Glycolipid Biosurfactants as Multifunctional Ingredients in Leave-On Skin Care Formulations: Properties, Performance, and Clean Beauty Applications

Objective(s): To characterize the structural chemistry, physicochemical properties, skin bioactivities, formulation aspects, sustainability, therapeutic applications, commercialization, and regulatory aspects of sophorolipids, rhamnolipids, and mannosylerythritol lipids as biosurfactants with focus on their potential in leave-on cosmetic and topical pharmaceutical formulations, as well as highlight research and development gaps. Data sources: Peer-reviewed scientific publications, patents, and market reports, as well as regulatory guidelines from the EU (Regulation (EC) No 1223/2009, and related Commission implementing acts), the US (FDA; Modernization of Cosmetics Regulation Act), and other regions. Study selection: All reports, patents, and publications addressing any aspect of the structure-property-performance-benefit relations of sophorolipids, rhamnolipids, and mannosylerythritol lipids as biosurfactants for cosmetic and/or pharmaceutical applications were included. A preference was given to primary studies reporting experimentally obtained data over reviews and other secondary sources. Summary of contents: The present review discusses the differences in the amphiphilic structure of sophorolipids, rhamnolipids, and mannosylerythritol lipids and their impact on the performance in leave-on and rinse-off formulations. The moisturizing, anti-inflammatory, and antimicrobial activities of glycolipids, as well as their emulsifying properties and versatility in formulation design, were also described. The commercial status of glycolipid biosurfactants, analytical techniques for physicochemical characterization, and regulatory aspects of their use in cosmetics and topical pharmaceutical formulations were briefly outlined and discussed in relation to sustainability. Conclusion: Sophorolipids, rhamnolipids, and mannosylerythritol lipids are promising biosurfactants with a variety of beneficial properties for leave-on topical formulations and drug delivery; however, their clinical applications still require further validation, and their cost-effectiveness needs to be proved. Keywords: Glycolipid biosurfactants; sophorolipids; rhamnolipids; mannosylerythritol lipids; leave-on cosmetics; topical drug delivery; skin barrier function