Design, Synthesis And Biological Activity Of Novel Naphthalimide Antitumor Agents

In the dissertation, four kinds of naphthalimide derivatives, based on the lead compound of Amonafide, were designed and synthesized. Their antitumor activities were evaluated against HeLa, A549, P388, HL-60, MCF-7, HCT-8, A375 cancer cell lines in vitro. The properties of their DNA-intercalating, BSA binding, cell cycle arrest and induction of apoptosis, were also systematically studied.The first section described the antitumor activities of naphthalimide-amino acid conjugates. Six target compounds were designed and synthesized by conjugating naphthalimide scaffold with flexible leucine moiety as side chain instead of conventional N,N-dimethyl-aminoethylenediamine functional group. The preliminary results showed that most of the derivatives had moderate antitumor activities with the IC50 values of 10"6-10-5 M. More importantly, compounds 8a-c exhibited exclusive antitumor activities against MCF-7 cell line. BSA binding experiment implied that hydrophobic substituents of compounds 8a-c proved to be a key structural unit for their binding abilities to BSA, which might provide some suggestions on the understanding of their exclusive antitumor selectivity against MCF-7 cell line. DNA binding experiments indicated that these derivatives behaved as DNA intercalating agents.The second section focused on the antitumor and pro-apoptotic function of Amonafide analogues. Ten target compounds were designed and synthesized by modification of the position-6 of naphthalimide by hydrophobic substituents. The preliminary results showed that most of the derivatives had comparable antitumor activities over Amonafide with the IC50 values of 10-6-10-5 M. More importantly, flow cytometric analysis indicated that the derivatives, such as compounds 5b,7b,7e, could effectively induce G2/M arrest and progress to apoptosis in a dose-dependent manner in HL-60 cell line after double staining with annexin V-FITC and propidium iodide. Detailed biological experiment exhibited that compound 5a induced G2/M phase growth arrest through inhibiting PI3K/Akt pathway and DNA fragmentation. Not only the expression levels of protein Cyclin B1, Cdkl changed in response to compound 5a treatment in HL-60 cells, but also we observed the inhibition of NF-κB nuclear translocation, up-regulation of Bax and down-regulation of Bcl-2. The activities of caspase-3,-9 increased, indicating that the mitochondrial pathway was involved in the apoptosis signal pathway. The results also showed that the phosphorylation of p85/PI3 K and Akt decreased following compound 5a treatment.The third section studied on the alternative modification of naphthalimide scaffold and evaluated their antitumor and apoptosis-inducing function. Nine target compounds were designed and synthesized by connecting naphthalimide and 4-(4-(3,3-diphenylallyl)piperazin-1-yl)benzoic acid moiety with different functional linkers, ethanolamine and sulfanilamide. The preliminary results showed that most of the derivatives had comparable antitumor activities over Amonafide with the IC50 values of 10-6-10-5 M. Interestingly, compound 12e exhibited the exclusive antitumor activity against MCF-7 among the tested cancer cell lines. More importantly, flow cytometric analysis indicated that these derivatives, such as compounds 12b and 13d, could effectively induce G2/M arrest and progress to apoptosis in a dose-dependent manner in HL-60 cell line after double staining with annexin V-FITC and propidium iodide. The present work provided a novel class of naphthalimide-based derivatives with potent apoptosis-inducing and improved antitumor activity for further optimization.The fourth section centered on the conjugation of indomethacin and naphthalimide scaffold, and evaluated their hypoxic/oxic cytotoxicity, apoptosis-inducing function and combination with COX-2. Four target compounds were designed and synthesized. The preliminary results showed that the derivatives had some antitumor activities and obvious apoptosis-inducing function. More importantly, amide derivatives 4c and 4d, exhibited the superior oxic cytotoxic and proapoptotic activities over their ester derivatives; while the ester derivatives 4a and 4b, showed excellent hypoxic cytotoxic activity. COX-2 titration experiments demonstrated that there was interaction between the target compound and COX-2 to some extent, which could provide some explanation for their special biological activity. The conjugates described herein represented powerful tools for the investigation of a novel class of selective inhibitors of COX-2.