ABSTRACT
The first rate-limiting enzyme of the serine synthesis pathway (SSP), phosphoglycerate dehydrogenase (PHGDH), is hyperactive in multiple tumors, which leads to the activation of SSP and promotes tumorigenesis. However, only a few inhibitors of PHGDH have been discovered to date, especially the covalent inhibitors of PHGDH. Here, we identified withangulatin A (WA), a natural small molecule, as a novel covalent inhibitor of PHGDH. Affinity-based protein profiling identified that WA could directly bind to PHGDH and inactivate the enzyme activity of PHGDH. Biolayer interferometry and LC-MS/MS analysis further demonstrated the selective covalent binding of WA to the cysteine 295 residue (Cys295) of PHGDH. With the covalent modification of Cys295, WA blocked the substrate-binding domain (SBD) of PHGDH and exerted an allosteric effect to induce PHGDH inactivation. Further studies revealed that with the inhibition of PHGDH mediated by WA, the glutathione synthesis was decreased and intracellular levels of reactive oxygen species (ROS) were elevated, leading to the inhibition of tumor proliferation. This study indicates WA as a novel PHGDH covalent inhibitor, which identifies Cys295 as a novel allosteric regulatory site of PHGDH and holds great potential in developing anti-tumor agents for targeting PHGDH.
ABSTRACT
OBJECTIVE： To separate and identify chemical components in ethyl acetate fraction and water fraction from Tripterygium wilfordii， and to provider basis for further pharmacological study. METHODS： The ethyl acetate fraction and water fraction from T. wilfordii were separated and purified by MCI GEL-CHP 20P column chromatography， C18 RP silica gel column chromatography， Sephadex LH-20 gel column chromatography and HPLC. The structures of compounds were analyzed and identified by 1H-NMR， 13C-NMR and physicochemical properties. RESULTS： Two compounds were isolated from ethyl acetate fraction of T. wilfordii， namely orthosphenic acid （compound 1）， dibutylphthalate （compound 2）. Eight glucosides were isolated from water extract of T. wilfordii， namely 2，6-dimethoxy-4-hydroxymethyl-phenyl-1-O-beta-D-glucopyranoside （compound 3）， 2，6-dimethoxy-4-hydroxyphenol-1-O-β-D-glucoside（compound 4）， 4-hydroxy-1-（2-hydroxyethyl）-phenyl-3-O-β-D-glucopyranoside （compound 5）， 3，4-dimethoxy-phenyl-1-O-β-D-glucopyranoside （compound 6），β-adenosine （compound 7）， ligustrin （compound 8）， epicatechin-8-C-β-D-galactoside （compound 9） and 2-hydroxynaringenin-7-O-β-glucoside （compound 10）. CONCLUSIONS： Chemical components of ethyl acetate fraction and water fraction are separated and identified from T. wilfordii.
ABSTRACT
Objective To understand the frequency distribution of causes to facilitate the diagnosis and treatment of chronic cough.Methods Patients were recruited according to the inclusion criteria:chronic cough more than 8 weeks;normal X-ray appearance;coughing symptoms as the main or only symptom.Disease history was referred and physical examination was conducted,according to the diagnosis criteria of chronic cough causeoriented processes.If laboratory examination results are missing for a patient,empirical treatment will be combined as a treatment for this patient.Finally,the curative effect and the cause of disease will be analyzed.Results Seventy-nine patients were followed up.Twenty-eight,12,22,10,and 7 patients respectively were suspected of having CVA,EB,UACS,AC and GERC,among whom,23,9,14,9 and 4 were confirmed for their diagnosis,and 84.1％,75.0％,63.6％,90.0％,and 57.1％ of them received effective targeted therapies,accounting for 29.1％,11.4％,24.1％,11.4％,and 6.3％ respectively of all patients.The overall response rate was 74.7％.Conclusion The diagnosis and treatment of chronic cough with combinational cause-oriented diagnostic process and empirical therapy produce high effective rate with low cost.In addition,it could help understand the local frequency distribution of causes of chronic cough.It may be worth wide clinical application.