Sesamin is a potent and specific inhibitor of delta 5 desaturase in polyunsaturated fatty acid biosynthesis.
Incubation with sesame oil increases the mycelial dihomo-gamma-linolenic acid content of an arachidonic acid-producing fungus, Mortierella alpina, but decreases its arachidonic acid content [Shimizu, S., K. Akimoto, H. Kawashima, Y. Shinmen and H. Yamada (1989) J. Am. Oil Chem. Soc. 66, 237-241]. The factor causing these effects was isolated and identified to be (+)-sesamin. The results obtained in experiments with both a cell-free extract of the fungus and with rat liver microsomes demonstrated that (+)-sesamin specifically inhibits delta 5 desaturase at low concentrations, but does not inhibit delta 6, delta 9 and delta 12 desaturases. Kinetic analysis showed that (+)-sesamin is a noncompetitive inhibitor (Ki for rat liver delta 5 desaturase, 155 microM). (+)-Sesamolin, (+)-sesaminol and (+)-episesamin also inhibited only delta 5 desaturases of the fungus and liver. These results demonstrate that (+)-sesamin and related lignan compounds present in sesame seeds or its oil are specific inhibitors of delta 5 desaturase in polyunsaturated fatty acid biosynthesis in both microorganisms and animals.
Department of Agricultural Chemistry, Kyoto University, Japan.
S
S
Shimizu
K
K
Akimoto
Y
Y
Shinmen
H
H
Kawashima
M
M
Sugano
H
H
Yamada
D000818:Animals; D000090943:Delta-5 Fatty Acid Desaturase; D004149:Dioxoles / Q000494:pharmacology*; D044943:Fatty Acid Desaturases / Q000037:antagonists & inhibitors*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D066298:In Vitro Techniques; D007700:Kinetics; D017705:Lignans; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D009090:Mucorales / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012715:Sesame Oil / Q000494:pharmacology
D000090943:Delta-5 Fatty Acid Desaturase; D004149:Dioxoles; D005231:Fatty Acids, Unsaturated; D017705:Lignans; D012715:Sesame Oil; D044943:Fatty Acid Desaturases; C054125:sesamin