Isolation, structure determination and cytotoxicity studies of tryptophan alkaloids from an Australian marine sponge Hyrtios sp.

Mass-guided fractionation of the MeOH extract from a specimen of the Australian marine sponge Hyrtios sp. resulted in the isolation of two new tryptophan alkaloids, 6-oxofascaplysin ( 2 ), and secofascaplysic acid ( 3 ), in addition to the known metabolites fascaplysin ( 1 ) and reticulatate ( 4 ). The structures of all molecules were determined following NMR and MS data analysis. Structural ambiguities in 2 were addressed through comparison of experimental and DFT-generated theoretical NMR spectral values. Compounds 1 – 4 were evaluated for their cytotoxicity against a prostate cancer cell line (LNCaP) and were shown to display IC 50 values ranging from 0.54 to 44.9 μM. [ABSTRACT FROM AUTHOR]