A new α-amino (compound I) has been isolated and purified from pea seedlings. The chemical structure was analyzed by chemical methods and by spectroscopy. The structure was found to be 2-alanyl-3-isoxazolin-5-one. Some properties of this compound were compared to those of synthetic isoxazolin derivatives. The mono-acetyl derivative of I was synthesized. The compound is very sensitive to UV-irradiation. © 1969.