Abstract
β-Hydroxyethylhydrazine forces flowering of pineapple plants, possibly by reducing auxin concentration. A specific and sensitive assay showed that β-hydroxyethylhydrazine (3.3 x 10-7M) inhibits noncompetitively and almost completely the oxidation of tryptamine to indoleacetaldehyde by extracts of pea-seedling (Pisum sativum L. var. Alaska). The relative rate of oxidation of putrescine to Δ1-pyrroline compared to that of tryptamine by these extracts and the inhibition of both reactions by β-hydroxyethylhydrazine suggest that diamine oxidase is inhibited. β-Hydroxyethylhydrazine is a potent inhibitor in vivo of animal diamine oxidase.