Structural Modification and Antitumor Research of Natural Products Pyripyropene A and Berberine

Author:Liu Yi

Supervisor:lv wei nan fa jun


Degree Year:2019





Metabolic dysfunction,including substance dysfunction and energy dysfunction,is one of the key hallmarks of cancer.The rapid proliferation,invasion and metastasis of tumor cells require large amount of energy,nutrients,biosynthetic precursors and macromolecular substances.In recent years,targeting the metabolic dysfunction has become a popular strategy in the field of anti-cancer therapy.Acyl-CoA:cholesterol Acyltransferase(ACAT)is the only intracellular enzyme that catalyzes the formation of cholesterol esters.It plays a vital role in maintaining cholesterol metabolism balance.So far,ACAT has been found to have two subtypes,ACAT1 and ACAT2.Among them,ACAT2 can not only regulate the balance of cholesterol metabolism in cells but also participate in the“escape”mechanism of hepatocellular carcinoma(HCC)cells.Pyripyropene A(PPPA),which isolated from the fermentation broth of Aspergillus fumigatus,was the first selective inhibitor of ACAT2to be discovered.The first part of the work focused on the structurally simplified PPPA analogues found in previous work of our group,and carried out structural modification and structure-activity relationship exploration at C-7,C-10 and C-13 sites.A series of compounds were designed and synthesized with improved activity and selectivity.In addition,to further optimize the SAR,we inserted oxygen atom at the C-9 position to enrich the diversity of the structures.Six compounds with higher ACAT2 inhibitory activity were selected for selectivity investigation.The result showed that all of the compounds had certain ACAT2 selectivity,among which the selectivity index(SI)of compounds A26 and A29 were 990 and 909 respectively,which were higher than PPPA(>200).The pharmacokinetic study and tissue distribution experiment of A26 showed that the stability of A26 was significantly improved compared with compound 21 in the previous work,and it could target tissues with high expression of ACAT2,which provided foundation for in vivo activity evaluation.Berberine(BBR)has a variety of pharmacological activities,including anti-infection and regulation of glucose metabolism and lipid metabolism.Recent studies have shown that BBR has a certain inhibitory activity on a variety of tumors.However,the druggability of BBR limits its further application.In the second part of the work,by introducing a long alkyl chain with multiple substituents,we designed and synthesized C-9 derivatives of BBR to improve cell permeability and anti-tumor activity.Among these compounds,the inhibitory activity of B10(IC50=0.9μM)on A549 cells was 60-fold better than BBR(IC50=54.5μM).The permeability test showed that the intracellular concentration of B10 was 3.6 times higher than that of BBR.Further studies showed that B10 could significantly affect mitochondrial function,including oxygen consumption rate(OCR),mitochondrial membrane potential(MMP)and mitochondrial morphology.Therefore,this work provides a new chance for tumor therapy by improving cell membrane permeability and affecting mitochondrial function to enhance the anti-tumor activity.