Clathriamide, an hexapeptide isolated from the marine sponge Clathria (Clathria) nicoleae

Chemical investigation of the aqueous fraction of the ethanol extract from the Brazilian endemic marine sponge Clathria (Clathria) nicoleae Vieira de Barros, Santos & Pinheiro, 2013, Microcionidae, sampled from a 55 m deep rhodolith bed at the Amazon River mouth, led to the isolation of a new hexapeptide, clathriamide (1). HP-20 resin was used to capture compound 1 from the aqueous fraction, which was purified by additional chromatographic steps. The absolute configuration of the amino acids of 1 was determined by advanced Marfey's analysis using 5-fluoro-2,4-dinitrophenyl-N alpha-L-tryptophanamide. The amino acid derivatives analyzed by ultra-performance liquid chromatography coupled to a mass spectrometry using a C-8 column enabled a good chromatographic resolution of L-Ile and L-alto-Ile, previously unfeasible using C-18 column. (C) 2019 Sociedade Brasileira de Farmacognosia. Published by Elsevier Editora Ltda.