Agelas pyrroles

The pyrrole-imidazole alkaloid taurodispacamide A (486) has been isolated from the Mediterranean sponge Agelas oroides. The structure was established from spectroscopic data. Taurodispacamide A (486) exhibited antihistaminic activity when tested on guinea pig ileum [415]. 

Most of the known natural brominated pyrrole alkaloids are found in sponges, and several new examples were isolated since the first survey (1). Reviews are available that discuss the occurrence and syntheses of these metabolites (1236-1238). The Papua New Guinea sponge Agelas nakamurai has yielded the new simple pyrroles 1222 and 1223 (1239). The dibromo analog (1224) of 1223 along with enantiomeric lactams 1225/1226, which were separated by chiral HPLC, and... 

Fattorusso E, Taglialatela-Scafati (2000) Two Novel Pyrrole-Imidazole Alkaloids from the Mediterranean Sponge Agelas oroides. Tetrahedron Lett 41 9917... 

Forenza, S., Minale, L., Riccio, R., and Fattorusso, E., New bromo-pyrrole derivatives from the sponge Agelas oroides, J. Chem. Soc., Chem. Commun., 1129, 1971. 

The racemic midpacamide (IS), possessing both pyrrole-2-carboxamide and N-methylated hydantoin moieties, has been isolated from an unidentified marine sponge collected in the Marshall Islands [35] and, subsequently, from the sponge Agelas mauritiana [36]. Two different total syntheses have been reported for this compound [37,38]. 

It should be noted that cyclooroidin (38) could be envisaged as the precursor of the nonimidazole bromopyrrole alkaloids longamides (see below). Two cyclooroidin analogs have been isolated agesamide (39) from Agelas sp. [68] and oxocyclostylidol (40) from Stylissa caribica [69]. This latter compound represents the first pyrrole-imidazole alkaloid that includes an oxidized pyrrole moiety. 

Marine sponges have furnished a rich collection of pyrroles, indoles, and a few carbazoles— many of which are halogenated. The simple pyrroles (262) and (263) have been isolated from Agelas oroides <94Mi 204-23), from which oridin had earlier been isolated. Another Agelas sp. afforded... 

Ageladine A (84), from the sponge Agelas nakamurai, is the first isolated pyrrole-imidazole alkaloid containing a 2-aminoimidazolopyridine moiety [78]. 

Bickmeyer, U., Drechsler, C., Kock, M., Assmann, M., (2004). Brominated pyrrole alkaloids from marine Agelas sponges reduce depolarization -induced cellular calcium elevation. Toxicon 44, 45-51. 

In Fig. 9.7 are displayed acyclic and cyclic dimeric members of the pyrrole-imidazole family. Nagelamide D, from Okinawan marine sponges of the genus Agelas, is a dimer comprised of oroidin monomer units connected between the C-10 and C-15 positions [80]. However, the assigned structure of this substance is questionable (see below). Sceptrin, isolated in 1981 by Faulkner and Clardy from Agelas sceptrum, is the first reported symmetric dimer comprised of hymenidin subunits [81]. 

Many simple derivatives of pyrrole and pyrrole-2-carboxylic acid have been isolated from Agelas. Most of them are antibiotic and cytotoxic, and may serve as a chemical defense against marine bacteria (Forenza, Minale, and Riccio, 1971 Chib et al, 1977 Fathi-Afshar and Allen, 1988 Tada and Tozyo, 1988 Kbnig and Wright, 1994 Iwagawa et al, 1998). Some of these structures are shown in Figure 19.49. 

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