Background: The use of exo-16,17-dihydro-gibberellin A5-13-acetate (DHGA5 ) in agriculture has been limited by its low synthetic yield. This study was aimed at optimizing the synthetic route of DHGA5 , designing and synthesizing new derivatives with strong plant growth inhibitory activities.
Results: Previous synthetic methods were replaced with a shorter, milder and faster reaction route with higher yield (76.3%) of DHGA5 . Based on this novel route, a series of new derivatives were designed and synthesized using DHGA5 as a lead compound and characterized and evaluated for biological activities in Arabidopsis thaliana. Among the 15 tested derivatives, compound 14j showed a lower medium inhibition concentration (IC50 , 73 μm) in Arabidopsis than that of DHGA5 (91 μm). Gibberellin deficient mutant assay further revealed that 14j had very different activities compared to DHGA5 as it specifically inhibits gibberellin biosynthetic pathways. In addition, 14j does not influence the interaction between gibberellin receptors (GID1) and the master growth repressor (RGA) based on yeast two-hybrid assay.
Conclusion: The optimized synthetic route provides a promising method for large-scale preparation of DHGA5 . Our biological assays indicate that 14j likely acts on gibberellin signaling elements other than GID1. These results indicate that novel plant growth regulators can be developed. © 2019 Society of Chemical Industry.
Keywords: action mechanism; derivatives; dihydro-gibberellin; natural products; optimization of synthetic pathways; plant growth regulators (PGRs).
© 2019 Society of Chemical Industry.