MXene-sensitized electrochemiluminescence sensor for thrombin activity detection and inhibitor screening

Thrombin, a crucial enzyme involved in blood coagulation and associated diseases, requires accurate detection of its activity and screening of inhibitors for clinical diagnosis and drug discovery. To address this, an electrochemiluminescence (ECL) method was developed to detect thrombin activity based on the sensitization of Ti₃C₂T_x MXene, which could sensitize the Ru(bpy)₃²⁺ ECL system greatly. The thrombin-cleavable substrate bio-S-G-R-P-V-L-G-C was used as recognizer to evaluate the activity of thrombin. Under the optimal conditions, the limit of detection for thrombin in serum was 83 pU/mL (S/N = 3) with a linear range from 0.1 nU/mL to 1 µU/mL. Moreover, the developed ECL biosensor was employed to screen for thrombin inhibitors from Artemisiae argyi Folium. Four potential thrombin inhibitors (isoquercitrin, nepetin, L-camphor, L-borneol) were screened out with inhibition rates beyond 50%, among which isoquercitrin had the best inhibition rate of 90.26%. Isoquercitrin and nepetin were found to be competitive inhibitors of thrombin, with [Formula: see text] values of 0.91 μM and 2.18 μM, respectively. Molecular docking results showed that these compounds could interact with the active sites of thrombin through hydrogen bonds including ASP189, SER195, GLY216, and GLY219. The electrochemical biosensor constructed provides a new idea for the detection of thrombin activity and screening of its inhibitors.

Study of the Variation of Phenolic Acid and Flavonoid Content from Fresh Artemisiae argyi Folium to Moxa Wool

Artemisiae argyi Folium (AAF) is a popular herbal medicine that is always employed in moxa sticks and by oral dosage in clinical use. Less attention has been paid to nonvolatile compounds as active compounds, such as phenolic acids and flavonoids. In this study, we focused on the variation rule of phenolic acids and flavonoids in the various transformations of Artemisiae argyi Folium. Using the established ultra-performance liquid chromatography (UPLC) method with an excellent methodology under “spider-web” mode, six phenolic acids and three flavonoids were simultaneously quantified in fresh and drying Artemisiae argyi Folium as well as in moxa wool and residue. Some interesting phenomena about the variation rule of phenolic acids and flavonoids were uncovered. First, a sharp increase was observed in the detected compounds’ content as the moisture gradually decreased, when fresh Artemisiae argyi Folium was exposed to sunlight and ambient or high temperature. Nevertheless, the increased phenolic acids were subjected to high temperature, leading to obvious degradation under oven-drying (60 °C and 80 °C). Second, a wide content distribution was revealed for the detected compounds in Artemisiae argyi Folium from different habitats, especially rutin, caffeic acid, chlorogenic acid, jaceosidin, eupatilin, and cryptochlorogenic acid. Third, accompanied by the elevated ratio of Artemisiae argyi Folium/moxa wool, the detected compounds conspicuously decreased in moxa wool and the correspondingly removed powder as residue. Importantly, a greater variation was found in moxa wool. Our findings contribute to the optimization of the drying process, the quality evaluation of the various transformations of Artemisiae argyi Folium, and the distinctive characterization of moxa wool produced at different ratios of Artemisiae argyi Folium/moxa wool.

Comparison of Artemisiae argyi Folium and Artemisiae lavandulaefoliae Folium by simultaneous determination of multi-components with single reference standard method and chemometric analysis

INTRODUCTION

Artemisiae argyi Folium and Artemisiae lavandulaefoliae Folium, two morphologically similar herbal medicines derived from Artemisia genus. Although the two Artemisia herbs have been used as medicines for a long time in China, the study of their phytochemical and bioactive composition is limited.

OBJECTIVE

To comprehensively compare and evaluate the composition of Artemisiae argyi Folium and Artemisiae lavandulaefoliae Folium, and find the chemical makers for quality evaluation of the two Artemisia herbal medicines.

METHODOLOGY

Eight compounds including six phenolic acids and two flavonoids were assayed by a single reference standard for simultaneous determination of multi-components method using 3-caffeoylquinic acid as the reference standard. The quantitative data were further analysed by chemometric approaches to compare and distinguish the two herbal medicines.

RESULTS

The credibility and feasibility of the single reference standard for simultaneous determination of the multi-components method were carefully validated. The validated method was applied to analyse 16 batches of Artemisiae argyi Folium and 10 batches of Artemisiae lavandulaefoliae Folium samples. The quantitative results showed that 3,5-di-O-caffeoylquinic acid was the most abundant constituent, and the contents of flavonoids were notably different between the two herbal medicines. The chemometric analysis results indicated the two flavonoids, jaceosidin and eupatilin could be used as chemical markers for quality evaluation of the two herbal medicines.

CONCLUSION

The single reference standard for simultaneous determination of the multi-components method coupled with chemometrics analysis could be a well-acceptable strategy to compare and evaluate the quality of Artemisiae argyi Folium and Artemisiae lavandulaefoliae Folium.