Mène-Saffrané Laurent
Department of Biology, University of Fribourg, Chemin du Musée, 10, 1700 Fribourg, Switzerland.
Antioxidants (Basel). 2017 Dec 25;7(1):2. doi: 10.3390/antiox7010002.
Vitamin E is one of the 13 vitamins that are essential to animals that do not produce them. To date, six natural organic compounds belonging to the chemical family of tocochromanols-four tocopherols and two tocotrienols-have been demonstrated as exhibiting vitamin E activity in animals. Edible plant-derived products, notably seed oils, are the main sources of vitamin E in the human diet. Although this vitamin is readily available, independent nutritional surveys have shown that human populations do not consume enough vitamin E, and suffer from mild to severe deficiency. Tocochromanols are mostly produced by plants, algae, and some cyanobacteria. Tocochromanol metabolism has been mainly studied in higher plants that produce tocopherols, tocotrienols, plastochromanol-8, and tocomonoenols. In contrast to the tocochromanol biosynthetic pathways that are well characterized, our understanding of the physiological and molecular mechanisms regulating tocochromanol biosynthesis is in its infancy. Although it is known that tocochromanol biosynthesis is strongly conditioned by the availability in homogentisate and polyprenyl pyrophosphate, its polar and lipophilic biosynthetic precursors, respectively, the mechanisms regulating their biosyntheses are barely known. This review summarizes our current knowledge of tocochromanol biosynthesis in plants, and highlights future challenges regarding the understanding of its regulation.
维生素E是13种维生素之一，对于无法自行合成它们的动物来说至关重要。迄今为止，属于生育三烯酚化学家族的六种天然有机化合物——四种生育酚和两种生育三烯酚——已被证明在动物体内具有维生素E活性。可食用的植物衍生产品，尤其是种子油，是人类饮食中维生素E的主要来源。尽管这种维生素很容易获取，但独立的营养调查显示，人类群体摄入的维生素E不足，且存在轻度至重度缺乏的情况。生育三烯酚主要由植物、藻类和一些蓝细菌产生。生育三烯酚代谢主要在能产生生育酚、生育三烯酚、植基色满醇-8和生育单烯酚的高等植物中进行研究。与已得到充分表征的生育三烯酚生物合成途径形成对比的是，我们对调节生育三烯酚生物合成的生理和分子机制的了解尚处于起步阶段。尽管已知生育三烯酚的生物合成分别受到尿黑酸和聚异戊二烯焦磷酸（其极性和亲脂性生物合成前体）可用性的强烈影响，但其生物合成的调节机制却几乎不为人知。本综述总结了我们目前对植物中生育三烯酚生物合成的认识，并突出了在理解其调控方面未来面临的挑战。
