Excretion of benzoic acid derivatives in urine of sheep given intraruminal infusions of 3-phenylpropionic and cyclohexanecarboxylic acids

Abstract

The quantitative relationship between the urinary excretion of benzoic acid @A) and the uptake of 3-phenylpropionic (PPA) and cyclohexanecarboxylic (CHCA) acids was assessed. PPA and CHCA are produced in the rumen by microbial fermentation of lignocellulosic feeds and metabolized, after absorption, to BA which Is excreted in the urine mainly as its glycine conjugate hippuric acid (HA). Ruminants excrete large quantities of benzoic acid (BA) derivatives in their urine due to the ingestion of lignocelluosic feedstuffs. The BA derivatives are the excretory products of hydroxycinnamic acids such as p-coumaric, caffeic and ferulic acids (Martin, 1983) and of hydroxycyclohexanecarboxylic acids such as quinic and shikimic acids (Martin, 1982~). These compounds are involved in the biosynthesis of lignin and are ubiquitous in vascular plants. Since these compounds are of no nutritional value they are often called xenobiotics, that is, foreign to the normal energy-yielding metabolism of the animal (Caldwell, 1989). By reduction and hydrolysis during microbial fermentation in the rumen, the hydroxycinnamic and hydroxycyclohexanecarboxylic acids are converted to phenylpropionic (PPA) and cyclohexanecarboxylic (CHCA) acids respectively. The PPA and CHCA are then absorbed from the rumen and posterior digestive tract compartments, and converted to BA mainly in the liver by oxidative reactions. BA can be excreted in the urine either as the free acid or as its conjugates with glycine or glucuronic acid (Martin, 1978). Fig. 1 shows the metabolic pathways for the formation of BA from PPA and CHCA. Hippuric acid (HA), the glycine conjugate of BA, is quantitatively the most important BA derivative. For

Hippurate: The Natural History of a Mammalian–Microbial Cometabolite

“…Interspecies variation in benzoic acid metabolism has been investigated in several studies; − as with man, it has been found that 95–100% of benzoic acid is excreted as hippurate in several animals including rodents, the rabbit, cat and the Capuchin and Rhesus monkey. However, differences in the excretion of benzoic acid metabolites were found in animals including the dog, ferret, hedgehog, pig and sheep, with up to 20% of administered benzoic acid excreted as benzoyl glucuronide and benzoic acid.…”

The Synergistic Contribution of Lactobacillus and Dietary Phytophenols in Host Health

“…Similar metabolic patterns were observed for other polyphenolic acids, suggesting a large and important metabolic flexibility of the gut microbiota [84]. Evidence for a metabolic pathway leading to the formation of BA from 3-HPP is supported by the established quality of intestinal microorganisms to carry out biological dehydroxylation of 3-HPP to 3-phenylpropionic acid, which can itself be further β-oxidized into BA by the colonic microbiota [85]. Alternatively, the absorbed cinnamic and phenylpropionic acids undergo βoxidation in the liver to produce BA, which is subsequently conjugated to glycine to form hippuric acid in the liver [86].…”

Safety and efficacy of aryl‐substituted primary alcohol, aldehyde, acid, ester and acetal derivatives belonging to chemical group 22 when used as flavourings for all animal species

“…In the rumen, 3-phenylpropionic acid originated by microbial metabolism of hydroxycinnamic acids, is absorbed and oxidised in organism and eliminated as benzoic acid in urine (Martin, 1982b). Also in sheep, Pagella et al, 1997; showed that 3-phenylpropionic acid (oxidation product of the two CG 22 compounds 3-phenylpropanol and 3-phenylpropanal) infused in the rumen was excreted in the urine mainly as hippuric acid. Conjugation of carboxylic acids with amino acids exhibits some species specificity.…”