19-Azasqualene-2,3-epoxide was more inhibitory than the corresponding N-oxide against 2,3-oxidosqualene cyclase (OSC) solubilized from Saccharomyces cerevisiae (IC50 7 +/- 12 and 25 +/- 5 mu M, respectively). Both compounds showed a reversible, noncompetitive-type inhibition on solubilized OSC. Different inhibitory properties between the compounds were especially evident when measuring [C-14]acetate incorporation into nonsaponifiable lipids extracted from treated cells. In cells treated with 19-azasqualene-2,3-epoxide at 30 mu M, the radioactivity associated with the oxidosqualene fraction, which was negligible in the controls, rose to over 40% Of the nonsaponifiable lipids, whereas it remained at a slightly appreciable level in cells treated with the N-oxide derivative under the same conditions. 19-Azasqualene-2,3-epoxide was also more effective than the N-oxide as a cell growth inhibitor (minimal concentration of compound needed to inhibit yeast growth: 45 and >100 mu M, respectively). The two inhibitors underwent different metabolic fates in the yeast: while 19-azasqualene-2,3-epoxide did not undergo any transformation, its N-oxide was actively reduced to the corresponding amine in whole and in "ultrasonically stimulated" cells. The N-oxide reductases responsible for this transformation appear to be largely confined within the microsomal fractions and require NADPH for their activity. A possible relationship between the inhibitory properties of the two compounds and their metabolic fates is discussed.
Titolo: | 19-azasqualene-2,3-epoxide and its N-oxide: metabolic fate and inhibitory effect on sterol biosynthesis in Saccharomyces cerevisiae | |
Autori Riconosciuti: | ||
Autori: | MILLA P; VIOLA F; CERUTI M; ROCCO F; CATTEL L; BALLIANO G | |
Data di pubblicazione: | 1999 | |
Abstract: | 19-Azasqualene-2,3-epoxide was more inhibitory than the corresponding N-oxide against 2,3-oxidosqualene cyclase (OSC) solubilized from Saccharomyces cerevisiae (IC50 7 +/- 12 and 25 +/- 5 mu M, respectively). Both compounds showed a reversible, noncompetitive-type inhibition on solubilized OSC. Different inhibitory properties between the compounds were especially evident when measuring [C-14]acetate incorporation into nonsaponifiable lipids extracted from treated cells. In cells treated with 19-azasqualene-2,3-epoxide at 30 mu M, the radioactivity associated with the oxidosqualene fraction, which was negligible in the controls, rose to over 40% Of the nonsaponifiable lipids, whereas it remained at a slightly appreciable level in cells treated with the N-oxide derivative under the same conditions. 19-Azasqualene-2,3-epoxide was also more effective than the N-oxide as a cell growth inhibitor (minimal concentration of compound needed to inhibit yeast growth: 45 and >100 mu M, respectively). The two inhibitors underwent different metabolic fates in the yeast: while 19-azasqualene-2,3-epoxide did not undergo any transformation, its N-oxide was actively reduced to the corresponding amine in whole and in "ultrasonically stimulated" cells. The N-oxide reductases responsible for this transformation appear to be largely confined within the microsomal fractions and require NADPH for their activity. A possible relationship between the inhibitory properties of the two compounds and their metabolic fates is discussed. | |
Editore: | American Oil Chemists Society:2211 West Bradley Avenue:Champaign, IL 61821:(217)359-2344, EMAIL: general@aocs.org, INTERNET: http://www.aocs.org, Fax: (217)351-8091 | |
Volume: | 34(7) | |
Pagina iniziale: | 681 | |
Pagina finale: | 688 | |
Parole Chiave: | 2; 3-oxidosqualene cyclase; lanosterol synthase; squalene-2; 3-epoxide cyclases; biological activity | |
Rivista: | LIPIDS | |
Appare nelle tipologie: | 03A-Articolo su Rivista |