Chelynotus semperi

Thiazolopyridoacridine alkaloids obtained from marine sources, kuanoniamines (2a-c), bright yellow metabolites from the mollusk Chelynotus semperi, display... 

The pyridoacridine alkaloids, kuanoniamines A-D (133-136) were isolated from an unidentified Micronesian tunicate and its nudibranch predator, Chelynotus semperi. The structures were established by extensive NMR spectral analysis. Cytotoxicity against KB cells ranged from IC50 values >10 ig/mL for kuanoniamine B (134), 5 ig/mL for kuanoniamine D (136), to 1 ig/mL for kuanoniamine A (133) [145]. Kuanoniamine A (133) has also been synthesised [146,147]. 

Kuanoniamines A-D (213-216) were isolated from an unidentified Mi-cronesian purple colonial tunicate and its predator, Chelynotus semperi, and exhibits cytotoxicity (177). Judging from the more than 20 examples mentioned above, it seems likely that these metabolites embracing the common tetracyclic unit (189) should be classed together biosynthetically. The diversity of source organisms would suggest that the metabolites are produced by symbionts. 

An examination of the composition of polyaromatic alkaloids of the mollusk Chelynotus semperi and an unidentified tunicate, both collected from Mante channel, Pohnpei, resulted in the identification of shermilamine B [129] and kuanoniamines A-D [130-133] (105). Shermilamine was originally found as a metabolite of a tunicate of the genus TruUdanmon (106). 

EtOAc (6 4) as eluant to yield pure kuanoniamine A. These metabolites were also isolated from a mollusk Chelynotus semperi, which was observed to eat the ascidian. 

Caroll, A. R. and Scheuer, P. J. (1990) Kuanoniamines A, B, C, and D pentacyclic alkaloids from a tunicate and its prosobranch mollusk predator Chelynotus semperi. J. Org. Chem. 55,4426-4431. 

In 1990, Scheuer et al. reported the isolation and structure elucidation of four thiazolopyridoacridine alkaloids, of which kuanoniamine A (439) possesses a quinolinequinoneimine (1) subunit, from both the lamellariid mollusk Chelynotus semperi and an unidentified purple colonial tunicate collected at the Mante Channel, Pohnpei 186). 

Kuanoniamines. Pyrido[2,3,4-k/]acridinone and -acridine alkaloids from the mollusc Chelynotus semperi which feeds on tunicates. 

Kuanoniamines A-D. The third group of acridine-derived alkaloids to be reported, was the kuanoniamines (35, 36) (Carroll and Scheuer 1990) isolated from a Micronesian tunicate and its prosobranch mollusc predator Chelynotus semperi. Structurally, the kuanoniamines differ from nordercitin and the related compounds discussed above only in the fusion of the thiazole to the pyridoacridine nucleus. Direct proton-carbon shift correlations were... 

Most of these alkaloids have already been encountered in didemnid ascidians (Figure 28.7) and mollusks Chelynotus semperi see Chapter 23). Isolation of bacteria associated with blue and green chemotypes showed that the antiproliferative activity of the extracts from these ascidians is not of bacterial origin (Martinez-Garcia et al., 2007). 

Thiazolopyridoacridine alkaloids obtained from marine sources, kuanoniamines (2a-c), bright yellow metabolites from the mollusk Chelynotus semperi, display only modest cytotoxicity. They strongly coordinate divalent ions (Fe, Co , Cu, Xeq 10 ° M ) and are pH indicators, their color changing from... 

---