Peptide Alkaloids, Peptides, and Proteins from Porifera

Cliona celata has furnished a series of linear peptide alkaloids, the celenamides A to D (278-281), in addition to the previously known clionamide (282) (168, 169). These compounds were isolated in the form of their polyacetates after acetylation of the methanolic extract of the homogenized sponge. The celenamides contain a unique amino acid a,P-didehydro-3,4,5-trihydroxyphenylalanine, as a subunit. The configuration of the double bond in the dehydroamino acid residue has been determined by synthesis of the hexa-acetate of 278 (170). 

Three diketopiperazines cyclo-(L-Pro-L-Leu) (283), cyclo-(L-Pro-L-Val) (284), and cyclo-(Pro-Ala) (285) have been identified from an extract of Tedania ignis (99). 

Matsunaga et al. 171-173) have described the first bioactive polypeptides derived from a sponge, the antimicrobial discodermins A, B, C, and D (286-289) from Discodermia kiiensis. Among other methods, fast atom bombardment (FAB) mass spectrometry was applied for determination of their structures. These were unusual since 286-289 contain several D-amino acids and 286-288 t-Leu residues. Discoder-min A (286), C (288), and D (289) also inhibited the development of starfish embryo. 

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Peptide Alkaloids, Peptides, and Proteins from Porifera.190... 

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