| Summary: | Two new bromotyrosine alkaloids, ceratinadins E (<b>1</b>) and F (<b>2</b>), were isolated from an Okinawan marine sponge <i>Pseudoceratina</i> sp. as well as a known bromotyrosine alkaloid, psammaplysin F (<b>3</b>). The gross structures of <b>1</b> and <b>2</b> were elucidated on the basis of spectroscopic data. The absolute configurations of <b>1</b> and <b>2</b> were assigned by comparison of the NMR and ECD data with those of a known related bromotyrosine alkaloid, psammaplysin A (<b>4</b>). Ceratinadins E (<b>1</b>) and F (<b>2</b>) are new bromotyrosine alkaloids possessing an 8,10-dibromo-9-methoxy-1,6-dioxa-2-azaspiro[4.6]undeca-2,7,9-trien-4-ol unit with two or three 11-<i>N</i>-methylmoloka’iamine units connected by carbonyl groups, respectively. Ceratinadin E (<b>1</b>) exhibited antimalarial activities against a drug-resistant and a drug-sensitive strains of <i>Plasmodium falciparum</i> (K1 and FCR3 strains, respectively).
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