Integrated strategy for the screening of cyclooxygenase‐2 inhibitors from triterpenoid saponins in Clematis tangutica.

Introduction: Screening of novel cyclooxygenase‐2 (COX‐2) inhibitors from complex natural products is not an easy task. Objectives: To establish an efficient and feasible strategy for screening COX‐2 inhibitors from triterpenoid saponins (TPSs) in Clematis tangutica. Methods: Taking TPSs in C. tangutica as example, an optimized macroporous resin (MR) method was established for the enrichment of TPSs. High‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry (HPLC‐QTOFMS) was performed to establish the phytochemical profiling of TPSs. Molecular docking was performed to predict the ligand–target interactions and discover the active substances. Chemometric techniques were performed to visualize the structure–effect relationships. High‐speed countercurrent chromatography and preparative HPLC were performed to prepare the targets. In vitro activity experiment of COX‐2 was performed to verify the virtual screening results. Results: TPSs in C. tangutica were well enriched with the recovery rate of (80.22 ± 2.37)%. Thirty‐four kinds of TPSs of oleanane type were deduced by HPLC‐QTOFMS. Five TPSs of clematangoside C, clematangoside D, clematangoticoside J, hederoside H1, and hederasaponin B showed stronger binding abilities with COX‐2. The structure with more sugar groups at C‐28 may be more conducive to the combination with COX‐2. Targets were prepared with purities all above 98%. The IC50 values of target TPSs were 6.03 ± 0.24, 12.44 ± 0.15, 9.36 ± 0.19, 4.78 ± 0.13, and 2.59 ± 0.11 μmol/L, respectively. Conclusion: The integrated strategy using MR, HPLC‐QTOFMS, molecular docking, chemometrics, target preparation, and in vitro verification was feasible for rapidly screening COX‐2 inhibitors from TPSs in C. tangutica. An integrated strategy was established for screening COX‐2 inhibitors from triterpenoid saponins of Clematis tangutica based on macroporous resin, HPLC‐QTOFMS, molecular docking, chemometrics, targets preparation and in vitro verification. As a result, five COX‐2 inhibitors including clematangoside C, clematangoside D, clematangoticoside J, hederoside H1 and hederasaponin B were screened out and isolated. The strategy could be used for the accurate screening of other active components from natural products with similar structures. [ABSTRACT FROM AUTHOR]