Eudistoma olivaceum

An additional sulfur-containing P-carboline belonging to the eudistomin family, N( 10)-methyleudistomin E (478) was obtained from the Caribbean tunicate Eudistoma olivaceum [363]. 

Davis, A. R., Alkaloids and ascidian chemical defense evidence for the ecological role of natural products from Eudistoma olivaceum, Mar. Biol., Ill, 375, 1991. 

Shen, G. Q. and Baker, B. J., Biosynthetic studies of the eudistomins in the tunicate Eudistoma olivaceum, Tetrahedron Lett., 35, 1141, 1994. 

Davis, A. R. and Wright, A. E., Interspecific differences in fouling of two congeneric ascidians (Eudistoma olivaceum and E. capsulatum) Is surface acidity an effective defense , Mar Biol., 102,... 

Unlike carbazoles, haiogenated (3-carbolines are abundant in nature [1[. For example, the simple eudistomin O (7-bromo-(3-carboline) (40) is a ubiquitous marine ascidian metabolite [44[. Indeed, the tunicate genus Eudistoma has furnished most of the extant haiogenated (3-carbolines, some of which have significant antiviral (polio, herpes) and microbial activity. The Caribbean Eudistoma olivaceum produces at least 15 brominated carbolines [1[. A study of Eudistoma gilboverde uncovered the new eudistomins 41-43[45[, and the Australian ascidian Pseudodistoma aureum has... 

Tunicates are the only marine invertebrates in which alkaloid biosynthesis has been extensively investigated (189). In addition to the eudistomins, described below, the tripeptide tunichromes have been investigated, by Nakanishi and coworkers at Columbia University, in the solitary tunicate Ascidia nigra (191) and shermilamine, a benzo-3,6-phenanthroline alkaloid, has been studied in Cystodytes dellechiajei, by Steffan and coworkers at the University of Munich (192). The origin of the (3-carboline ring system of the eudistomins has been studied, by Baker s group at Florida Tech, in Eudistoma olivaceum (193, 194). 

Radiotracer experiments were used to elucidate the biosynthetic precursors to eudistomin H (7) and I (8) in Floridian collections of Eudistoma olivaceum. Both radiolabeled tryptophan and proline were incorporated by E. olivaceum into eudistomins H and I and tryptamine was incorporated into eudistomin I, to the exclusion of eudistomin H. Bromotryptamine and bromotryptophan are incorporated into eudistomin H (Scheme 30). These results suggest eudistomin biosynthesis proceeds from the amino acids via decarboxylation, halogenation, then condensation with proline. 

Scheme 30. Biosynthetic origin of Eudistomins H and I in Eudistoma olivaceum.

The manzamine alkaloids are characterized by a complex pentacyclic diamine linked to C-l of a B-carboline moiety. The first B-carboline compound (norharman and harman) was reported from a bioluminiscent marine dino-flagellate Noctiluca miliaris [31], followed by the discovery of the eudistomins from Eudistoma olivaceum [32, 33, 34], Their occurrence has been reported not only from sponges and tunicates, but also from the Bryozoan Costaticella hastata [35], and Cribricellina cribraria [36] and lately from the Cnidaria (Villagorgia rubra) exemplified by the Villagorgins [37]. 

Rinehart, K.L. Kobayashi, J. Harbour, G.C. Hughes, R.G. Mizsak, S.A. Scahill, T.A. Eudistomins C E K and L Potent Antiviral Compounds Containing Novel Oxathiazepine Ring from Caribbean Tunicate Eudistoma olivaceum. J. Am. Chem. Soc. 1984, 106, 1524-1526. 

Eudistomin C 158 Eudistoma olivaceum Riterella sigiUinoides Caribbean [91.I2S] New Zealand [119]... 

Eudistomin E 159 Eudistoma olivaceum Eudistoma album Caribbean [91.12S] New Caledonia [100]... 

The )8-carboline system alkylated at C-1 occurs frequently in the indole alkaloid series and in some cases in the 1,2,3,4-tetrahydro form, as shown above. The simplest homolog with a methyl substituent is caUed harman (Fig. 12). It has been found in several plant families and also in the higher fungus Coriolus maximus (174). Recently, particular interest in 1-substituted /3-carboline derivatives has also resulted from the antiviral activity against herpes simplex virus type 1 (HSV-1) discovered in eudis-tomins alkaloids (e.g., eudistomin S Fig. 12), isolated from the tunicate organism Eudistoma olivaceum (175). 

Kinzer, K. F., Cardellina, J. H. II, (1987). Three new P -carbolines from the Bermudian tunicate Eudistoma olivaceum. Tetrahedron Lett. 28,925-926. 

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