title: Effects of various squalene epoxides on coenzyme Q and cholesterol synthesis.
abstract: 2,3-Oxidosqualene is an intermediate in cholesterol biosynthesis and 2,3:22,23-dioxidosqualene act as the substrate for an alternative pathway that produces 24(S),25-epoxycholesterol which effects cholesterol homeostasis. In light of our previous findings concerning the biological effects of certain epoxidated all-trans-polyisoprenes, the effects of squalene carrying epoxy moieties on the second and third isoprene residues were investigated here. In cultures of HepG2 cells both monoepoxides of squalene and one of their hydrolytic products inhibited cholesterol synthesis and stimulated the synthesis of coenzyme Q (CoQ). Upon prolonged treatment the cholesterol content of these cells and its labeling with [(3)H]mevalonate were reduced, while the amount and labeling of CoQ increased. Injection of the squalene monoepoxides into mice once daily for 6days elevated the level of CoQ in their blood, but did not change the cholesterol level. The same effects were observed upon treatment of apoE-deficient mice and diabetic GK-rats. This treatment increased the hepatic level of CoQ10 in mice, but the amount of CoQ9, which is the major form, was unaffected. The presence of the active compounds in the blood was supported by the finding that cholesterol synthesis in the white blood cells was inhibited. Since the ratio of CoQ9/CoQ10 varies depending on the experimental conditions, the cells were titrated with substrate and inhibitors, leading to the conclusion that the intracellular isopentenyl-PP pool is a regulator of this ratio. Our present findings indicate that oxidosqualenes may be useful for stimulating both the synthesis and level of CoQ both in vitro and in vivo.
authors.affiliation: Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden; Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 17176 Stockholm, Sweden. Electronic address: magnus.bentinger@dbb.su.se.
authors.forename: Magnus
authors.initials: M
authors.lastname: Bentinger
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kania
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland.
authors.forename: Witold
authors.initials: W
authors.lastname: Danikiewicz
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kaczorowska
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Wojcik
authors.affiliation: Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 17176 Stockholm, Sweden.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Brismar
authors.affiliation: Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden; Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 17176 Stockholm, Sweden.
authors.forename: Gustav
authors.initials: G
authors.lastname: Dallner
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Chojnacki
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Swiezewska
authors.affiliation: Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden; Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 17176 Stockholm, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Tekle
mesh_terms: D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002784:Cholesterol / Q000031:analogs & derivatives* / Q000096:biosynthesis*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D012968:Etidronic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D045782:Hemiterpenes / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D008148:Lovastatin / Q000494:pharmacology; D008297:Male; D008798:Mevalonic Acid / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009943:Organophosphorus Compounds / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D000068296:Risedronic Acid; D013185:Squalene / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D014233:Tricarboxylic Acids / Q000494:pharmacology; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D045782:Hemiterpenes; D009943:Organophosphorus Compounds; D014233:Tricarboxylic Acids; C075117:squalestatin 1; D014451:Ubiquinone; C015171:2,3,22,23-dioxidosqualene; C520393:oxidosqualene; C004809:isopentenyl pyrophosphate; C028358:24,25-epoxycholesterol; D013185:Squalene; D002784:Cholesterol; D008148:Lovastatin; C024989:coenzyme Q10; D000068296:Risedronic Acid; D012968:Etidronic Acid; C030571:ubiquinone 9; D008798:Mevalonic Acid
keywords: Cholesterol inhibition; Coenzyme Q induction; Dolichol; Mevalonate pathway; Squalene epoxides