Rabbit erythrocyte hemolysis by lipophilic, aryl molecules

Microbial Degradation of Indole and Its Derivatives

Indole and its derivatives, including 3-methylindole and 4-chloroindole, are environmental pollutants that are present worldwide. Microbial degradation of indole and its derivatives can occur in several aerobic and anaerobic pathways; these pathways involve different known and characterized genes. In this minireview, we summarize and explain the microbial degradation of indole, indole-3-acetic acid, 4-chloroindole, and methylindole.

The effect of 3-methylindole on the uptake and incorporation of 14C-choline into phospholipids in lung tissue slices

3-Methylindole (3MI) is the causative agent in the development of acute bovine pulmonary edema. Microscopic studies revealed a structural disruption in the lamellar bodies of type II cells, indicating an abnormal metabolism of phospholipid in the lung of 3MI treated animals. In the present study, lung slices from 4 goats were used to investigate the changes in phosphatidylcholine metabolism induced by 3MI. Eighteen slices were cut from each healthy lung and divided into control and 3MI groups. After a 4-hr pretreatment with 3MI (.19 or .57 mM) or carrier, the level of incorporation of 14C-choline into phosphatidylcholine, sphingomyelin and their water soluble intermediates was studied. The uptake of 14C-choline and its incorporation into phosphatidylcholine and sphingomyelin was depressed by 3MI treatment. In the water soluble fractions, the radioactivity increased in free choline and CDP-choline, while it decreased in P-choline. This suggests that choline kinase and the P-choline transferases have become relatively more rate limiting and may play a role in the depressed de novo synthesis of phosphatidylcholine induced by 3MI.

Dissimilation of tryptophan and related indolic compounds by ruminal microorganisms in vitro

Intraruminal doses of L-tryptophan cause acute pulmonary edema and emphysema in cattle. The D and L isomers of tryptophan and 22 related indolic compounds were incubated with ruminal microorganisms in vitro. Incubation of L-[U-benzene ring-(14)C]tryptophan with ruminal microorganisms for 24 h resulted in 39% of the added radioactivity being incorporated into skatole, 7% into indole, and 4% into indoleacetate (IAA). D-Tryptophan was not degraded to any of these metabolites. The major pathway of skatole formation from L-tryptophan appeared to be by the decarboxylation of IAA. Incubation of [2-(14)C]IAA with ruminal microorganisms for 24 h resulted in 38% incorporation into skatole. L-[5-Hydroxy]tryptophan was degraded to 5-hydroxyskatole and 5-hydroxyindole, whereas 5-hydroxyindoleacetate was degraded to only 5-hydroxyskatole. Incubation of indolepyruvate, indolelactate, and indolealdehyde with ruminal microorganisms resulted in the formation of both skatole and indole. Under similar conditions, indoleacetaldehyde was converted to IAA and tryptophol. The addition of increasing concentrations of glucose (0 to 110 mM) reduced the formation of both skatole and indole from L-tryptophan and resulted in the accumulation of IAA. Antibiotics reduced the degradation of L-tryptophan to skatole and indole, with kanamycin and neomycin particularly effective in reducing the decarboxylation of IAA to skatole.

Induction of pulmonary edema and emphysema in cattle and goats with 3-methylindole

Microorganisms from rumen converted L-tryptophan and indoleacetic acid to 3-methylindole in vitro. Oral doses of 3-methylindole caused interstitial pulmonary edema and emphysema in cattle and goats. Intravenous infusion of this metabolite also induced pulmonary disease in cattle. These results demonstrate than an end product of ruminal fermentation of tryptophan can induce acute pulmonary disease in cattle and goats.