Toxic Nitro Compounds in Lotus1

Abstract

AbstractToxic aliphatic nitro compounds were recently detected in species of the genus Lotus. Nitro‐bearing species, if used as forage, might be harmful to livestock. Therefore, this investigation was initiated in the greenhouse and laboratory to study the distribution, types, and concentration of nitro compounds in species of Lotus, and to determine the toxicity of cultivars of L. pedunculatus Cav. to 1‐week‐old chicks. Leaves of 83 species of Lotus, collected from herbarium specimens or plants grown in soil (Dagor series of fine‐loamy, mixed, mesic family of Cumulic Haploxeroll) in the greenhouse, were analyzed for nitro compounds. Nitro‐bearing species for which sufficient material was available were analyzed chromatographically for the type of nitro metabolite. The toxicity of cultivars of L. pedunculatus was determined by feeding dried plant and aqueous extracts of the foliage to 1‐week‐old chicks. Nitro compounds were detected in 17 of 83 species of Lotus. No nitro compounds were detected in three commercial cultivars of L. corniculatus L. Hydrolysis of nitro compounds yielded only 3‐nitropropionic acid (3‐NPA). Nitro levels in leaflets of L. pedunculatus averaged 27 to 29 mg NO2/g of plant. Dried plant or extracts of three cultivars of L. pedunculatus produced nitro poisoning in 1‐week‐old chicks. The data indicate that several species of Lotus synthesize toxic nitro compounds that yield 3‐NPA upon hydrolysis. Species of Lotus should be screened for nitro compounds before developing cultivars to prevent the seeding of potentially poisonous plants on grazing land.