC、表皮和皮肤真皮中的少量燕麦 CERs，表明该方法具有较高的灵敏度。因此，该方法可用于研究各种药物和化妆品产品中燕麦 CERs 的皮肤渗透情况，而不会受到皮肤成分（如表皮脂质）的干扰。
