Design,Synthesis And Activity Research Of New Water Soluble Analogues Of FL118

FL118 is a novel camptothecin derivative that is obtained by computer high-throughput screening?HTS?in the cancer cell model of the Roswell Park Cancer Institute in the genetic engineering of the Survivin gene as a target and Survival marker.FL118 has a high inhibitory effect on a variety of cancer cells.The effect of FL118 on the inhibition of tumor growth in mice is 10¹00 times of irinotecan and topotecan.FL118 showed a significant inhibitory effect on irinotecan and topotecan-resistant tumor cells,and it is less toxic to the body.However,The FL118molecule still showed poor water solubility,unstable lactone ring,and low bioavailability.In recent years,the design and application of prodrugs have become more and more extensive.The prodrugs not only maintain or enhance the efficacy of the original drugs,but also overcome some shortcomings of the original drugs.In view of the above defects of FL118,the prodrug design of FL118 is carried out for enhancing water solubility and improving the bioavailability in this paper,and the20?S?-position of FL118 was coupled with water-soluble amino acid as ligand.The anti-tumor activity of new analogues were evaluated.?1?Design and synthesis of FL118 amino acid ester prodrugsBased on the investigation of the structure-activity relationship of FL118,the designed FL118 amino acid ester prodrug was molecularly docked with the target human survivin protein gene 1XOX by the deffirent docking method and parameters.The binding mode and tight binding degree between the ester prodrug and the targeting protein provided a theoretical reference for screening the antitumor activity of the subsequent compound.According to synthesis method of FL118 derivatives in the previous research word,6-nitropiperonal,tricycloketone lactone and L-type Boc protected amino acids were used as raw materials to design.and the synthetic route of the target product were optimized.Ten FL118 amino acid ester prodrugs?purity>98%?were synthesized by reduction,Friedlander condensation,esterification and deprotection reaction,and the structure were determined by ¹H NMR and ¹³C NMR,the total yield was 20%³2%.?2?The biostability and activity of FL118 amino acid ester prodrugUsing FL118 as a positive control,the in vitro stability of FL118 amino acid ester prodrugs 6a⁶j was investigated in PBS buffer and human plasma,and the compound 6a showed the worst biological stability with the half-live of 0.6 h in PBS and 0.3 h in human plasma.The compound 6f showed the best.Stability with the half-live of 13.3 h in PBS and 6.1 h in human plasma respectively.These FL118amino acid ester prodrugs 6a⁶j were continuously degradated to raw FL118 in PBS and human plasma,which indicated that the ester prodrug of FL118 owned good water solubilty,increaseed the bioavailability and effectively extend its half-life.The cytotoxicity of the synthesized FL118 amino acid ester prodrugs was evaluated by MTT assay.These compounds showed good antitumor activity in the four tumor cell lines.The IC₅₀ value of compound 6b to HCT116 is 0.025?M similar to FL118.In vivo antitumor activities of compounds 6c,6i and 6j were examined by xenografted colon cancer nude mouse model experiments,and the compounds 6c and 6j produced potent antitumor activity at a dose of 8 mg/kg,which was not as good as FL118,but their toxicity were obviously lower than that of FL118,and further intensive anti-tumor experiments in vivo can be considered.In short,Ten FL118 amino acid ester prodrug 6a⁶j were synthesised,which showed good solubility in water,and constantly release raw FL118 in biological media,and the bioavailability of these FL118 produgs were improved obviously,the biological half-life in the body were extened effectively.The vivo toxicity of these produgs were significantly reduced than FL118,at the same time they also showed the effective anti-tumor activity,so they looks like potent development in the future.