Abstract
Screening of a marine natural products library for inhibitors of TGF-β revealed five pyrimidinedione derivatives, biemamides A-E (1-5). The structures were determined by 2D NMR and HRMS experiments; absolute configurations were established by advanced Marfey's analysis and ECD calculations. Biemamides A-E specifically inhibited in vitro TGF-β induced epithelial to mesenchymal transition in NMuMG cells. Additionally, using Caenorhabditis elegans, selected biemmamides were found to influence in vivo developmental processes related to body size regulation in a dose-dependent manner.