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

A critical examination of human data for the biological activity of quercetin and its phase-2 conjugates

This critical review examines evidence for beneficial effects of quercetin phase-2 conjugates from clinical intervention studies, volunteer feeding trials, and in vitro work. Plasma concentrations of quercetin-3-O-glucuronide (Q3G) and 3'-methylquercetin-3-O-glucuronide (3'MQ3G) after supplementation may produce beneficial effects in macrophages and endothelial cells, respectively, especially if endogenous deglucuronidation occurs, and lower blood uric acid concentration via quercetin-3'-O-sulfate (Q3'S). Unsupplemented diets produce much lower concentrations (<50 nmol/l) rarely investigated in vitro. At 10 nmol/l, Q3'S and Q3G stimulate or suppress, respectively, angiogenesis in endothelial cells. Statistically significant effects have been reported at 100 nmol/l in breast cancer cells (Q3G), primary neuron cultures (Q3G), lymphocytes (Q3G and3'MQ3G) and HUVECs (QG/QS mixture), but it is unclear whether these translate to a health benefit in vivo. More sensitive and more precise methods to measure clinically significant endpoints are required before a conclusion can be drawn regarding effects at normal dietary concentrations. Future requirements include better understanding of inter-individual and temporal variation in plasma quercetin phase-2 conjugates, their mechanisms of action including deglucuronidation and desulfation both in vitro and in vivo, tissue accumulation and washout, as well as potential for synergy or antagonism with other quercetin metabolites and metabolites of other dietary phytochemicals.

Diverse forage improves lipid metabolism and antioxidant capacity in goats, as revealed by metabolomics

It is well established that promoting the balance of nutrients and plant secondary metabolites (PSM) by feeding diverse forage physiologically improves ruminant production. However, the underlying mechanism remains unclear. To investigate the physiological mechanism related to the improvement of physiological stress tolerance, ruminants were fed diverse forage. Oxidative stress markers were quantified, and serum metabolomics was performed. Six crossbred Shiba wethers (32.8 ± 9.2 kg BW) were arranged in a replicated 3 × 3 Latin square design. The treatments were feeding only Sudan grass hay (100% SDN); feeding a mixture of Sudan grass and alfalfa hay (70:30, SDN-ALF); and feeding a mixture of Sudan grass, timothy grass, and alfalfa hay (35:35:30; SDN-TMT-ALF). Each diet group was fed its specific diet for 21 days with a 14-day adaptation period. Feed intake and digestibility, blood biochemistry, total antioxidant capacity (TAC), and superoxide dismutase (SOD) were analysed. In addition, blood serum metabolites were assessed by liquid chromatography-tandem mass spectrometry. The DM intake and DM, organic matter, and CP digestibility were higher (P < 0.05) in the SDN-TMT-ALF group than in the SDN group. The TAC was higher (P < 0.01) in the SDN-TMT-ALF and SDN-ALF groups (809.51 and 813.7 µM, respectively) than the SDN group (720.69 µM), while the SOD level was unchanged (P = 0.06) among the treatments. Total serum cholesterol and NH3 levels were higher (P < 0.05) in the SDN-TMT-ALF group (89.17 mg/dL and 242.42 µg/dL, respectively) than in the SDN group (71.00 mg/dL and 89.17 µg/dL). Additionally, the levels of nine metabolites in serum differed among the treatments (P < 0.05). Linoleic acid (LA) and cortisone, which are related to LA metabolism and the steroid biosynthesis pathway, were upregulated by the SDN-ALF and SDN-TMT-ALF diets compared to the SDN diet, suggesting the contribution of ALF to altering the metabolites. The levels of hippuric acid, which is a metabolite of phenolic compounds, were higher (P < 0.001) in the animals fed SDN, which contained higher phenolic and luteolin concentrations than the other diets. Pathway analysis suggested that the higher cortisone levels were derived from cholesterol due to upregulated glycolysis metabolism, which was positively related to increased ingestion, digestibility, and serum LA levels in animals given mixed forage. In conclusion, physiological stress tolerance in the animals was regulated by upregulation of LA and steroid hormone metabolism, which was associated with an increase in TAC rather than the ability of the animal to regulate its PSM intake.

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

Fecal microbiota transplantation (FMT) has emerged as a highly effective therapy for recurrent Clostridioides difficile infection (rCDI) and also a potential therapy for other diseases associated with dysbiotic gut microbiota. Monitoring metabolic changes in biofluids and excreta is a noninvasive approach to identify the biomarkers of microbial recolonization and to understand the metabolic influences of FMT on the host. In this study, the pre-FMT and post FMT urine samples from 11 rCDI patients were compared through metabolomic analyses for FMT-induced metabolic changes. The results showed that p-cresol sulfate in urine, a microbial metabolite of tyrosine, was rapidly elevated by FMT and much more responsive than other microbial metabolites of aromatic amino acids (AAAs). Because patients were treated with vancomycin prior to FMT, the influence of vancomycin on the microbial metabolism of AAAs was examined in a mouse feeding trial, in which the decreases in p-cresol sulfate, phenylacetylglycine, and indoxyl sulfate in urine were accompanied with significant increases in their AAA precursors in feces. The inhibitory effects of antibiotics and the recovering effects of FMT on the microbial metabolism of AAAs were further validated in a mouse model of FMT. Overall, urinary p-cresol sulfate may function as a sensitive and convenient therapeutic indicator on the effectiveness of antibiotics and FMT for the desired manipulation of gut microbiota in human patients.