Aplysina caissara

The Mexican sponge Aplysina gerardogreeni contains calafianin (2106) (1880) (structure revised and confirmed by total synthesis, (1881-1883)), the known aerothionin, and the new phenylacetic acid 2107 (1880). These studies confirm that calafianin (2106) and aerothionin have the same absolute configuration (1883). Whereas aerothionin displays antibacterial activity against Mycobacterium tuberculosis, calafianin does not (1884). The Brazilian sponge Aplysina caissara contains the new caissarines A (2108) and B (2109) (1885). 

Saeki BM, Granato AC, Berlinck RGS, Magalhaes A, Schefer AB, Ferreira AG, Pinheiro US, Flajdu E (2002) Two Unprecedented Dibromotyrosine-Derived Alkaloids from the Brazilian Endemic Marine Sponge Aplysina caissara. J Nat Prod 65 796... 

Undoubtedly the most structurally and biogenetically intriguing bromotyrosines are the many spirocyclohexadienyl isoxazoles, which are too numerous to describe fully here [1[. Of those examples containing a single spiro unit, recently isolated compounds include ianthesine A (84) from the Australian sponge lanthdla sp. [72], caissarine A (85) from a Brazilian Aplysina caissara [73], and the unnamed 86 from an Australian non-verongid sponge Oceanapia sp. ]74]. 

Saeki, B.M., Granato, A.C., Berlinck, R.G.S., Magalhaes, A.S., Schefer, A.B., Ferreira, A.G., Pinheiro, U.S., and Hajdu, E. (2002) Two unprecedented dibromotyrosine-derived alkaloids from the Brazihan endemic marine sponge Aplysina caissara. J. Nat. Prod., 65, 796—799. 

Structurally related to aerothionin and homoaerothionin, caissarine B (76), recently isolated from the Brazilian sponge Aplysina caissara, is the only bromo-tyrosine-derived alkaloid bearing a l,7-diamino-3-hydroxyheptane chain, a diamine moiety that has no precedent among natural products (66). 

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