Novel betaines from a micronesian sponge Dysidea herbacea.

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