title: Synthesis and bioactivity of C-29 brassinosteroid analogues with different functional groups at C-6.
abstract: In this paper, we report the synthesis and bioactivity of four synthetic analogues of 28-homobrassinosteroids, in order to evaluate the influence in bioactivity when the C-6 keto group is replaced by different functional groups. The synthetic analogues are 6-deoxo-28-homocastasterone [(22R,23R)-stigmasta-2alpha,3alpha,22,23-tetraol], 6alpha-hydroxy-28-homocastasterone [(22R,23R)-stigmasta-2alpha,3alpha,6alpha,22,23-pentaol], 6beta-hydroxy-28-homocastasterone [(22R,23R)-stigmasta-2alpha,3alpha,6beta,22,23-pentaol], and [(22R,23R)-6alpha-fluorostigmasta-2alpha,3alpha,22,23-tetraol]. Results indicate that replacement of the 6-keto moiety by an beta or alpha hydroxyl group led to a decrease in activity, whereas the 6-deoxo analogue showed a very low activity, confirming the importance of an electronegative moiety at C-6 to observe hormonal potency. The 6alpha-fluorinated analogue elicited a low activity, similar to that of the 6-deoxo analogue.
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria (C1428EGA), Buenos Aires 1428, Argentina.
authors.forename: Javier A
authors.initials: JA
authors.lastname: Ramírez
authors.forename: Carme
authors.initials: C
authors.lastname: Brosa
authors.forename: Lydia R
authors.initials: LR
authors.lastname: Galagovsky
mesh_terms: D002778:Cholestanones / Q000138:chemical synthesis / Q000737:chemistry* / Q000302:isolation & purification; D008958:Models, Molecular; D008968:Molecular Conformation; D012275:Oryza / Q000502:physiology*; D010937:Plant Growth Regulators / Q000138:chemical synthesis / Q000737:chemistry* / Q000302:isolation & purification; D036226:Seedlings / Q000502:physiology; D013265:Stigmasterol / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D002778:Cholestanones; D010937:Plant Growth Regulators; C070164:homocastasterone; D013265:Stigmasterol