New Antimalarial and Antimicrobial Tryptamine Derivatives from the Marine Sponge .

Chemical study of the CH₂Cl₂-MeOH (1:1) extract of the sponge collected in Mayotte highlighted three new tryptophan derived alkaloids, 6,6'-bis-(debromo)-gelliusine F (), 6-bromo-8,1'-dihydro-isoplysin A () and 5,6-dibromo-8,1'-dihydro-isoplysin A (), along with the synthetically known 8-oxo-tryptamine () and the three known molecules from the same family, tryptamine (), ()-6-bromo-2'-demethyl-3'--methylaplysinopsin () and ()-6-bromo-2'-demethyl-3'--methylaplysinopsin (). Their structures were elucidated by 1D and 2D NMR spectra and HRESIMS data. All compounds were evaluated for their antimicrobial and their antiplasmodial activities. Regarding antimicrobial activities, the best compounds are () and (), with minimum inhibitory concentration (MIC) of 0.01 and 1 µg/mL, respectively, towards , and (), with MIC values of 1 µg/mL towards . In addition the known 8-oxo-tryptamine () and the mixture of the ()-6-bromo-2'-demethyl-3'--methylaplysinopsin () and ()-6-bromo-2'-demethyl-3'--methylaplysinopsin () showed moderate antiplasmodial activity against with IC values of 8.8 and 8.0 µg/mL, respectively.