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Indoxyl sulfate is a dietary protein metabolite and also a metabolite of the common amino acid tryptophan. It has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821). It is a circulating uremic toxin stimulating glomerular sclerosis and interstitial fibrosis. Indoxyl sulfate is one of the well-known substances of a group of protein-bound uremic retention solutes. Indoxyl sulfate increases the rate of progression of renal failure. In plasma, indoxyl sulfate is a protein-bound uremic solute that induces endothelial dysfunction by inhibiting endothelial proliferation and migration in vitro. Some studies suggest that indoxyl sulfate is also involved in oxidative stress. In hemodialyzed patients, serum levels of indoxyl sulfate are associated with levels of pentosidine, a marker of carbonyl and oxidative stress. In vitro, indoxyl sulfate increases reactive oxygen species (ROS) production in tubular cells and increases NAD(P)H oxidase activity in endothelial cells. Indoxyl sulfate impairs osteoblast function and induces abnormalities of bone turnover. Indoxyl sulfate strongly decreases the levels of glutathione, one of the most active antioxidant systems of the cell (PMID: 10681668 , 14681860 , 17471003 , 17403109). Indoxyl sulfate is a microbial metabolite found in Escherichia (PMID: 19946322).

Sulforaphane (SFN) is the most characterized isothiocyanate. SFN has received a great deal of attention because of its ability to simultaneously modulate multiple cellular targets involved in cancer development, including: (i) DNA protection by modulating carcinogen-metabolizing enzymes and blocking the action of mutagens; (ii) inhibition of cell proliferation and induction of apoptosis, thereby retarding or eliminating clonal expansion of initiated, transformed, and/or neoplastic cells; (iii) inhibition of neoangiogenesis, progression of benign tumors to malignant tumors, and metastasis formation. SFN is therefore able to prevent, delay, or reverse preneoplastic lesions, as well as to act on cancer cells as a therapeutic agent. Taking into account this evidence and its favorable toxicological profile, SFN can be viewed as a conceptually promising agent in cancer prevention and/or therapy. SFN is the hydrolysis product of glucoraphanin, particularly high in the young sprouts of broccoli and cauliflower. SFN can also be obtained by eating cruciferous vegetables such as brussel sprouts, broccoli, cauliflower, bok choy, kale, collards, arugula, broccoli sprouts, chinese broccoli, broccoli raab, kohlrabi, mustard, turnip, radish, watercress and cabbage (PMID:17134937).

Doxycycline is only found in individuals that have used or taken this drug. It is a synthetic tetracycline derivative with similar antimicrobial activity. Animal studies suggest that it may cause less tooth staining than other tetracyclines. It is used in some areas for the treatment of chloroquine-resistant falciparum malaria (malaria, falciparum). [PubChem]Doxycycline, like minocycline, is lipophilic and can pass through the lipid bilayer of bacteria. Doxycycline reversibly binds to the 30 S ribosomal subunits and possibly the 50S ribosomal subunit(s), blocking the binding of aminoacyl tRNA to the mRNA and inhibiting bacterial protein synthesis. Doxycycline prevents the normal function of the apicoplast of Plasmodium falciparum, a malaria causing organism.

(+)-Epicatechin is found in apple. (+)-Epicatechin or ent-Epicatechin is one of the 4 catechin diastereoisomers.

(-)-Catechin 3-O-gallate is a polyphenol compound found in foods of plant origin (PMID: 20428313)

(-)-Epicatechin 3-O-gallate is found in almond. (-)-Epicatechin 3-O-gallate is isolated from tea and numerous other plant species including rhubarb and grapes.

(+)-epicatechin-3-O-gallate is a gallate ester obtained by formal condensation of the carboxy group of gallic acid with the (3S)-hydroxy group of (+)-epicatechin. It has a role as a metabolite. It is a catechin, a gallate ester and a polyphenol. It is functionally related to a gallic acid and a (+)-epicatechin. Epicatechin-3-gallate is a natural product found in Camellia sinensis, Punica granatum, and other organisms with data available. Epicatechin gallate is a metabolite found in or produced by Saccharomyces cerevisiae.

7-Hydroxyindole sulfate belongs to the class of organic compounds known as arylsulfates. These are organic compounds containing a sulfate group that carries an aryl group through an ether group. 7-Hydroxyindole sulfate is a uremic toxin (PMID: 30087103).

4-Isothiocyanato-1-butene is found in brassicas. Chief volatile isothiocyanate of enzymically treated seeds of Brassica napus (rape) and other crucifers. 4-Isothiocyanato-1-butene is formed from 3-Butenyl glycosinolate LBB62-U.

6-Hydroxyindole sulfate belongs to the class of organic compounds known as arylsulfates. These are organic compounds containing a sulfate group that carries an aryl group through an ether group. 6-Hydroxyindole sulfate has been identified in blood (PMID: 31250215).

4-Hydroxycinnamic acid, also known as p-Coumaric acid, is a coumaric acid in which the hydroxy substituent is located at C-4 of the phenyl ring. It has a role as a plant metabolite. It is a conjugate acid of a 4-coumarate. p-coumaric acid is an organic compound that is a hydroxy derivative of cinnamic acid. There are three isomers of coumaric acid: o-coumaric acid, m-coumaric acid, and p-coumaric acid, that differ by the position of the hydroxy substitution of the phenyl group. p-Coumaric acid is the most abundant isomer of the three in nature. p-Coumaric acid exists in two forms trans-p-coumaric acid and cis-p-coumaric acid. It is a crystalline solid that is slightly soluble in water, but very soluble in ethanol and diethyl ether. 4-Hydroxycinnamic acid belongs to the class of organic compounds known as hydroxycinnamic acids. Hydroxycinnamic acids are compounds containing an cinnamic acid where the benzene ring is hydroxylated. 4-Hydroxycinnamic acid exists in all living species, ranging from bacteria to humans. Outside of the human body, 4-Hydroxycinnamic acid is found, on average, in the highest concentration within a few different foods, such as pepper (Capsicum frutescens), pineapples, and sunflowers and in a lower concentration in spinachs, kiwis, and sweet oranges. 4-Hydroxycinnamic acid has also been detected, but not quantified in several different foods, such as wild rices, soursops, garden onions, hyssops, and avocado.

m-Coumaric acid, also known as 3-coumarate, belongs to the class of organic compounds known as hydroxycinnamic acids. Hydroxycinnamic acids are compounds containing an cinnamic acid where the benzene ring is hydroxylated. m-Coumaric acid exists in all living organisms, ranging from bacteria to humans. m-Coumaric acid (CAS: 588-30-7) is a polyphenol metabolite from caffeic acid, formed by the gut microflora. Outside of the human body, m-Coumaric acid is found, on average, in the highest concentration within a few different foods, such as olives, corns, and beers. m-Coumaric acid has also been detected, but not quantified in several different foods, such as carrots, strawberries, grape wines, garden tomato, and bilberries. MCT-mediated absorption of phenolic compounds per se and their colonic metabolites would exert a significant impact on human health (PMID:16870009, 15479001, 15479001). m-Coumaric acid is transported by the monocarboxylic acid transporter (MCT). The amount of this compound in human biofluids is diet-dependant. m-Coumaric acid is detected after the consumption of whole grain.

Moclobemide is only found in individuals that have used or taken this drug. It is a reversible monoamine oxidase inhibitor (MAOI) selective for isoform A (RIMA) used to treat major depressive disorder.The mechanism of action of moclobemide involves the selective, reversible inhibition of MAO-A. This inhibition leads to a decrease in the metabolism and destruction of monoamines in the neurotransmitters. This results in an increase in the monoamines, relieving depressive symptoms.

Isoleucyl-Isoleucine is a dipeptied compoosed of two isoleucine residues. It is an incomplete breakdown product of protein digestion or protein catabolism. Some dipeptides are known to have physiological or cell-signaling effects although most are simply short-lived intermediates on their way to specific amino acid degradation pathways following further proteolysis. This dipeptide has not yet been identified in human tissues or biofluids and so it is classified as an 'Expected' metabolite.

Leucylleucine is a dipeptide composed of two leucine residues. It is an incomplete breakdown product of protein digestion or protein catabolism. Some dipeptides are known to have physiological or cell-signalling effects although most are simply short-lived intermediates on their way to specific amino acid degradation pathways following further proteolysis.

ent-Robinetinidol 3-O-gallate

Phenylpyruvic acid is a keto-acid that is an intermediate or catabolic byproduct of phenylalanine metabolism. It has a slight honey-like odor. Levels of phenylpyruvate are normally very low in blood or urine. High levels of phenylpyruvic acid can be found in the urine of individuals with phenylketonuria (PKU), an inborn error of metabolism. PKU is due to lack of the enzyme phenylalanine hydroxylase (PAH), so that phenylalanine is converted not to tyrosine but to phenylpyruvic acid. In particular, excessive phenylalanine can be metabolized into phenylketones through, a transaminase pathway route involving glutamate. Metabolites of this transamination reaction include phenylacetate, phenylpyruvate and phenethylamine. In persons with PKU, dietary phenylalanine either accumulates in the body or some of it is converted to phenylpyruvic acid. Individuals with PKU tend to excrete large quantities of phenylpyruvate, phenylacetate and phenyllactate, along with phenylalanine, in their urine. If untreated, mental retardation effects and microcephaly are evident by the first year along with other symptoms which include: unusual irritability, epileptic seizures and skin lesions. Hyperactivity, EEG abnormalities and seizures, and severe learning disabilities are major clinical problems later in life. A "musty or mousy" odor of skin, hair, sweat and urine (due to phenylacetate accumulation); and a tendency to hypopigmentation and eczema are also observed. The neural-development effects of PKU are primarily due to the disruption of neurotransmitter synthesis. In particular, phenylalanine is a large, neutral amino acid which moves across the blood-brain barrier (BBB) via the large neutral amino acid transporter (LNAAT). Excessive phenylalanine in the blood saturates the transporter. Thus, excessive levels of phenylalanine significantly decrease the levels of other LNAAs in the brain. But since these amino acids are required for protein and neurotransmitter synthesis, phenylalanine accumulation disrupts brain development, leading to mental retardation. Phenylpyruvic acid is also a microbial metabolite, it can be produced by Lactobacillus plantarum (PMID: 9687465).

2,4-Dimethylthiazole is found in animal foods. 2,4-Dimethylthiazole is a constituent of beef aroma.