Amathia alternata

Altematamides A-C (92-94), bromotryptamine peptides from the Atlantic bryozoan Amathia alternata, show modest antibacterial activities against Staphylococcus aureus, Staphylococcus epidermidis,... 

Lee N-K, Fenical W, Lindquist N (1997) Altematamides A-D New Bromotryptamine Peptide Antibiotics from the Atlantic Marine Bryozoan Amathia alternata. J Nat Prod 60 697... 

The same authors (32J also found that Amathia alternata contained four brominated alkaloids. One, 75, is closely related to one of the metabolites, 74, from A. convoluta, while the others are indoles (see Section 2.3.2). 

As noted above Amathia alternata contains three brominated indoles, 76-78 as well as the p-phenylethylamlne derivative 78 [32]. The three indole derivatives from A. alternata are clearly related to the other Amathla compounds they are amides from indolylethylamine (rather than phenylethylamlne) and the amino acid valine—once more with additional methylatlon and brominatlon. In this series indolylethylamine is likely to be formed from typtophan in much the same way that phenylethylamlne is derived from phenylalanine in the other Amathia compounds. 

All of the Amathia brominated amides are presumably biosynthesised from amino acids by similar pathways in the related bryozoans. The amathamides are amides derived formally by reaction of 2-(2,4-dlbromo-5-methoxyphenyl)ethanamlne, 68, with proline followed variously by introduction of a double bond, or methyl, methoxy or bromine substituents. The A. convoluta metabolites 70-74, and 75 from A. alternata are all also derived formally from 2-(2,4-dibromo-5-methoxy-phenyDethanamlne, 68—either by direct amide formation with tyrosine, or by having an additional aminopropyl group which is then... 

---