RESUMEN
(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.
Asunto(s)
Colesterol/biosíntesis , Cetosteroides/química , Cetosteroides/farmacología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Humanos , Cetosteroides/síntesis químicaRESUMEN
(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.
Asunto(s)
Compuestos Epoxi/síntesis química , Sitoesteroles/síntesis química , Compuestos Epoxi/química , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Modelos Moleculares , Estructura Molecular , Sitoesteroles/químicaRESUMEN
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.
Asunto(s)
Anticolesterolemiantes/síntesis química , Anticolesterolemiantes/farmacología , Cetocolesteroles/síntesis química , Cetocolesteroles/farmacología , Anticolesterolemiantes/química , Línea Celular Tumoral , Humanos , Cetocolesteroles/químicaRESUMEN
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.
Asunto(s)
Carcinoma Hepatocelular/metabolismo , Colestenos/farmacología , Colesterol/metabolismo , Neoplasias Hepáticas/metabolismo , Carcinoma Hepatocelular/tratamiento farmacológico , Colestenos/química , Relación Dosis-Respuesta a Droga , Humanos , Neoplasias Hepáticas/tratamiento farmacológico , Relación Estructura-Actividad , Células Tumorales CultivadasRESUMEN
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.
Asunto(s)
Carcinoma Hepatocelular/metabolismo , Colestenonas/metabolismo , Carcinoma Hepatocelular/patología , Línea Celular Tumoral , Colesterol/biosíntesis , Endocitosis , HumanosRESUMEN
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.