New synthetic brassinosteroids: a 5α-hydroxy-6-ketone analog with strong plant growth promoting activity

Synthesis of Five Known Brassinosteroid Analogs from Hyodeoxycholic Acid and Their Activities as Plant-Growth Regulators

“…In this sense, several studies have been focused on determining the structural requirements that these compounds should possess to elicit strong biological activity [18,19,20]. It has been concluded that the activity of BRs depends on the oxygen atoms spatial situation, and a new way to relate the structure of BRs with their activity has been proposed [21,22]. Namely, the activity is attributed to the different conformations that BR molecules can adopt, one of them being the active conformation.…”

“…These spatial orientations can be indicated as distances or angles between the oxygen atoms present in a brassinosteroid. However, in recent decades, efforts have been focused on the synthesis of new BR analogs, keeping common patterns of organic functions in the A/B rings and cis-trans fusion between them, as occurs in some natural BRs, but with moderate or dramatic structural changes (shorter side chains, different oxygenated functions, spirostanic, aromatic and cyclic substituents, methyl esters, carboxylic acids) [21,23,24,25]. Surprisingly, some of these analogs have presented very important biological activity.…”

Extraction and characterization of brassinosteroids from residues of the biodiesel chain

“…In plant tissues they are usually present as glycosides or conjugated to fatty acids. Chemical synthesis of brassinosteroids is possible, but it is very expensive and time-consuming; moreover the biological activity of synthetic compound is lower than natural compounds (Ishiguro et 1980; Back et al, 1997;Brosa et al, 1998). Biological methods to produce brassinosteroids are known through crown gall cells cultures (USPatent 5,084,388).…”

A rapid and simple one-pot procedure for the synthesis of 3β-acetoxy-5α-hydroxy-6-oxo steroids

“…In general, the limited number of protocols for the preparation of such compounds start from derivatives of 3β-hydroxy-∆ 5 -steroids and involve the oxidation of 5,6-diols (iii), 1,3 or the oxidative cleavage of 5ξ,6-epoxides by treatment with Jones reagent 2 or CrO 3 (iv) 5 (Scheme 1).…”