Leucetta microraphis

Leucetta microraphis [413]. Taurospongin A (485) is a sulfated acetylenic fatty acid derivative from Hippospongia sp. from Okinawa. It inhibits both DNA polymerase b and HIV reverse transcriptase [414]. 

The nonribosomal cyclic peptide leucamide A, 352, was isolated from the marine sponge Leucetta microraphis from the Great Barrier Reef of Australia <2002JOC4989, 2002JOC1636>. It was isolated as the principal active component and found to inhibit the growth of three tumor cell lines (stomach carcinoma, liver carcinoma, liver carcinoma with mutated p53). The compound is composed of seven amino acids and amino-acid-derived residues L-leucine, oxazole, L-alanine, methyloxazole, thiazole, L-valine, and L-proline. 

Leucamide A, a bioactive cyclic hexapeptide first isolated from the Australian marine sponge Leucetta microraphis and stmc-turaUy confirmed by total synthesis. It contains an unique mixed 4,2-bis-heterocycle tandem pair consisting of methyloxazole and thiazole subunit showing moderate cytotoxicity toward several tumor cell lines [S. Kehraus et al., J. Org. 

Cardellina II, J.H., and J. Meinwald Leucettidine, a Novel Pteridine from the Calcareous Sponge Leucetta microraphis. J. Org. Chem. 46, 4782 (1981). 

A triunsaturated aldehyde with 21 carbon atoms has been isolated from the species Leucetta microraphis harvested in Japan (Okinawa). This aldehyde is only weakly cytotoxic (Watanabe et al., 2000a). 

The species Leucascandra caveolata, harvested in New Caledonia, and Leucetta microraphis, of AustraHan origin, yielded leucascandroHdes A and B (D Ambrosio et al., 1996, 1999) and leucamide A (Kehraus et al., 2002), respectively. 

Leucettidine is a derivative of pteridine without specific biological properties, isolated from the species Leucetta microraphis harvested in Bermuda. Again, it is currently the only derivative of pteridine that has been isolated from a calcareous sponge, but similar molecules have been isolated from diatoms, crustaceans, and tunicates (Cardel-lina and Meinwald, 1981). 

Chan, G.W., Mong, S Hemling, M.E., Freyer, AJ., Offen, P.H., DeBrosse, C.W., Sarau, H.M., and Westley, J.W. (1993) New leukotriene B4 receptor antagonist leucettamine A and related imidazole alkaloids from the marine sponge Leucetta microraphis. ]. Nat Prod., 56,116-121. 

Dalisay, D.S., Tsukamoto, S., and Molinski, T.F. (2009a) Absolute configuration of the a,co-bisfunctionalized sphingolipid leucettamol A from Leucetta microraphis by deconvolution exciton coupled CD. J. Nat. Prod., 72, 353-359. 

Kong, F. and Faulkner, D.J. (1993) Leucettamols A and B, two antimicrobial lipids from the calcareous sponge Leucetta microraphis. J. Org. Chem., 58, 970-971. 

Watanabe, K., Tsuda, Y, Iwashima, M., and Iguchi, K. (2000a) A new bioactive triene aldehyde from the marine sponge Leucetta microraphis. J. Nat. Prod., 63, 258-260. 

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