水稻籽粒维生素E及组分在品种间的变异与分布

维生素E是人与动物必须从食物中摄取的微量营养元素之一,根据侧链的饱和度可将其分为生育酚和三烯生育酚,水稻种子中均含二者。本研究利用反相高效液相色谱法测定了18份籼稻和16份粳稻品种糙米中维生素E各异构体的含量。结果表明,种子中各异构体的含量在籼稻与粳稻间存在显著差异,粳稻种子中的生育酚和维生素E含量一般要高于籼稻;籼稻种子中三烯生育酚与生育酚的比值(1.61)极显著高于粳稻(0.95),籼稻中以γ-三烯生育酚为主,而粳稻中主要含α-生育酚。水稻种子中同种类型异构体(即α-型间或γ-型间)含量间具有显著正相关,但γ-型与α-型异构体间呈显著负相关。这些数据为进一步研究水稻种子中维生素E的代谢调控和营养品质改良提供了有益的表型数据。

Variation and Distribution of Vitamin E and Composition in the Seeds among Different Rice Varieties

Vitamin E, including of tocotrienols and tocopherols, is one of miner nutrients that must be acquired regularly from dietary sources. The structure of tocotrienols differs from that of tocopherols by the presence of three trans-double bonds in the hydrocarbon chain. In this study, a reverse-phase HPLC method was used to simultaneously measure the contents of either tocopherols or tocotrienols in the brown rice, and their contents were compared among 18 indica and 16 japonica cultivars. The results showed that the contents of these vitamin E isomers were extremely different between indica and japonica rice, and the mean content of total tocopherol or vitamin E was significantly higher (P<0.01) in japonica rice than in indica rice, while the total tocotrienol content showed no differences between them. The principal isomer of vitamin E was also different between the two subspecies, for example, γ-tocotrienol was the predominant compound in indica rice, on the contrary, in japonica rice, the most abundant isomer was α-tocopherol. The ratio of total tocotrienols to tocopherols was also significantly higher (P<0.01) in indica (1.61) than in japonica rice (0.95). Pearson’s correlation analysis demonstrated that α-tocopherol content was positively correlated with α-tocotrienol content in rice. The same relationship was also presented between the contents of γ-tocopherol and γ-tocotrienol, but there was a negative correlation between contents of α- and γ-isomers. Taking together, all the present results provide some useful information for research on vitamin E metabolism or nutritional improvement in rice.