Stereochemistry of leukotriene B4 metabolites formed by the reductase pathway in porcine polymorphonuclear leukocytes: inversion of stereochemistry of the 12-hydroxyl group.
Leukotriene B4 (LTB4), a potent proinflammatory agent, is a major metabolite of arachidonic acid in polymorphonuclear leukocytes (PMNL). When porcine PMNL were incubated with LTB4 and the products purified by reversed-phase high-pressure liquid chromatography (HPLC), we previously identified two metabolites: 10,11-dihydro-LTB4 and 10,11-dihydro-12-oxo-LTB4 [Powell, W. S., & Gravelle, F. (1989) J. Biol. Chem. 264, 5364-5369]. Further analysis of the reaction products by normal-phase HPLC has now revealed the presence of a third major metabolite of LTB4. This product is not formed in detectable amounts in the first 5 min of the reaction but accounts for about 20-30% of the reaction products after 60 min, when LTB4 has been completely metabolized. The mass spectrum and gas chromatographic properties of the new metabolite are identical with those of 10,11-dihydro-LTB4, suggesting that it is a stereoisomer of this compound. This product was identified as 10,11-dihydro-12-epi-LTB4 [i.e., 5(S),12(R)-dihydroxy-6,8,14-eicosatrienoic acid] by comparison of its chromatographic properties with those of the authentic chemically synthesized compound. Both 10,11-dihydro-LTB4 and 10,11-dihydro-12-oxo-LTB4 were enzymatically converted to 10,11-dihydro-12-epi-LTB4 by porcine PMNL, the former compound being the better substrate. The reaction was reversible, since both 10,11-dihydro-12-epi-LTB4 and 10,11-dihydro-12-oxo-LTB4 could be converted to 10,11-dihydro-LTB4.(ABSTRACT TRUNCATED AT 250 WORDS)
Wainwright
S
S
Endocrine Laboratory, Royal Victoria Hospital, Montreal, Quebec, Canada.
Falck
J R
JR
Yadagiri
P
P
Powell
W S
WS
D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006878:Hydroxides; D017665:Hydroxyl Radical; D007975:Leukotriene B4 / Q000378:metabolism*; D009504:Neutrophils / Q000201:enzymology*; D013552:Swine
D006878:Hydroxides; D007975:Leukotriene B4; D017665:Hydroxyl Radical; D000429:Alcohol Oxidoreductases