A new ELISA for quantification of brassinosteroids in plants.

Starting from (22R,23R)-2α,3α,22,23,26-pentahydroxy-5α-cholestan-6-one 26-hemisuccinate, conjugates of 28-norcastasterone with horse radish peroxidase and bovine serum albumin were prepared. The latter conjugate was injected into rabbits; produced polyclonal antibodies were used to quantitate 6-keto-brassinosteroids. The newly developed analytical system was used in combination with two other immunoenzymatic assays for brassinosteroids to determine individual compounds of this series. In addition, a direct method of brassinosteroid analysis was proposed. It has the advantage of requiring no sample pretreatment steps such as extraction with organic solvents and chromatography.