Forming 4-Methylcatechol as the Dominant Bioavailable Metabolite of Intraruminal Rutin Inhibits p-Cresol Production in Dairy Cows

Abstract

Rutin, a natural flavonol glycoside, elicits its diverse health-promoting effects from the bioactivities of quercetin, its aglycone. While widely distributed in the vegetables and fruits of human diet, rutin is either absent or inadequate in common animal feed ingredients. Rutin has been supplemented to dairy cows for performance enhancement, but its metabolic fate in vivo has not been determined. In this study, plasma, urine, and rumen fluid samples were collected before and after the intraruminal dosing of 100 mg/kg rutin to 4 Holsteins, and then characterized by both targeted and untargeted liquid chromatography-mass spectrometry (LC-MS)-based metabolomic analysis. In plasma and urine, 4-methylcatechol sulfate was identified as the most abundant metabolite of rutin, instead of quercetin and its flavonol metabolites, and its concentration was inversely correlated with the concentration of p-cresol sulfate. In rumen fluid, the formation of 3,4-dihydroxyphenylacetic acid (DHPAA) and 4-methylcatechol after rapid degradation of rutin and quercetin concurred with the decrease of p-cresol and the increase of its precursor, 4-hydroxyphenylacetic acid. Overall, the formation of 4-methylcatechol, a bioactive microbial metabolite, as the dominant bioavailable metabolite of rutin and quercetin, could contribute to their beneficial bioactivities in dairy cows, while the decrease of p-cresol, a microbial metabolite with negative biological and sensory properties, from the competitive inhibition between microbial metabolism of rutin and tyrosine, has the potential to reduce environmental impact of dairy operations and improve the health of dairy cattle.

p-Cresol Sulfate Is a Sensitive Urinary Marker of Fecal Microbiota Transplantation and Antibiotics Treatments in Human Patients and Mouse Models

“…It has been shown that the supplementation of Lactobacillus strains decreased the excretion of urinary p-cresol sulfate in healthy women [20]. Besides microbial interventions, chemical intervention of p-cresol biogenesis could also be achieved as shown in our recent studies, in which microbial AAA degradation, including 4HPAA decarboxylase-catalyzed p-cresol production, was competitively inhibited by green tea polyphenol intake in humans [21] and rutin feeding in dairy cows [22]. Therefore, profiling p-cresol and other AAA degradation products in urine and feces can serve as an effective analytical approach to determine the status of microbial AAA metabolism and its sensitivity to microbial and chemical interventions.…”

Biotransformation and Gut Microbiota-Mediated Bioactivity of Flavonols

“…The rupture of the flavonol skeleton is completely afforded by gut bacteria, while subsequent phase II conjugation is primarily catalyzed by mammalian enzymes. Hydrogenation, hydroxylation, and side chain shortening can be mediated by both mammalian and microbial enzymes, whereas dehydroxylation and demethoxylation almost fully result from microbiota. , Taking quercetin as an example, ring fission of the skeleton yielded 3,4-dihydroxyphenylpropionic acid (3,4-DHPPA) and 1,3,5-trihydroxybenzene (phloroglucinol); the former was further catabolized to produce 3,4-dihydroxyphenylacetic acid (3,4-DHPAA), an important metabolite of quercetin. , Furthermore, 3,4-DHPAA was degraded into multiple aromatic catabolites via dihydroxylation, decarboxylation, methylation, and shortening of the side chain . Three phenolic acids, i.e., 3,4-DHPAA, 3-methoxy-4-hydroxyphenylacetic acid (homovanillic acid, HVA), and 3-hydroxyphenylacetic acid (3-HPAA), were identified as major catabolites in the urine of healthy subjects, contributing to 22% of rutin intake. , Additionally, 4-hydroxyphenylacetic acid (4-HPAA), 3,4-dihydroxybenzoic acid (protocatechuic acid, PCA), 4-hydroxybenzoic acid (4-HBA), benzoic acid (BA), 3-hydroxyphenylpropionic acid (3-HPPA), phloroglucinol, 3,4-dihydroxytoluene (3,4-DHT), 3-hydroxyhippuric acid (3-HHA), 4-hydroxyhippuric acid (4-HHA), and hippuric acid (HA) were detected in urinary or fecal excretion of humans or rats with feeding administration, in rumen fluid of cows after rutin ingestion, or in co-fermentation of flavonol in vitro with human fecal extract or selected bacterial strains. ,,,− The degradation pathways of quercetin in vivo are presented in Figure .…”