Isolation and identification of hemostatic steroidal glycosides from Ypsilandra thibetica.

The phytoconstituents of the fraction with hemostatic activity of the 70% aqueous ethanol extract of Ypsilandra thibetica Franch. were investigated. As a result, fourteen previously unreported spirostanol saponins, ypsilandrosides Z1-Z14, and nine known analogues were isolated and characterized by MS, NMR, and chemical methods. Among them, ypsilandrosides Z1-Z4 (1-4) have a rare 12-O-ß-d-glucopyranosyl group, while ypsilandrosides Z5-Z8 (5-8) possess a rare double bond between C-4 and C-5, and a hydroxyl or carbonyl located at the C-6. All isolates were further tested for their hemostatic activity. The results suggested that five spirostanol tetraglycosides show favorable inducing platelet aggregation activities. Among them, ypsilandroside G (16) displayed significant inducing platelet aggregation activity with an EC50 value of 57.17 µM. Furthermore, the preliminary structure-activity relationship of these spirostanol glycosides' hemostatic activity was discussed.

Ypsilandrosides U-Y, five new steroidal saponins from Ypsilandra thibetica.

Phytochemical reinvestigation on the whole plants of Ypsilandra thibetica obtained four new spirostanol glycosides, named ypsilandrosides U-X (1-4), and one new cholestanol glycoside, named ypsilandroside Y (5). Their structures have been established by extensive spectroscopic data and chemical methods. Among them, compound 4 is a rare spirostanol glycoside which possesses a novel 5(6 → 7) abeo-steroidal aglycone, while compound 1 is a first spirostanol bisdesmoside attached to C-3 and C-12, respectively, isolated from the genus Ypsilandra. The induced platelet aggregation activity of the isolates was tested.

[Determination of cadmium in tobacco using thermospray-chemical vapor generation-AAS system].

A new and sensitive method for the determination of cadmium was developed using thermospray chemical vapor generation AAS system. The sample and KBH4 solutions were introduced into two separate thermospray tubes by peristaltic pumps and then thermosprayed into a reaction tube. The aerosol of the sample and KBH4 were mixed and reacted in the reaction tube, and after gas-liquid separation in a cyclonic spray chamber, the water vapor was removed by a desolvating unit, while the analyte was transferred into the quartz T-cell and determined by AAS. This design improved the stability and sensitivity by thermospray chemical vapor sample introducing technique. The effect of several experimental parameters of the proposed system was optimized. Under the optimized experimental conditions, the detection limits of 18 ng x L(-1) with RSD of 2.1% was obtained for cadmium determination. This method has been successfully applied to the determination of cadmium in tobacco with the recoveries of 94%-103%.