New fatty acids from the Red Sea sponge <i>Mycale euplectellioides</i>

<div><p>Chemical investigation of the Red Sea sponge <i>Mycale euplectellioides</i> afforded two new compounds; hexacosa-(6<i>Z</i>,10<i>Z</i>)-dienoic acid methyl ester (<b>1</b>) and hexacosa-(6<i>Z</i>,10<i>Z</i>)-dienoic acid (<b>2</b>), along with two known compounds: icosa-(8<i>Z</i>,11<i>Z</i>)-dienoic acid methyl ester (<b>3</b>) and β-sitosterol (<b>4</b>). The structures were elucidated by the interpretation of their spectral data. The total methanol extract (TME) of the sponge exhibited potent antimicrobial activity against the different strains at a concentration of 100 mg/mL. All tested fractions did not exhibit any activity against <i>Serratia marcescens</i> and tested fungal strains. The TME and different fractions displayed anti-inflammatory and antipyretic activities at doses of 100 and 200 mg/kg compared with indomethacin (8 mg). The TME exhibited a remarkable hepato-protective effect in CCl₄-induced liver damage compared with silymarin. Furthermore, compounds <b>1</b> and <b>2</b> displayed weak activity against A549 non-small cell lung cancer, the U373 glioblastoma and the PC-3 prostate cancer cell lines.</p>