Rapid screening of active components group with Topoisomerase I inhibitory activity in Sophora alopecuroides L. based on ultrafiltration coupled with UPLC-QTOF-MS

Abstract

Background: Topoisomerase I (Topo I) is a key target of many antitumor drugs in vivo. Alkaloids in Sophora alopecuroides L. can reportedly inhibit Topo I activity, but the pharmacodynamic material basis has not yet been determined. Objective: The objective of this study is to rapidly identify active components group which inhibit Topo I in S. alopecuroides L. Methods: Affinity ultrafiltration-ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry (UF-UPLC-QTOF-MS) screening system based on Topo I protein was established to screen and isolate a total alkaloid fraction in S. alopecuroides L. Topo I inhibitory activity and anti-tuomor proliferation activity of the screened components were evaluated, and their molecular mechanisms were studied. Results: Six compounds bound specifically to Topo I were obtained. Further screening showed that matrine, cytisine, and sophoridine presented higher inhibitory activity on Topo I and were able to inhibit the proliferation of breast cancer MDA-MB-468 cells with IC50 values of 9.40 ± 1.12 mM, 17.4 ± 2.20 mM and 10.4 ± 1.37 mM, respectively. To the best of our knowledge, their dual molecular mechanisms against Topo I have been discussed here for the first time: (1) stabilization of Topo I-DNA complex and (2) inhibition or blocking of Topo I binding to DNA. Conclusion: Matrine, cytisine, and sophoridine from S. alopecuroides L. were defined as the active components group with Topo I inhibitory activity and their pharmacological mechanism was confirmed, which provided an important base for further research and development of antitumor components fromS. alopecuroides L.