采用柱前衍生高效液相色谱-荧光检测法(HPLC-FLD)对来源于青海省甘德、达日、班玛、玛沁、同德和祁连6 个县15 个样地的唐古特大黄(Rheum tanguticum Maxim. ex Balf.)地下部分的脂肪酸成分进行了检测和分析,并在此基础上对脂肪酸成分进行了主成分分析。结果显示:从各产地唐古特大黄中均检测出15 种脂肪酸成分,包括12种饱和脂肪酸(即癸酸、十一酸、十二酸、十四酸、十五酸、棕榈酸、硬脂酸、二十酸、二十一酸、二十二酸、二十三酸和二十四酸)和3 种不饱和脂肪酸(即亚麻酸、亚油酸和油酸),其中,饱和脂肪酸中棕榈酸含量最高、不饱和脂肪酸中亚油酸含量最高。不同产地唐古特大黄的总脂肪酸含量为2. 38 ~54. 22 μg·g-1 ,其中不饱和脂肪酸占17. 31% ~48. 97%;各脂肪酸成分存在明显的地域性差异,产自玛沁县MQ1 样地的样品中总脂肪酸含量最高,产自祁连县QL2 样地的样品中不饱和脂肪酸所占比例最高。主成分分析结果显示:前3 个主成分的累计贡献率较高,达到87. 387%,其中特征向量较大的脂肪酸均为偶数长碳链脂肪酸(碳原子数大于12),表明偶数长碳链脂肪酸为唐古特大黄的特征性脂肪酸成分。综合分析结果表明:青海省不同地域复杂多变的地理和气候条件可能是造成唐古特大黄脂肪酸组成及含量差异的主要因素。

   Fatty acid composition in under-ground part of Rheum tanguticum Maxim. ex Balf. From fifteen plots of six counties of Gande, Dari, Banma, Maqin, Tongde and Qilian in Qinghai Province were determined and analyzed by the method of high performance liquid hromatography-fluorescence detection (HPLC-FLD) with pre-column derivatization, and on this basis, principal component analysis on fatty acid composition was carried out. The results show that all of fifteen fatty acids are detected in R. tanguticum from different locations, which includes twelve saturated fatty acids (viz. decanoic acid, undecanoic acid, dodecanoic acid, myristic acid, entadecanoic acid, palmitic acid, octadecanoic acid, arachidic acid, heneicosylic acid, docosanoic acid, tricosanoic acid and tetracosanoic acid) and three unsaturated fatty acids (viz. linolenic acid, linoleic acid and oleic acid). In which, palmitic acid content is the highest in saturated fatty acids, and linoleic acid content is the highest in unsaturated fatty acids. The content of total fatty acids in R. tanguticum from different locations is 2. 38-54. 22 μg·g^-1, in which, unsaturated fatty acids account for 17. 31% -48. 97%. There is an obvious regional difference in fatty acid compositions. The content of total fatty acids in sample from MQ1 plot of Maqin County is the highest, and the proportion of unsaturated fatty acids in sample from QL2 plot of Qilian County is the highest. The result of principal component analysis shows that accumulative contribution rate of the first three principal components is high with a value of 87. 387%, in which, fatty acids with high eigenvector are all even number and long carbon chain fatty acids (with carbon atom number being higher than 12), meaning that even number and long carbon chain fatty acids are characteristic fatty acid composition of R. tanguticum. Comprehensive analysis result indicates that complex and changeable climate and geographical conditions of different regions in Qinghai Province are probably the main factors to cause differences in composition and content of fatty acids in R. tanguticum.