| Summary: | Octocoral <i>Sinularia leptoclados</i> has been identified as a source of bioactive 9,11-secosteroids. This study adopted a targeted isolation approach to the discovery and analysis of five 9,11-secosteroids, including two novel compounds named sinleptosterols A (<b>1</b>) and B (<b>2</b>) as well as five known analogues (8<i>α</i>H-3<i>β</i>,11-dihydroxy-24-methylene-9,11-secocholest-5-en-9-one (<b>3</b>), 8<i>β</i>H-3<i>β</i>,11-dihydroxy-24-methylene-9,11-secocholest-5-en-9-one (<b>4</b>), leptosterol A (<b>5</b>), (24<i>S</i>)-3<i>β</i>,11-dihydroxy-24-methyl-9,11-secocholest-5-en-9-one (<b>6</b>), and 3<i>β</i>,11-dihydroxy-9,11-secogorgost-5-en-9-one (<b>7</b>)) in terms of <sup>1</sup>H-NMR patterns and potency against neutrophilic inflammation. The structure of secosteroids <b>1</b> and <b>2</b> was deduced from general spectroscopic analysis and an examination of NMR spectra. Among the above-mentioned isolates, compound <b>4</b> had the most pronounced effect in inhibiting elastase release and superoxide anion generation, with the IC<sub>50</sub> values of 2.96 and 1.63 μM, respectively.
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