Hydroxyheptadecatrienoic acid

John, H., Schlegel, W. (1999). Determination of the pKa of 12-S-hydroxyheptadecatrienoic acid hy studies of its vial surface adsorption using high-performance liquid... 

Thromboxane synthetase has been solubilized and partially purified from human >53 gnd bovine blood platelets and from sheep and bovine lung. The enzyme activity also has been studied in platelet membranes by several workers.39-63 Recent studies indicate that the same enzyme catalyses the formation of TXA2 and hydroxyheptadecatrienoic acid (HHT) in a bimolecular reaction and that the formation of both products is inhibited in parallel.34,60,61 These studies also show that the formation of HHT does not involve TXA2 as an Intermediate and that TXA2 is converted exclusively into TXB2. PGH, the endoperoxlde from eicosapentaenoic acid (C2O 5 3,8,11,14,17) is converted into thromboxane A (TXA ) by platele... 

In washed human platelets, NDGA inhibited the formation of 12-LOX products as well as the COX product 12-hydroxyheptadecatrienoic acid (12-HHT), with an IC50 of 5 pM, while boswellic acids (mixture of a- and P-isomers) at concentrations up to 400 pM exerted no effect. In addition, in a cell-free system, the non-enzymatic peroxidation of AA by iron (II)-ascorbate was not affected by boswellic acid at concentrations up to 400 pM, whereas NDGA abolished the peroxidation of AA in this test at a concentration of 10 pM. These results suggest that the activity of boswellic acids is selective in the 5-LOX pathway, and the mechanism of inhibition is different from that of the classic antioxidant 5-LOX inhibitors (NDGA, caffeic acid, quercetin) [96]. 

LT leukotriene, TX thromboxane, HPETE hydroperoxy eicosatetraenoic acid, hydroxy eicosatetraenoic acid, HHT12 hydroxyheptadecatrienoic acid (17 carbon), MDA malondialdehyde (3 carbon)... 

Campbell PB, Tolson TA. Modulation of human monocyte leukotactic responsiveness by thromboxane A2 and 12-hydroxyheptadecatrienoic acid (12-HHT). J Leukoc Biol 1988 43 117 124. 

---