New 2-Methoxy Acetylenic Acids and Pyrazole Alkaloids from the Marine Sponge Cinachyrella sp.

Three new 2-methoxy acetylenic acids (1-3) and a known derivative (4), in addition to three new natural pyrazole alkaloids (5-7) were isolated from an Indonesian marine sponge of the genus Cinachyrella. Compounds 5 and 6 have previously been reported as synthetic compounds. The structures of the new compounds were established on the basis of one- and two-dimensional NMR spectroscopy as well as by mass spectrometric data. The absolute configuration of the new acetylenic acid derivatives (1-3) was established by ECD spectroscopy. All isolated compounds were evaluated for their cytotoxicity against L5178Y mouse lymphoma cells. Compounds 1-4 exhibited strong activity with an IC50 value of 0.3 µM. A plausible biosynthetic pathway for the pyrazole metabolites 5-7 is proposed.