Sulfated steroids isolated from the marine sponge <i>Petrosia</i> ( <i>Strongylophora</i> ) <i>strongylata</i> and their antimicrobial activity

The extract of <i>Petrosia (Strongylophora) strongylata</i> was separated to trace sulfated terpenoids, which were expected to be present in the crude extract based on its ¹H NMR spectrum. As a result, seven sulfated (<b>1-7</b>) sterols and one highly oxygenated steroid (<b>8</b>), including two unreported analogs (<b>4</b> and <b>7</b>), were isolated and identified. The MIC measurement of all isolated compounds against six bacterial cell lines demonstrated that compounds <b>1-7</b> efficiently inhibit the growth of Gram-positive bacteria. Compound <b>8</b>, which lacks the sulfate group in the structure, displayed no activity even at a concentration of 128 µM. This study demonstrated that the sulfate groups in the structures of sterols play a critical role in the growth inhibition of Gram-positive bacteria, suggesting the potential of sulfated sterols for use as antimicrobial agents. The modes of action of these compounds and their molecular -targets are currently under investigation.