In the course of our chemical screening program on metabolities from actinomycetes, we have searched for compounds which showed color reactions by both ninhydrin and ferric chloride reagents, with the ultimate aim to find analogs of physiologically active phenolic amines. As a result, we have found two unusual amino acids, i.e., L-β-(5-hydroxy-2-pyridyl)alanine (1) which is a L-tyrosine analog, and L-β-(3-hydroxyureido)-alanine (9) which is a L-glutamine antagonist. The structures of 1 and 9 were elucidated from the physico-chemical properties of these amino acids and derivatives, and supported by synthesis. Antibacterial activities of 1 and its methylester (2) were antagonized by L-tyrosine, and those of 9 and its derivative (17) by L-glutamine. The isolation and structure determination as well as some of the biological properties of these amino acids are subjects of this article.