Sesamin inhibits lysophosphatidylcholine acyltransferase in Mortierella alpina

The filamentous fungus, Mortierella alpina, accumulates complex lipids rela tively rich in arachidonic acid (C-20:4 Delta (5,8,11,14)). The lignan, ses amin, has been used to reduce arachidonic acid production by specifically i nhibiting Delta (5)-desaturation [Shimizu, Akimoto, Shinmen, Kawashima, Sug ano and Yamada (1991) Lipids 26, 512-516]. Microsomal membrane preparations from M. alpina exhibit acyl-CoA:1-acyl lysophosphatidylcholine acyltransfe rase (LPCAT) activity. LPCAT is an enzyme involved in channelling fatty aci d substrates to phosphatidylcholine for subsequent desaturation. Sesamin wa s found to inhibit this enzyme as measured in both spectrophotometric and r adioactive assays. The inhibitory effect of sesamin on LPCAT was only evide nt in species of Mortierella. and could not be demonstrated in other organi sms.