Lipoxygenase distribution

Lipoxygenases, which catalyse the oxidation of unsaturated fatty acids containing the cis,cis-l,4-pentadiene moiety to the corresponding 1 -hydroperoxy-f rans,ds-2,4-diene (Table 2.3), are widely distributed in plants and animals. The mammalian... 

Diethylcarbamazine is an anthelmintic drug that does not resemble other antiparasitic compounds although it has some relationship with piperazine derivatives and it has been useful in the management of filariasis due to Wuchereria bancrofti or Brugia malayi and Loa loa and of tropical eosinophilia. It is a lipoxygenase inhibitor and alters the surface structure of the parasite making it more susceptible to destruction by the host. It is well absorbed and widely distributed. It is eliminated with an half-life of 5-13 hours both by metabolism and excretion unchanged in the urine. 

Lipoxygenase, a dioxygenase that is distributed widely among plants, catalyzes the hydroperoxidation of cis-cis pentadienes. The position of hydroperoxidation may vary with different lipoxygenases. Some lipoxygenases catalyze a secondary reaction involving substrate and hydroperoxide which results in chain scission, carbonyl formation, dimerization, and destruction of certain dyes. Various lipoxygenases are classified with respect to the secondary reaction. 

The cellular locations of leukotriene biosynthesis are determined by the distribution and location of the enzymes needed for their production. 5-Lipoxygenase is found in only a limited number of specific cell types, predominantly of myeloid extraction. Because of this restricted expression, production of LTA4 is largely limited to those cells (e.g., basophils, eosinophils, neutrophils, macrophages, mast cells, and monocytes) (66). These cells produce LTA4, further process it to either LTB4 or LTC4, or secrete it. 

Lipoxygenases (LOX) constitute a family of lipid peroxidizing enzymes, which are distributed widely in the plant and animal kingdoms. These enzymes preferentially metabolize substrates that are polyunsaturated fatty acids containing a series of cis double bonds, which are the essential fatty acids for human beings (Kuhn Thiele, 1999). Lipoxygenases are dioxygenases in nature and... 

Triterpenes are widely distributed in plants, and in many cases are the principles responsible for their anti-inflammatory effects. Many of these compounds are active in different in vivo experimental models such as hind paw edema induced by carrageenan, serotonin and phospholipase A2 ear edema induced by phorbol and daphnane esters, ethylphenylpropiolate, arachidonic acid and capsaicin adjuvant arthritis and experimental models of allergy. Other effects have been studied in vitro, and some triterpenes are active against inflammatory enzymes like 5-lipoxygenase, elastase and phospholipase A2. Others inhibit histamine, collagenase and interleukin release, lipid peroxidation and free radical-mediated processes, metabolism of endogenous corticoids, and complement and protein-kinase activities. 

As housekeeping enzymes, lipoxygenases are found constitutively and ubiquitously in various cell types such as haematopoietic cells, epithelial cells and endocrine cells. When the tissue distribution of lipoxygenases is discussed, we should note that the enzyme activity may be attributed to contaminant blood cells or resident macrophages and granulocytes [113]. 

Table 4 Distribution of 12- and 15-lipoxygenases in various animal species ...

---