2016, Moreira da Silva, Rodrigo, Verjee, Sheela, De Gaitani, Cristiane Masetto, Moraes de Oliveira, Anderson Rodrigo, Pires Bueno, Paula Carolina, Cavalheiro, Alberto José, Peporine Lopes, Norberto, Butterweck, Veronika

The 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.