Synthesis of Brassinosteroid Tetrahemisuccinates and Their Effect on the Initial Growth of Spring Barley Plants

Russian Journal of Bioorganic Chemistry - For the first time, conjugates of 24-epibrassinolide and 24-epicastasterone with succinic acid were obtained in the form of tetrahemisuccinates by the...     

Synthesis of [26,27-2H6]brassinosteroids from 23,24-bisnorcholenic acid methyl ester

A number of hexadeuterated brassinosteroids (BS) containing a hydroxy group at C-22 or a 22R,23R-diol function were prepared starting from 23,24-bisnorcholenic acid methyl ester for biosynthetic studies. Synthesis of the cyclic part was accomplished via the initial hydroboration-oxidation of Delta(5)-double bond. The key step in the synthesis of the side chain involved addition of (2S)-[3,4-(2)H(6)]2,3-dimethylbutylphenyl sulfone to the corresponding C-22 aldehydes.     

Synthesis of [26-2H(3)]brassinosteroids

A number of [26-2H(3)]brassinosteroids were prepared for biochemical studies. The parent, nondeuterated compounds were considered to be biosynthetic intermediates in brassinosteroid biosynthesis. Claisen rearrangement was used to construct the steroidal side chain. Deuterium was introduced by reducing the corresponding intermediates with lithium aluminium deuteride.     

Synthesis of C24-functionalized hydroxysterols

The syntheses of (24S)-24,25-epoxycholesterol, (24S)-hydroxycholesterol, and 24-ketocholesterol are described. The compounds belong to oxysterols, which can be considered to be the modulators of cholesterol metabolism. The asymmetric hydroxylation of desmosterol acetate according to Sharpless was used as the key reaction in the stereoselective introduction of functionality in position 24.     

Novel synthesis of zymosterol

A modified scheme for the synthesis of zymosterol, one of the biosynthetically important yeast sterols, starting from from 3-benzoyloxyergosta-8(14),22-dien-15-one has been suggested.     

Role of trophic and hormonal factors in exogenous regulation of the formation of reproductive organs in yellow lupine (Lupinus luteus L.)

During the formation and ripening of beans in yellow lupine, their intactness may be increased by treatment of the plants with the microelement molybdenum or the growth factor 24-epibrassinolide. Early stages of the effects of either factor involved activation of various metabolic pathways; eventually, the supply of fruit elements with free amino acids was improved and the seed productivity of the plants, increased.     

The role of reactive oxygen species and calcium ions in the implementation of the stress-protective effect of brassinosteroids on plant cells

The effect of the brassinosteroids (BS) 24-epibrassinolide and 24-epicastasterone on the thermoresistance of wheat coleoptiles (Triticum aestivum L.) and their generation of the superoxide anion radical and antioxidant enzymes activity were investigated. The treatment of coleoptiles with 10 nM solutions of BS caused a transient increase in O ₂ ^⊙? generation and a subsequent increase in the activity of superoxide dismutase and catalase and an improvement in heat resistance. Pretreatment of coleoptiles with the NADPH oxidase inhibitor imidazole leveled the increase in production of the superoxide anion radical and prevented an increase in the activity of antioxidant enzymes and the development of cell thermostability. The investigated effects of BS were also depressed by the pretreatment of coleoptile segments with extracellular calcium chelator EGTA and inhibitor of ADP-ribosyl cyclase nicotinamide. A conclusion was made about the participation of calcium ions and reactive oxygen species generated by the action of NADPH oxidase in the implementation of the stress-protective effect of the BS in the cells of wheat coleoptiles.     

A new synthesis of cerebrosterol and its 24-epimer from lithocholic acid

A new method for the synthesis of both isomers of 24-hydroxycholesterol starting from lithocholic acid is proposed.     

Oxysterols: genesis and basic functions

The structural peculiarities of the most widespread oxysterols, the products of oxidative transformations of cholesterol are discussed. The transformations proceed with the participation of enzymatic systems of the body or as a result of various nonenzymatic reactions. The pathways of their formation from cholesterol are also considered. The role of oxysterols in the maintenance of cholesterol homeostasis and in the development of atherosclerosis is reviewed. The possibility of using oxysterols as markers of pathological processes is demonstrated.