Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); The ethanolic extract of the stem bark of Croton heliotropiifolius Kunth (Euphorbiaceae) showed significant in vitro inhibition of acetylcholinesterase using a dilution spectrophotometric assay and antifungal activity against Candida albicans with a thin layer chromatography (TLC) bioautographic assay. In order to isolate the active compounds, bioassay-guided fractionation was undertaken using HPLC to localize the active compounds. Different zones of the HPLC-UV chromatogram were linked to acetylcholinesterase inhibition or to antifungal activities. In parallel to this HPLC-based activity profiling, HPLC-PDA-ESI-MS and HPLC-TOF-HRMS were used for the early identification of some of the compounds present. The targeted isolation of the active compounds was performed by medium pressure liquid chromatography (MPLC-UV) and further semi-preparative HPLC. Using this approach, nine compounds were isolated, one of them being a new indole alkaloid derivative. The structures of the isolated compounds were elucidated by spectroscopic methods including UV...
(4-hydroxy-N-desmethyltamoxifen), an active metabolite
generated via actions of CYP3A4/5 and CYP2D6, is a more potent selective
estrogen receptor modulator (SERM) than tamoxifen. In the MCF-7 human mammary
tumor xenograft model with female athymic mice, (Z)-endoxifen,
at an oral dose of 4– 8 mg/kg, significantly inhibits tumor growth.
(Z)-Endoxifen's potential as an alternative
therapeutic agent independent of CYP2D6 activities, which can vary widely in
ER+ breast cancer patients, is being actively evaluated. This paper
describes confirmation of the configuration of the active
(Z)-isomer through 2D NMR experiments, including NOE (ROESY) to
establish spatial proton–proton correlations, and identification of the
major impurity as the (E)-isomer in endoxifen drug substance by
HPLC/HRMS (HPLC/MS-TOF). Stability of NMR solutions was confirmed by HPLC/UV
analysis. For pre-clinical studies, a reverse-phase HPLC–UV method, with
methanol/water mobile phases containing 10 mM ammonium formate at pH 4.3, was
developed and validated for the accurate quantitation and impurity profiling of
drug substance and drug product. Validation included demonstration of linearity,
method precision, accuracy, and specificity in the presence of impurities...