Oxygenation of (3Z)-alkenals to 4-hydroxy-(2E)-alkenals in plant extracts: a nonenzymatic process.
There is large interest in 4-hydroxy-(2E)-alkenals because of their cytotoxicity in mammals. However, the biosynthetic pathway for these compounds has not been elucidated yet. In plants, 4-hydroxy-(2E)-alkenals were supposed to be derived by the subsequent actions of lipoxygenase and a peroxygenase on (3Z)-alkenals. The presence of 9-hydroxy-12-oxo-(10E)-dodecenoic acid (9-hydroxy-traumatin) in incubations of 12-oxo-(9Z)-dodecenoic acid (traumatin) in the absence of lipoxygenase or peroxygenase, has prompted us to reinvestigate its mode of formation. We show here that in vitro 9-hydroxy-traumatin, 4-hydroxy-(2E)-hexenal and 4-hydroxy-(2E)-nonenal, are formed in a nonenzymatic process. Furthermore, a novel product derived from traumatin was observed and identified as 11-hydroxy-12-oxo-(9Z)-dodecenoic acid. The results obtained here strongly suggest that the 4-hydroxy-(2E)-alkenals, observed in crude extracts of plants, are mainly due to autoxidation of (3Z)-hexenal, (3Z)-nonenal and traumatin. This may have implications for the in vivo existence and previously proposed physiological significance of these products in plants.
Noordermeer
M A
MA
Bijvoet Center for Biomolecular Research, Utrecht University, The Netherlands.
Feussner
I
I
Kolbe
A
A
Veldink
G A
GA
Vliegenthart
J F
JF
D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism*; D002457:Cell Extracts; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008041:Linoleic Acids / Q000378:metabolism; D008042:Linolenic Acids / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism; D008084:Lipoxygenase / Q000378:metabolism; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology / Q000378:metabolism*
C119006:9-hydroxy-12-oxo-10(E)-dodecenoic acid; D000447:Aldehydes; D002457:Cell Extracts; D005229:Fatty Acids, Monounsaturated; D008041:Linoleic Acids; D008042:Linolenic Acids; D008054:Lipid Peroxides; D010940:Plant Proteins; D011994:Recombinant Proteins; C038649:13-hydroperoxy-9,11-octadecadienoic acid; C057375:13-hydroperoxy-9,11,15-octadecatrienoic acid; C080589:3-nonenal; D006861:Hydrogen Peroxide; D008084:Lipoxygenase