A new polyoxygenated dihydropyrano[2,3-c]pyrrole-4,5-dione derivative, pyranonigrin F （1）, together with a related known compound, pyranonigrin A （2）, were isolated and identified from Penicillium brocae MA-231, an endophytic fungus obtained from the fresh tissue of the marine mangrove plant Avicennia marina. The structures of these metabolites were determined based on comprehensive spectral interpretation and the absolute configuration of compound 1 was established by X-ray crystallographic analysis. Compounds 1 and 2 showed potent activity against a broad spectrum of human-, aqua-, and plant-pathogens.
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 tricycloalternarene derivatives： tricycloalternarene 3a （5）, tricycloalternarene lb （6）, and tricycloalternarene 2b （7）; and two alternariol congeners： djalonensone （8） and alternariol （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 gg/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 ofindole-diterpenoids from fungal genus Alternaria.
