Formulation and Antibacterial Evaluation of a Glycerin Soap Incorporated with Cymbopogon citratus Essential Oil

Abstract

oap remains one of the most widely used hygiene products for reducing microbial contamination of the skin. In recent years, interest has increased in the development of natural antimicrobial agents as alternatives to synthetic antiseptics. The present study aimed to formulate a glycerin-based soap incorporating Cymbopogon citratus essential oil and to evaluate its physicochemical properties and antibacterial activity. Different soap formulations were prepared using coconut oil, sodium hydroxide, glycerin, ethanol, sugar and distilled water. Increasing concentrations of Cymbopogon citratus essential oil (0.5–2.5%) were incorporated to obtain formulations S1–S5, while S0 served as the reference formulation without essential oil. The physicochemical properties of the soaps were evaluated by determining pH and foaming capacity. Antibacterial activity was assessed using an experimental contamination model involving sterile gloves inoculated with Escherichia coli, followed by washing and microbiological analysis. The results showed that the formulated soaps exhibited pH values ranging from 9.0 to 12.1. Foaming tests demonstrated satisfactory foaming ability, with the highest foam height observed for formulation S2. Antibacterial evaluation revealed that formulations containing higher concentrations of essential oil (S4 and S5) showed complete inhibition of bacterial growth after washing, comparable to commercial antiseptic soaps. These findings suggest that incorporation of Cymbopogon citratus essential oil into glycerin-based soap may represent a promising approach for developing natural antibacterial cleansing products. Further studies involving additional microorganisms and dermatological tolerance evaluations are recommended. Keywords : Soap formulation; Glycerin soap; Cymbopogon citratus; Essential oil; Antibacterial activity; Natural antiseptic