Chemical constituents of marine mangrove-derived endophytic fungus Alternaria tenuissima EN-192

摘要

A chemical investigation of the ethyl acetate extract of the fermentation broth of Alternaria tenuissima EN-192,an endophytic fungus obtained from the stems of the marine mangrove plant Rhizophora stylosa,resulted in the isolation of nine known secondary metabolites,including four indole-diterpenoids:penijanthine A (1),paspaline (2),paspalinine (3),and penitrem A (4); three tricycloaltemarene derivatives:tricycloalternarene 3a (5),tricycloaltemarene lb (6),and tricycloalternarene 2b (7); and two altemariol congeners:djalonensone (8) and altemariol (9).The chemical structures of these metabolites were characterized through a combination of detailed spectroscopic analyses and their comparison with reports from the literature.The inhibitory activities of each isolated compound against four bacteria were evaluated and compounds 5 and 8 displayed moderate activity against the aquaculture pathogenic bacterium Vibrio anguillarum,with inhibition zone diameters of 8 and 9 mm,respectively,at 100 μ.g/disk.To the best of our knowledge,this is the first report on the secondary metabolites of mangrove-derived Alternaria tenuissima and also the first report of the isolation of indole-diterpenoids from fungal genus Alternaria.