Amathia convoluta, amathamide

Tyrosine-derived metabolites in this section do not include spiro-cyclohexadienyl-isoxazolines and related compounds (Sect. 3.22.3.3) or bastadins (Sect. 3.22.3.4), but they do include tyrosine-derived alkaloids that were covered in the Alkaloids section in the first survey (1). The prolific bryozoan Amathia convoluta, collected in Tasmania, has yielded amathamide G (1953) (1814), the latest of several amath-amide alkaloids from the genus Amathia (1). A Florida collection of this animal furnished the new convolutamines A-E (1954—1958) (1815), F (1959), and G (1960) (1425), and a Tasmanian sample of this bryozoan afforded convolutamine H (1961) (1319). A study of Amathia convoluta from the North Carolina coast has yielded volutamides A-E (1962-1966) (1816). Volutamides B and C reduce feeding by the pinfish (Lagodon rhomboids) and the urchin (Arbacia punctulata), respectively, and volutamides B and D are toxic toward larvae of the hydroid Eudendrium carneum. The New Zealand Amathia wilsoni contains the six novel amathaspiramides A-F (1967-1972) (1817). 

Convolutamides A-F form another series of cytotoxic pyrrolidinone alkaloids related to amathamides they were also isolated from the bryozoan Amathia convoluta but from animals harvested in Florida. All these amides differ only in the length of the acyl chain, which may have 14,16, 18, or 20 carbon atoms. 

Related aromatic amines that repel fish and are toxic to the larvae of some Hydraria were isolated from Amathia convoluta harvested at shallow depths on the coast of North Carolina (USA). Volutamides A-E differ from amathamides and convolutamides in the presence of one or two additional amine functions (Montanari et al, 1996). 

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... 

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