Quality Marker Discovery and Quality Evaluation of Eucommia ulmoides Pollen Using UPLC-QTOF-MS Combined with a DPPH-HPLC Antioxidant Activity Screening Method.

Pollen, as an important component of Eucommia ulmoides (EUP), is rich in nutrients and is receiving increasing attention. At present, there are no reports on research related to the chemical composition and quality standards of EUP, and there are significant quality differences and counterfeit phenomena in the market. This study used a UPLC-QTOF-MS system to identify 49 chemical components in EUP for the first time. In the second step, 2,2-diphenyl-1-picrylhydrazyl (DPPH)-HPLC antioxidant activity screening technology was used to identify the main active components of EUP, quercetin-3-O-sophoroside (QSH), quercetin-3-O-sambubioside (QSB), and quercetin 3-O-neohesperidoside (QNH), and their purification, preparation, and structure identification were carried out. Third, molecular docking was used to predict the activity of these components. Fourth, the intracellular ROS generation model of RAW264.7 induced by H2O2 was used to verify and evaluate the activity of candidate active ingredients to determine their feasibility as Q-markers. Finally, a quality control method for EUP was constructed using the three selected components as Q-markers. The identification of chemical components and the discovery, prediction, and confirmation of characteristic Q-markers in EUP provide important references for better research on EUP and the effective evaluation and control of its quality. This approach provides a new model for the quality control of novel foods or dietary supplements.

[Advantage analysis of flow-through cell method in quality evaluation of Chinese patent medicine: a case study of Danshen Tablets].

To explore the quality consistency evaluation method for multi-component traditional Chinese medicine and establish a dissolution evaluation method suitable for the characteristics of multi-component Chinese patent medicine, this study discussed the characteristics and advantages of the flow-through cell method in the dissolution evaluation of Chinese patent medicine by comparing the impact of the small cup method and the flow-through cell method on the dissolution behavior of water-soluble and lipid-soluble major active components of Danshen Tablets. Dissolution tests were performed using the small cup method as described in the 2020 edition of the Chinese Pharmacopoeia and the newly introduced flow-through cell method(closed-loop method) with water solution containing 0.5% SDS as dissolution medium. Cumulative dissolution curves of the water-soluble component salvianolic acid B and the lipid-soluble component tanshinone Ⅱ_A in Danshen Tablets were plotted, and fitting and similarity analysis of the dissolution models was conducted to identify the characteristics and advantages of the flow-through cell method. For the small cup method, 150 mL of water containing 0.5% SDS was used as the dissolution medium, with a rotation speed of 75 r·min~(-1) and a temperature of(37±0.5) ℃, and 3 mL of samples were taken at 15, 30 min, 1, 2, and 4 h, with fresh dissolution medium added at the same temperature and volume. For the flow-through cell method, a closed-loop system was used. Danshen Tablets were placed in the flow-through cell with approximately 6.7 g of glass beads, and 150 mL of water containing 0.5% SDS was used as the dissolution medium. The flow rate was set at 20 mL·min~(-1), and the temperature and sampling were the same as the small cup method. The results showed that compared with the small cup method, the flow-through cell method had stronger discriminative power and higher sensitivity in distinguishing the dissolution behavior of the two components, and could better reflect the differences in formulation quality, especially for water-insoluble lipid-soluble components. Given that there were no essential differences in the in vitro release kinetics between the two methods, the flow-through cell method could not only replace the traditional small cup method but also better guide the formulation development and identify quality issues of formulations.

[Degradation kinetics of ß-nicotinamide mononucleotide based on reliable HPLC quantitative method].

To explore the stability characteristics of ß-nicotinamide mononucleotide(NMN) and provide data support for NMN production, preparation, and related product development, this study established a simple HPLC content determination method for NMN in simple substrate and investigated the degradation behavior, degradation products, and degradation kinetics of NMN under various chemical, physical, and biological conditions. The HPLC method employed a Welch Xtimate AQ-C_(18) column(4.6 mm×250 mm, 5 µm), a detection wavelength of 266 nm, a column temperature of 30 ℃, a flow rate of 1.0 mL·min~(-1), an injection volume of 5 µL, and a mobile phase consisting of methanol(A) and a 10 mmol·L~(-1) ammonium formate aqueous solution(B) with a gradient elution(0-6.7 min, 0-4% A; 6.7-13 min, 4%-18% A; 13-14.2 min, 18% A; 14.2-15 min, 18%-0 A; 15-22 min, 0 A). This method provided good separation between NMN and potential impurities and degradation products, and had a wide linear range, short analysis time, good durability, high accuracy, an average sample recovery rate of 98.71%, and an RSD of 1.2%. The instrument precision had an RSD of 0.26%, and the linearity within the examined range was excellent(R~2≥0.999 9). This method can be applied for NMN content determination in simple substrate. The degradation process of NMN in aqueous solution followed apparent first-order kinetics, with the degradation rate primarily influenced by high temperature and pH. NMN was more stable in low-temperature, neutral, or weakly acidic/alkaline environments. Strong acids or strong alkalis could accelerate its degradation, and its degradation rate was less affected by pepsin and trypsin. In an aqueous solution at room temperature, it followed the kinetic equation lg C_t=0.005 7t + 4.817 2, with t_(0.9) and t_(1/2) values of 95.58, 860.26 h, respectively. The results suggest that pH and temperature are the main factors affecting the stability of NMN in aqueous solution, and low temperature, moisture protection, and a weakly acidic environment are more conducive to the storage and application of NMN and its products.