12-epi Leukotriene B3

12-epi LTB3 is an LTB isomer that would not be formed either by known enzymatic or non-enzymatic processes. The conversion of LTA into different isomers of LTB is complex, and has generated confusion in the past. The enzymatic hydrolysis of LTA leads to LTB, which is the corresponding 5(S),12(R)-dihydroxy acid containing a 6(Z),8(E),10(E) conjugated triene. Non-enzymatic hydrolysis of LTA produces none of this material, but instead produces both the 12(S) and the 12(R) isomers of LTB in which the triene component now contains a 6-trans double bond. 12-epi (or 12(S)) LTB isomers which contain the natural 6-cis olefin are not produced either by enzymatic or by non-enzymatic processes. Further, 3-series LTs (derived from Mead acid) are only seen in essential fatty acid deficiency. Mead acid is a good substrate for 5-lipoxygenase, leading to LTA3. Enzymatic conversion of LTA3 to LTB3 is very low because LTA3 is actually an inhibitor of LTA hydrolase. Non-enzymatic hydrolysis of LTA3 leads to 6-trans-12-epi LTB3, and to 6-trans LTB3. The biological activity of 12-epi LTB3 has not been explored.