New Spiro-Sesquiterpenoids from the Marine Sponge Myrmekioderma sp.

Three new spiro-sesquiterpenoids, myrmekiones A-C (1-3), were isolated from the marine sponge Myrmekioderma sp. collected from the South China Sea. The structures of 1-3 were experimentally illuminated though comprehensive NMR spectra, X-ray diffraction analysis and calculated ECD. These three compounds possessed a special spiro skeleton. Compound 1 was characterized by a chamigrane-type structure, it is the first time to obtain the single-crystal of this type of oil compounds. 2 and 3 were a pair of diastereoisomers that possessed an acorane skeleton. This study expands the chemical diversity of marine origin spiro-metabolites.