RESUMO
High cone voltage was used to improve the quantification sensitivity of large molecular weight compounds in high-performance liquid chromatography electrospray ionization mass spectrometry (HPLC/ESI-MS), with ginsenosides as example. Investigations on the effect of cone voltage showed that within a voltage range of 30-130 V, for all the ginsenosides tested, i.e., Rb(1), Rb(2), Rc, Rd, Re, R(f) and R(g1), an increase in the applied cone voltage can significantly increase the sensitivity of the method. The maximum sensitivity in the determination decreases with the decreasing molecular weight of the ginsenosides in the order of Rb(1) > Rb(2) > Rc > Re > Rd > R(g1) > R(f). At the high cone voltage of 130 V, both molecular weight and structural information was obtained from a single mass spectrum. It can also be used for isomer differentiation and determination of O-glycosidic linkages in ginsenosides. Linear relationships between the peak area response and concentration were observed in the range of 50-2 x 10(5) ng/mL, with the correlation coefficients >0.99. The limits of detection reached down to pg for ginsenosides. The method was successfully applied to the determination of ginsenosides in commercial ginseng samples.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Ginsenosídeos/química , Microquímica/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos , Peso Molecular , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Electrospray ionization (ESI) mass spectrometry was utilized to investigate noncovalent complexes between beta-cyclodextrin (beta-CD) and five novel polyamide acids containing N-methylpyrrole and N-methylimidazole. The 1:1 binding mode was specified by examining the binding stoichiometry from ESI mass spectra. It found that polyamide acids with beta-CD have binding affinities in the order: ImImImbetaCOOH > ImPyImbetaCOOH > ImPyPybetaCOOH > PyPyPybetaCOOH > NO(2)PyPyPybetaCOOH. The method gives, simultaneously, the binding constants between beta-CD and polyamide acids based on a novel linear equation.
Assuntos
Imidazóis/química , Nylons/química , Pirróis/química , beta-Ciclodextrinas/química , Algoritmos , Modelos Lineares , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Three hairpin polyamides were designed and synthesized by a haloform reaction and DCC/HOBt coupling reaction without amino protection and deprotection. Their anticancer activity were investigated with three kinds of cell lines--hepatic carcinoma, lung carcinoma and gastric carcinoma, and the values of IC50 were at range of 10(-7) to approximately 10(-8) M.
Assuntos
Antineoplásicos/síntese química , Imidazóis/síntese química , Nylons/síntese química , Pirróis/síntese química , Antineoplásicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Imidazóis/farmacologia , Nylons/farmacologia , Pirróis/farmacologia , Células Tumorais CultivadasRESUMO
The electrospray ionization tandem mass spectrometric (ESI-MS/MS) characteristics and fragmentation mechanisms of eight distamycin analogues containing N-methylpyrrole and N-methylimidazole were investigated. The members of two isomeric groups of distamycin analogues with the same elemental composition can be distinguished by MS/MS spectra of protonated molecules and of significant fragment ions.
