Abstract
Brassinazole is a potent brassinosteroid (BR) biosynthesis inhibitor and is shown to be useful to elucidate the function of BR. We have modified the chemical structure of brassinazole to improve selectivity. Development of the derivatives that have rigid conformation could lead to creation to the drugs without side effects. Therefore, introduction of double bond to the chemical structure of brassinazole was conducted. Moreover, these compounds have been synthesized using the rational approach of Topliss' decision tree. Generally, this approch allows us to obtain the most active derivatives in a few steps. A variety of substituents introduced at phenyl ring have investigated in this series, together with the determination of the effects of double bond of brassinazole is isomerization (E and Z geometry). These compounds were tested against cress stem elongation. As a result, inhibition of BR biosynthesis by these new compounds appears to be linked to combination of E geometry and 4'-chrorine at phenyl ring. The new lead for BR biosynthesis inhibitory activity has been predicted and will be used in further structure-activity relationship studies on brassinazole.
