Cyclostellettamines A -F (1 -6) isolated from the sponge Pachychalina sp. and cyclostellettamines G -I, K and L (7 -11) obtained by synthesis were evaluated in bioassays of antimicrobial activity against susceptible and antibiotic-resistant Staphylococcus aureus, Pseudomonas aeruginosa and antibiotic-susceptible Escherichia coli and Candida albicans, as well as in antimycobacterial activity against Mycobacterium tuberculosis H37Rv bioassays. The results obtained indicated that cyclostellettamines display different antimicrobial activity depending on the alkyl-chain size, suggesting that, if a mechanism-of action is implied, it is dependent on the distance between the two pyridinium moieties of cyclostellettamines.
Mar. Drugs2006, 4 2
3-Alkylpyridine alkaloids are very common secondary metabolites from marine sponges of the order Haplosclerida. Here, we report on the identification and synthesis of the first cyclic monomeric 3-alkylpyridinium alkaloid from natural sources. Due to the lack of a pure sample of the new compound, structure elucidation had to rely on HPLC and MS n .
Four new 3-alkyl pyridinium alkaloids, the viscosalines B(1) (1 a), B(2) (1 b), E(1) (2 a), and E(2) (2 b), were isolated from the Arctic sponge Haliclona viscosa. The structure elucidation of these isomeric compounds was challenging due to ambiguous fragments that derive during "standard" mass spectrometric fragmentation experiments. The final structure elucidation relied on the use of a combination of synthesis, liquid chromatography, and mass spectrometry. Three different mass spectrometers were used to differentiate between the synthetic structural isomers: a time-of-flight (TOF) mass spectrometer and two ion-trap mass spectrometers with different ion-transfer technologies (i.e., skimmer versus funnel optics). Although at first none of the spectrometers returned spectra that permitted structure elucidation, all three mass spectrometers provided analysis that successfully differentiated between the isomers after thorough method optimization. The use of in-source collision-induced dissociation (CID) with the ion trap and TOF instrument returned the most interesting results. The mode of fragmentation of the viscosalines under different experimental conditions is described herein. After successful optimization of the mass spectrometric method applied, the chromatographic method was improved to distinguish the previously inseparable isomers. Finally, both the liquid chromatography and mass spectrometric methods were applied to the natural products and the results compared to those from the synthetic compounds.
The Arctic sponge Haliclona viscosa is a rich source of 3-alkyl pyridinium alkaloids. Herein, we report the identification of two new haliclamines from the crude extract of this sponge. Due to the lack of sponge material, identification relied on HR-LCMS measurements and comparison with synthetic compounds.
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