Moreira da Silva, RodrigoVerjee, SheelaDe Gaitani, Cristiane MasettoMoraes de Oliveira, Anderson RodrigoPires Bueno, Paula CarolinaCavalheiro, Alberto JoséPeporine Lopes, NorbertoButterweck, Veronika2016-11-092016-11-0920160163-38641520-602510.1021/acs.jnatprod.5b01139http://hdl.handle.net/11654/23426The clerodane diterpene casearin X (1)​, isolated from the leaves of Casearia sylvestris, is a potential new drug candidate due to its potent in vitro cytotoxic activity. In this work, the intestinal absorption mechanism of 1 was evaluated using Caco-​2 cells with and without active carboxylesterases (CES)​. An LC-​MS method was developed and validated for the quantification of 1. The estn. of permeability coeffs. was possible only under CES-​inhibited conditions in which 1 is able to cross the Caco-​2 cell monolayer. The mechanism is probably by active transport, with no significant efflux, but with a high retention of the compd. inside the cells. The enzymic hydrolysis assay demonstrates the susceptibility of 1 to first-​pass metab. as substrate for specific CES expressed in human intestine.en01A - Beitrag in wissenschaftlicher Zeitschrift1084-1090