title: Biosynthesis of GA73 Methyl Ester in Lygodium Ferns.
abstract: Biosynthesis of GA73 methyl ester (GA73-Me), the principal antheridiogen in Lygodium ferns, was investigated. From the methanol extract of prothallia of Lygodium circinnatum, GA25, GA73, GA73-Me, GA88-Me, and a few unknown GA73 derivatives were detected by GC-MS. Because the presence of GA25 suggests that GA24, a direct precursor of GA25, could also be present in L. circinnatum prothallia, we used feeding experiments to investigate the possibility that GA24 is a precursor of GA73-Me. In L. circinnatum prothallia, [2H2]GA24 was converted into [2H2]GA73-Me and a trace amount of [2H2]GA9-Me, whereas [2H3]GA9 was converted into [2H3]GA9-Me and [2H3]monohydroxy-GA9-Me. Because GA73-Me, GA9-Me, and their monohydroxy derivatives had been identified by GC-MS from the culture medium of L. circinnatum prothallia, our results suggest that GA73-Me is biosynthesized from GA24 via GA73, and that neither GA9 nor GA9-Me is a precursor of GA73-Me. Though the possibility had been suggested that GA73-Me is biosynthesized from 9,15-cyclo-GA9 (GA103), [2H2]GA103 was not converted into [2H2]GA73-Me.
authors.affiliation: Department of Applied Biological Chemistry (T.Y., N.O., N.M.) and Biotechnology Research Center (H.Y.), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113, Japan.
authors.forename: T.
authors.initials: T
authors.lastname: Yamauchi
authors.forename: N.
authors.initials: N
authors.lastname: Oyama
authors.forename: H.
authors.initials: H
authors.lastname: Yamane
authors.forename: N.
authors.initials: N
authors.lastname: Murofushi
authors.forename: H.
authors.initials: H
authors.lastname: Schraudolf
authors.forename: M.
authors.initials: M
authors.lastname: Pour
authors.forename: H.
authors.initials: H
authors.lastname: Seto
authors.forename: L. N.
authors.initials: LN
authors.lastname: Mander