No abstract

Two novel diastereoisomeric bicyclic ketals, colomitides A and B (1 and 2, resp.), together with the known (4RS)-3,4-dihydro-4,8-dihydroxynaphthalen-1(2H)-one (3) and preussomerin E (4), were isolated from liquid cultures of an unidentified freshwater fungus YMF 1.01029. Colomitides possess an unusual 2,7-dioxabicyclo[3.2.1]octane skeleton. The chemical structures and relative configurations of compounds 1 and 2 were elucidated by spectroscopic means, including 2D-NMR (HMBC, HMQC, TOCSY, ROESY, and (1)H,(1)H-COSY). Compounds 1, 2, and 4 showed noticeable antifungal and antibacterial activities.

Three new naphthoquinones, astropaquinones A-C (1-3), were isolated from cultures of the freshwater fungus Astrosphaeriella papuana YMF 1.01181, together with the known compound, 6-hydroxy-2,4-dimethoxy-7-methylanthraquinone (4). The structures of the compounds were settled mainly by interpretation of their 1D and 2D NMR spectra. Astropaquinone B (2) and C (3) were found to possess a rare pyranonaphthoquinone skeleton containing a lactol ring. Furthermore, compounds 1-4 showed moderate antagonistic activity against nine fungi and four bacterial strains.

From cultural filtrates of the freshwater fungus Ophioceras dolichostomum YMF1.00988 a novel neolignan with an unprecedented dibenzo-1,6-dioxacyclodecane carbon skeleton, ophiocerol (1), was isolated, and the known compounds isoamericanoic acid A (2) and caffeic acid (3) were identified. The structure of the novel compound was determined by interpretation of its spectroscopic data, including 1D and 2D, (1)H and (13)C NMR (COSY, HMQC, HMBC, NOESY), and MS. Compounds 1-3 were assayed for their nematicidal activity against Bursaphelenchus xylophilus as well as their antifungal activity against several plant pathogen fungi.

Other natural products U 0800Colomitides A (I) and B (II): Novel Ketals with an Unusual 2,7-Dioxabicyclo[3.2.1]octane Ring System from the Aquatic Fungus YMF 1.01029 -[isolation, structure elucidation and screening of antimicrobial activity]. -(DONG, J.-Y.; WANG, L.-M.; SONG, H.-C.; SHEN, K.