Target type: biologicalprocess
The chemical reactions and pathways resulting in the breakdown of platelet activating factor, 2-O-acetyl-1-O-octadecyl-sn-glycero-3-phosphocholine. [PMID:16371369]
Platelet-activating factor (PAF) catabolism is a crucial process for maintaining vascular homeostasis and preventing excessive inflammation. PAF, a potent lipid mediator, is rapidly inactivated by a series of enzymatic reactions. The primary pathway involves the sequential action of two enzymes:
* **PAF acetylhydrolase (PAF-AH)**: This enzyme hydrolyzes the acetyl group at the sn-2 position of PAF, producing lyso-PAF. PAF-AH is present in various tissues, including plasma, platelets, and endothelial cells.
* **Lyso-PAF acyltransferase**: This enzyme adds a fatty acid to lyso-PAF, generating inactive lyso-PAF derivatives. This step can be carried out by various acyltransferases, and the specific fatty acid incorporated can influence the activity of the final product.
In addition to these enzymatic reactions, other mechanisms contribute to PAF inactivation, including:
* **Cellular uptake**: PAF can be taken up by cells, particularly macrophages, which have high levels of PAF-AH. This uptake can be followed by degradation within the cells.
* **Binding to albumin**: PAF can bind to albumin in plasma, reducing its availability for interaction with target cells.
* **Oxidation**: PAF can be oxidized, leading to inactivation.
The catabolic process of PAF plays a critical role in preventing the detrimental effects of excessive PAF accumulation, including:
* **Increased vascular permeability**: PAF promotes vascular leakage, leading to edema and tissue damage.
* **Platelet aggregation**: PAF triggers platelet aggregation, contributing to thrombosis and cardiovascular disease.
* **Inflammation**: PAF is a potent pro-inflammatory mediator, contributing to the inflammatory cascade.
By effectively inactivating PAF, these catabolic mechanisms ensure proper vascular function and prevent pathological consequences.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Platelet-activating factor acetylhydrolase | A platelet-activating factor acetylhydrolase that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q13093] | Homo sapiens (human) |
| Group 10 secretory phospholipase A2 | A group 10 secretory phospholipase A2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:O15496] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| ly 171883 | LY 171883: structure in first source; leukotriene receptor antagonist tomelukast : A member of the class of acetophenones that is 1-phenylethanone substituted at position 2 by a hydroxy group, a propyl group at position 3 and a 4-(1H-tetrazol-5-yl)butoxy group at position 4. A leukotriene antagonist, it exhibits anti-asthmatic activity. | acetophenones; aromatic ether; phenols; tetrazoles | anti-asthmatic drug; leukotriene antagonist |
| vitamin k 3 | Vitamin K 3: A synthetic naphthoquinone without the isoprenoid side chain and biological activity, but can be converted to active vitamin K2, menaquinone, after alkylation in vivo. | 1,4-naphthoquinones; vitamin K | angiogenesis inhibitor; antineoplastic agent; EC 3.4.22.69 (SARS coronavirus main proteinase) inhibitor; human urinary metabolite; nutraceutical |
| raloxifene | raloxifene : A member of the class of 1-benzothiophenes that is 1-benzothiophene in which the hydrogens at positions 2, 3, and 6 have been replaced by p-hydroxyphenyl, p-[2-(piperidin-1-yl)ethoxy]benzoyl, and hydroxy groups, respectively. | 1-benzothiophenes; aromatic ketone; N-oxyethylpiperidine; phenols | bone density conservation agent; estrogen antagonist; estrogen receptor modulator |
| 1,6-bis(cyclohexyloximinocarbonyl)hexane | 1,6-bis(cyclohexyloximinocarbonyl)hexane: selective inhibitor of canine platelet diglyceride lipase | carbamate ester; organonitrogen compound | |
| vorinostat | vorinostat : A dicarboxylic acid diamide comprising suberic (octanedioic) acid coupled to aniline and hydroxylamine. A histone deacetylase inhibitor, it is marketed under the name Zolinza for the treatment of cutaneous T cell lymphoma (CTCL). Vorinostat: A hydroxamic acid and anilide derivative that acts as a HISTONE DEACETYLASE inhibitor. It is used in the treatment of CUTANEOUS T-CELL LYMPHOMA and SEZARY SYNDROME. | dicarboxylic acid diamide; hydroxamic acid | antineoplastic agent; apoptosis inducer; EC 3.5.1.98 (histone deacetylase) inhibitor |
| 5,5-dimethylhydantoin | 5,5-dimethylhydantoin: RN given refers to parent cpd | imidazolidine-2,4-dione | |
| benzenesulfonamide | sulfonamide | ||
| plumbagin | plumbagin : A hydroxy-1,4-naphthoquinone that is 1,4-naphthoquinone in which the hydrogens at positions 2 and 5 are substituted by methyl and hydroxy groups, respectively. plumbagin: a superoxide anion generator | hydroxy-1,4-naphthoquinone; phenols | anticoagulant; antineoplastic agent; immunological adjuvant; metabolite |
| wy 48252 | Wy 48252: leukotriene D4 antagonist | ||
| 4-[1-[4-[2-(dimethylamino)ethoxy]phenyl]-2-phenylbut-1-enyl]phenol | stilbenoid | ||
| spiroglumide | spiroglumide: a CCK receptor antagonist; antigastrin; structure given in first source | ||
| 3-octylthio-1,1,1-trifluoro-2-propanone | 3-octylthio-1,1,1-trifluoro-2-propanone: a pesticide synergist; inhibits juvenile hormone esterase | ||
| varespladib | aromatic ether; benzenes; dicarboxylic acid monoamide; indoles; monocarboxylic acid; primary carboxamide | anti-inflammatory drug; antidote; EC 3.1.1.4 (phospholipase A2) inhibitor | |
| tamoxifen | stilbenoid; tertiary amino compound | angiogenesis inhibitor; antineoplastic agent; bone density conservation agent; EC 1.2.3.1 (aldehyde oxidase) inhibitor; EC 2.7.11.13 (protein kinase C) inhibitor; estrogen antagonist; estrogen receptor antagonist; estrogen receptor modulator | |
| orlistat | orlistat : A carboxylic ester resulting from the formal condensation of the carboxy group of N-formyl-L-leucine with the hydroxy group of (3S,4S)-3-hexyl-4-[(2S)-2-hydroxytridecyl]oxetan-2-one. A pancreatic lipase inhibitor, it is used as an anti-obesity drug. Orlistat: A lactone derivative of LEUCINE that acts as a pancreatic lipase inhibitor to limit the absorption of dietary fat; it is used in the management of obesity. | beta-lactone; carboxylic ester; formamides; L-leucine derivative | anti-obesity agent; bacterial metabolite; EC 2.3.1.85 (fatty acid synthase) inhibitor; EC 3.1.1.3 (triacylglycerol lipase) inhibitor |
| arachidonyltrifluoromethane | AACOCF3 : A fatty acid derivative that is arachidonic acid in which the OH part of the carboxy group has been replaced by a trifluoromethyl group arachidonyltrifluoromethane: structure given in first source; inhibits 85-kDa phospholipase A2 | fatty acid derivative; ketone; olefinic compound; organofluorine compound | EC 3.1.1.4 (phospholipase A2) inhibitor |
| amentoflavone | biflavonoid; hydroxyflavone; ring assembly | angiogenesis inhibitor; antiviral agent; cathepsin B inhibitor; P450 inhibitor; plant metabolite | |
| ochnaflavone | ochnaflavone : A biflavonoid with an ether linkage between the B-rings of the apigenin and luteolin subunits. It has been isolated from several members of the Ochnaceae plant family. ochnaflavone: from Lonicera japonica; structure given in first source | aromatic ether; biflavonoid; hydroxyflavone | anti-inflammatory agent; antiatherogenic agent; antibacterial agent; EC 3.1.1.4 (phospholipase A2) inhibitor; leukotriene antagonist; plant metabolite |
| manoalide | manoalide : A sesterterpenoid isolated from the marine sponge Luffariella variabilis and which has been shown to exhibit inhibitory activity towards phospholipase A2. manoalide: phospholipase A2 inhibitor; sesterterpene from marine sponge L. variabilis; structure given in first source | butenolide; lactol; sesterterpenoid | EC 3.1.1.4 (phospholipase A2) inhibitor; EC 5.99.1.2 (DNA topoisomerase) inhibitor; EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor; metabolite |
| ym 26734 | YM 26734: inhibits group II phospholipase A2; structure given in first source | ||
| indoxam | indoxam: structure in first source | ||
| darapladib | darapladib: a selective lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) inhibitor, on biomarkers of cardiovascular (CV) risk | ||
| sb-435495 | SB-435495: structure in first source | ||
| 14-methyl-20-oxa-5,7,14,26-tetraazatetracyclo(19.3.1.1(2,6).1(8,12))heptacosa-1(25),2(26),3,5,8(27),9,11,16,21,23-decaene | 14-methyl-20-oxa-5,7,14,26-tetraazatetracyclo(19.3.1.1(2,6).1(8,12))heptacosa-1(25),2(26),3,5,8(27),9,11,16,21,23-decaene: has antineoplastic activity; also inhibits Fms-like tyrosine kinase-3; structure in first source |