Synthesis And Bioactivity Of Emodin/Rhein-Triazole Derivatives

Cancer is one of the diseases that endanger human health,and it has become the third leading cause of death in my country.Studies have found that chronic inflammation is closely related to the occurrence,development and efficacy of anticancer therapy.Persistent infection within the host induces chronic inflammation,repeated tissue damage and tissue regeneration lead to permanent genomic alterations.Therefore,the development of highly selective anticancer drugs and highly active antiinflammatory drugs to improve the efficacy of cancer treatment is still one of the current important scientific issues.Emodin and rhein are anthraquinone compounds widely present in Chinese herbal plants and have been shown to have anticancer and anti-inflammatory activities.However,its poor water solubility,low bioavailability,and liver and kidney toxicity hinder its clinical application.Studies have found that nitrogen-containing derivatives can enhance its activity.Anthraquinones can intercalate into DNA and bind noncovalently to DNA topoisomerase II to exert anticancer effects.Therefore,we used emodin and rhein as the parent structures and retained the anthraquinone backbone structure to insert into DNA and interact with DNA topoisomerase II as a strategy.Structural modifications were carried out on its 3-position hydroxyl and carboxyl groups,respectively.Triazoles were formed by click chemistry to link different kinds of polar substituents,including 1 alcohol,2 esters,4 acids,5 sugars,and 2 active substances,to improve their water solubility and obtain highly selective anticancer precursors and highly active anti-inflammatory compounds.A total of 29 compounds were synthesized in this experiment.All compounds were tested by 1H NMR,13C NMR,MS to confirm the structure.All compounds were tested for cytotoxic activity by MTT method,and 4 compounds were cytotoxic to breast cancer cells.LR-09 is active against breast cancer cells MDA-MB 453,MCF-7 and BT-20,and its IC50 values are 4.478±0.53μM,4.540±0.370μM and 4.033±2.271 μM,respectively,showing strong selectivity.The IC50 values of LR-02 against breast cancer cells MCF-7 and BT-20 were 12.575±0.870μM and 15.095± 1.110μM,respectively.The IC50 value of LE-04 against breast cancer cell BT-20 was 15.205±2.425μM.The IC50 value of LR-10 against breast cancer cell MCF7 was 16.085±0.559μM.The above four compounds were docked with DNA,and it was found that in addition to LE-04,compounds LR-02,LR-09 and LR-10 could be inserted into DNA molecules.In the docking with DNA topoisomerase Ila molecules,it was found that the binding energies of the four compounds with DNA topoisomerase Ila were all less than 5 kcal/mol.In human topoisomerase Ⅱ ELISA.it was found that LR-02 could reduce the content of human topoisomerase Ⅱ in breast cancer MCF-7.Its anticancer effect may be related to the expression of topoisomerase Ⅱ.In breast cancer cells MDA-MB-453 and MCF-7,LR-09 could not reduce the content of topoisomeraseⅡ.The anti-inflammatory activity of compounds without cytotoxic activity was screened,and it was found that emodin and rhein triazole derivatives had significant anti-inflammatory activities,and could significantly inhibit LPS-induced NO secretion in mouse mononuclear macrophage RAW264.7 cells(all p values were less than 0.001).Among them,the compound LR-08 had the best anti-inflammatory activity,and had a significant inhibitory effect on NO secretion at a concentration of 1μM.Second,compounds LR-10,LR-12,LR-15 and LE-06 were able to significantly inhibit NO secretion at a concentration of 2μM.Compound LE-06 was able to significantly inhibit NO secretion at a concentration of 2.5μM.Compounds LE-04,LE-05,LE-07,LE-16 and LE-11 were able to significantly inhibit NO secretion at a concentration of 5μM.