Brassinosteroids 4 Cholestanols 4 Steroids, Heterocyclic 4 article 4 biological activity 4 brassinosteroid 4 fluorination 4 synthesis 4 unclassified drug 28 homocastasterone 2 2alpha fluoro 3alpha,22,23 trihydroxy 5alpha stigmastan 6 one 2 2alpha fluoro 3beta,22,23 trihydroxy 5alpha stigmastan 6 one 2 2alpha, 3alpha difluoro 22,23 dihydroxy 5alpha stigmastan 6 one 2 2alpha,3alpha difluoro 5alpha stigmast 22 en 6 one 2 3,3 difluoro 22,23 dihydroxy 5alpha stigmastan 6 one 2 3,3 difluoro 5alpha stigmast 22 en 6 one 2 Biological Assay 2 Difluorinated steroids 2 Fluorinated steroids 2 Halogenation 2 Magnetic Resonance Spectroscopy 2 Molecular Structure 2 Oryza sativa 2 Plant hormones 2 Steroids 2 Structure-Activity Relationship 2 analytic method 2 carbon 2 cell receptor 2 chemical bond 2