Eudistoma species

Makarieva TN, Dmitrenok AS, Dmitrenok PS, Grebnev BB, Stonik VA (2001) Pibocin B, the First A -O-Methylindole Marine Alkaloid, a Metabolite from the Far-Eastern Ascidian Eudistoma Species. J Nat Prod 64 1559... 

Novel pterins from a Eudistoma species Ascidian. In another report, Ireland and coworkers reported the isolation and structural characterization of several novel pterins from a methanol extract of an Indonesian Eudistoma sp. ascidian. In characterizing the 1,3,0 -trimethylisoxanthopterin skeleton, 120, the authors acquired both 10 and 4 Hz optimized HMBC data. From these experiments, the authors were able to assign... 

An interesting clavine structure, pibocin (11 Fig. 2), was isolated from a tunicate, Eudistoma species (55). This marine animal represents another taxonomic kingdom from which EA have been isolated. The preponderance of symbiotic fungi as EA sources in plants highlights the possibility that a fungal symbiont of the Eudistoma species might be the source of pibocin or a pibocin precursor, but this... 

Davis, R.A., Christensen, L.V., Richardson, A.D., Moreira da Rocha, R and Ireland, C.M. (2003b) Rigidin E, a new pyrrolopyrimidine alkaloid from a Papua New Guinea tunicate Eudistoma species. Mar. Drugs, 1, 27-33. 

Makarieva, T.N., Dmitrenok, A.S., Dmitrenok, P.S., Grebnev, B.B., and Stonik, V.A. (2001) Pibocin B, the first N-O-methylindole marine alkaloid, a metabolite from the Far-Eastern ascidian Eudistoma species./. Nat. Prod., 64,1559-1561. 

Van Wagoner, R.M., Jompa, J., Tahir, A, and Ireland, C.M. (2001) A novel modified pterin from a Eudistoma species ascidian. /. Nat. Prod., 64,1100-1101. 

Currently, there has been no study of the secondary metabolites of Cephalochordata. Studies of Urochordata have been considerable but have focused on the class Ascidiacea (ascidians or sea squirts), which contain entire series of alkaloids, often with antiviral and anti-tumor properties. The ascidians share with sharks, which are primitive cartilaginous fish, the absence of liability to tumor development. In many species there is no epibio-sis, which often indicates the presence of cytotoxic and/or antibacterial substances, but antiviral substances were discovered among ascidians with epibionts (Eudistoma sp. and eudistomins (see below). 

The eudistomins constitute a broad family of P-carboline alkaloids which are found mainly in the genus Eudistoma (mostly from E. olivaceum) but also in a few species of Lissoclinum (eudistomine U, isolated from L. vareau see above) and in Ritterella (see below), which all belong to the order Aplousobranchia. This series of alkaloids was discovered in 1978 during the same expedition of the American vessel Alpha Helix that led to the discovery of the didemnins. The 30 eudistomins currently known are almost all brominated and may be divided into four structural types, which are presented in Figure 28.19. 

Several P-carboHne alkaloids related to eudistomins were isolated from Eudistoma glaucus and other species of Eudistoma, such as E. album, E.fragum, and E. gUboverde. Generally, these derivatives have antiviral and antitumor activities similar to those of eudistomins, but eudistomi-din A is also an antagonist of calmodulin (Kobayashi, Nakamura, and Ohizumi, 1986). Some members of this series are presented in Figure 28.21. 

Figure 28.19 Eudistomins isolated from species ofthe genus Eudistoma.

Eudistones A and B were obtained from an undetermined species of Eudistoma from the Seychelles Islands. Tintamine, shermilamine E and cydoshermil-amine D are three sulfur-containing pyridoacridines. These new alkaloids were extracted from Cystodytes viola-tinctus, whose specific name refers to the animal s color and whose origin is the lagoon of Mayotte. Tintamine is the first example of a pyridoacridine associated with a tropolone and shermilamine E is a rare example of an N-oxide derivative isolated from a marine organism. 

Among other examples of complex pyridoacridines, cystodamine (hydroxyacididemine) and sebastianines A and B have been isolated from the same species, Cystodytes dellechiajei, harvested in the Mediterranean (Tunisia) and in the South Atlantic (Brazil) respectively. Amoamines A and B, isolated from an undetermined species of Eudistoma harvested in the Marshall Islands, are the first known examples of pyridoacridines containing a pyrrole attached to the tetracyclic system of pyridoacridine. All of these products are cytotoxic. 

Many other alkaloids have been isolated from polydtorid ascidians, and we will present only some of the most important structures. Among these, it is worth mentioning two hydroxy derivatives of staurosporine and rigidins A-E, which form a group of pyrrolopyrimidine derivatives. Some of them are calmodulin antagonists. These derivatives were isolated from species of the genera Cystodytes and Eudistoma. 

According to Brand et al. (1989), a few species of aplousobranch ascidians, such as Eudistoma amplus, Euherdmania sp., Leptoclinides dubius and L lissus, also contain vanadium in their blood cells. 

---