Oxytropis falcata Bunge, known as “the King of Herbs” in Tibetan medicine, is used for treatment of hyperpyrexia, pain, wounds, inflammation and anthrax. However, it is difficult to isolate compound with high-purity from O. falcata because of its complexity. In this work, an efficient method was successfully established for the separation of 3-hydroxy-3-methylglutaryl (HMG) flavonoid glycosides from O. falcata by 2D preparative chromatography (2D-HPLC). An ODS C18 preparative column was used for the first-dimension preparation, and the XCharge C18 preparative column with different separation selectivity to the ODS C18 stationary phase was used for the second-dimension preparation. Four HMG flavonoid glycosides (oxytroflavosides A–D) and two flavonoid glycosides (oxytroflavosides F and G) were separated with purities over 98%. Their structures were elucidated by nuclear magnetic resonance spectroscopy. The 2D-HPLC method used in this study is effective for preparative separation of HMG flavonoid glycosides from O. falcata. Additionally, this method shows great potential for the separation of flavonoid glycosides from other plant extracts.

Sweet-waxy maize is a special type of maize with recessive mutations of waxy gene and a gene disturbed sugar-starch transition, and its starch is composed of nearly pure amylopectin. The starch physicochemical properties of four inbred lines and six hybrids of sweet-waxy maize are studied. The starch granules are irregular and large in hybrids and oval and small in inbred lines. The chain length, molecular weight, and crystallinity are significantly different among the samples. However, no distinct difference is observed between hybrids and inbred lines. The branching degree of hybrids (except THN2000) is significantly higher than that of inbred lines. The pasting, gelatinization, retrogradation temperatures, peak and breakdown viscosities, retrogradation enthalpy, and percentage are lower in inbred lines than in hybrids. By contrast, trough, final, and setback viscosities and gelatinization enthalpy are indistinctly different between the hybrids and inbred lines. Among the six hybrids, HTN2 is suitable to make glutinous food due to its high viscosity, whereas MTN2 may enable the production of food with minimal retrogradation. The high viscosity of JH1501 and the low retrogradation percentage of JSW15525 among the four inbred lines endow different advantages on quality breeding.