Search

Five novel antifungal bengazoles from the marine sponge Jaspis sp. are characterized by a derived Mosher ester method and an analysis of exciton coupling in the circular dichroism spectra of the tetra-p-bromobenzoate esters from known bengazole A and synthetic model tetrol. Tetrol is prepared from L-fucose by a seven-step stereoselective process. The fatty acid methyl esters of the bengazoles differ throughout the C12 to C18 chain and are in the series of n, iso or anteiso. Bengazole A has C10 absolute configuration of S and a side chain configuration of 2R,3S,4R,6S.

Structural assignment studies using 2D NMR spectroscopy of the ocean derived marine sponge Phorbas sp.'s antifungal and cytostatic macrolides, Phorboxazoles A and Phorboxazoles B. Research reveals that they slow antifungal activity against Candida albicans at 0.1 micro g per disk and exhibit unusual cytostatic activity. The 2D NMR spectroscopy study includes COSY, RCT, HMQC, and HMBC.

Chromatographic techniques help isolate five new alkaloids, lissoclin A,B,C, lissoclinotoxin C and the dimeric lissoclinotoxin D, along with the lissoclinotoxin A, 6-bromotryptamine and 2-phenylethylamine from Lissoclinum sp., collected from the Great Barrier Reef, Australia. Lissoclin A produces a new benzo-1,3-oxathiazoline by a photorearrangement reaction. 13C NMR studies and conversion experiments help assign the structures of lissoclinotoxin A. The chiral lissoclinotoxin A shows stereosiomerism due to restricted inversion about the benzopentathiepin ring and exhibits antifungal activity against Candida albicans.

The two novel cytotoxic nucleosides trachycladine A 9-(2'-C-methyl-5'-deoxy-beta-D-ribofuranosyl)-2-chloroadenine and trachycladine B 9-(2'-C-methyl-5'-deoxy-beta-D-ribofuranosyl)-2-hypoxanthine obtained from the sponge Trachycladus laevispirulifer are successfully being used in clinical trials against hairy cell leukemia. The 13C NMR and 1H analysis shows that 1 and 2 have a nucleoside structure. The experimental set up of the synthesis of 1 and 2 is discussed.

An analysis of antifungal compounds from marine invertebrates involved isolating and establishing the structure of the key antifungal compound from an ascidian Didemnidae, (R)-(E)-1-aminotridec-5-en-2-ol. The new compound seems to be linked to sphingosine, an ostensibly omnipresent amphiphilic amino alcohol.

A clarification of the absolute configurations of 14 out of the 15 stereocenters in the cytostatic marine macrolides phorboxazoles A and B is reported. This was accomplished using a combination of techniques, including synthesis of a suitable model compound for nuclear magnetic resonance spectroscopic comparisons. The absolute configuration around the oxane hemiketal and macrolide rings in phorboxazole A is assigned as 5S, 9R, 11S, 13R, 15R, 22R, 23S, 24S, 25R, 26R, 33S, 35R, 37R, 38R. Since phoboxazole B was determined as the C13 epimer of phorboxazole A by J analysis, it can be deduced that it has the same configuration as phorboxazole A at the other stereocenters.

A diverse set of 16 high-throughput organic synthesis libraries, consisting of 48 samples per library, has been purified by both preparative supercritical fluid chromatography (SFC) and preparative high-performance liquid chromatography (HPLC). This paper details the relative effectiveness of these two purification techniques in terms of success, yield, and purity of final product.