Rapid Identification of Common Secondary Metabolites of Medicinal Herbs Using High-Performance Liquid Chromatography with Evaporative Light Scattering Detector in Extracts

The discovery and identification of novel natural products of medicinal importance in the herbal medicine industry becomes a challenge. The complexity of this process can be reduced by dereplication strategies. The current study includes a method based on high-performance liquid chromatography (HPLC), using the evaporative light scattering detector (ELSD) to identify the 12 most common secondary metabolites in plant extracts. Twelve compounds including rutin, taxifolin, quercetin, apigenin, kaempferol, betulinic acid, oleanolic acid, betulin, lupeol, stigmasterol, and β-sitosterol were analyzed simultaneously. The polarity of the compounds varied greatly from highly polar (flavonoids) to non-polar (triterpenes and sterols). This method was also tested for HPLC-DAD and HPLC-ESI-MS/MS analysis. Oleanolic acid and ursolic acid could not be separated in HPLC-ELSD analysis but were differentiated using LC-ESI-MS/MS analysis due to different fragment ions. The regression values (R2 > 0.996) showed good linearity in the range of 50–1000 µg/mL for all compounds. The range of LOD and LOQ values were 7.76–38.30 µg/mL and 23.52–116.06 µg/mL, respectively. %RSD and % trueness values of inter and intraday studies were mostly <10%. This method was applied on 10 species of medicinal plants. The dereplication strategy has the potential to facilitate and shorten the identification process of common secondary metabolites in complex plant extracts.

New Determination Method of Two Bioactive Saponins in Lysimachia capillipes Hemsl. by Quantitative Analysis of Multi-Components by Single-Marker

Capilliposide B (CPS-B) and Capilliposide C (CPS-C), as the key components in Lysimachia capillipes Hemsl., increasingly aroused the interest and research concern of many researchers due to the good bioactivities. Nowadays, the reference standards of CPS-B and CPS-C yield were very limited. Due to the deficit of reference standards, the determination could be difficult to carry out, and the quality control and evaluation would be restrained afterwards. To solve this urgent problem, a quantitative analysis of multi-components by single-marker (QAMS) method was proposed and established based on high-performance liquid-chromatography tandem evaporative light-scattering detector. In this QAMS method, the content of the two bioactive components could be calculated by buddlejasaponin IV, which is applied as an external standard and readily obtained. And the methodological experiments were evaluated and indicated accuracy, stability and feasibility of this QAMS method. Therefore, in this study, this built method would properly meet the requirement of determination of CPS-B, CPS-C and quality control of the L. capillipes Hemsl. plant.

Determination of Polyvinyl Acetate in Chewing Gum Using High-Performance Liquid Chromatography–Evaporative Light Scattering Detector and Pyrolyzer–Gas Chromatography–Mass Spectrometry

Polyvinyl acetate (PVAc) is used in various adhesive, paint, and transparent tape applications. It is also used as a food additive in food manufacturing to make chewing gum and fruit and vegetable glazes; however, guidelines on the amount of food additives that is used have not yet been established. In this study, a method was developed for analysis of polyvinyl acetate (PVAc) using high-performance liquid chromatography with an evaporative light scattering detector (HPLC–ELSD) and pyrolyzer–gas chromatography–mass spectrometry (Py–GC–MS). The analytical methods were applied to commercially available chewing gum. In the HPLC–ELSD analysis, the linearity was acceptable (R2 > 0.999), and the limits of detection and quantification were 22.2 and 67.3 µg/mL, respectively. The accuracies of PVAc were 87–115% at spike levels of 200–1000 µg/mL for the intra- and inter-day tests. The contents of PVAc in the chewing gum samples were n.d. (not detected)—13.8 g/kg. The presence of PVAc in chewing gum was verified with Py–GC–MS analysis, finding the typical pyrolysates of PVAc, such as acetic acid, benzene, toluene, styrene, indane, naphthalene, and acenaphthene. The developed analytical methods can be applied for successful identification of PVAc in chewing gum.

Evaluation of the Effects of Paclobutrazol and Cultivation Years on Saponins in Ophiopogon japonicus Using UPLC-ELSD

Nowadays, there is a growing concern about the quality of herbs used in traditional Chinese medicine. In this study, we evaluated the impacts of paclobutrazol and cultivation period on steroid saponins in Ophiopogon japonicus. A rapid method to simultaneously determine three principle steroid saponins (ophiopogonins B, D, and D′) using ultraperformance liquid chromatography combined with an evaporative light-scattering detector was developed. The contents of three saponins in paclobutrazol-treated and nontreated Sichuan O. japonicus and those in the 2-year and 3-year Zhejiang O. japonicus were analyzed. The results showed that the saponin contents were sharply reduced in paclobutrazol-treated O. japonicus as compared to the control, whereas the concentrations of the three targeted saponins in Zhejiang O. japonicus varied with the increase in cultivation years, reflecting varied effects on saponins. Our study provided chemical evidences for further quality control and agricultural practices of O. japonicus.