Acute Intraperitoneal Toxicity of Some Plant Growth Substances for Mice

Abstract

Zimmerman and Wilcoxon 1 report the rooting and bending responses of plants to various “growth-promoting” compounds. Of the agents we studied, they find the per cent concentrations necessary for positive bending or injury to be (in order of decreasing toxicity): indolacetic acid 0.5; alpha-naphthalenacetic acid 1.5; indolproprionic acid 2.0; indolbutyric acid 2.0; and phenylacetic acid 3.0. In the human body the indole acids are derived presumably from tryptophane, and indolacetic acid can be recovered from urine. In carcinomata indolacetic acid occurs in concentration twice that of surrounding tissues according to Kögl, Haagen-Smit and Tönnis. 2

We desired to determine whether any correlation exists between the relative toxicity of these compounds for plants and their relative toxicity in mammals. Mice, observed for 4 weeks, were used as test animals. The substances were dissolved in water or di-ethylene glycol, and fresh 1% dilutions were injected intraperitoneally. Indolacetic acid∗ kills half or more of the animals injected at 25 mg. per kg., alpha-naphthalenacetic acid† at 100 mg. per kg., indolproprionic and† at 100 mg. per kg., indolbutyric acid† at 100 mg. per kg., and phenylacetic acid§ at 300 mg. per kg.

Deaths occur in 10 to 20 minutes with large doses, and are delayed from 48 hours to 13 days with amounts just above tolerance. Respiratory embarrassment and failure were the only consistent toxic manifestations noted. Pulmonary congestion was seen in one-third of the animals examined at necropsy; gross pathologic changes other than pulmonic were not observed in animals dying within 48 hours. Solutions of indolacetic acid which were exposed to light and air for 7 days become amber-colored and are less toxic than fresh preparations, killing at 200 mg. per kg.