title: A new look into the reaction between ergosterol and singlet oxygen in vitro.
abstract: The reaction of ergosterol (ERGO) with singlet oxygen in vitro was studied by using different combinations of the photosensitizers (i.e. rose Bengal and eosine) and solvents (i.e. pyridine, ethanol and methyl tert-butyl ether) and all the products obtained were isolated and fully characterized (mp, Rf, UV, 1H-NMR, 13C-NMR, EI-MS, ESI-MS and HR-MS). In pyridine. together with the expected (22E)-5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol, EEP, the keto derivative (22E)-3beta-hydroxyergosta-5,8(9),22-trien-7-one. KE, was obtained. In ethanol the expected EEP was obtained together with (22E)-5alpha,8alpha-epidioxyergosta-6,9,22-trien-3beta-ol, EEP9(11), and (22E)-ergosta-6,9,22-triene-3beta,5alpha,8alpha-triol, DHOE, as main products and (22E)-ergosta-5,7,9,22-tetraen-3beta-ol, DHE, in trace amounts In methyl tert-butyl ether, a complex mixture of EEP, KE, DHOE, EEP9(11), DHE, together with (22E)-7alpha-hydroperoxyergosta-5.8(9),22-trien-3beta-ol, EHP, and (22E)-ergosta-5,8(9),22-triene-3beta, 7alpha-diol, EH, was obtained. The minor products were characterized and showed strong dependence on the reaction medium. The regioselective and stereoselective character of the singlet oxygen attack on the ERGO diene moiety is discussed in terms of ERGO HOMO's properties.
authors.affiliation: UMYMFOR, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, 3, Ciudad Universitaria, 1428-Buenos Aires, Argentina.
authors.forename: María A
authors.initials: MA
authors.lastname: Ponce
authors.forename: Javier A
authors.initials: JA
authors.lastname: Ramirez
authors.forename: Lydia R
authors.initials: LR
authors.lastname: Galagovsky
authors.forename: Eduardo G
authors.initials: EG
authors.lastname: Gros
authors.forename: Rosa
authors.initials: R
authors.lastname: Erra-Balsells
mesh_terms: D004801:Eosine Yellowish-(YS) / Q000737:chemistry; D004875:Ergosterol / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008958:Models, Molecular; D015394:Molecular Structure; D017319:Photosensitizing Agents / Q000737:chemistry / Q000528:radiation effects; D012395:Rose Bengal / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D017319:Photosensitizing Agents; D012997:Solvents; D026082:Singlet Oxygen; D012395:Rose Bengal; D004801:Eosine Yellowish-(YS); D004875:Ergosterol