ABSTRACT
Two new cytochalasans, marcytoglobosins A (1) and B (2) were isolated from the marine sponge associated fungus Chaetomium globosum 162105, along with six known compounds (3-8). The complete structures of two new compounds were determined based on 1D/2D NMR and HR-MS spectroscopic analyses coupled with ECD calculations. All eight isolates were evaluated for their antibacterial activity. Among them, compounds 3-8 displayed antibacterial effects against Staphylococcus epidermidis, Bacillus thuringiensis, Pseudomonas syringae pv. Actinidiae, Vibrio alginolyticus, and Edwardsiella piscicida with minimum inhibitory concentration (MIC) values ranging from 10 to 25â µg/mL.
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-3ß-ol (2), 3ß-hydroxy-7α-ethoxy-5α,6α-epoxy-8(14)-cholestene (3), 3ß,5α-dihydroxy-6α-ethoxychofesta-7,9(11)-diene (4), 3ß,5α-dihydroxy-6ß-ethoxycholest-7-ene (5), (22E,24R)-24-ethoxy-3ß,5α-dihydroxy-6ß-ethoxyergosta-7,22-diene (6), (22E)-3ß,5α-dihydroxy-6ß-ethoxycholesta-7,22-diene (7), 24-ethoxy-3ß,5α-dihydroxy-6ß-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 7.5â 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.
