title: Alkaloids from the Tunicate Polycarpa aurata from Chuuk Atoll.
abstract: Two new alkaloids, polycarpine (1) and N,N-didesmethylgrossularine-1 (4), have been isolated from extracts of the ascidian Polycarpa aurata collected in Chuuk, Federated States of Micronesia. Three degradation products of 1 were also isolated. The structures of 1, 2, and 4 were determined by X-ray crystallography. The dimeric disulfide 1 inhibited the enzyme inosine monophosphate dehydrogenase, but the inhibition could be reversed by addition of excess dithiothreitol suggesting that 1 reacts with sulfhydryl groups on the enzyme.
authors.affiliation: Institute of Biochemistry and Cell Biology, Syntex Discovery Research, Palo Alto, California 94304.
authors.forename: Sayed A.
authors.initials: SA
authors.lastname: Abas
authors.forename: M. Bilayet
authors.initials: MB
authors.lastname: Hossain
authors.forename: Dick
authors.initials: D
authors.lastname: van Der Helm
authors.forename: Francis J.
authors.initials: FJ
authors.lastname: Schmitz
authors.forename: Maureen
authors.initials: M
authors.lastname: Laney
authors.forename: Ronnel
authors.initials: R
authors.lastname: Cabuslay
authors.forename: Randall C.
authors.initials: RC
authors.lastname: Schatzman