Antimicrobial Terpenoids and Polyketides from the Algicolous Fungus Byssochlamys spectabilis RR-dl-2-13.

Four new carotane sesquiterpenoids, byssocarotins A-D ( 1 - 4 ), two new nor-sesquiterpenoids, byssofarnesin ( 5 ) and byssosesquicarin ( 6 ), and three new polyketides, byssoketides A and B ( 7 and 8 ) and (8 R )-paecilocin A ( 9a ), were obtained from a macroalga-associated strain (RR-dl-2-13) of the fungus Byssochlamys spectabilis . These isolates were identified by a combination of spectroscopic methods, including mass spectroscopy, nuclear magnetic resonance, electronic circular dichroism, and X-ray diffraction. Compounds 1 - 4 greatly contribute to the diversity of rarely occurring 2,15-epoxycarotane sesquiterpenoids, while 5 and 6 are degradation products of farnesane and sesquicarane precursors, respectively. Compound 7 is a structurally unique furan fatty acid derivative that possesses an aldehyde group and a large conjugated unit, and 8 features a hemiketal group. During antimicrobial assays, 8 showed antagonism against the phytopathogenic fungi Glomerella cingulata , Fusarium oxysporum f. sp. cucumerium , and F. oxysporum f. sp. cubense and the marine-derived bacteria Vibrio parahaemolyticus and V. harveyi with MIC values of 13 to 50 μg/mL.