ABSTRACT 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-Nα-L-tryptophanamide. The amino acid derivatives analyzed by ultra-performance liquid chromatography coupled to a mass spectrometry using a C8 column enabled a good chromatographic resolution of L-Ile and L-allo-Ile, previously unfeasible using C18 column.

Previous studies on Passiflora edulis (sour passion fruit) rinds reported some biological activities and there is a growing interest on rinds flour as a possible functional food, but its alkaloid composition was not detailed investigated. This work reports on for the first time in the literature the identification of norharman in P. edulis rinds, by using stir bar sorptive extraction combined with ultra-fast liquid chromatography coupled to tandem mass spectrometry [SBSE(EG-Silicone)-UFLC-MS/MS)]. This β-carboline alkaloid is suspected to be neurotoxic. Therefore, another purpose of this study was to develop methods of targeted quantification of norharman in P. edulis rinds extracts using polydimethylsiloxane as stationary phase (SBSE(PDMS)) and a copolymer of polydimethylsiloxane and polyethylene glycol as stationary phase (SBSE(EG-Silicone)) combined with high performance liquid chromatography with fluorescence detection (HPLC-Flu) and ultra-fast liquid chromatography coupled with tandem mass spectrometry (UFLC-MS/MS). Norharman extraction by SBSE(PDMS) and SBSE(EG-Silicone) was optimized and compared, and the analytical performance of SBSE(EG-Silicone) method was superior to that of SBSE(PDMS). The analysis of a sample of dried P. edulis rind indicated (332.16 ± 8.43) pg g-1 of norharman.

Samples of pulp and seeds of sour (P. edulis) and sweet (P. alata) passionfruit were subjected to targeted analysis to identify β-carboline alkaloids, using combined UHPLC-MS (ultrahigh performance liquid chromatography-mass spectrometry) and SBSE(PDMS) (stir bar sorption extraction using polydimethylsiloxane as stationary phase) for sample preconcentration. All the samples contained harmane and harmine; harmaline was found only in P. alata seeds and in P. edulis pulp, while harmalol was found only in P. alata seeds. An analysis of sweet passionfruit by SBSE(PDMS) combined with LC/Flu (liquid chromatography/fluorescence detection) indicated 1.03 × 10-1 ± 3.05 × 10-3 µg harmane L-1 pulp and 7.44 × 10-5 ± 2.55 × 10-6 µg harmane g-1 seeds, but harmine was not detectable by the quantitative method. Our findings underscore the need for further studies about passionfruit food safety, in view of the potential toxicity of β-carboline alkaloids.