Actions of selected proteins, peptides and amino acid derivatives on mouse embryonic development in vitro

1. The actions of various compounds with antiproliferative and/or immunomodulatory activities including the ribosome-inactivating protein gelonin, the tetrapeptide tuftsin, the opioid peptide leucine-enkephalin, the antireproductive tripeptide Thr-Ser-Lys, the melatonin analog 6-methoxy-2-benzoxazolinone, and the amino acid derivatives 5-hydroxytryptamine and oxalysine on mouse embryonic development and organogenesis in vitro were investigated. 2. The various compounds were tested up to a concentration of 300 micrograms/ml. It was found that only 6-methoxy-2-benzoxazolinone, a derivative of tryptophan, produced an increase in the number of abnormal embryos and reductions in the final somite numbers and axial lengths of embryos. 3. 6-Methoxy-2-benzoxazolinone treatment also resulted in an increased incidence of abnormal morphogenesis of various organ primordia, including abnormal yolk sac circulation, twisting of body axis, absence of forelimb bud and opening of cranial neural tube.