Institute of Applied Dermatopharmacy, Martin Luther University Halle-Wittenberg, Halle/Saale.
Phospholipid Research Center, Heidelberg.
Pharmazie. 2020 Aug 1;75(8):365-370. doi: 10.1691/ph.2020.9174.
Natural phospholipid (PL) excipients are native, biocompatible and relatively inexpensive alternatives to synthetic emulsifiers. A well-known PL excipient is lecithin, which primarily contains phosphatidylcholine (PC) and (depending on the purity grade) also contains a well-defined mixture of other PLs with a fatty acid composition, which reflects their natural source. Since all of these lipid species are emulsifiers, natural PLs can be considered as a mixture of (co-) emulsifiers. Many different HLB values for lecithins are given in the literature, which is why this needs to be clarified. To assess this, HLB values of thirteen different plant derived PLs differing in PC content were determined using a centrifugation stress method to determine the relative stability of an emulsion with the respective emulsifier and different oil phases. It could be shown that the studied PLs can be characterized by a broad HLB range, which may be linked to the composition of the PLs and the oil used. In order to emphasize the results of the HLB determination, it could be demonstrated that stable emulsions could be prepared with a wide range of oils using the plant-based PLs and that the preparation method of the emulsions is important in order to obtain stable emulsions. Therefore, assigning a specific exact HLB value to natural PLs instead of a wider range is inappropriate. The broad HLB ranges indicate the suitability of the studied PL emulsifiers for the preparation of oil-in-water emulsions for a wide range of oils: It is recommended to experimentally evaluate the suitability of these natural emulsifiers for the preparation of stable emulsions and to benefit from the wide range of HLB values of these emulsifiers instead of relying on inaccurate and confusing HLB values in the literature.
天然磷脂 (PL) 赋形剂是天然的、生物相容的，且相对便宜，可替代合成乳化剂。一种广为人知的 PL 赋形剂是卵磷脂，它主要含有磷脂酰胆碱 (PC)，并且（取决于纯度等级）还含有定义明确的其他 PL 混合物，其脂肪酸组成反映了它们的天然来源。由于所有这些脂质种类都是乳化剂，因此天然 PL 可以被认为是（共）乳化剂的混合物。文献中给出了许多不同的卵磷脂 HLB 值，因此需要对此加以澄清。为了评估这一点，使用离心力法测定了十三种不同的植物源性 PL 中 PC 含量的 HLB 值，以确定具有各自乳化剂和不同油相的乳液的相对稳定性。结果表明，所研究的 PL 可以用较宽的 HLB 范围来表征，这可能与 PL 的组成和所用的油有关。为了强调 HLB 测定的结果，可以证明使用植物源性 PL 可以用较宽的油范围来制备稳定的乳液，并且乳液的制备方法对于获得稳定的乳液很重要。因此，将特定的确切 HLB 值分配给天然 PL 而不是更宽的范围是不恰当的。较宽的 HLB 范围表明所研究的 PL 乳化剂适用于制备各种油的水包油乳液：建议通过实验评估这些天然乳化剂用于制备稳定乳液的适用性，并利用这些乳化剂广泛的 HLB 值，而不是依赖文献中不准确和令人困惑的 HLB 值。
