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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brassinolide (2 alpha, 3 alpha, 22 alpha, 23 alpha-tetrahydroxy-24 alpha-methyl -B-homo-7-oxa-5 alpha-cholestan-6-one), a novel plant growth-promoting steroid isolated from rape pollen, and its hitherto unknown 22 beta, 23 beta-isomer were synthesized from a C-24 epimeric 60:40 mixture of 22-dehydroxampesterol (24 alpha-methyl) and brassicasterol (24 beta-methyl) from oysters. The method of synthesis favored the formation of the 22 beta, 23 beta-isomer by better than 4:1. Comparative plant growth-promoting capabilities of brassinolide, both natural and synthetic, and its three side chain cis-glycolic isomers in the bean second internode bioassay showed that the natural and synthetic brassinolides were equally active and caused splitting of the internode at the 0.1 microgram level. The least active was the 22 beta, 23 beta-isomer of brassinolide. The isomers with the 22 alpha, 23 alpha and 24 alpha, and the 22 beta, 23 beta and 24 beta configurations were highly active and were required at about 10 times the concentration of brassinolide to cause the same physiological response. In the bean first internode bioassay, an auxin-induced growth test system which employs isolated bean plant segments, the isomer with 22 beta, 23 beta and 24 beta configuration caused a greater response than brassinolide. Two of the four tetrahydroxy ketones obtained in the synthesis of the isomers were also active in both assays.
Steroids 1981 Nov
PMID:Synthesis and biological activity of brassinolide and its 22 beta, 23 beta-isomer: novel plant growth-promoting steroids. 732 86

New androstane brassinosteroids with 17beta-ester groups - butyrates, heptafluorobutyrates, and laurates (4-18) - were prepared. Brassinolide activity was evaluated using both the bean second internode bioassay and the rice lamina inclination test. Brassinosteroid 16 was found to be the most active by the bean second internode bioassay. This activity in the bean second internode bioassay corresponded with the field yield, while the RLIT bioassay does not.
Steroids 2005 Oct
PMID:Syntheses of new androstane brassinosteroids with 17beta-ester groups--butyrates, heptafluorobutyrates, and laurates. 1592 13

Brassinosteroid (BR) phytohormones play indispensable roles in plant growth and development. Brassinolide (BL) and 24-epibrassinolide (24-epiBL) are the most active ones among the BRs reported thus far. Unfortunately, the extremely low natural content and intricate synthesis process limit their popularization in agricultural production. Earlier reports to discover alternative compounds have resulted in molecules with nearly same scaffold structure and without diversity in chemical space. In the present study, receptors structure based BRs regulation mechanism was analyzed. First, we examined the detailed binding interactions and their dynamic stability between BL and its receptor BRI1 and co-receptor BAK1. Then, the binding modes and binding free energies for 24-epiBL and a series of representative BRs binding with BRI1 and BRI1-BAK1 were carried out by molecular docking, energy minimization and MM-PBSA free energy calculation. The obtained binding structures and energetic results provided vital insights into the structural factors affecting the activity from both receptors and BRs aspects. Subsequently, the obtained knowledge will serve as valuable guidance to build pharmacophore models for rational screening of new scaffold alternative BRs.
Steroids 2015 Dec
PMID:Unveiling the molecular mechanism of brassinosteroids: Insights from structure-based molecular modeling studies. 2636