Biosynthesis of leukotrienes

Leukotriene C was originally discovered in the class of white blood cells called polymorphonuclear leukocytes (PMNs) and was named after the source (leukocytes) and the triene structure.

It is a potent muscle contractant that is involved in the pathogenesis of asthma, through constriction of the small airways in the lung.

LTs are formed from the initial attack on arachidonate of a lipoxygenase, which adds O2 to C-5, giving 5-HPETE.

A dehydration to give the epoxide coupled with isomerization of double bonds gives leukotriene A4.

Hydrolysis of the epoxide ring yields leukotriene B4.

Transfer of the thiol group of glutathione yields leukotriene C4.

Subsequent modifications of the peptide chain yield related compounds, leukotrienes D and E.