Formestane

Selective, irreversible and competitive type I steroidal aromatase inhibitor. Shows minor androgenic activity. Reduces plasma levels of estrogen and shows antitumor effects in vivo. Orally active.

Profiling of urinary formestane and confirmation by isotope ratio mass spectrometry.[Pubmed:23933120]

Steroids. 2013 Nov;78(11):1103-9.

Formestane (F, androst-4-en-4-ol-3,17-dione) is an irreversible aromatase inhibitor with the ability to suppress the estrogen production from anabolic steroids. Consequently, F is mentioned on the World Anti-Doping Agency (WADA) prohibited list and because studies have shown that F is produced endogenously in small amounts, a threshold for urinary excreted F of 150 ng/mL was introduced. Lower concentrations could be due to endogenous production and need further investigation to prove the exact origin through determination of the carbon isotope ratio. However, because the current screening methods are a lot more sensitive, F is detected in practically every urine sample. A strict implementation of this WADA rule would imply that almost every urine sample needs additional investigation to verify an exogenous or endogenous origin. The main aim of this study was to propose and introduce a lower concentration limit of 25 ng/mL beneath which the detected F is considered as being endogenous and no further investigation is needed. The data presented in this paper suggests that this threshold provides a good balance between a sufficiently large detection window and not having to perform isotope ratio mass spectrometry (IRMS) analyses on negative urine samples.

Synthesis and bioconversions of formestane.[Pubmed:24074257]

J Nat Prod. 2013 Oct 25;76(10):1966-9.

In an effort to generate new steroidal aromatase inhibitors, Formestane (4-hydroxyandrost-4-ene-3,17-dione) (1) was biotransformed by Rhizopus oryzae to yield the known 4beta,5alpha-dihydroxyandrostane-3,17-dione as the major product (5) and bioconverted by Beauveria bassiana to afford the known reduced 4,17beta-dihydroxyandrost-4-en-3-one (6) and 3alpha,17beta-dihydroxy-5beta-androstan-4-one (7) and the new 4,11alpha,17beta-trihydroxyandrost-4-en-3-one (8). All the metabolites showed more potent activities than their parent congener in the aromatase and MCF-7 breast cancer assays. The bioactivities and structural elucidation of these metabolites as well as the semisynthesis of Formestane (1) from testosterone (2) are reported herein.

Interactions of an anticancer drug Formestane with single and double stranded DNA at physiological conditions.[Pubmed:26036658]

J Photochem Photobiol B. 2015 Aug;149:27-36.

Mode of interactions of anticancer drug Formestane (FMT) with single and double stranded DNA has been investigated at different temperatures and at two physiological pH values i.e. 7.4 (human blood pH) and 4.7 (stomach pH). Fluorescence spectroscopy, UV-Vis spectroscopy, cyclic voltammetry and square wave voltammetry were employed to probe the interaction between FMT and DNA. The observed fluorescence quenching of dsDNA-ethidium bromide system by the anticancer drug FMT confirmed the intercalative mode of binding between the FMT and dsDNA. The absorption spectra and voltammetric results indicate FMT gets intercalated between dsDNA bases and the strength of interaction is independent on the ionic strength. Comparison of the mode of interaction of FMT with dsDNA and ssDNA was discussed. The calculated binding constants for FMT-dsDNA and FMT-ssDNA complexes at pH 7.4 were found to be 1.52x10(5)M(-1) and 1.24x10(6)M(-1), respectively. Stoichiometric coefficients and thermodynamic parameters of FMT-dsDNA and FMT-ssDNA complexes were evaluated. The association between the anticancer drug FMT with DNA is maximum at pH 7.4 which depicts the most stable complexes are formed at human blood pH. The decrease in peak current of FMT resulting from its interaction with DNA was employed for determination of dsDNA and ssDNA concentration at physiological conditions.

Detection of formestane abuse by mass spectrometric techniques.[Pubmed:25516450]

Drug Test Anal. 2014 Nov-Dec;6(11-12):1133-40.

Formestane (4-hydroxy-androstenedione) is an aromatase inhibitor prohibited in sports and included, since 2004, in the list of prohibited substances updated yearly by the World Anti-Doping Agency (WADA). Since the endogenous production of Formestane has been described, it is mandatory for the anti-doping laboratories to use isotope ratio mass spectrometry (IRMS) to establish the exogenous origin before issuing an adverse analytical finding. The described IRMS methods for Formestane detection are time-consuming, requiring usually two consecutive liquid chromatographic sample purifications in order to have final extracts of adequate purity before the mass spectrometric analysis. After establishing a procedure for the determination of the origin of Formestane by IRMS without the need of derivatization, and integrated in the overall analytical strategy of the laboratory for pseudo-endogenous steroids, a mass spectrometric analysis by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) of Formestane metabolites was carried out in order to investigate whether other biomarkers of Formestane abuse could be integrated in order to avoid time-consuming and expensive IRMS confirmations for Formestane. From the metabolic studies performed, the inclusion of 3beta,4alpha-dihydroxy-5alpha-androstan-17-one (4alpha-hydroxy-epiandosterone) in the routine GC-MS procedures has demonstrated to be diagnostic in order to reduce the number of unnecessary confirmations of the endogenous origin of Formestane.