Ritterella sigillinoides

Eudistomin K (155) (135) and its sulfoxide (171) (136) were isolated from the New Zealand ascidian Ritterella sigillinoides. The sulfoxide (171) also shows antiviral activity. The structure of 155 was determined by X-ray analysis (137) and that of 171 by semisynthesis from 155. Three other /3-carbolines, named eudistomins R, S, and T (172-174) were obtained from a Bermudian tunicate (E. olivaceum) by using an amino-bonded HPLC column (138). A 2-methyl-1,2,3,4-tetrahydro- -carboline with an /V-methylpyrrolidine at C-l, named woodinine (175), was isolated from a New Caledonian ascidian (Eudistoma fragum) (139), extracts of which exhibit antimicrobial activity. 

In their publication in 1987, Rinehart et ai, stipulate that the structure of eudistomin B is still uncertain. Eudistomin U has been isolated from Lissoclinum fragile [vide supra p. 1337), eudistomin V has been isolafed from the ascidian Polyclinidae Pseudodistoma aureum vide infra), and another ascidian Polyclinidae, Ritterella sigillinoides, also contains several examples of eudisfomins vide infra). 

---