- UTILIZATION OF TACE INHIBITORS FOR THE TREATMENT OF ACNE
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An in vitro method of screening for candidate compounds for the preventive or curative treatment of acne entails determination of the ability of a compound to inhibit the expression or the activity of TACE, and also to the administration of inhibitors of the expression or of the activity of this enzyme, in the treatment of acne.
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- Competition of mechanisms in the photochemical cleavage of the C-X bond of aryl-substituted vinyl halides
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The photolysis of aryl halides caused homolysis of the carbon-halogen bond and formation of aryl radicals. In contrast, photolysis of vinyl halides can induce both heterolysis of the C-X bond, thereby generating vinyl cations, and homolysis, giving vinyl radicals. Examples of this competition among pathways is reported here for three vinylic precursors, namely, 1,2,2- triphenylbromoethene (1), 1-phenyl-2,2-bis(o-methoxyphenyl)-1-bromoethene (11), and β-bromostyrene (19). Incursion of the photoinduced S(RN)1 process, through the intermediacy of the vinyl radical, is verified in the presence of reducing nucleophiles, such as the enolate ions of ketones, and in part with (EtO)2PO-. Conversely, incursion of the heterolytic path, and intermediacy of the vinyl cation, occurs in the presence of weak electron-donor anions, such as NO2-, N3-, and Cl-. The vinyl cation produced from 19, which is less stable than those derived from 1 and 11, gives phenylacetylene via an E1-type elimination. An estimate is provided for the intramolecular rate of interception of the vinyl cation derived from 11 by the ortho-methoxy groups of the β-o-anisyl substituents. Finally, evidence against a photoinduced electron transfer from RO- ions to vinyl halide 1 is presented.
- Galli, Carlo,Gentili, Patrizia,Guarnieri, Alessandra,Kobayashi, Shinjiro,Rappoport, Zvi
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p. 9292 - 9299
(2007/10/03)
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