Synthesis And Antitumor Activity In Vitro Of Dibenzoxanthenes And 18β-Glycyrrhetinic Acid Derivatives

In recent years,the incidence of cervical cancer in China has continued to increase and is trending toward younger age,which is a long-term threat to women’s physical and mental health.Chemotherapy is the main method of clinical treatment of cervical cancer,but the chemotherapy of cervical cancer has some limitations due to the toxic and side effects of current clinical chemotherapy drugs and multidrug resistance during chemotherapy.Therefore,the search for new drugs that can inhibit the development of cervical cancer has become the focus of research in the field of medicine today.Xanthene was originally widely used as a chemical fluorescent dye,but later it was found to have antiviral,anti-inflammatory,antibacterial,antioxidant and other pharmacological activities.Many studies have shown that this class of compounds has great potential in antitumor development.18β-glycyrrhetinic acid is a pentacyclic triterpenoid obtained from the rhizome of licorice,which has many pharmacological activities such as antibacterial,anti-inflammatory,hepatoprotective,antioxidant,etc.Studies in the domestic and overseas have shown that it has the potential to be used as a parent compound for structural modification to improve the anti-tumor effects.Therefore,in this paper,we designed and synthesized a series of dibenzoxanthenes and18β-glycyrrhetinic acid derivatives,respectively,and explored their antitumor activities and mechanisms.The main contents include:（1）The binaphthols were obtained by coupling reaction using 6-cyano-2-naphthol and 6-bromo-2-naphthol as raw materials,and then four dibenzoxanthene compounds 4a-4d substituted by methoxy,ethoxy,propoxy and butoxy respectively at the 13c-position were synthesized by oxidizing with copper-amine complexes as catalysts,and their structures were characterized.Screening of their antitumor activity by MTT assay revealed that compounds 4a-4d were the most cytotoxic to He La cells in vitro.In addition,they were found to exert anti-tumor effects through cell cycle arrest,inhibition of tumor cells migration and invasion,activation of ROS-mediated mitochondrial apoptosis pathway and inhibition of PI3K/Akt autophagy pathway by flow cytometry,cell cycle distribution,mitochondrial membrane potential,intracellular ROS level,Ca²⁺content,as well as comet electrophoresis,cell scratch assay,transwell invasion,MDC staining,western blot and other experimental studies.（2）Related studies have shown that derivatives of 18β-glycyrrhetinic acid linked by ester bonds at the C-30 position exhibit great anticancer effects.Therefore,in this paper,six glycyrrhetinic acid derivatives were synthesized by introducing phenyl groups with different substituents at the C-30 position of 18β-glycyrrhetinic acid through esterification reaction,and the structures were confirmed by HRMS,¹H-NMR,and ¹³C-NMR.In vitro cytotoxicity indicated that compound 7a showed good anti-proliferative activity against He La cells,and compound 7a was found to induce apoptosis in He La cells by DAPI staining and Annexin-V/PI double-staining method.Further studies revealed that the compound increased intracellular ROS and Ca²⁺content,induced a decrease in mitochondrial membrane potential,inhibited cell proliferation by blocking the cell cycle in S phase,and inhibited cell migration by down-regulating FAK expression.In addition,the mechanism of apoptosis induction by compound 7a was found to be related to the regulation of the expression of mitochondria-associated proteins Bcl-2 and Bax and activation of the Caspase family cascade reaction.The above results showed that the antitumor activity of the parent glycyrrhetinic acid was improved by the introduction of phenyl group with different substituents in the C-30 position,and compound 7a was found to induce apoptosis in He La cells through the ROS-mediated mitochondrial pathway.The dibenzoxanthenes and 18β-glycyrrhetinic acid derivative 7a synthesized in this paper showed good in vitro antitumor activity against He La cells,and both of these compounds induced apoptosis in He La cells through the mitochondrial pathway,which is an important reference value for the development of dibenzoxanthenes and pentacyclic triterpenoids,and provides a theoretical basis for these two classes of compounds as potential anticancer molecules.