R. Azizi - Department of Hygiene, Science and Research Branch, Islamic Azad University, Tehran
A.A. Motallebi Moghanjoughi - Department of Hygiene, Science and Research Branch, Islamic Azad University, Tehran
M. Nazemi - Persian Gulf and Oman Sea Ecological Research Center, Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), Bandar Abbas, Iran
M. Sharif Ruhani - Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extention (AREEO)
M. Afshar Nasab - Kherad higher education center٫ Bushehr, Iran.

Due to numerous reasons, marine-obtained resources have attracted the interest of researchers. One of the subjects attracted the interest of researchers in recent years in the field of biologist marine algae due to their nutritional value, their benefits for health and their biological activities. In this study, the powder was extracted using acetone, then the extract purified by silica gel column chromatography with n-hexane and ethyl acetate combination to isolate the steroid compounds. Isolated compound was run through TLC and sprayed with vanillin-sulphuric acid reagent to detect the steroid compounds and profile of isolated compounds obtained by gas chromatography (GC). Antibacterial activity of steroids extracted of green algae Ulva fasciata from Qeshm Island in the Persian Gulf were assessed (in vitro). The antibacterial activity of the fractions was determined by Broth Dilution Methods against clinical Gram-negative bacteria: Escherichia coli, Pseudomonas aeruginosa, Salmonella. typhi and Gram-positive bacteria: Staphylococcus aureus, Bacillus subtilis, Bacillus cereus. The steroids; cholest-۷-en-۳ol and cholestan-۳-one, cyclic ۱, ۲-ethanediyl acetal compounds in column fraction were identified by GC. The results showed the minimum bactericidal concentration (MBC) of the cholest-۷-en-۳ol and cholestan-۳-one, cyclic ۱,۲-ethanediyl acetal for S. aureus and Bacillus cereus were ۵۰۰ μg ml-۱, the MBC of the cholest-۷-en-۳ol for B. subtilis was ۵۰۰ μg ml-۱ and ۱۰۰۰ μg ml-۱ detected for cholestan-۳-one, cyclic ۱,۲-ethanediyl acetal. The compounds had neither antibacterial activity on gram negative bacteria. Based on our results, extracted steroids from U. fasciata can be considered as a source of novel antibiotics.

Green algae, Ulva fasciata, Antibacterial activities, Natural products, Persian Gulf