薄层色谱法检测甘薯呋喃萜类毒素

甘薯呋喃萜类毒素是甘薯受到损害后产生的强制性代谢产物，可用乙醚提取。乙醚提取物分别用５％Ｎａ２ＣＯ３和蒸馏水洗涤，无水硫酸钠干燥，蒸去乙醚。残渣（粗品）采用薄层色谱法进行检测，以纯品甘薯酮和甘薯酮醇作标样。结果表明：在２０℃条件下，在石油醚－醋酸乙酯（２１，Ｖ／Ｖ）和苯－甲醇（９１，Ｖ／Ｖ）两种溶剂系统中，对甘薯酮（Ｃ）、甘薯酮醇（Ａ）、化合物Ｂ和Ｄ的呋喃萜类毒素具有较好的分离效果，Ｒｆ值的重复性也较好。展开后的薄层板可以通过ＣＳ－９３０ＴＬＣ扫描仪在５２７ｎｍ下扫描定量。

Determination of Furanoterpenoid Toxins from Sweet Potato by Thin Layer Chromatography

Sweet potato root tissue, when infected with different pathogens, invaded by insects, or irritated by certain chemicals, turns black-brown and produces and accumulates a large amount of furanoterpenoids such as ipomeamarone, ipomeamaronol, ipomeanine and 4-ipomeanol, which are toxic to animals. The furanoterpenoids from sweet potato root tissues infected with Ceratocystis fimbriata were extracted with ether. The extract solution was washed with 5% Na2CO3 and followed with distilled water and dried with dehydrated sodium sulfate (Na2SO4). The resulting ether extract was evaporated and the residue (crude sample) was dissolved in a small volume of chloroform. The determination of furanoterpenoid toxins was made on the plates at 20 degrees C and 30 degrees C respectively. The chloroform-soluble fraction was spotted on a silica gel G thin-layer plate and developed using different solvent systems, n-hexane and ethylacetate (4:1, V/V) , benzene and methanol (9:1, V/V) and petroleum ether and ethylacetate (2:1, V/V), until the solvent front migrated 10 cm from the starting spots. After development, Ehrlich's reagent was sprayed on the plate to detect the compounds. In the experiment, pure ipomeamarone and ipomeamaronol were used as standards. Thin-layer chromatograms on silica gel plates showed the furanoterpenoids were resolved effectively. The repeatability of Rf value was good. The resolution was the best in the solvent systems of benzene-methanol and petroleum ether-ethylacetate at 20 degrees C. After spraying Ehrlich's reagent, ipomeamarone (C) appeared as a light pink spot which soon changed to a dark gray, ipomeamaronol (A) as a purple red spot, compound B and D as a purple red and a gray spot respectively. Compound A, B, C and D had Rf values of 0.05, 0.14, 0.55 and 0.64 (n-hexane-ethylacetate), of 0.15, 0.29, 0.61 and 0.71 (petroleum ether-ethylacetate), of 0.40, 0.55, 0.71 and 0.79 (benzene-methanol), respectively. The separated spots were scanned by CS-930 TLC scanner at 527 nm and quantitative determination by external standard calibration. Ipomeamarone was detected by thin-layer chromatography and the limits of detection were 0.005 microg for pure and 0.02 microg for crude sample.