Abstract
Chemical investigation of the marine sponge Dysidea avara, collected from the South China Sea, yielded 13 steroids, including nine new (1-9) and four known (10-13) ones. The new structures were elucidated as (3S,14R)-3,14-dihydroxycholesta-5,8-dien-7-one (1), (22E,24R)-7α-ethoxy-5α,6α-epoxyergosta-8(14),22-dien-3β-ol (2), 3β-hydroxy-7α-ethoxy-5α,6α-epoxy-8(14)-cholestene (3), 3β,5α-dihydroxy-6α-ethoxychofesta-7,9(11)-diene (4), 3β,5α-dihydroxy-6β-ethoxycholest-7-ene (5), (22E,24R)-24-ethoxy-3β,5α-dihydroxy-6β-ethoxyergosta-7,22-diene (6), (22E)-3β,5α-dihydroxy-6β-ethoxycholesta-7,22-diene (7), 24-ethoxy-3β,5α-dihydroxy-6β-ethoxycholest-7-ene (8 and 9), by extensive spectroscopic analyses, such as HR-ESI-MS, 1D and 2D NMR data. The absolute configuration of 1 was assigned by comparison the experimental ECD spectra with the calculated ones. Among the 13 metabolites, compounds 1, 4, 11, 12, and 13 showed NF-κB inhibitory activities in human HER-293 cells with IC50 values of 6.4, 18.7, 8.1, 9.6, and 7.5 μM, respectively. Preliminary structure-activity relationship analysis unveiled that the conjugated ketones or unsaturated double bonds might be the functional groups for the five active steroids.
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