Citrus limonoid metabolism

Metabolism in Citrus. Recently, Hasegawa et al. (6) have established the presence of a deoxylimonoid pathway in Citrus. Methyl-14c VIII was metabolized in leaves of calamondin to form a deoxy derivative, showing the presence of epoxidase activity which is required for the first step of the deoxylimonoid pathway. Compound XVIII, the product of the second step, was also isolated from grapefruit seeds (6). Furthermore, deoxylimonate A-ring lactone hydrolase, which is involved in the third step of the pathway, was also detected in grapefruit seeds (6). These findings clearly show that limonoids are metabolized in Citrus not only via the 17-dehydrolimonoid pathway as previously established (22), but also via the deoxylimonoid pathway. 

Hahlbrock K, Scheel D (1989) Physiology and molecular biology of phenylpropanoid metabolism. Annu Rev Plant Physiol Plant Mol Biol 40 347-369 Hasegawa S, Herman Z (1992) Biosynthesis of limonoids in Citrus. In Petroski RJ, McCormick SP (eds) Secondary-metabolite biosynthesis and metabolism. Plenum Press, New York, pp 305-317... 

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