<jats:title>Abstract</jats:title><jats:p>Two new polyoxygenated steroids, (1<jats:italic>α</jats:italic>,3<jats:italic>β</jats:italic>,7<jats:italic>α</jats:italic>,11<jats:italic>α</jats:italic>,12<jats:italic>β</jats:italic>)‐gorgost‐5‐ene‐1,3,7,11,12‐pentol 12‐acetate (<jats:bold>1</jats:bold>) and 11‐<jats:italic>O</jats:italic>‐acetyl‐22‐epihippuristanol (<jats:bold>2</jats:bold>), and a new alkaloid, 2,3,5,6,11,11b‐hexahydro‐2‐hydroxy‐1<jats:italic>H</jats:italic>‐indolizino[8,7‐<jats:italic>b</jats:italic>]indole‐2‐carboxylic acid (<jats:bold>3</jats:bold>), together with three known compounds, 22‐epihippuristanol (<jats:bold>4</jats:bold>), hippuristanol (<jats:bold>5</jats:bold>), and tryptamine (<jats:bold>6</jats:bold>), were isolated from the EtOH/CH<jats:sub>2</jats:sub>Cl<jats:sub>2</jats:sub> extracts of the South China Sea gorgonian <jats:italic>Isis minorbrachyblasta.</jats:italic> The structures of the new compounds were determined by spectroscopic methods. Compound <jats:bold>1</jats:bold> showed weak cytotoxicity against A549, HONE1, and HeLa cancer cell lines and strong antilarval activity towards <jats:italic>Bugula neritina</jats:italic> larvae with an <jats:italic>EC</jats:italic><jats:sub>50</jats:sub> value of 5.8 μg/ml. Compound <jats:bold>5</jats:bold> showed moderate cytotoxicity against A549, HONE1, and HeLa cell lines, and the epimer mixture <jats:bold>4</jats:bold>/<jats:bold>5</jats:bold> (weight ratio 3 : 2) exhibited potent cytotoxicity against A549 and HONE1 cell lines with <jats:italic>IC</jats:italic><jats:sub>50</jats:sub> values of 4.2 and 4.8 μg/ml, which indicated that epimers <jats:bold>4</jats:bold> and <jats:bold>5</jats:bold> might have a synergistic effect on their cytotoxicity against A549 and HONE1 cell lines.