Ma'edamines C and D, New Bromotyrosine Alkaloids Possessing a Unique Tetrasubstituted Pyridinium Moiety from an Okinawan Marine Sponge Suberea sp.

Two new bromotyrosine alkaloids, ma'edamines C and D, were isolated from an Okinawan marine sponge Suberea sp. The structures of ma'edamines C and D were elucidated on the basis of spectroscopic data. Ma'edamines C and D were the first natural products possessing a unique tetrasubstituted pyridinium moiety such as N-alkyl-3,5-diethyl-2-propylpyridinium and N-alkyl-3,5-diethyl-4-propylpyridinium, respectively. Ma'edamines C and D exhibited moderate cytotoxicity against murine leukemia cell line L1210 in vitro.