Functional diversity of tocochromanols in plants |
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Authors: | Peter Dörmann |
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Institution: | (1) Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany |
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Abstract: | Tocochromanols encompass a group of compounds with vitamin E activity essential for human nutrition. They accumulate in photooxidative
organisms, e.g. in some algae and in plants, where they localize to thylakoid membranes and plastoglobules of chloroplasts.
Tocochromanols contain a polar chromanol head group with a long isoprenoid side chain. Depending on the nature of the isoprenoid
chain, tocopherols (containing a phytyl chain) or tocotrienols (geranylgeranyl chain) can be distinguished in plants. The
tocochromanol biosynthetic pathway has been studied in Arabidopsis and Synechocystis in recent years, and the respective mutants and genes were isolated. Mutant characterization revealed that tocopherol protects
lipids in photosynthetic membranes and in seeds against oxidative stress. In addition to its antioxidant characteristics,
tocopherol was shown be involved in non-antioxidant functions such as primary carbohydrate metabolism. A considerable proportion
of tocopherol is synthesized from free phytol suggesting that excess amounts of phytol released from chlorophyll breakdown
during stress or senescence might be deposited in the form of tocopherol in chloroplasts. |
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Keywords: | Antioxidant Oxidative stress Phytol Tocopherol Tocotrienol Vitamin E |
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