Elisiário J Tavares da Silva

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Aromatase inhibitors (AIs), which block the conversion of androgens to estrogens, are used for hormone-dependent breast cancer treatment. Exemestane, a steroidal that belongs to the third-generation of AIs, is a mechanism-based inhibitor that binds covalently and irreversibly, inactivating and destabilizing aromatase. Since the biological effects of(More)
BACKGROUND Aromatase, the cytochrome P-450 enzyme (CYP19) responsible for estrogen biosynthesis, is an important target for the treatment of estrogen-dependent breast cancer. In fact, the use of synthetic aromatase inhibitors (AI), which induce suppression of estrogen synthesis, has shown to be an effective alternative to the classical tamoxifen for the(More)
Several therapeutic approaches are used in estrogen receptor positive (ER(+)) breast cancers, being one of them the use of aromatase inhibitors (AIs). Although AIs demonstrate higher efficacy than tamoxifen, they can also exhibit de novo or acquired resistance after prolonged treatment. Recently, we have described the synthesis and biochemical evaluation of(More)
A new convergent synthesis of the antitumor steroid formestane (4-OHA) 5 has been performed from the easily available epimeric mixture of 5 alpha- and 5 beta-androst-3-en-17-one 1a and 1b in order to attempt a yield improvement. A two-step oxidative route followed by base-catalyzed isomerization was applied to the 5 alpha- and 5 beta-epimers 1a and 1b,(More)
The title compound, alternatively called 24-nor-5 beta-chol-22-ene-3 beta,7 alpha,12 alpha-triyl triformate, C(26)H(38)O(6), has a cis junction between two of the six-membered rings. All three of the six-membered rings have chair conformations that are slightly flattened and the five-membered ring has a 13 beta,14 alpha-half-chair conformation. The 3 beta,(More)
Around 60-80% of all breast tumors are estrogen receptor-positive. One of the several therapeutic approaches used for this type of cancers is the use of aromatase inhibitors. Exemestane is a third-generation steroidal aromatase inhibitor that undergoes a complex and extensive metabolism, being catalytically converted into chemically active metabolites.(More)
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