菹草红色类胡萝卜素结构的初步鉴定

 研究了从菹草中分离纯化的3个红色素组分r1、r2和r3的紫外可见吸收光谱、红外光谱、化学测试反应及质谱特性。结果表明,r1、r2和r3在丙酮、甲醇、乙醇、氯仿、二硫化碳中的可见吸收光谱均为平滑的、较对称的单峰(对应的峰波长为λmax),与角黄素、虾青素的相似,在正己烷中则呈现不对称"三指状"谱峰趋势,而β-胡萝卜素在正己烷等几种溶剂中可见吸收光谱则呈典型的"三指状"谱峰;与正己烷相比,随溶剂极性增强,λmax增大,溶剂对r1、r2和r3吸收光谱的形状、精细结构和λmax影响显著, r1、r2和r3的λmax平均值均比虾青素、角黄素和β-胡萝卜素的λmax平均值大。 不同溶剂中,r1、r2和r3的红外光谱显示出含羰基多烯化合物的特征峰（1 660～1 750 cm-1区域存在差异）。r1、r2和r3的化学测试反应也证明其分子中含羰基,而不含5,6 或 5,8-环氧基团。结合低分辨和高分辨电子轰击质谱 （EIMS）的测定分析,证明菹草红色素r1、r2和r3是分子式均为C40H50O2、分子量均为562且都含有羰基的类胡萝卜素,其结构不同于虾青素、角黄素和β-胡萝卜素,与紫杉红素(rhodoxanthin)的基本结构相同,是紫杉红素的同分异构体。

Preliminary Identification of Red Carotenoids from Potamogeton crispus L.

Three red pigments r1, r2 and r3 were extracted and separated from Potamogeton crispus L, the UV-Vis spectra, FT-IR spectra, test by chemical reaction and Mass spectra were studied. The visible spectra of r1, r2 and r3 in acetone, methanol, ethanol, chloroform and carbon disulphide had only a single, rounded, almost symmetrical absorption peak, the shape of visible spectra was similar to that of canthaxanthin and astaxanthin. but the visible spectra of them in hexane had a asymmetrical absorption peak that were approximate to the "three-peaked spectra"; but the visible spectra of β-carotene(non-oxocarotenoids) was typical "three-peak spectra". As compared with the spectra in hexane, the λmax of r1, r2 and r3 increased along with the strengthening in solvents polarity, and the shape, fine structure and λmax of their spectra were greatly affected by the solvents. The average λmax of r1, r2 and r3 in the six solvents were larger than that of astaxanthin, canthaxanthin and β-carotene, respectively. The FT-IR spectra of r1, r2 and r3 showed the characteristic frequencies of polyene chain compounds containing carbonyl groups (there were differences in 1 660-1 750 cm-1 ). The test by chemical reaction showed that r1, r2 and r3 were carotenoids containing carbonyl groups ( not 5, 6 or 5, 8-Epoxides). It is an important evidence to prove that r1, r2 and r3 are carotenoids containing carbonyl groups and having molecular formula C40H50O2 , molecular weight 562 determined by low and high resolution EI-MS. They have no identical structure with canthaxanthin, astaxanthin and β-carotene. The results show that r1, r2 and r3 are the isomers of rhodoxanthin.