Kuanoniamine

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

Dihydrothiazoloquinoline is a key intermediate in the synthesis of natural sulfur-containing pyridoacridine alkaloids—kuanoniamines and derdercitins, where the starting dienone is converted after a multistep reaction sequence to an a-bromo-ketone, which in turn was cyclized with thiourea to the desired dihydrothiazoloquinoline, photochemically convertible to the final alkaloid derivatives 39 (Scheme 21) (92JA10081, 95TL4709, 95JA12460). 

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. 

Gunawardana, G. P., Koehn, F. E., Lee, A. Y., Clardy, J., He, H., and Faulkner, D. J., Pyridoacridine alkaloids from deep-water sponges of the family Pachastrellidae structure revision of dercitin and related compounds and correlation with kuanoniamines, J. Org. Chem., 57, 1523, 1992. 

The Jacobson synthesis of benzothiazoles 235 involves oxidative cyclization of an arylthioamide 236 on an unsubstituted ortho- )osit on, using potassium ferricyanide in a basic medium (Scheme 94) <1999J(P1)1437>. This method has been applied to the synthesis of various benzothiazoles, including analogues of kuanoniamine A <20040BC3039>. 

Pyridoacridine alkaloids have been isolated from sponges ascidians, anemones, and a prosobranch. Two thiazole-containing compounds were obtained, namely kuanoniamine E, 429, and kuanoniamine E, 430 <2002JNP1198>. 

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). 

The same strategy has been applied to the preparation of a number of pyridoacridine alkaloids, which include 2-bromoleptoclinidone 29 (90LA205), 11-hydroxyascididemin 30 (93H943) and kuanoniamine A 146 (93H943), and also for the synthesis of neocalliactine acetate 139 (92LA1205 93H943) (a derivative of calliactine 32). 

The pyridoacridine alkaloids isolated from the Micronesian sponge Oceanapia sp. were tested for insecticidal activity, cytotoxicity properties, as well as for their ability to bind to adenosine receptors and to benzodiazepine binding sites of GABAa receptors [91]. Kuanoniamines C... 

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