Evaluation and characterization of antimicrobial properties of pregnenolone-derivatives on Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli

Recently, steroid-antibiotic conjugates have been developed as potential therapeutic agents for infectious diseases. In this work the antibacterial activity of two pregnenolone-derivatives was evaluated on S. aureus, K. pneumoniae and E. coli, using the dilution method and the minimum inhibitory concentration (MIC). The results indicate that bacterial growth of S. aureus was inhibited with cefotaxime (MIC = 0.25 mg/ml), gentamicin (MIC = 0.0125 mg/ml), hemisuccinate-pregnenolone (MIC = 1 mg/ml), ethylenediamine-hemisuccinate- pregnenenolone (MIC = 0.25 mg/ml) and the mixture of the two pregnenolone-derivatives (MIC = 0.5 mg/ml). Other results, showed that bacterial growth of E. coli was also inhibited with cefotaxime (MIC = 0.25 mg/ml), gentamicin (MIC = 0.00625 mg/ml), hemisuccinate-pregnenolone (MIC = 1 mg/ml), ethylenediamine-hemisuccinate-pregnenenolone (MIC = 0.5 mg/ml) and the mixture of two pregnenolone-derivatives (MIC = 0.5 mg/ml). Alternative experiments showed that bacterial growth of K. pneumoniae was inhibited with cefotaxime (MIC = 0.125 mg/ml), gentamicin (MIC = 0.0.125 mg/ml), hemisuccinate-pregnenolone (MIC = 1 mg/ml), ethylenediamine-hemisuccinate-pregnenenolone (MIC = 0.5 mg/ml) and the mixture of two pregnenolone-derivatives (MIC = 0.5 mg/ml). Our results suggest that effect induced by pregnenolone-derivatives could be by the interaction with some bacterial membrane factors that are specific for bacterial resistance. In this sense, the antibacterial activity of pregnenolone- derivatives can depend of the nature of functional groups involved in their chemical structure that seems to be the key required for antibacterial activity.