Development of a multifunctional and self-preserving cosmetic formulation using sophorolipids and palmarosa essential oil against acne-causing bacteria

Abstract Aims The objective of this study was to evaluate the antibacterial effect of sophorolipids in combination with palmarosa essential oil and to develop a cosmetic formulation against acne-causing bacteria. Methods and Results The antibacterial activity of sophorolipids, palmarosa oil and their combined effect was evaluated by broth microdilution and checkerboard methods. Antioxidant activity was determined by the DPPH method. The results showed that the compounds presented antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis. The combination of sophorolipid and palmarosa oil resulted in synergistic and additive interaction reducing the concentration needed for the effectiveness against S. aureus and S. epidermidis, to 98.4% and 50%, respectively. The compounds interaction showed an additive effect for antioxidant activity. The cosmetic formulation without any chemical preservative presents antibacterial activity against S. aureus, S. epidermidis and Cutibacterium acnes. The pH values and organoleptic characteristics of formulations remained stable under all conditions tested. Conclusions The association of sophorolipids and palmarosa oil resulted in a self-preserving cosmetic formulation with great stability, and effective antioxidant and antibacterial activities against acne-causing micro-organisms. Significance and Impact of the Study This study showed the development of an effective multifunctional cosmetic formulation with natural preservatives to treat acne vulgaris and other skin infections.