Novel Thiazine Substituted 9-Anilinoacridines: Synthesis, Antitumour Activity and Structure Activity Relationships

Background: 9-anilinoacridines are acting as DNA-intercalating agents which plays an important role as antitumor drugs, due to their anti-proliferative properties. Some anticancer agents contain 9-anilinoacridines such as amsacrine (m-AMSA), and nitracrine (Ledakrine) have been already developed. Methods: In this study, novel 9-anilinoacridines substituted with thiazines 4a-r were designed, synthesized, characterized by physical and spectral data and their cytotoxic activities against DLA cell lines were evaluated. Results: Among those compounds, 4b, c, e, g, i, j, k, m, o, p, q, r exhibited significant short term in vitro cytotoxic activity against Daltons lymphoma ascites (DLA) cells with CTC50 value of 0.18 to 0.31 mu M. The compounds 4b, c, e, g, y j, k, m, o, p, q, r are also exhibited significant long term in vitro anti-tumour activity against human tumor cell lines, HEp-2 (laryngeal epithelial carcinoma) by Sulforhodamine B assay with CTC50 value of 0.20 to 0.39 mu M. The compounds 4b, i, j exhibited significant in vivo antitumor activity with % Increase in Life Span (ILS) 48-82%. Conclusion: Results obtained in this study clearly demonstrated that many of the thiazine substituted 9-anilinoacridines exert interesting anti-tumour activity. The compounds 4b, i, j have significant anti-tumour activity and useful drugs after further refinement. The above derivatives will encourage to design future antitumor agents with high therapeutic potentials.