Lee_2025_Enzyme.Microb.Technol_189_110672

Chemical preservatives have been traditionally used to enhance the shelf life of cosmetics; however, due to rising concerns regarding their potential adverse effects on human health, there has been an increasing shift towards the use of natural antibacterial agents. Castor oil, predominantly composed of ricinoleic acid, has demonstrated potential as an antibacterial agent. This study aimed to synthesize a multifunctional compound by combining ricinoleic acid, known for its antimicrobial properties, with ergosterol, recognized for its cholesterol-lowering effects. In this study, we synthesized ricinoleic acid ergosterol ester (RAEE) using castor oil and ergosterol as substrates and Proteus vulgaris K80 lipase as the catalyst. RAEE was purified using Prep-LC and its purity was verified through LC-MS analysis. Zeta potential measurements on bacterial cell membranes indicated RAEE's capability to adhere to bacterial surfaces. When administered in an emulsion formulation, RAEE exhibited antibacterial activity against Bacillus subtilis and Pseudomonas fluorescens. Additionally, propidium iodide uptake assays and fluorescence microscopy showed that RAEE induced bacterial cell death by increasing membrane permeability. Scanning electron microscopy of RAEE-treated bacteria revealed roughened cell surfaces with abnormal features, illustrating RAEE's substantial potential as a natural preservative in the cosmetics industry.