title: Activity of the aldehyde and alcohol of gibberellins A12 and A 14, two derivatives of gibberellin A 15 and four decomposition products of gibberellin A 3 in 13 plant bioassays.
abstract: The biological activities of the aldehyde and alcohol of gibberellins (GAs) A12 and A14, 3α-OH-GA15, 3β-OH-GA15 wrong lactone (i.e. GA37 wrong lactone) and the four major decomposition products of GA3 (isogibberellic, allogibberic, epiallogibberic and Δ9(11)-dehydroallogibberic acids) were tested over a wide range of concentrations on 13 plant bioassays in order to ascertain certain of the structural requirements for biological activity. Generally modification of the basic GA-molecule decreased its activity in all assays except for derivatives of GA12 and GA14 (suggesting conversion of these derivatives to more polar, active GAs). Modification of the 3-OH from the usual 3β to 3α configuration markedly reduced activity. Neither the presence of an inverted lactone ring (i.e. 3β-OH-GA15 wrong lactone) nor changes to the lactone ring of GA3 (4→10) to form iso-GA3 (4→2) appreciably reduce activity. Further decomposition of GA3 to allogibberic and Δ9(11)-dehydroallogibberic acid reduced activity only slightly, but epimerization of allogibberic acid at C-9 essentially eliminated biological activity.
authors.affiliation: Long Ashton Research Station, University of Bristol, BS18 9AF, Bristol, UK.
authors.forename: G V
authors.initials: GV
authors.lastname: Hoad
authors.forename: R P
authors.initials: RP
authors.lastname: Pharis
authors.forename: I D
authors.initials: ID
authors.lastname: Railton
authors.forename: R C
authors.initials: RC
authors.lastname: Durley