Identification and investigation of antibacterial effects of steroidal fraction from the marine sponge Axinella sinoxea Alvarez & Hooper, 2009 in Larak island, the Persian Gulf

Steroids are one of the most important and abundant secondary metabolites of marine sponges. The aim of this study was to investigate the antibacterial properties of steroidal fractions derived from the Persian Gulf sponge Axinella sinoxea. Extraction was first done by Acetone and then the fractions were separated through column chromatography with silica gel. Identification of steroidal fractions were done by thin layer chromatography (TLC) and gas chromatography coupled with mass spectrometry (GC–MS). Then, antibacterial properties of steroids were identified and minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) were investigated by tubular dilution. Two types of steroids including Stigmasta-5,24(28)-dien-3-ol,(3β-24Z) and Ergosta-5,22-dien-3-ol,(3β,22E,24S) were determined. The extracted steroids showed different results regarding the growth inhibition and bactericidal effect on Gram negative (Escherichia coli, Klebsiella pneumoniae and Vibrio harveyi) and Gram positive (Micrococcus roseus and Staphylococcus aureus) bacteria at different experimental doses. In conclusion, promising results were found regarding the antimicrobial effects of the extracted steroids of the marine sponge from Larak island A. sinoxea. These findings reveal the necessity of more comprehensive investigations for the synthesis of pharmaceutical and antibiotic materials from the  bioactive compounds.