Conformation-Activity Relationship of Bioactive Compounds

Molecular conformations of cytotoxic ascidiacyclamide (a cyclic peptide from marine ascidian), antitumor swinholide A (a cyclic macrolide from marine sponge), antifimgal eureobasidin E (a cyclic depsipeptide antibiotic) and neurotransmitter achatin-I (a linear tetrapeptide from giant snail) have been determined by X-ray single crystal analyses to discuss possible relationship with their bioactivities.