Publications of 2019 – Clathriamide, a peptide from the sponge Clathria (Clathria) nicoleae

The article “Clathriamide, an hexapeptide isolated from the marine sponge Clathria (Clathria) nicoleae” results of part of Vitor F. Freire PhD project on the investigation of marine sponge metabolites. The sample of Clathria (Clathria) nicoleae was provided to us by the Rio de Janeiro research team at Jardim Botânico, Fernando C. Moraes, Wladimir C. Paradas, Leonardo T. Salgado, Renato C. Pereira, Rodrigo L. Moura and Gilberto M. Amado-Filho. This team participated directly in the expedition to the Amazon river mouth that resulted in the discovery of a very extense coral reef. The discovery of this coral reef was a major breakthrough, reported in the article “An extensive reef system at the Amazon River mouth“. During the expedition several species of marine sponges were collected. One of which was Clathria (Clathria) nicoleae, investigated by Vitor.

The beautiful sponge picture was provided by the late Professor Gilberto M. Amado-Filho, who very sadly passed away in a motorcycle accident in 2019.

Clathriamide was isolated and identified from the sponge aqueous extract, using a procedure developed in our laboratory. The absolute configuration of the amino acids was established by hydrolysis of the peptide followed by derivatization with the recently developed reagent 5-fluoro-2,4-dinitrophenyl-Nα-L-tryptophanamide and UPLC-MS analysis. The 5-fluoro-2,4-dinitrophenyl-Nα-L-tryptophanamide reagent was developed by Mariam N. Salib and Professor Tadeusz Molinski, at the University of California, San Diego. See their article, here.

Why the use of Professor Molinski’s reagent was absolutely necessary to establish the complete absolute stereochemistry of clathriamide?

Because the regular Marfey-derivatized isoleucine standards did not resolved by UPLC-MS analyses. The use of Molinski’s reagent and of a UPLC C8 reversed phase column were essential to resolve the two isoleucine standards we used to complete the absolute configuration assignment of clathriamide. The authors thank to Professor Molinski for the generous gift of his reagent.

Clathriamide article was submitted to the Brazilian Journal of Pharmacognosy, in recognition to the outstanding editorial work by Professor Cid Aimbiré M. dos Santos (Departamento de Farmácia, Universidade Federal do Paraná) to the Brazilian Journal of Pharmacognosy. As the editor-in-chief of the journal, Professor Cid devoted large efforts to increase its quality and visibility, which increased the IF of this journal to almost 2.0.

The article is open-access, and can be downloaded here.