Study On The Design And Synthesis Strategy Of Rhein Derivatives Targeted At Rac1 Ptotein Of Tumor Cell

Objective:The paper chooses radiosensitization node protein Racl as the research subject, study on the interaction model between anthraquinone compounds and Rac1 protein by means of the technology of molecular docking, guiding synthesis of rhein derivatives according to the result of molecular docking, and verifying the target of rhein derivatives through the in vitro experiment, exploring a new strategy to the design and synthesis of compounds capable of binding Rac1 protein.Methods:(1) The molecular docking software AutoDock4.2 and other softwars are adopted here to analyze the interaction model between the anthraquinone compounds and Rac1 protein.(2) Based on the material of rhein, the rhein derivatives containing N fatty amine and piperazine were synthesized by organic reaction and interpreting the structure via the spectrum technology.(3) The growth inhibition effect of rhein derivatives on nasopharyngeal carcinoma, liver cancer, lung cancer, ovarian cancer, osteosarcoma cells was detected by MTT assay and the effect on Rac1 protein activation was tested by Western Blotting.Results:(1) Five common anthraquinone compounds including chrysophanol, emodin, rhein, physcion, and aloe-emodin can interact with two different active pockets of Rac1 protein effectively, among them, the rhein has the lowest binding free energy with Racl protein.(2) The affinity between rhein piperazine derivatives & rhein fatty amine derivatives and Rac1 protein are higher than that of rhein.(3) The fatty amine derivatives RN-2, piperazine derivatives RP-3 and RP-4 have been successfully synthesized and confirmed by spectrum.(4) The MTT experiment shows that rhein derivatives RX-1 and RN-2 have a strong inhibition effect for six kinds of cancer cells, all the values of IC50 are lower than the rhein. The cells of HepG2 2.15 have high sensitivity to rhein and other derivatives.(5) After the four rhein derivatives treatment six cells respectively, compared to the control group, the expressions of Racl protein was high except for the ovarian cancer SKOV3 cell. For the nasopharyngeal carcinoma CNE-1 and CNE-2 cells, the RP-4 compound shows stronger activation ability in active Rac1 protein than other compounds (P<0.001). In comparison with control group, RN-2 compound has stronger activation ability of Rac1 protein for liver cancer HepG2 2.15 and lung cancer A549 (P<0.01).(6)The results of Molecular docking and Western Blotting indicate that the rhein derivatives which activate the Racl protein, has formed the hydrogen bond with amino acid Asn39, Ala59 in activity of the Racl protein.Conclusion:Rac1 protein may be an antitumor target of Rhein derivatives, aliphatic amine and piperazine structure is connected onto 8-hydroxy of rhein, to help improve the binding ability with Rac1 protein and possess the potential ability to activate the expression of Racl protein. The amino acid Asn39, Ala59 in activity of the Rac1 protein is expected to become one of the important indicators for screening the Rac1 protein activator.