Epimeric mixtures of brassinosteroid analogs: Synthesis, plant growth, and germination effects in tomato (Lycopersicum esculentum Mill.)

Brassinosteroids (BRs) play an important role in the growth and development of plants. Herein, we describe the synthesis of epimeric mixtures of BR analogs with 24-norcholane type side chains, S/R configuration at C22 and A/B ring cis-type fusion. All epimeric mixtures were synthetized from hyodeoxycholic acid. The biological activity of mixtures was evaluated by using rice lamina inclination test and germination of tomato (Lycopersicum esculentum) seeds. The results show that these epimeric mixtures exhibit similar bioactivity to brassinolide in both bioassays. Thus, our results corroborate that the A/B junction has almost no effect on bioactivity and open the possibility of using epimeric mixtures instead of pure compounds. In this approach, the synthesized BR analogs maintain a good level of bioactivity, whereas the synthesis is shorter, cheaper and with higher yields. All these factors make this alternative very interesting for potential application.