Design,Synthesis Of Novel Steroid Monomers And Dimers Based On A-ring Modification And Their Anticancer Activities

Cancer is still the second leading cause of death after cardiovascular disease worldwide,and the current traditional chemotherapy regimens are gradually limited by cancer resistance.Over the past three decades,many natural steroids and their derivatives have been shown to have a variety of biological activities,such as Abiraterone,Chenodeoxycholic acid,and Obeticholic acid,which have been successfully developed as commercial drugs.In particular,abiraterone acetate has always been one of the best-selling targeted drugs against prostate cancer.A total of 85 new compounds belonging to four series and three key intermediates were designed and synthesized in this work,and their structures were confirmed by NMR and HRMS spectra.Among of them,three lead compounds with potent antitumor activities were obtained by antitumor activity test in vitro,and one of which had good antitumor activity and low cytotoxicity,and its antitumor mechanism was further studied.The main findings were as follows:1. Twenty-one novel A-ring fused steroidal benzopyrazines were designed and synthesized,and their antiproliferative activities were evaluated by Cell Counting Kit-8（CCK-8）assay.Through the introduction of 4,4-dimethyl,the efficient preparation ofα-enol ketones（B4 and B8）could be easily achieved even at room temperature,thereby the A-ring benzobenzopyrazine steroids（B5a-f and B10a-o）were ensured to be efficiently synthesized.The compounds containing F（B10d）and Cl atom（B10f）had better inhibitory activities on human prostate cancer cell line PC-3（>52%）at a concentration of 20μM.The closer the substituents in benzene ring were to 4,4-dimethyl,the better the activities were,which were also verified by the molecular docking scores of 8 pairs of isomers.In addition,two aromatic rings of A-ring fused benzopyrazine interacted with Thr306 and Gly444（or Gly303）of the receptor protein（PDB:6CIZ）to formed two stable hydrogen bonds respectively,which proved that A-ring fused benzopyrazine was an effective modification strategy.2. Fifteen new A-Ring fused steroidal pyrazinamides were synthesized usingα-enol ketone intermediate（B8）as the starting substrate.The compound C5n containingβ-phenylethylamine structure not only had good anti-prostate cancer activity(IC₅₀,0.93μM),but also had lower toxic side effects（SI,28.71）.It was proved that C5n could induce PC-3cell apoptosis and arrest the cell cycle at the G2/M phase.Molecular docking results showed that C5n could interact with Arg239,Ala302 and Gly444 of receptor protein 6CIZ to form three stable hydrogen bonds.These results suggested that C5n was expected to be a lead compound for the development of new anti-prostate cancer drugs.3. In the synthesis of A ring fused steroid pyrazines,the A-norsteroid D2t was obtained unexpectedly by benzilic acid rearrangement.The activity test showed that it had a good inhibitory activity on PC-3 and Hep G2,with IC50 values of 3.72 and 14.49μM,respectively.Therefore,A-norsteroid（D1）was generated through theα-enol ketones under alkaline conditions,and thirty new A norsteroid derivatives D2a-z and D2aa-ad were designed and obtained.The results of molecular docking showed that the modification of D1 could significantly improve the binding ability of D1 to target protein 6CIZ.4. Polyhydroxy marine steroids have good biological activities such as antitumor,antibacterial,antiviral and so on.In this paper,nineteen new steroidal dimers were synthesized based on dehydroepiandrosterone（DHEA）.Firstly,DHEA was dimerized by diacyl chloride,then the△⁵ double bond were epoxidized by m-CPBA;Finally the5 α-hydroxy-6-carbonyl steroid dimers（E3a-g）was obtained by Jones oxidation,and 5 α,6β,5’β,6’α-tetrahydroxy steroid dimers（E4a-g）were achieved through ring opening reaction induced by perchloric acid.In summary,this work confirmed the potential of the A-ring fused and A norsteroid to be an antitumor drug.The epoxy and ring opening modification of dimers provides the possibility for the synthesis of polyhydroxysteroid dimers.The antiproliferative measurement,mechanism study and virtual screening of antitumor activity of the A-ring fused steroids provided active guidance for the design,development and utilization of these kinds of compounds.