Synthesis of 3-oxalinolenic acid and beta-oxidation-resistant 3-oxa-oxylipins.
3-Oxalinolenic acid (3-oxa-9(Z),12(Z),15(Z)-octadecatrienoic acid or (6(Z),9(Z),12(Z)-pentadecatrienyloxy)acetic acid) was synthesized from 5(Z),8(Z),11(Z),14(Z),17(Z)-eicosapentaenoic acid by a sequence involving the C15 aldehyde 3(Z),6(Z),9(Z),12(Z)-pentadecatetraenal as a key intermediate. Conversion of the aldehyde by isomerization and two steps of reduction afforded 6(Z),9(Z),12(Z)-pentadecatrienol, which was coupled to bromoacetate to afford after purification by HPLC >99%-pure 3-oxalinolenic acid in 10-15% overall yield. 3-Oxalinolenic acid was efficiently oxygenated by soybean lipoxygenase-1 into 3-oxa-13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid, and this hydroperoxide could be further converted chemically into 3-oxa-13(S)-hydroxy-9(Z),11 (E),15(Z)-octadecatrienoic acid and 3-oxa-13-oxo-9(Z),11 (E),15(Z)-octadecatrienoic acid. The 3-oxa-hydroperoxide also served as the substrate for the plant enzymes allene oxide synthase, divinyl ether synthase, and hydroperoxide lyase to produce 3-oxa-12-oxo-10,15(Z)-phytodienoic acid and other 3-oxa-oxylipins that were characterized by MS. 3-Oxalinolenic acid was not oxygenated by 9-lipoxygenase from tomato but was converted at a slow rate into 3-oxa-9(S)-hydroperoxy-10(E),12(Z),15(Z)-octadecatrienoic acid by recombinant maize 9-lipoxygenase. Recombinant alpha-dioxygenase-1 from Arabidopsis thaliana catalyzed the conversion of 3-oxalinolenic acid into a 2-hydroperoxide, which underwent spontaneous degradation into a mixture of 6,9,12-pentadecatrienol and 6,9,12-pentadecatrienyl formate. A novel alpha-dioxygenase from the moss Physcomitrella patens was cloned and expressed and was found to display the same activity with 3-oxalinolenic acid as Arabidopsis thaliana alpha-dioxygenase-1. Lipoxygenase-generated 3-oxa-oxylipins are resistant toward beta-oxidation and have the potential for displaying enhanced biological activity in situations where activity is limited by metabolic degradation.
Hamberg
Mats
M
Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden. mats.hamberg@ki.se
Chechetkin
Ivan R
IR
Grechkin
Alexander N
AN
Ponce de León
Inés
I
Castresana
Carmen
C
Bannenberg
Gerard
G
D002851:Chromatography, High Pressure Liquid; D049308:Dioxygenases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008401:Gas Chromatography-Mass Spectrometry; D008042:Linolenic Acids / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D008084:Lipoxygenase / Q000378:metabolism; D008956:Models, Chemical; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010944:Plants / Q000201:enzymology
C513619:3-oxalinolenic acid; D008042:Linolenic Acids; D049308:Dioxygenases; D008084:Lipoxygenase