Kahalalides: Bioactive peptide from a marine mollusk Elysia rufescens and its algal diet Bryopsis sp

In addition to the previously reported bioactive kahalalide F six new peptides are described. Six of these, including kahalalide F, are cyclic depsipeptides, ranging from a C-31 tripeptide to a C-75 tridecapeptide isolated from a sacoglossan mollusk, Elysia rufescens. The mollusk feeds on a green alga, Bryopsis sp., which has also been shown to elaborate some of these peptides in smaller yields, in addition to an acyclic analog of F, kahalalide G. The bioassay results of antitumor, antiviral, antimalarial, and OI (activity against AIDS opportunistic infections) tests are reported.