Glycolipid Biosurfactants in Skincare Applications: Challenges and Recommendations for Future Exploitation

Abstract

The 21st century has seen a substantial increase in the industrial applications of glycolipid biosurfactant technology. The market value of the glycolipid class of molecules, sophorolipids, was estimated to be USD 409.84 million in 2021, with that of rhamnolipid molecules projected to reach USD 2.7 billion by 2026. In the skincare industry, sophorolipid and rhamnolipid biosurfactants have demonstrated the potential to offer a natural, sustainable, and skin-compatible alternative to synthetically derived surfactant compounds. However, there are still many barriers to the wide-scale market adoption of glycolipid technology. These barriers include low product yield (particularly for rhamnolipids) and potential pathogenicity of some native glycolipid-producing microorganisms. Additionally, the use of impure preparations and/or poorly characterised congeners as well as low-throughput methodologies in the safety and bioactivity assessment of sophorolipids and rhamnolipids challenges their increased utilisation in both academic research and skincare applications. This review considers the current trend towards the utilisation of sophorolipid and rhamnolipid biosurfactants as substitutes to synthetically derived surfactant molecules in skincare applications, the challenges associated with their application, and relevant solutions proposed by the biotechnology industry. In addition, we recommend experimental techniques/methodologies, which, if employed, could contribute significantly to increasing the acceptance of glycolipid biosurfactants for use in skincare applications while maintaining consistency in biosurfactant research outputs.

Purified Acidic Sophorolipid Biosurfactants in Skincare Applications: An Assessment of Cytotoxic Effects in Comparison with Synthetic Surfactants Using a 3D In Vitro Human Skin Model

“…It should be noted that sophorolipids could only be used as a substitute to synthetic surfactants if they are able to demonstrate equal or better performance in skincare formulation at a reasonable market price [55,56]. Therefore, having demonstrated that the Acidic SL utilised in the present study have comparable effects with SLES on the 3D in vitro skin model, in addition to being produced from sustainable natural resources (e.g., industrial waste materials such as vegetal cooking oil waste), and having enhanced solubilisation and foaming functions, Acidic SL could offer a potential natural/sustainable alternative to SLES in skincare applications [5,56].…”

“…The development of skincare routines with ingredients that have little or no deleterious effects on the healthy human skin and the skin microbiome, and/or with added functionalities such as skin surface moisturisation, microbiome restoration, and immunomodulation in diseased skin, is highly desirable in the formulation of skincare products [1][2][3]. However, surface active agents including sodium lauryl ether sulphate (SLES), which are a major component of many skincare formulations, are mostly synthesised from less sustainable and poorly degradable petrochemical resources [1,4,5]. In addition, these surfactants are reported to have the potential to cause skin irritation, allergic reaction, and skin microbiome dysbiosis, as well as contributing to ecotoxicity [2,4].…”

“…In particular, acidic sophorolipids (Acidic SL), which are a congener of sophorolipids, have been demonstrated to have little or no cytotoxic effects on human keratinocytes and skin dermal fibroblastic cells when assessed in vitro for potential use in skincare applications [7,8,12]. However, a major limitation to the skincare applications of sophorolipid biosurfactants has been the unwillingness to incorporate crude, impure, and/or poorly characterised sophorolipid congeners into skincare products [5,13]. Such a drawback stems from requirements by the EU Cosmetic Legislation (2013/674/EU) for manufacturers to specify the purity, molecular weight, and physio/bio-chemical properties of compounds used in formulations (extensively reviewed elsewhere by Adu and colleague) [5,13].…”

“…However, a major limitation to the skincare applications of sophorolipid biosurfactants has been the unwillingness to incorporate crude, impure, and/or poorly characterised sophorolipid congeners into skincare products [5,13]. Such a drawback stems from requirements by the EU Cosmetic Legislation (2013/674/EU) for manufacturers to specify the purity, molecular weight, and physio/bio-chemical properties of compounds used in formulations (extensively reviewed elsewhere by Adu and colleague) [5,13]. In addition, most studies on the cytotoxicity assessment of Acidic SL were conducted using 2D in vitro cultures; this allowed for the experimentation on a monolayer of cells only (e.g., keratinocytes and dermal fibroblasts) as opposed to the myriad tissues that make up the complex in vivo human skin [7,8,12,[14][15][16].…”

Sustainable biosurfactant production from secondary feedstock—recent advances, process optimization and perspectives

“…Lactonic sophorolipids and mono-rhamnolipids displayed selective inhibitory effects, significantly impairing melanoma cell viability at a concentration of 40 μg mL −1 , compared to a higher concentration of 60 μg mL −1 for healthy human keratinocytes. Necrosis was identified as the primary mechanism of cell death induced by these glycolipids (Feuser et al, 2021a;Adu et al, 2022).…”