Brassinosteroids synthesis

Androstane type of brassinosteroids, synthesis, 59-60 Antheridiol, synthesis, 37 Arthropods, effect of brassinosteroids, 268-275... 

Be this as it may, the CH oxidation has become an attractive and promising preparative method in natural-product synthesis. For example, dioxiranes have been used to introduce selectively a hydroxy group at the C-25 position of steroids, a challenging task not readily achieved with other oxidants. A specific case is the TFD oxidation of brassinosteroid (equation 33) . 

This ene reaction can be used to effect synthesis of the side chain present in the plant growth brassinosteroids (equation I). 

Nomura, T. Kitasaka, Y. Tokatsuto, S. Reid, J.B. Fukami, M. Yoko, T. Brassinosteroid/sterol synthesis and plant growth affected by Ika and Ikb mutation of pea. Plant Physiol. 1999, 119, 1517-1526. 

Chemical synthesis of brassinosteroids, phytohormones with a seven-membered O-heterocycle in some of them 02KPS99. 

The original discovery of brassinolide, a natural plant-growth promoter extracted from bee-collected pollen, was made at the USDA Agricultural Research Center in Beltsville, Maryland. Although the USDA terminated brassinosteroid research, others around the world have carried on the work. This volume addresses the history, biochemistry, physiology, practical applications, production, synthesis, and entomological effects of these compounds. 

During the decade since publication in 1979 of the structure of brassinolide (I), and the synthesis of the first brassinosteroid (2), also in 1979, events related to the "brassins project have taken some interesting turns. At this point (October 1990), there seems to be little interest in developing brassinosteroids for agricultural... 

This brief review covers the period of the last ten years in the development of brassinosteroid chemistry in our laboratory. Our interest has been focused on the synthesis of natural brassinosteroids (brassinolide, homobrassinoli-de, epibrassinolide, norbrassinolide, etc.), their analogues and intermediates starting from stigmasterol, ergosterol, or pregnenolone. Some aspects of biological activity are discussed. 

Some structure-activity relationships, synthesis of new brassinosteroids, and new sensitive bioassays for brassinosteroids are presented. 

It has been assumed (21) that the fresh-weight gain of radish cotyledons by kinetin is due to the activation of de novo synthesis of the hydrolytic enzyme invertase. Seeking a similar influence of brassinosteroids on this enzyme we also found, that brassinolide 1 and (22S,23S)-homobrassinolide 3 treatment resulted in an increased activity of the soluble invertase even to a remarkably higher extent than kinetin in the case of brassinolide 1 (Figure 2). This increase... 

Effect of Brassinosteroids on Protein Synthesis and Plant-Cell Ultrastructure under Stress... 

S, 238-homobrasslnollde and 24-epibrassinolide activated total protein synthesis and Induced Cfe TIOVO polypeptide synthesis at normal and high temperatures. Molecular weight determinations showed that some of the proteins Induced by brassinosteroids at normal temperature corresponded to heat shock proteins. 22St23S-homobrasslnollde also... 

Brassinosteroids (BSs) represent a new group of plant hormones that possess a broad spectrum of physiological activities (1,2). A most Intriguing property of BSs Is their capacity to Increase stress resistance In plants, but the mechanism of such an antistress activity still remains unknown (1). As cell stress resistance Is usually associated with stress protein synthesis (3 4) our aim was to study the BS effect on protein synthesis and ultrastructure of wheat leaf cells at normal temperature and under heat shock conditions. We have also studied the Influence of BSs on mesophyll cell ultrastructure under saline stress. 

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