The ATP-binding cassette (ABC) transporter ABCG2 is a significant urate transporter with a high capacity, and it plays a crucial role in the development of hyperuricemia and gout. Therefore, it has the potential to be targeted for therapeutic interventions. Cortex Fraxini, a traditional Chinese medicine (TCM), has been found to possess anti-hyperuricemia properties. However, the specific constituents of Cortex Fraxini responsible for this effect are still unknown, particularly the compound that is responsible for reducing uric acid levels in vivo. In this study, we propose a target screening protocol utilizing bio-affinity ultrafiltration mass spectrometry (BA-UF-MS) to expediently ascertain ABCG2 ligands from the plasma of rats administered with Cortex Fraxini. Our screening protocol successfully identified fraxin as a potential ligand that interacts with ABCG2 when it functions as the target protein. Subsequent investigations substantiated fraxin as an activated ligand of ABCG2. These findings imply that fraxin exhibits promise as a drug candidate for the treatment of hyperuricemia. Furthermore, the utilization of BA-UF-MS demonstrates its efficacy as a valuable methodology for identifying hit compounds that exhibit binding affinity towards ABCG2 within TCMs.

The ATP-binding cassette (ABC) transporter ABCG2 is a significant urate transporter with a high capacity, and it plays a crucial role in the development of hyperuricemia and gout. Therefore, it has the potential to be targeted for therapeutic interventions. Cortex Fraxini, a traditional Chinese medicine (TCM), has been found to possess anti-hyperuricemia properties. However, the specific constituents of Cortex Fraxini responsible for this effect are still unknown, particularly the compound that is responsible for reducing uric acid levels in vivo. In this study, we propose a target screening protocol utilizing bio-affinity ultrafiltration mass spectrometry (BA-UF-MS) to expediently ascertain ABCG2 ligands from the plasma of rats administered with Cortex Fraxini. Our screening protocol successfully identified fraxin as a potential ligand that interacts with ABCG2 when it functions as the targeted protein. Subsequent investigations substantiated fraxin as an activator of ABCG2. These findings imply that fraxin exhibits promise as a drug candidate for the treatment of hyperuricemia. Furthermore, the utilization of BA-UF-MS demonstrates its efficacy as a valuable methodology for identifying hit compounds that exhibit binding affinity towards ABCG2 within TCMs.

Knee osteoarthritis (KOA), also referred to as hypertrophic or degenerative arthritis, is a prevalent joint disorder. Current clinical management strategies include pharmacological therapy, physical intervention, surgical procedures, and adjunctive treatments. While these approaches can alleviate KOA symptoms to some extent, they often come with limitations, such as side effects, limited efficacy, or invasiveness. Osthole (OST), a natural coumarin derivative, has been widely studied for its medicinal properties, particularly in alleviating joint pain and improving articular function. In this study, CCK8 assay, transmission electron microscopy (TEM), H&E staining, and serum biochemical analysis were employed to demonstrate that OST exerts protective effects on chondrocytes both in vitro and in vivo, with no significant toxicity observed. Subsequent investigations using TEM, acridine orange staining, flow cytometry, and western blotting revealed that OST promotes autophagy and suppresses apoptosis in chondrocytes. Further mechanistic studies through qRT-PCR and luciferase reporter assays indicated that OST downregulates miR-34a, thereby upregulating Bcl-2 expression and inhibiting apoptosis via the miR-34a/Bcl-2 pathway. In summary, these findings indicate that OST protects chondrocytes in both cellular and animal models, attenuating LPS-induced stress and reducing inflammation and apoptosis in KOA rats. The downregulation of miR-34a and subsequent increase in Bcl-2 expression contribute to its anti-apoptotic effect. These results provide a theoretical foundation for the development of OST-based patented drugs and their potential clinical translation in KOA therapy.