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An Australian marine sediment-derived isolate, Nocardiopsissp. (CMB-M0232), yielded a new class of prenylated diketopiperazine, indicative of the action of a uniquely regioselective diketopiperazine indole prenyltransferase. The bridged scaffold of nocardioazine A proved to be a noncytotoxic inhibitor of the membrane protein efflux pump P-glycoprotein, reversing doxorubicin resistance in a multidrug resistant colon cancer cell. [ABSTRACT FROM AUTHOR]

Chemical analysis of a marine-derived Streptomycessp. (CMB-M0423) isolated from beach sand off Heron Island, Australia, yielded three new members of the rare pyrroloterpene biosynthetic structure class. Identified by detailed spectroscopic analysis as the first reported examples of naturally occurring 2-nitropyrroles, heronapyrroles A−C (1−3) displayed promising biological activitywith low to submicromolar IC50activity against Gram-positive bacteria but no cytotoxicity toward mammalian cell lines. [ABSTRACT FROM AUTHOR]

Chemical analysis of a Streptomycessp. (CMB-MQ030) isolated from a Fijian marine sediment yielded two new diketopiperazines, naseseazines A and B (1, 2), featuring a new dimeric framework. Structures were determined by detailed spectroscopic analysis and C3Marfey’s analysis. [ABSTRACT FROM AUTHOR]

Four new alkaloids have been isolated during chemical investigations into a southern Australian marine sponge, Stellettasp. Detailed spectroscopic analysis, supported by chemical degradation and partial synthesis, permitted structure elucidation of bistellettazines A−C ( 1− 3), the first reported examples of terpenyl-pyrrolizidine conjugates, and bistellettazole A ( 4), a unique cyclic terpenyl-imidazole conjugate. The alkaloids 1− 4feature unprecedented carbon skeletons that are proposed to share a common convergent biosynthetic origin, arising via the biogenic equivalent of a Diels−Alder addition between two hypothetical polyenyl norsesquiterpene precursors. [ABSTRACT FROM AUTHOR]

Chemical fractionation of a southern Australian marine sponge, Trachycladus laevispirulifer, yielded 9-(5′-deoxy-5′-thio-β-d-xylofuranosyl)adenine disulfide as the first recorded natural occurrence of a nucleoside disulfide, and only the second of a xylo-nucleoside. Structure elucidation of the disulfide was achieved by detailed spectroscopic analysis and comparison to synthetic model compounds. The antibacterial, antifungal, and anticancer properties of the disulfide are documented and the literature surrounding natural and synthetic thionucleosides is reviewed. [ABSTRACT FROM AUTHOR]