Novel Betaines from a Micronesian Sponge <i>Dysidea </i><i>h</i><i>erbacea</i>

Three new betaines, dysibetaine PP (<b>1</b>), dysibetaine CPa (<b>2</b>), and dysibetaine CPb (<b>3</b>), were isolated from an aqueous extract of the marine sponge <i>Dysidea herbacea</i> collected in Yap state, Micronesia. The structure of <b>1</b> was determined by spectral methods as well as chemical degradation to be a novel dipeptide betaine, and those for <b>2</b> and <b>3</b> were determined to be unprecedented cyclopropane betaines. Compounds <b>2</b> and <b>3</b> showed weak affinity toward the <i>N</i>-methyl-d-aspartic acid-type and the kainic acid-type glutamate receptors, respectively, in a radioligand binding assay.