Formulation and evaluation of liquid hand soap incorporating Plectranthus scutellarioides (Mayana) leaf ethanolic extract against Staphylococcus aureus

Abstract

This study aimed to evaluate the antibacterial activity of liquid hand soap formulated with varying concentrations of <i>Plectranthus scutellarioides</i> (Mayana) leaf ethanolic extract against <i>Staphylococcus aureus. </i> The research focused on determining the potential of Mayana extract as a natural alternative to synthetic antimicrobial agents in combating common skin pathogens. Specifically, it sought to assess whether different concentrations of the extract, when incorporated into a liquid soap formulation, could effectively inhibit the growth of <i>S. aureus</i> under laboratory conditions.

To carry out the study, fresh Mayana leaves were collected, air-dried, pulverized, and subjected to ethanol extraction using the maceration technique. The resulting crude extract was incorporated into a liquid soap base at varying concentrations of 25%, 50%, and 75%. A standardized bacterial strain of <i>Staphylococcus aureus</i> was prepared and inoculated onto Mueller-Hinton agar plates, where wells were filled with the different treatments including positive (ciprofloxacin), negative (distilled water and soap base), and extract-only controls. All treatments were replicated thrice and incubated for 24 hours to observe antibacterial activity.

Data were analyzed by measuring the zones of inhibition (ZOI) around each well using a vernier caliper. The values obtained were subjected to one-way ANOVA to assess the significance of differences among treatment groups. The statistical analysis revealed a highly significant difference (p < 0.05) between the means, confirming the varying antibacterial effects of the different treatments. This provided a solid basis for determining the optimal extract concentration in the soap formulation.

The 25% extract formulation exhibited the greatest antibacterial activity among the Mayana soap treatments, with a mean inhibition zone of 24.5 mm. This was notably higher than the zones produced by the 50% and 75% extract soaps, suggesting that higher concentrations may reduce diffusion efficiency due to increased viscosity. The pure extract alone also showed inhibitory effects (21 mm), while ciprofloxacin had the highest activity at 39.3 mm. The soap base and distilled water, on the other hand, exhibited no antibacterial activity, affirming that the inhibition observed was due solely to the presence of the Mayana extract.

The findings support the antibacterial efficacy of <i>Plectranthus scutellarioides</i> extract, particularly at a 25% concentration when used in a liquid hand soap formulation. This concentration provides a balance between potency and formulation stability, making it a promising natural ingredient for topical antimicrobial products. Further studies are recommended to explore its safety, long-term stability, and effectiveness against other pathogens, paving the way for its potential commercial application in natural personal care products.