OXO FATTY ACIDS
There are a number of aldehydic fatty acids (w-oxo acids) in plants which derive from fatty acid hydroperoxides and play important cell signaling roles.
These molecules form the well known “traumatin” family which includes traumatin (12-oxo-9Z-dodecenoic acid, the precursor of traumatic acid), and autoxidation derivatives (9-hydroxy- and 11-hydroxy-traumatin). Traumatic acid is considered as a plant growth hormone.
Traumatin hydro-derivatives were shown to be formed by a non-enzymatic oxidation process (Noordermeer MA et al., Biochem Biophys Res Comm 2000, 277, 112). Traumatin and other w-oxo acids were shown to be the products of the successive actions of lipoxygenase and hydroperoxide lyase on linoleic and linolenic acids (Gardner HW, Lipids 1998, 33, 745). The main biological property of traumatin is the ability to stimulate wound healing in plants (Zimmerman et al., Plant Physiol 1979, 63, 536). Traumatin and derivatives are likely to play a role in defense against fungi, bacteria and arthropods (Farmer EE, Plant Mol Biol 1994, 26, 1423).
The homolytic cleavage of fatty acid peroxides by hydroperoxide lyase gives an alcohol (or hydrocarbon) and a w-oxo acid (aldehydic fatty acid) (Gardner HW et al., Plant Physiol 1991, 97, 1059).
In mushrooms (Psalliota), the production of 10-oxo-8E-decenoic acid from linoleic acid was demonstrated (Wurzenberger M et al., Lipids 1986, 21, 261).
In algae, the cleavage of 13-hydroperoxides of linoleic and linolenic acids produced 13-oxo-9Z-11E-tridecadienoic acid (Vick BA et al., Plant Physiol 1989, 90, 125).
This compound was shown to be also produced by soybean cotyledons (Kondo Y et al., Biochim Biophys Acta 1995, 1255, 9).
The heterolytic cleavage of 9- and 13-hydroperoxides in higher plants leads to the production of traumatin and 9-oxononanoic acid (Delcarte J et al., Biotechnol Agron Soc Environ 2000, 4, 157).
It was shown that in mammal (rabbit liver) another enzymatic pathway (P-450 and reductase) was also able to generate 13-oxo-9-11-tridecadienoic acid as in algae (Rota C et al., Biochem J 1997, 323, 565).