Antimicrobial Activity of Pregnenolone in vitro

The antimicrobial effect of pregnenolone on clinical and reference strains of Escherichia coli and Staphylococcus aureus was tested. Pregnenolone was found to have inhibitory activity against all tested bacterial strains. Slightly higher sensitivity is shown by the strains of S. aureus. When applied directly, pregnenolone has a weak antimicrobial effect due to its very low water solubility, as it is in oleose state because the formulation studied in this experiment contains tocopherol (a fat-soluble vitamin) as a co-solvent. When emulsified with lecithin, as well as with methanol, its solubility in water increases and penetrates over a longer distance in the agar around the points of its application. Applied as an emulsion, it shows significantly higher inhibitory activity against E. coli and S. aureus. Even the non-emulsified version should still be useful in vivo due to the fact that intracellular environments are much more lipophilic than serum, the target of most antimicrobial substances is the intracellular space, and non-emulsified pregnenolone has been shown to have very high intracellular uptake.