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 (7and8) and (8R)-paecilocin A (9a), were obtainedfrom a macroalga-associated strain (RR-dl-2-13) of the fungusByssochlamys spectabilis. These isolates were identified by acombination of spectroscopic methods, including mass spectroscopy, nuclear magnetic resonance, electronic circular dichroism, andX-ray diffraction. Compounds1-4greatly contribute to the diversity of rarely occurring 2,15-epoxycarotane sesquiterpenoids, while5and6are degradation products of farnesane and sesquicarane precursors, respectively. Compound7is a structurally unique furanfatty acid derivative that possesses an aldehyde group and a large conjugated unit, and8features a hemiketal group. Duringantimicrobial assays,8showed antagonism against the phytopathogenic fungiGlomerella cingulata,Fusarium oxysporumf. sp.cucumerium, andF. oxysporumf. sp.cubenseand the marine-derived bacteriaVibrio parahaemolyticusandV. harveyiwith MIC valuesof 13 to 50 mu g/mL