title: Isolation of 13 New Ritterazines from the Tunicate Ritterella tokioka and Chemical Transformation of Ritterazine B(1).
abstract: Thirteen new ritterazines, ritterazines N-Z (2-14), were isolated from the tunicate Ritterella tokioka. Chemical transformation of ritterazine B, the most active among the ritterazines, by reduction, oxidation, methanolysis, and acetylation furnished compounds 20, 21, 23, and 25-29. Cytotoxicity of 26 natural products and chemically modified ritterazine B disclosed important structural features of the ritterazines for cytotoxic activity.
authors.affiliation: Laboratory of Aquatic Natural Products Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.
authors.forename: Seketsu
authors.initials: S
authors.lastname: Fukuzawa
authors.forename: Shigeki
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Fusetani