不同类型柑橘果实汁胞中类黄酮的液相色谱质谱联用分析

Flavonoid composition of Citrus juice sacs determined by high-performance liquid chromatography coupled with tandem electrospray ionization mass spectrometry

以我国柑橘主产区商业成熟期27份甜橙(Citrus sinensis)、柚(Citrus grandis)和葡萄柚(Citrus paradisi)果实汁胞为试验材料,利用液相色谱-串联质谱(HPLC-MS/MS)联用技术,研究不同柑橘资源类黄酮(flavonoids)组成和含量的差异。结果表明:类黄酮的组成在不同类型柑橘中存在较大差异。本研究共检测到41种类黄酮,其中,黄烷酮(flavanones)在甜橙和葡萄柚中含量最丰富,且以甜橙中含量最高[平均为353.06μg·g^(-1)(DW)],葡萄柚中次之,柚中含量最低[平均仅为52.16μg·g^(-1)(DW)];检测到黄酮(flavones)23种,包括鲜见报道的麦黄酮(tricin)及其糖苷;甜橙和葡萄柚中多甲氧基黄酮(PMFs)含量平均高出柚20倍。不同类型柑橘中,黄烷酮、黄酮醇(flavonols)和PMFs含量差异趋势与总类黄酮基本一致,因此总类黄酮含量差异较大,且以甜橙中含量最高,平均为584.41μg·g^(-1)(DW);其次是葡萄柚;柚中最低,平均含量仅为184.91μg·g^(-1)(DW)。依据汁胞中41种类黄酮的含量进行主成分分析,可将所检测柑橘资源分为3类,与柑橘分类结果基本吻合,说明类黄酮组分及含量受基因型控制,进一步验证了利用类黄酮进行柑橘资源化学分类的可行性。

High-performance liquid chromatography coupled with tandem electrospray ionization mass spectrometry was applied to determine flavonoids in juice sacs of 27 Citrus germplasms widely cultivated in China,including 10 sweet orange cultivars（Citrus sinensis）,12 pummelos（Citrus grandis） and 5 grapefruits（Citrus paradisi）.Forty-one flavonoids,including 8 flavanones,23 flavones,7 flavonols and 3 polymethoxyflavones（PMFs）,were identified and quantified.The results show that there were significant differences in total flavonoids levels among different species.Total flavonoids of sweet orange [averagely 584.41 μg·g^（-1）（DW）] was the highest among all species,followed by grapefruit [averagely 333.64 μg·g^（-1）（DW）],while pummelo accumulated the lowest level of total flavonoids.Sweet orange has the highest level of flavanones [353.06 μg·g^（-1）（DW）],followed by grapefruit [137.85 μg·g^（-1）（DW）] and pummelo [52.16 μg·g^（-1）（DW）].Flavones were detected at relatively low levels,including tricin and O-glycoside which had not been reported in Citrus fruits yet.Levels of PMFs in sweet oranges and grapefruits were 20-fold higher than those in pummelos.The accumulation of flavanones,flavonols and PMFs showed similar pattern to total flavonoid contents in different types of Citrus,which resulted in big difference in levels of total flavonoid content.The highest accumulation of an average of 584.41 μg·g^（-1）（DW） was detected in sweet oranges,followed by grapefruits,while the lowest level of an average of 184.91 μg·g^（-1）（DW） was observed in pummelos.Principal component analysis（PCA） shows that the grouping by metabotype as represented by flavonoids content was in line with the grouping by genotype of Citrus species,revealing that the content of flavonoids was closely related to the genotype of Citrus.