Silver complexation and tandem mass spectrometry for differentiation of triterpenoid saponins from the roots of Pulsatilla chinensis (Bunge) Regel.
For detection and differentiation of two types of triterpenoid saponins based on different aglycons of the lupane and oleanane skeleton from the roots of Pulsatilla chinensis (Bunge) Regel, the silver ion was introduced and electrospray ionization multi-stage tandem mass spectrometry was applied to analyze eleven triterpenoid saponin silver complexes. The quasi-molecular ion [M+Ag](+) was observed in the full-scan MS spectra of all the silver complexes. The MS(2) data of the [M+Ag](+) ion provided structural information on the sugar sequence of the oligosaccharide chains and the aglycon of the saponins. There are two patterns in the cleavage pathway of oleanane-type saponins. One is elimination of the sugar chain and subsequent loss of the carboxylic group which is the same as the cleavage of lupine-type saponins. The other is loss of the distinguishing ions at m/z 72 and 28 (C(2)H(4)) followed by loss of the carboxylic group. Diagnostic fragmentation pathways of the silver complexes of the saponins allow successful identification of the two types of saponins from the roots of Pulsatilla chinensis (Bunge) Regel.
An active molecule from Pulsatilla chinensis, Pulsatilla saponin A, induces apoptosis and inhibits tumor growth of human colon cancer cells without or with 5-FU.
Colon cancer is one of the common types of digestive malignancy. The efficacy of the first-line chemotherapy drug for colon cancer, fluorouracil (5-FU), remains limited in clinical settings due to poor efficacy and significant side effects. In the present study, the anticancer activity of an active compound from Pulsatilla chinensis extracts, Pulsatilla saponin A (PsA), was isolated and examined in vitro and in vivo. It was demonstrated that PsA significantly inhibited the growth of human colon cancer HT-29 cells. This inhibitory activity was also observed when the compound was tested in a colon cancer xenograft mouse model. Additionally, the synergic antitumor effects of PsA and 5-FU on colon cancer cells were observed. Using annexin V and terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling assays, it was demonstrated that levels of apoptosis induction in HT-29 cells treated with PsA or 5-FU were significantly increased compared with the untreated control cells (P<0.05). Western blot analyses were then performed, and the results revealed an increase in tumor protein 53 and cleaved caspase 9, and a decrease in B-cell lymphoma 2 protein expressions in PsA and PsA + 5-FU treated colon cancer cells compared with the vehicle-treated (PBS) cells. In summary, PsA exhibited anticancer activity in human colon cancer cells in vitro and in vivo, in isolation and synergistically with 5-FU, through apoptosis induction.
Study on Electrical Explosion Mechanism and Ignition Characteristics of Copper and Aluminum Powder Under Ignition Solid Propellant
In order to study the characteristic of the electrical explosion of copper and aluminum powders, a multilayer generator was designed, an experimental system was set up, and the parameters of metal powder electrical explosion were measured and analyzed. The results show that the duration of the electrical explosion process increases significantly due to the addition of metal powder. The duration of aluminum powder electrical explosion jet flow is ~86.36 ms due to its self-sustained combustion, which releases a large amount of energy, and a small fraction of aluminum powder particles is not burned. The duration of copper powder electrical explosion jet flow is ~15.84 ms, and most of the copper powder particles are in the solid state. The current pause process is absent; instead, the first discharge process is connected to the second discharge process. The effect of copper powder on the first discharge process is greater than that of aluminum powder. Furthermore, the ignition ability of copper powder electrical explosion to solid propellant is stronger than that of aluminum powder in a closed bomb experiment. These results are indubitably meaningful for the application of metal powder electrical explosion and ignition of solid propellant in an electrothermal chemical gun.