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Experiments on the effect of brassinosteroids and their salicylates on the mycelium biomass during submerged cultivation of oyster mushroom (Pleurotus ostreatus) were carried out. It was shown that their addition to the nutrient medium at a concentration of 0.05 mg/l significantly increases the biomass of the mycelium. It was found that, when exposed to 24- epi- and 28-homocastasterone for 9 days, the mycelium colony developed only in the depths of the culture liquid, and the mycelium was formed into glomeruli with a dense structure. The use of salicylates 24-epicastasterone and 6-deoxo-24-epicastasterone promoted the development of an extensive colony of mycelium both on the surface and in the depth of the culture liquid. Salicylates also influenced the structure of the mycelium – the jellyfish-like loose mycelium was observed in flasks with a medium containing 24-epi and 6-deoxo-24-epicastasterone salicylates. For the first time, the determination of the content of endogenous brassinosteroids in the fruiting body and mycelium of P. ostreatus was carried out.

The dependence of the action of lactone-structure brassinosteroids in composition with a growth-inhibiting dose of glyphosate on the root system and the aerial part of fiber flax (Linum usitatissimum L.) and spring barley (Hordeum vulgare L.) seedlings was determined. The species specificity of growth responses to seed incrustation by such mixtures was identified. The concentration ranges of brassinosteroids, in which their interaction with the herbicide is most pronounced, were detected. In this case, there is an increase (on spring barley seedlings) or weakening (on fiber flax seedlings) of the inhibitory effect of glyphosate on the root system.

The effect of polymetallic stress (Mn

The effect of polymetallic stress (Mn2+, Cd2+, Cu2+, Ni2+, Zn2+, Pb2+, and Al3+) of different duration and intensity on the endogenous brassinosteroids (BS) content and photochemical activity of photosystem II in barley plants was studied. The content of steroid hormones was determined by a two-stage enzyme immunoassay. It was established for the first time that barley plants responded to polymetallic stress by changing the endogenous content of various phytosteroid groups (24S-methylBS, 24-epiBS, 28-homoBS, B-lactoneBS, and 6-ketoBS). It was shown that the stress-dependent dynamics of changes in the endogenous content of various BS groups is characterized by organ specificity and is determined by the age of plants, the intensity of the acting stressor, and the specificity of brassinosteroids. The observed changes in the endogenous status of BS in barley plants under polymetallic stress are accompanied by inhibition of growth processes, a decrease in the content of the main photosynthetic pigments, and a slight decrease in the efficiency of photochemical processes in PS II (Fv/Fm, ETR, qN, and NPQ). Considering the multifunctional stress-protective effect of brassinosteroids, it is assumed that the change in the endogenous status of BS against the background of polymetallic pollution is adaptive and allows minimizing the damaging effects of toxic heavy metals and aluminum.

We compared the defensive response of rape plants to treatment with 24-epibrassinoldide (10 nM, EBL) before the onset of salt stress (preadaptation stage) and under conditions of chloride salination (150 mM NaCl). It is shown that salt stress inhibits some growth parameters by 30-35%. EBL, regardless of the plant treatment method, showed a pronounced protective effect, first of all, at the level of the assimilating surface, the main photosynthetic pigments, and the photochemical activity of photosystem II. It was established for the first time that the pretreatment of plants with EBL followed by salt stress is accompanied by suppression of NaCl-induced accumulation of proline and an increase in superoxide dismutase activity, whereas the addition of a hormone under salt stress increases the content of carotenoids, which leads to a decrease in the level of lipid peroxidation.

We compared the defensive response of rape plants to treatment with 24-epibrassinoldide (10 nM, EBL) before the onset of salt stress (preadaptation stage) and under conditions of chloride salination (150 mM NaCl). It is shown that salt stress inhibits some growth parameters by 30-35%. EBL, regardless of the plant treatment method, showed a pronounced protective effect, first of all, at the level of the assimilating surface, the main photosynthetic pigments, and the photochemical activity of photosystem II. It was established for the first time that the pretreatment of plants with EBL followed by salt stress is accompanied by suppression of NaCl-induced accumulation of proline and an increase in superoxide dismutase activity, whereas the addition of a hormone under salt stress increases the content of carotenoids, which leads to a decrease in the level of lipid peroxidation.

An improved synthesis that could produce gram quantities of castasterone was proposed. The starting material was stigmasterol, the cyclic part of which was transformed in the first synthetic step into the 3α,5-cyclo-6-ketone. The side-chain carbon skeleton in the target compound was constructed with the required stereochemistry of the C-24 methyl via addition of methylacetylene, hydrogenation of the propargyl alcohol over Lindlar catalyst, and Claisen rearrangement. Diols were introduced using Sharpless asymmetric dihydroxylation of the intermediate ∆2,22-dienone in the presence of (DHQD)2AQN. A unique feature of the synthesis was the avoidance of chromatographic separations of propargyl alcohols with similar chromatographic mobilities because the C-22 diastereomers were enriched in subsequent redox reactions.

Morphology, nitrogen-fixing activity and seed productivity of the introduced wild long-rhizome yellow alfalfa (Medicago falcata L.) under exogenous treatment with microbial preparations and phytohormone (homobrassinolide) were studied in field experiments. It was revealed that growth activators increase seed productivity and nitrogen-fixing activity in the cultivated taproot alfalfa type and, on the whole, have no effect on metabolism in the long-rhizome morphotype plants. To solve the problem it is necessary to develop Rhizobium preparations increasing nitrogen-fixing activity of the long-rhizome alfalfa plants on the basis of natural isolates and the use of phytohormones with due regard to the peculiarities of the ontogenesis of the long-rhizome M. falcata morphotype.

Brassinosteroids (BSs) are phytohormones, the chemical structure of which is closest to the chemical structure of animal steroid hormones. It was shown by a number of researchers that BSs contributed to plant growth and development [1]. It was also demonstrated that BS caused an increase in the plant resistance to pathogens [2] and adverse climatic factors [3]. Receptors of BS were found to be located in plasmalemma [4]. Phosphorylation of certain proteins was demonstrated to be an early BS-induced response [5]. These findings suggest that BSs are incorporated into the signaling systems of plant cells. However, it is still unclear which types of signaling systems may incorporate BSs. It was also suggested that BSs constituted a previously unknown signaling system [2]. Because it is well known that the lipoxygenase signaling system is involved in cell response to various pathogens, mechanical injuries, elicitors, and some other primary signals [6], the goal of this work was to study the possibility of the brassinosteroid-induced activation of this signaling system. Effects of 24-epibrassinosteroid (EPB), the most active form of BS, on concentrations of oxygenated derivatives of linoleic acid (indicators of lipoxygenase activity) and on the level of phosphorylation of soluble proteins of pea leaves (it is well known that reactions of protein phosphorylation/dephosphorylation are a very important component of signaling systems) were studied. It was suggested that the analysis of lipoxygenase activity and the use of phospholipase A 2 (PLA 2 ) inhibitor provided an opportunity to elucidate the contribution of the lipoxygenase metabolism to the initial phase of the EPB-induced response of the cells. Bromphenylacyl bromide (BPB) was used as a phospholipase A 2 inhibitor decreasing the rate of release of unsaturated fatty acids (lipoxygenase substrate). The lipoxygenase activity level was assessed using the methodological approach based on the appearance of two conjugated bonds and absorption maximum at 232 nm during the reaction of formation of oxygenated derivatives of linoleic acid.

The effect of brassinosteroids on the resistance of millet plants (Panicum miliaceum L.) to damaging heating and soil drought was investigated. The pretreatment of the seeds with 20 nM of 24-epibrassinolide and 28-homobrassinolide solutions increased the survival rate of seedlings after their exposure to hyperthermia (heating in bath of water ultrathermostat at 47 °C for 10 min). Under the influence of brassinosteroids the increase in activity of antioxidant enzymes (superoxide dismutase, catalase, and guaiacol peroxidase) and the decrease in the content of lipid peroxidation product malondialdehyde in millet seedlings after heat stress were observed. In this case, the protective effect of 24-epibrassinolide was more significant as compared to the effect of 28-homobrassinolide. In the conditions of drought (the decrease of soil moisture to 25% of field water capacity) plants grown from seeds treated by 24-epibrassinolide exhibited ability for growth and higher activity of the antioxidant enzymes compared to control plants. A conclusion concerning the essential role of the induction of antioxidant enzymes in implementation of the protective effect of brassinosteroids on millet plants under abiotic stresses and the prospects of practical application of presowing treatment with them for prolonged non-specific activation of plant resistance was made.

The cleavage of the heterocycle in 20(-izoxasolin-3-yl)steroids effected by molybdenum hexacarbonyl in aqueous acetonitrile results in formation of 22,25-oxido-20(22),23-dienesteroids.

A number of 24-norbrassinolide biosynthetic precursors containing low polar functional groups (3beta3-OH, 3-keto-, delta2- or 2alpha,3alpha-epoxy-) in A-cycle and (22R,23R)-diol in the side chain has been prepared. Studies of these compounds as proliferation regulators in MCF-7 human breast cancer and LnCaP human prostate adenocarcinoma cells showed that most nonpolar (22R,23R)-derivatives effectively suppressed proliferation. Dependence of proliferation on concentration of studied compounds was found in human prostate carcinoma LnCaP cells (IC50 = 13-28 microM at 72 h of incubation in a medium containing 10% FBS; suppression of DNA biosynthesis). A number of compounds induced apoptosis (23-33%); arrested cell cycle in S- and G2/M-phases; and caused partial cells detachment during prolonged incubations.

Methods of stereoselective synthesis of oxysterols are considered by the examples of (25R)-26-hydroxycholesterol, (24S)-24,25-epoxycholesterol, and (24S)-24-hydroxycholesterol containing functional groups in the terminal fragments of their side chains. Special attention is paid to the problems of construction of chiral centers C24 and C25.

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.

Androstane and delta15-androstane analogues of brassinosteroids were synthesized from dehydroepiandrosterone. The key stage, hydroxylation of 17beta-acetoxyandrost-2-en-6-one double bond with OsO4, yielded the corresponding 2alpha,3alpha- and 2beta,3beta-diols. The target 2alpha,3alpha-isopropylidenedioxy-6,6-ethylenedioxy-5alpha-androst-15-en-17-one and its 2beta,3beta-isomer were obtained by dehydrosilylation of the corresponding silylene ethers with palladium acetate.

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 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.

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.

Auf das 16-Dehydropregnenolonacetat (I) last man in Tetrahydrofuran oder Isopropanol verschiedene Trialkylborane einwirken.