[Molecular modeling of interaction of 17(20)Z- and 17(20)E-pregna-5,17(20)-dien-21-oyl amides with the nuclear receptor LXRbeta].

Aiming the search of novel regulators of lipid metabolism and their potential targets, in this study we performed molecular modeling of eight isomeric 17(20)Z- and 17(20)E-pregna-5,17(20)-dien-21-oyl amides differing in structure of the amide moiety. Analysis of the low energy conformers revealed that all 17(20)E-isomers had three main energy minima (corresponding to values of the dihedral angle theta20,21 (C17 = C20-C21 = 0) to approximately 0 degrees, to approximately 120 degrees and to approximately 240 degrees), the most occupied minimum was found to correspond to theta20,21 to approximately 0 degrees; while 17(20)Z-isomers had either one or two pools of low energy conformations. Molecular docking of these compounds to the ligand-binding site of the nuclear receptor LXRbeta (a potential target) indicates high probability of binding for E-isomers and the absence of that for Z-isomers. Results of the molecular modeling were confirmed by an experiment in which stimulation of triglyceride biosynthesis in Hep G2 cells in the presence of 17(20)E-3beta-hydroxypregna-5,17(20)-dien-21-oyl (hydroxyethyl)amide was demonstrated.

[Screening of potential substrates or inhibitors of cytochrome P450 17A1 (CYP17A1) by electrochemical methods].

The electrochemical reduction of the recombinant form of human cytochrome P450 17A1 (CYP17A1) was investigated. Hemeprotein was immobilized on electrode modified with biocompatable nanocomposite material based on the membrane-like synthetic surfactant didodecyldimethylammonium bromide (DDAB) and gold nanoparticles. Analytical characteristics of DDAB/Au/CYP17A1 electrodes were investigated with cyclic voltammetry, square wave voltammetry, and differential pulse voltammetry. Analysis of electrochemical behaviour of cytochrome P450 17A1 was conducted in the presence of substrate pregnenolone (1), inhibitor ketoconazole (2), and in the presence of synthetic derivatives of pregnenolone: acetylpregnenolone (3), cyclopregnenolone (4), and tetrabrompregnenolone (5). Ketoconazole, azole inhibitor of cytochromes P450, blocked catalytic current in the presence of substrate pregnenolone (1). Compounds 3-5 did not demonstrate substrate properties towards electrode/CYP17A1 system. Compound 3 did not block catalytic activity towards pregnenolone, but compounds 4 and 5 inhibited such activity. Electrochemical reduction of CYP17A1 may serve as an adequate substitution of the reconstituted system which requires additional redox partners - for the exhibition of catalytic activity of hemoproteins of the cytochrome P450 superfamily.

[Regulation of cholesterol biosynthesis and metabolism in Hep G2 cells by delta8(14)-15-ketoergostane derivatives].

The comparative study of effects of 5alpha-cholest-8(14)-en-15-on-3beta-ol (I), (22E)-5alpha-ergosta-8(14),22-dien-15-on-3beta-ol (II), (22S,23S)-22,23-oxido-5alpha-ergost-8(14)-en- 15-on-3beta-ol (III) and (22R,23R)-22,23-oxido-5alpha-ergost-8(14)-en-15-on-3beta-ol (IV) on HMG-CoA reductase, CYP27A1 and CYP3A4 genes expression in Hep G2 cells was performed. In the contrast to 15-ketocholestane derivative (I), 15-ketoergostane derivatives (II - IV) decreased the HMG- CoA reductase mRNA level; (22R,23R)-22,23-oxido-5alpha-ergost-8(14)-en-15-on-3beta-ol (IV) significantly increased CYP3A4 mRNA level (320% from control). Ketosterol (II) was found to be a more potent inhibitor of cholesterol biosynthesis in Hep G2 cells at a prolong incubation, compared with ketosterol (I). The side chain conformation of compounds (I) - (IV) was evaluated by computational modeling; the correlation between biological activity of these compounds and conformational flexibility of their side chains was found. The results obtained indicated that delta8(14)-15-ketoergostane derivatives may be used as a sterol biosynthesis and metabolism regulators in liver cells.

[Synthesis of secasterol and 24-episecasterol and their toxicity in MCF-7 cells].

A convergent synthesis of biosynthetic precursors of brassinosteroids - secasterol and 24-episecasterol with Δ²-bond in cycle A is described. The key stages in the construction of the side chain of these compounds were Julia olefination of steroid 22-aldehyde followed by asymmetric Sharpless dihydroxylation of the intermediate Δ²²-olefin. Toxicity of synthesized compounds against breast carcinoma MCF-7 cells was studied.

[(22R,23R)-3beta-Hydroxy-22,23-epoxy-5alpha-ergost-8(14)-en-15-one: improved synthesis and toxicity to MCF-7 cells].

The chemical synthesis of (22R,23R)-3beta-hydroxy-22,23-epoxy-5alpha-ergost-8(14)-en-15-one from (22E)-3beta-acetoxy-5alpha-ergosta-7,14,22-triene was improved. The stages of obtaining and isomerizing (22E)-3beta-acetoxy-14alpha,15alpha-epoxy-5alpha-ergosta-7,22-diene were optimized. The introduction of the (22R,23R)-epoxide cycle was carried out by a basic treatment of intermediate (22S,23R)-3beta,23-diacetoxy-22-iodo-5alpha-ergost-8(14)-en-15-one. In cells of human mammary gland carcinoma MCF-7 (22R,23R)-3beta-hydroxy-22,23-epoxy-5alpha-ergost-8(14)-en-15-one showed a high toxicity (TC(50) = 0.4 +/- 0.1 microM for 48-h incubation in serum-free medium).

[Effects of (22S,23S)- and (22R,23R)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-ones on cholesteryl esters biosynthesis and acyl-CoA:cholesterol acyl transferase activity in Hep G2 cells].

Novel synthetic oxysterols (22S,23S)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one (I) and (22R,23R)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one (II) influenced cholesteryl esters biosynthesis in human hepatoma Hep G2 cell line from [14C]acetate (85% and 180% compared to control at the concentrations of 5 microM). The level of cholesteryl esters biosynthesis in Hep G2 cells from [14C]oleate increased in the presence of ketosterol (I) in a dose dependent manner, whereas the level of cholesteryl esters biosynthesis in the presence of ketosterol (II) reached the maximal value (269+/-20% from control) at the concentration of 1 microM. In a cell free system ketosterol (I) increased the rate of ACAT-dependent cholesterol acylation like 25-hydroxycholesterol, however, ketosterol (II), efficiently stimulating initial rate of ACAT-catalyzed cholesterol esterification, caused in rapid inactivation of this enzyme.

[Biological activity of phytosterols and their derivatives].

The review deals with results of recent studies on biological activity of C29- and C28-sterols of plant origin (phytosterols) in mammals and in cultured mammalian cells. The review considers the following problems: phytosterols and nutrition; phytosterols and cholesterol level; phytosterols and intestinal absorption of lipids; the role of phytosterols in lipid metabolism regulation; phytosterols and mammalian cells in culture; products of phytosterols oxydation; phytoecdysteroids and induced gene expression.

[Cytotoxic derivatives of (22R,23R)-22,23-dihydroxystigmastane].

(22R,23R)-22,23-dihydroxystigmast-4-en-3-one, (22R,23R)-22,23-dihydroxystigmast-4-en-3,6-dione, (22R,23R)-3beta,5alpha,6beta,22,23-pentahydroxystigmastane, (22R,23R)-5alpha,6alpha-oxido-3beta,22,23-trihydroxystigmastane, (22R,23R)-5beta,6beta-oxido-3beta,22,23-trihydroxystigmastane, and (22R,23R)-3beta,6beta,22,23-tetrahydroxystigmast-4-ene were synthesized. Their cytotoxicities were comparatively studied using the MCF-7 line of carcinoma cells of human mammary gland and cells of human hepatoma of the Hep G2 line.

[Effects of (22S,23S)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one and (22R,23R)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one on lipid biosynthesis and exogeneous cholesterol metabolism in hep G2 cells].

Novel synthetic oxysterols (22S,23S)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one (I) and (22R,23R)-33-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one (II) efficiently inhibited cholesterol biosynthesis in human hepatoma Hep G2 cell line at a short time incubation in a serum free medium (IC50 = 1.9 +/- 0.2 and 0.6 +/- 0.2 microM, respectively). Cultivation of Hep G2 cells in the presence of compound 5 microM concentration of both (1) and (II), led to significant depression of cholesterol biosynthesis (52% and 57% from control), and remarkable changes in fatty acids, triglycerides, and cholesteryl esters biosynthesis. Compounds (I) and (II) stimulated transformation of exogeneous cholesterol to polar products secreted into the culture medium (156% and 175% from control), that was shown in experiments in Hep G2 cells prelabeled with [3H]cholesterol.

[Delta5-7-Ketosterols with modified side chain: the synthesis and the effects on viability and cholesterol biosynthesis in Hep G2 cells].

(22E)-3beta-Hydroxysitosta-5,22-dien-7-one, (22R, 23R)-3beta,22,23-trihydroxysitost-5-en-7-one, and (22R, 23R)-3beta-hydroxy-22,23-isopropylidenedioxysitost-5-en-7-one were synthesized. The cytotoxicity and effects on cholesterol biosynthesis of the resulting 7-ketosterols, 7-ketocholesterol, and (22S,23S)-3beta-hydroxy-22,23-oxidositost-5-en-7-one were studied in hepatoblastoma Hep G2 cells.

[A simple synthesis of 3beta-acetoxy-20-oxomethylpregn-5-ene and 3beta-acetoxy-20-hydroxymethylpregn-5-ene].

3beta-Acetoxy-20-oxomethylpregn-5-ene and 3beta-acetoxy-20-hydroxymethylpregn-5-ene were synthesized from (22R,23R)-sitost-5-ene-3beta,22,23-triol in 66% overall yields.

[22,23-epoxides of sitosterol and related 7-oxygenated delta5-sterols].

(22S,23S)-22,23-Epoxysitosterol, (22R,23R)-22,23-epoxysitosterol, (22S,23S)-22,23-epoxy-7-ketositosterol, (22R,23R)-22,23-epoxy-7-ketositosterol, (22S,23S)-22,23-epoxy-7alpha-hydroxysitosterol, (22R,23R)-22,23-epoxy-7alpha-hydroxysitosterol, (22S,23S)-22,23-epoxy-7beta-hydroxysitosterol, and (22R,23R)-22,23-epoxy-7beta-hydroxysitosterol were synthesized. Their 1H and 13C NMR and the mass spectra of their trimethylsilyl derivatives were studied.

[New delta8(14)-ketosterols with an oxygenated side chain].

New analogues of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one (15-ketosterol) with modified 17-chains [(22S,23S,24S)- and (22R,23R,24S)-3beta-hydroxy-24-methyl-22,23-oxido-5alpha-cholest-8(14)-en-15-ones and (22RS,23xi,24S)-24-methyl-5alpha-cholesta-3beta,22,23-triol-15-one] were synthesized from (22E,24S)-3beta-acetoxy-24-methyl-5alpha-cholesta-8(14),22-dien-15-one. The chiralities of their 22 and 23 centers were determined by NMR spectroscopy. The isomeric 22,23-epoxides effectively inhibited cholesterol biosynthesis in hepatoma Hep G2 cells (IC50 0.9 +/- 0.2 and 0.7 +/- 0.2 microM, respectively), and their activities significantly exceeded those of 15-ketosterol (IC50 4.0 +/- 0.5 microM), (22E,24S)-3beta-hydroxy-24-methyl-5alpha-cholesta-8(14),22-dien-15-one (IC50 3.1 +/- 0.4 microM), and the 3beta,22,23-triol synthesized (IC50 6.0 +/- 1.0 microM). The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 3; see also http://www.maik.ru.

[The effect of 15-ketosterol analogues with a 5,6-dimethylhept-3-en-2-yl chain at C17 on cholesterol metabolism in Hep G2 hepatoma cells]. / Vliianie analogov 15-ketosterina, soderzhashchikh 5,6-dimetilgept-3-en-2-il'nuiu tsep' pri C17, na metabolizm kholesterina v kletkakh gepatomy HepG2.

The effect on cholesterol metabolism in Hep G2 hepatoma cells was studied for new analogues of 15-ketosterol [3beta-hydroxy-5alpha-cholest-8(14)-en-15-one] (I): (24S)-3beta-hydroxy-24-methyl-5alpha-cholesta-8(14),22-diene-15-one (II), (24S)-3alpha-hydroxy-24-methyl-5-alpha-cholesta-8(14),22-diene-15-one (III), and (24S)-24-methyl-5alpha-cholesta-8(14),22-diene-3,15-dione (IV). Analogues (I) and (II) were found to be equally effective inhibitors of cholesterol biosynthesis after a 3-h incubation with Hep G2 cells; however, (II) produced a stronger inhibitory effect after a 24-h incubation or after an incubation of cells preliminarily treated with the inhibitor in a medium containing no ketosterol. The ability of ketosterols to inhibit cholesterol biosynthesis decreased in the order (II) > (IV) > (III). Ketosterol (II) inhibited, whereas ketosterol (III) stimulated the biosynthesis of cholesteryl esters. (IV) stimulated the biosynthesis of cholesteryl esters at a concentration of 1-10 microM and exerted no marked effect at a concentration of 30 microM. These results indicate that delta8(14)-15-ketosterols containing a modified side chain are of interest as regulators of cholesterol metabolism in liver cells. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 5; see also http: // www.maik.ru.

[Palmitates of isomeric 15-oxygenated delta8(14)-sterols]. / Pal'mitaty izomernykh 15-oksigenirovannykh delat 8(14)-sterinov.

3 beta-Hexadecanoyloxy-5 alpha-cholest-8(14)-en-15-one, 3 alpha-hexadecanoyloxy-5 alpha-cholest-8(14)-en-15-one, 15 beta- hexadecanoyloxy-5 alpha-cholest-8(14)-en-3 beta-ol, 15 alpha-hexadecanoyloxy-5 alpha-cholest-8(14)-en-3 beta-ol, 15 beta-hexadecanoyloxy-5 alpha-cholest-8(14)-en-3-one, and 15 alpha-hexadecanoyloxy-5 alpha-cholest-8(14)-en-3-one were synthesized and their chromatographic and 1H NMR characteristics were determined. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 2; see also http://www.maik.ru.

[Synthesis of new analogs of 15-ketosterine from ergosterine]. / Sintez novykh analogov 15-ketosterina iz érgosterina.

Ergosteryl acetate was converted through three stages into 3 beta-acetoxy-24-methyl-5 alpha-cholesta-8(14),22-diene-15-one in 32% overall yield. The product was transformed to 3 beta-hydroxy-24- methyl-5 alpha-cholesta-8(14),22-diene-15-one, 3 alpha-hydroxy-24-methyl-5 alpha-cholesta-8(14),22-diene-15-one, and 24-methyl-5 alpha-cholesta-8(14),22-diene-3,15-dione. The compounds were characterized by 1H and 13C NMR spectra. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 1; see also http://www.maik.ru.

[Interaction of acyl derivatives of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one and 3alpha-hydroxy-5alpha-cholest-8(14)-en-15-one with hepatoma hep G2 cells]. / Vzaimodeistvie atsil'nykh proizvodnykh 3beta-gidroksi-5alpha-kholest-8(14)-en-15-ona i 3alpha-gidroksi-5-alpha-kholest-8(14)-en-15-ona s kletkami gepatomy Hep G2.

Effects of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one (I), 3alpha-hydroxy-5alpha-cholest-8(14)-en-15 one (II), 3beta-hexadecanoyloxy-5alpha-cholest-8(14)-en-15-one (III), 3alpha-hehadeeanoyloxy-5alpha-cholest-8(14)-en-15-one (IV), 3beta-acetoxy-5alpha-cholest-8(14)-en-15-one (V), 3alpha-acetoxy-5alpha-cholest-8(14)-en-15-one (VI) on cholesterol metabolism in hepatoma Hep G2 cells were studied. Compound III slowly bind to Hep G2 cells followed by internalization and metabolic transformation (at a concentration of 30 microM the total binding of compound III was (3.9 +/- 0.4) nmol per 1 mg of cell protein for 24 h incubation). Compound I depressed and compound III stimulated the uptake of low density lipoproteins radiolabeled with oleyl cholesteryl ether [14C-CE]LDL (58% and 149% from control). Compounds I and II inhibited cholesterol biosynthesis from [14C]acetate (with IC50 values of 4.0 +/- 0.7 and 8.0 +/- 1.5 microM). Effects of compounds V and VI were less potent; compounds III and IV were inactive. Compound II activated cholesterol acylation, estimated by incorporation of [14C]-oleic acid into cholesteryl esters (170% from control at a concentration of 30 microM). The results indicate correlation between polarity of the compound and its ability to regulate cholesterol metabolism in Hep G2 cells.

[Inhibition of oxidation of human blood low density lipoproteins by carotenoids from paprika]. / Ingibirovanie okisleniia lipoproteinov nizkoi plotnosti plazmy krovi cheloveka karotinoidami papriki.

beta-Carotene (C1), acyl derivatives of capsanthin (C2), and acyl derivatives of capsorubin (C3) were isolated from red paprika (Capsicum annuum) oleoresin. Incorporation of carotenoids C1, C2, and C3 into human plasma LDLs changed the LDL flotation coefficient distribution for LDL fraction 1.019 < d < 1.050 g/ml. The comparative studies of Cu(2+)-catalyzed oxidation for LDL, LDL-C1, LDL-C2, and LDL-C3 revealed that carotenoids C1, C2, and C3 efficiently suppressed the oxidation of LDL, inhibited the formation of conjugated dienes from polyunsaturated fatty acid residues, lowered the content of small dense LDL subfraction, and inhibited the transformation of cholesterol to auto oxidized products (in particular to 5,6-epoxycholesterol, 7-ketocholesterol and 7 beta-hydroxycholesterol). This suggests that the main carotenoids may effectively inhibit LDL oxidation in vitro with probable lowering the "atherogenic" LDL subfraction production in vivo.

[A simple method for preparation of 18alpha-glycyrretinic acid ant its derivatives]. / Prostoi metod polucheniia 18alpha-glitsirretinovoi kisloty i ee proizvodnykh.

Treatment of 18 beta-glycyrrhizic acid with a methanolic solution of HCl resulted in a 1:1 mixture of methyl esters of 18 alpha- and 18 beta-glycyrrhetinic acids. Benzoylation of the mixture led to methyl esters of 3-benzoyl-18 alpha-glycyrrhetinic acid and 3-benzoyl-18 beta-glycyrrhetinic acid, which were separated by chromatography on silica gel. 18 alpha-Glycyrrhetinic acid was prepared by alkaline hydrolysis of methyl 3-benzoyl-18 alpha-glycyrrhetinate and was further used for the syntheses of 3-keto-18 alpha-glycyrrhetinic acid and methyl esters of 18 alpha-glycyrrhetinic acid and 3-keto-18 alpha-glycyrrhetinic acid.

[Transformation of 3beta-(2-hydroxyethoxy)-5alpha-cholest-8(14)-en-15-one in a polar metabolite in HepG2 hepatoma cells]. / Prevrashchnie 3beta-(2-gidroksiétoksi)5alpha-kholest-8(14)-en-15-ona v poliarnyi metabolit v kletkakh gepatomy HepG2.

Incubation of 3 beta-(2-hydroxy-2[3H]-ethoxy)-5 alpha-cholest-8(14)-en-15-one with Hep G2 cells led to the accumulation of a radioactive polar product in the culture medium, which was identified as 3 beta-(2-hydroxyethoxy)-15-keto-5 alpha-cholest-8(14)-ene-24-oic acid. Its structure was confirmed by a chemical counter synthesis. The labeled ketosterol was rapidly (tau 1/2 = 6 min) and reversibly bound by Hep G2 cells. The intracellular concentration of 15-ketosterol decreased during incubation mainly due to the formation of a polar metabolite, secreted to the medium. The level of cholesterol biosynthesis was 22 +/- 5% of the control value in Hep G2 cells at a 15-ketocholesterol concentration in the medium of 30 microM. However, further incubation for 3 h in the medium without the ketosterol led to restoration of the level of biosynthesis to 85 +/- 11% of the control value. These results suggest that inhibition of the cholesterol biosynthesis by 15-ketocholesterol in Hep G2 cells depends on the intracellular concentration of the inhibitor, which, in turn, is determined by the rate of its conversion into the polar metabolite. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2003, vol. 29, no. 6; see also http://www.maik.ru.