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Showing 41 - 50 of 61345 pathways
SMPDB ID Pathway Chemical Compounds Proteins


Pw012894 View Pathway

Abscisic Acid Glucose Ester Metabolism

Arabidopsis thaliana
Abscisic acid glucose ester metabolism is a pathway that begins in the chloroplast and enters the cytosol and endoplasmic reticulum body by which violaxanthin becomes abscisic acid glucose ester, synthesizing abscisic acid in the process. Abscisic acid glucose ester synthesis and reformation back to abscisic acid provides a mechanism for precisely controlling abscisic acid concentration (quickly removing and adding abscisic acid when required). First, neoxanthin synthase catalyzes the opening of the violaxanthin epoxide ring to form neoxanthin. Second, a yet unidentified neoxanthin isomerase is theorized to isomerize neoxanthin to 9'-cis-neoxanthin. Third, 9-cis-epoxycarotenoid dioxygenase (NCED) uses oxygen to cleave 9'-cis-neoxanthin to form xanthoxin and C25-allenic-apo-aldehyde. This enzyme requires Fe2+ as a cofactor. Next, a xanthoxin transporter is theorized to export xanthoxin from the chloroplast into the cytosol to continue abscisic acid biosynthesis, but it has yet to be discovered. Fourth, xanthoxin dehydrogenase, located in the cytosol, catalyzes the conversion of xanthoxin and NAD to abscisic aldehyde, NADH, and a proton with the help of a molybdenum cofactor (MoCo). Fifth, abscisic-aldehyde oxidase converts abscisic aldehyde, water, and oxygen into hydrogen peroxide, hydrogen ion, and abscisic acid. Sixth, abscisic acid glucosyltransferase uses UDP to convert abscisic acid into abscisic acid glucose ester. Abscisic acid glucose ester can then be converted back to abscisic acid via abscisic acid glucose ester beta-glucosidase located in the endoplasmic reticulum body (coloured dark green in the image). Consequently, it is theorized that ABA-GE transporters are required for this enzyme to access its substrates from the cytosol.


Pw000364 View Pathway
drug action

Acebutolol Action Pathway

Homo sapiens
Acebutolol is a selective β1-receptor antagonist, which possesses mild intrinsic sympathomimetic activity (ISA) in its therapeutically effective dose range. Activation of β1-receptors by epinephrine increases the heart rate and output. Acebutolol blocks these receptors which lowers the heart rate and blood pressure. In addition, beta blockers prevent the release of renin, which is a hormone produced by the kidneys which leads to constriction of blood vessels.


Pw000312 View Pathway
drug action

Acenocoumarol Action Pathway

Homo sapiens
Acenocoumarol is an anticoagulant that inhibits the liver enzyme vitamin K reductase. This leads to the depletion of the reduced form of vitamin K (vitamin KH2). As vitamin K is a cofactor for the gamma-carboxylation and subsequent activation of the vitamin K-dependent coagulation factors (II, VII, IX, and X), this ultimately results in reduced cleavage of fibrinogen into fibrin and decreased coagulability of the blood.


Pw000687 View Pathway
drug action

Acetaminophen Action Pathway

Homo sapiens
The mechanism of action of Acetaminophen is thought to be due to its ability to block prostaglandin synthesis by inhibiting cyclooxygenase 1 and 2 (COX-1 and -2), also called prostaglandin G/H synthase 1 and 2. COX-1 and -2 catalyze the conversion of arachidonic acid to prostaglandin G2 and prostaglandin G2 to prostglandin H2. Prostaglandin H2 is the precursor to a number of prostaglandins (e.g. PGE2) involved in fever, pain, swelling, inflammation, and platelet aggregation. Acetaminophen antagonizes COX by binding to the upper portion of the active site, preventing its substrate, arachidonic acid, from entering the active site. Prostaglandins have been shown in many animal models to be mediators of certain kinds of intraocular inflammation. In studies performed in animal eyes, prostaglandins have been shown to produce disruption of the blood-aqueous humor barrier, vasodilation, increased vascular permeability, leukocytosis, and increased intraocular pressure.


Pw000616 View Pathway
drug metabolism

Acetaminophen Metabolism Pathway

Homo sapiens
Acetaminophen (APAP) is metabolized primarily in the liver. Glucuronidation is the main route, accounting for 45-55% of APAP metabolism, and is mediatied by UGT1A1, UGT1A6, UGT1A9, UGT2B15 in the liver and UGT1A10 in the gut. APAP can also by metabolized via sulfation, accounting for 30-35% of the metabolism. In the liver, this step is catalyzed by the sulfotransferases SULT1A1, SULT1A3, SULT1A4, SULT1E1 and SULT2A1. Moreover, APAP can also be activated to form the toxic N-acetyl-p-benzoquinone imine (NAPQI) under the mediation of CYP3A4, CYP2E1, CYP2D6 CYP1A2, CYP2E1 and CYP2A6.


Pw002090 View Pathway

Acetate metabolism

Escherichia coli
The acetate biosynthesis starts with acetyl-CoA reacting with phosphate through a phosphate acetyltransferase resulting in the release of a coenzyme A and an acetyl phosphate. The latter compound in turn reacts with ADP through an acetate kinase resulting in the release of an ATP and an acetate. The acetate reacts with ATP and coenzyme A through an acetyl-CoA synthase resulting in the release of a diphosphate, an AMP and an acetyl-CoA. Acetyl-CoA can be biosynthesized by acetoacetate reacting with an acetyl-CoA through an acetoacetyl-CoA transferase resulting in the release of an acetate and an acetoacetyl-CoA. The acetoacetyl-CoA reacts with an acetyl-CoA acetyltransferase resulting in the release of an coenzyme A and 2 acetyl-CoA


Pw000128 View Pathway
drug action

Acetylsalicylic Acid Action Pathway

Homo sapiens
Acetylsalicylic acid, also known as ASA or aspirin, belongs to a class of drugs known as non-steroidal anti-inflammatory drugs (NSAIDs). In addition to its anti-inflammatory properties, aspirin also acts as an analgesic, antipyretic and antithrombotic agent. Like most other NSAIDs, aspirin exerts its therapeutic effects by inhibiting prostaglandin G/H synthase 1 and 2, better known as cyclooxygenase-1 and -2 or simply COX-1 and -2. COX-1 and -2 catalyze the conversion of arachidonic acid to prostaglandin G2 and prostaglandin G2 to prostaglandin H2. Prostaglandin H2 is the precursor to a number of other prostaglandins, such as prostaglandin E2, involved in pain, fever and inflammation. The antipyretic properties of aspirin arise from inhibition of prostaglandin E2 synthesis in the preoptic region of the hypothalamus. Interference with adhesion and migration of granulocytes, polymorphonuclear leukocytes and macrophages at sites of inflammation account for its anti-inflammatory effects. The analgesic effects of aspirin likely occur due to peripheral action at the site of injury and possibly within the CNS. Aspirin is unique from other NSAIDs in that it is an irreversible COX inhibitor. Aspirin irreversibly acetylates a serine side chain of COX rendering the enzyme inactive. Enzyme activity can only be regained by production of more cyclooxygenase. This unique property of aspirin and its higher selectivity for COX-1 over COX-2 makes it an effective antiplatelet agent. Platelets contain COX-1, a key enzyme in the production thromboxane A2 (TXA2), which is a potent inducer of platelet aggregation. Since platelets lack the ability to make more enzyme, TXA2 production is inhibited for the lifetime of the platelet (approximately 8 – 12 days). Aspirin is commonly used at low doses to prevent cardiovascular events such as strokes and heart attacks. At higher doses, aspirin may be used as an analgesic, anti-inflammatory and antipyretic. Aspirin may cause gastric irritation and bleeding by inhibiting the synthesis of prostaglandins that enhance and maintain the protective gastric mucous layer.


Pw060826 View Pathway
drug action

Acrivastine H1-Antihistamine Action

Homo sapiens
Acrivastine is a second-generation alkylamine H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. Reducing the activity of the NF-κB immune response transcription factor through the phospholipase C and the phosphatidylinositol (PIP2) signalling pathways also decreases antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors. Furthermore, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release. First-generation antihistamines readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects (e.g. nervousness and insomnia). Second-generation antihistamines are more selective for H1-receptors of the peripheral nervous system (PNS) and do not cross the blood-brain barrier. Consequently, these newer drugs elicit fewer adverse drug reactions.


Pw000726 View Pathway

Activation of PKC through G protein coupled receptor

Homo sapiens
G protein-coupled receptors sense stimuli outside the cell and transmit signals across the plasma membrane. Activation of protein kinase C (PKC) is one of the common signaling pathways. When a class of GPCRs are activated by a ligand, they activate Gq protein to bind GTP instead of GDP. After the Gq becomes active, it activates phospholipase C (PLC) to cleave the membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol 1,4,5-trisphosphate (IP3) and diacyl glycerol (DAG). IP3 is a soluble molecule and is capable of diffusing through the cytoplasm to the ER, where it binds to the Ins3P receptor and opens the calcium channel, releasing the calcium from ER into the cytoplasm. The increases in the concentration of DAG and calcium activate the kinase activity of PKC.


Pw000174 View Pathway

Acute Intermittent Porphyria

Homo sapiens
Acute intermittent porphyria (AIP), the second most common form of porphyria, is caused by a defect in the HMBS gene which codes for porphobilinogen deaminase. A defect in this enzyme results in accumulation of 5-aminolevulinic acid or porphobilinogen in both urine and serum. Most Patients are completely free of symptoms between attacks. Symtpoms include abdominal pain, constipation, vomitting, hypertension, muscle weakness, seizures, delirium, coma, and depression. A high-carbohydrate diet is typically recommended; in severe attacks, a glucose 10% infusion is recommended, which may aid in recovery.
Showing 41 - 50 of 61345 pathways