Synthesis and antibacterial activity of pregnenolone-vitamin B1 conjugate

In this work was synthesized a pregnenolone derivative; the route involved preparation of pregnenolone hemisuccinate (2) by ester-ification of pregnenolone (1) with succinic anhydride followed by formation of the hemisuccinate of pregnenolone-vitamin B1 conjugate (3). The antibacterial activity of compound 3, as well as 2 and vitamin B1, was evaluated in vitro on S. aureus, K. pneumoniae and E. coli using dilution method and the minimum inhibitory concentration (MIC). The structure of 3 was confirmed by spectroscopy and spectrometry data. The ¹H NMR spectrum showed, up field shifts at 2.52 and 2.58 ppm for methyls present in the heterocyles rings; at 2.90 and 3.77 methy-lenes of the hydroxietilen moiety bonded to thiazol ring, in addition the hydrogens of the methylene between the pyrimidine and thiazol ring appears at 4.39 ppm. At down field there are two chemical shifts (7.54, 8.33) corresponding to protons in the heterocyles. The results of the biological activity indicate that the bacterial growth of the microorganisms studied was inhibited by 3, and 2 in a manner dose-dependent, but not by vitamin B1. These data suggest that quaternary amine group involved in the HPVB1 conjugate requires the hydrophobic region of the steroid in order to interact with some components of bacterial cell, disturbing the bacterial growth and to cause cell death.