Ascidians aromatic alkaloids from

Kang, H., Fenical, W., (1997). Ningalins A-D Novel aromatic alkaloids from a western Australians ascidian of the genus Didemnum. J. Org. Chem. 62,3254-3262. 

Schmitz, F.J., DeGuzman, F.S., Hossain, M.B., and Van der Helm, D. (1991) Cytotoxic aromatic alkaloids from the ascidians Amphicarpa meridiana and Leptodinides sp. meridine and 11-hydroxy-ascididemnin. J. Org. Chem., 56, 804-808. 

Dilip de Silva, E., Miao, S., Andersen, R.J., Wayne, L., and Clardy, J. (1992) Trididemnic acids A and B, aromatic alkaloids from the Northeastern Pacific ascidian Trididemnum sp. Tetrahedron Lett., 33, 2917-2920. 

Much interest and research over the past 15 or so years has been directed towards ascidian metabolites because of the high incidence of pharmacological activity that they display. Few comprehensive reviews exist on the topic the only general ones being those produced by Davidson in 1993 [1,2] and the Marine Natural Product literature reviews by Faulkner which always contain a section on tunicate metabolites [3-13]. Although a number of non-nitrogenous metabolites have been isolated from the tunicates, the majority of compoimds isolated have been derived from amino acids. In particular, the two most commonly encountered classes are cyclic peptides and polycyclic aromatic alkaloids. 

These are perhaps the most diverse group of aromatic alkaloids isolated from ascidians. Their structures span a range of complexity, starting with 6-bromoindole-3-aldehyde (105) (previously reported from a marine Pseudomonas sp.), and the brominat quinazolinedione (106) from Pyura sacciformis [76]. 

In 1990, Schmitz et al. reported the isolation and structure elucidation of a pentacyclic aromatic alkaloid, meridine (445), and its tautomer, isomer-idine (446), from the ascidian Amphicarpa maridiana collected at Stenhouse Bay in South Australia 151,152). 

Berlinck, R. G. S., Britton, R., Piers, E., Lim, L., Roberge, M., Moreira da Rocha, R., Andersen, R. J., (1998). Granulatimide and Isogranulatimide, Aromatic Alkaloids with G2 Checkpoint Inhibition Activity Isolated from the Brazilian Ascidian Didemnum granulatum Structure Elucidation and Synthesis. J. Org. Chem. 63, 9850-9856. 

Berlinck, R.G.S., Britton, R Piers, E Lim, L Roberge, M Moreirade Rocha, R and Andersen, R.J. (1998) Granulatimide and isogranulatimide, aromatic alkaloids with G2 checkpoint inhibition activity isolated from the Brazilian ascidian Didemnum granulatum structure elucidation and synthesis. J. Org. Chem., 63, 9850-9856. 

Kim, J., Pordesimo, E.O., Toth, S.L, and Schmitz, F.J. (1993) Paniherinine, a cytotoxic aromatic alkaloid, and 7-deaza-inosme from the ascidian Aplidiumpontbrinum./. Nat. Prod., 56, 1813-1816. 

Although the division between the peptides and other nitrogen-containing metabolites derived from ascidians is not a clear cut one, the literature published on the non-peptidic, tunicate-derived alkaloids which contain aromatic (often in combination with heteroaromatic) rings has been summarised. The few linear peptides (which contain aromatic amino acid residues) have also been included because of their apparent structural... 

Compared with didemnids, polydinid ascidians contain few alkaloids but many aromatic derivatives, including meroterpenes. The macrocyclic orthonitrites isolated from a spedes of Aplidium harvested in Australia are the first known examples in nature of such nitrogenous derivatives. Table 28.11 presents the main types of metabolite isolated from polydinid ascidians. 

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