Experimental Evidence for Ion Accumulation Time Affecting Qualitative and Quantitative Analysis of Ophiopogons in Ophiopogon Extract by Hybrid Ion Trap Time-of-Flight Mass Spectrometry

Influence of ultrafiltration membrane on ophiopogonins and homoisoflavonoids in Ophiopogon japonicus as measured by ultra-fast liquid chromatography coupled with ion trap time-of-flight mass spectrometry

Ultrafiltration is one of the most fascinating technologies, which makes it possible to improve the quality of traditional medicines for application in the pharmaceutical industry. However, researchers have paid little attention to the effect of ultrafiltration membrane on traditional medicines chemical constituents. In this work, Ophiopogon japonicus (L.f) Ker-Gawl. was used as an example to illuminate the influence of ultrafiltration with different material and molecular weight cut-off (MWCO) membrane on natural chemical constituents as measured by ultra-fast liquid chromatography coupled with ion trap time-of-flight mass spectrometry (UFLC-IT-TOF/MS). Our results indicated that ultrafiltration membrane significantly impacted homoisoflavonoids, especially homoisoflavonoids that were almost completely retained on the polyethersulfone (PES) membrane. We also found that the larger number of aglycone hydroxy and sugar moiety in steroid saponins, the higher the transmittance. Furthermore, the passage rate (%) of ophiogenin type saponins was higher than that of others. The possible adsorptive mechanisms were hydrogen bonding, hydrophobic interactions, and benzene ring interaction by π-π stacking. In conclusion, it is crucial to choose appropriate ultrafiltration membrane based on the characteristics of produce products for application of ultrafiltration technique.

Simultaneous Qualitative and Quantitative Analysis of Multiple Chemical Constituents in YiQiFuMai Injection by Ultra-Fast Liquid Chromatography Coupled with Ion Trap Time-of-Flight Mass Spectrometry

YiQiFuMai injection (YQFM) is a modern lyophilized powder preparation derived from the traditional Chinese medicine Sheng-mai san (SMS) used for treating cardiovascular diseases, such as chronic heart failure. However, its chemical composition has not been fully elucidated, particularly for the preparation derived from Ophiopogon japonicus. This study aimed to establish a systematic and reliable method to quickly and simultaneously analyze the chemical constituents in YQFM by ultra-fast liquid chromatography coupled with ion trap time-of-flight mass spectrometry (UFLC-IT-TOF/MS). Sixty-five compounds in YQFM were tentatively identified by comparison with reference substances or literature data. Furthermore, twenty-one compounds, including three ophiopogonins, fifteen ginsenosides and three lignans were quantified by UFLC-IT-TOF/MS. Notably, this is the first determination of steroidal saponins from O. japonicus in YQFM. The relative standard deviations (RSDs) of intra- and inter-day precision, reproducibility and stability were <4.9% and all analytes showed good linearity (R² ≥ 0.9952) and acceptable recovery of 91.8%–104.2% (RSD ≤ 5.4%), indicating that the methods were reliable. These methods were successfully applied to quantitative analysis of ten batches of YQFM. The developed approach can provide useful and comprehensive information for quality control, further mechanistic studies in vivo and clinical application of YQFM.

Determination of Noncovalent Binding Using a Continuous Stirred Tank Reactor as a Flow Injection Device Coupled to Electrospray Ionization Mass Spectrometry

Described is a new method based on the concept of controlled band dispersion, achieved by hyphenating flow injection analysis with ESI-MS for noncovalent binding determinations. A continuous stirred tank reactor (CSTR) was used as a FIA device for exponential dilution of an equimolar host-guest solution over time. The data obtained was treated for the noncovalent binding determination using an equimolar binding model. Dissociation constants between vancomycin and Ac-Lys(Ac)-Ala-Ala-OH peptide stereoisomers were determined using both the positive and negative ionization modes. The results obtained for Ac-L-Lys(Ac)-D-Ala-D-Ala (a model for a Gram-positive bacterial cell wall) binding were in reasonable agreement with literature values made by other mass spectrometry binding determination techniques. Also, the developed method allowed the determination of dissociation constants for vancomycin with Ac-L-Lys(Ac)-D-Ala-L-Ala, Ac-L-Lys(Ac)-L-Ala-D-Ala, and Ac-L-Lys(Ac)-L-Ala-L-Ala. Although some differences in measured binding affinities were noted using different ionization modes, the results of each determination were generally consistent. Differences are likely attributable to the influence of a pseudo-physiological ammonium acetate buffer solution on the formation of positively- and negatively-charged ionic complexes.