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Food Lipids: Chemistry, Nutrition, and Biotechnology

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aerial parts of plants, constitutes the first barrier against invasion by pathogens, <strong>and</strong><br />

also limits the penetration of compounds such as pesticides <strong>and</strong> herbicides. When<br />

pathogens succeed in crossing the cuticle, the plant copes with such aggression by<br />

an array of defense mechanisms <strong>and</strong>, especially, by triggering the synthesis of toxic<br />

compounds. The pathway involving hydroperoxide-dependent epoxidation <strong>and</strong> the<br />

secondary conversion of epoxy acids into vicinal dihydroxy acids in the presence of<br />

epoxide hydrolase may have significance in plants for protection against fungi <strong>and</strong><br />

other pathogens [245]. In addition, epoxy fatty acid derivatives may work as an<br />

elicitor to induce resistance to pathogens in rice (Oryza sativa L.) [246].<br />

B. Autoxidation<br />

Autoxidation of PUFAs has been demonstrated to result in aging <strong>and</strong> disorders of<br />

animal tissues [247,248] <strong>and</strong> in meat deterioration [249]. However, it had not drawn<br />

much attention from plant scientists until recently, since high activity of LOX is<br />

widely distributed in plants. Autoxidation of PUFAs has been suggested to be responsible<br />

for deterioration of postharvest plant commodities [248; unpublished results]<br />

<strong>and</strong> senescence of plant tissues [250]. Accumulated data show that the antioxidant<br />

defense system is involved in stress responses of plant tissues [251].<br />

Trihydroxyoctadecenoic <strong>and</strong> hydroxyoctadecadienoic acids in oxidized phosphatidylcholine<br />

are responsible for bitterness in soy products <strong>and</strong> in water suspensions<br />

of oat (Avena sativa L.) flour. These bitter-tasting hydroxylated fatty acids are<br />

proposed to originate from the free radical decomposition of HPOD [217].<br />

REFERENCES<br />

1. N. H. Grace. Physiological activity of a series of naphthyl acids. Can. J. Res. 17:247<br />

(1939).<br />

2. M. E. Synerholm <strong>and</strong> P. W. Zimmerman. Preparation of a series of �-(2,4-dichlorophenoxy)-aliphatic<br />

acids <strong>and</strong> some related compounds with a consideration of their<br />

biochemical role as plant growth regulators. Contrib. Boyce Thompson Inst. 14:369<br />

(1947).<br />

3. F. Knoop. Der Abbau aromatischer Fettsauren im Tierkorper. Beitr. Chem. Physiol.<br />

Pathol. 6:150 (1905).<br />

4. P. K. Stumpf <strong>and</strong> G. A. Barber, Fat metabolism in higher plants: VII. �-Oxidation of<br />

fatty acids by peanut mitochondria. Plant Physiol. 31:304 (1956).<br />

5. C. A. Rebeiz, P. Castelranco, <strong>and</strong> A. H. Engelbrecht. Fractionation <strong>and</strong> properties of<br />

an extra-mitochondrial enzyme system from peanuts catalyzing the �-oxidation of<br />

palmitic acid. Plant Physiol. 40:281 (1965).<br />

6. M. Yamada <strong>and</strong> P. K. Stumpf. Fat metabolism in higher plants: XXIV. A soluble �oxidative<br />

system from germinating seeds of Ricinus communis. Plant Physiol. 40:653<br />

(1965).<br />

7. T. C. Cooper <strong>and</strong> H. Beevers. �-Oxidation in glyoxysomes from castor bean endosperm.<br />

J. Biol. Chem. 244:3507 (1969).<br />

8. D. Hutton <strong>and</strong> P. K. Stumpf. Characterization of the �-oxidation system from maturing<br />

<strong>and</strong> germinating castor bean seeds. Plant Physiol. 44:508 (1969).<br />

9. T. C. Cooper. The activation of fatty acids in castor bean endosperm. J. Biol. Chem.<br />

246:3451 (1971).<br />

10. C. Bieglmayer, J. Graf, <strong>and</strong> H. Ruis. Membranes of glyoxysomes from castor-bean<br />

endosperm: Enzymes bound to purified-membrane preparations. Eur. J. Biochem. 37:<br />

553 (1973).<br />

Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.

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