The name linatine (I) was assigned to a vitamin B6 antagonist isolated from linseed meal. Compound I inhibited the growth of chickens and Azotobacter cinelandii 0, the assay organism. An LDso of 2-mg per week-old chick was counteracted by simultaneous injection of 1 mg of pyridoxine. Acid hydrolysis of I yielded L-glutamic acid and a toxic substance (11), LDso = 0.5 mg in 1-week-old chicks, which was characterized as 1-aminoa-proline, mp 155" dec, [a]: + 113" (c 2, 0.5 M HCI); 3-nitrobenzylidene derivative, mp 123 O; 2-hydroxy-5-nitrobenzylidene derivative, mp 136", [a]? +151" (c 0.35, ethanol).