Synthesis, bioactivity assessment, molecular docking and ADMET studies of new chromone congeners exhibiting potent anticancer activity.

In consideration of the chromones' therapeutic potential and anticancer activity, a new series of chromanone derivatives have been synthesized through a straightforward reaction between 6-formyl-7-hydroxy-5-methoxy-2-methylchromone (2) and various organic active compounds. The cytotoxic activity of the newly synthesized congeners was investigated against MCF-7 (human breast cancer), HCT-116 (colon cancer), HepG2 (liver cancer), and normal skin fibroblast cells (BJ1). The obtained data indicated that compounds 14b, 17, and 19 induce cytotoxic activity in the breast MCF7, while compounds 6a, 6b, 11 and 14c showed highly potent activity in the colon cancer cell lines. Overall, the results demonstrate that the potential cytotoxic effects of the studied compounds may be based on their ability to induce DNA fragmentation in cancer cell lines, down-regulate the expression level of CDK4 as well as the anti-apoptotic gene Bcl-2 and up-regulate the expression of the pro-apoptotic genes P53 and Bax. Furthermore, compounds 14b and 14c showed a dual mechanism of action by inducing apoptosis and cell cycle arrest. The docking studies showed that the binding affinity of the most active cytotoxic compounds within the active pocket of the CDK4 enzyme is stronger due to hydrophobic and H-bonding interactions. These results were found to be consistent with the experimental results.

Camptothecin structure simplification elaborated new imidazo[2,1-b]quinazoline derivative as a human topoisomerase I inhibitor with efficacy against bone cancer cells and colon adenocarcinoma.

Camptothecin is a pentacyclic natural alkaloid that inhibits the hTop1 enzyme involved in DNA transcription and cancer cell growth. Camptothecin structure pitfalls prompted us to design new congeners using a structure simplification strategy to reduce the ring extension number from pentacyclic to tetracyclic while maintaining potential stacking of the new compounds with the DNA base pairs at the Top1-mediated cleavage complex and aqueous solubility, as well as minimizing compound-liver toxicity. The principal axis of this study was the verification of hTop1 inhibiting activity as a possible mechanism of action and the elaboration of new simplified inhibitors with improved pharmacodynamic and pharmacokinetic profiling using three structure panels (A-C) of (isoquinolinoimidazoquinazoline), (imidazoquinazoline), and (imidazoisoquinoline), respectively. DNA relaxation assay identified five compounds as hTop1 inhibitors belonging to the imidazoisoquinolines 3a,b, the imidazoquinazolines 12, and the isoquinolinoimidazoquinazolines 7a,b. In an MTT cytotoxicity assay against different cancer cell lines, compound 12 was the most potent against HOS bone cancer cells (IC50 = 1.47 µM). At the same time, the other inhibitors had no detectable activity against any cancer cell type. Compound (12) demonstrated great penetrating power in the HOS cancer cells' 3D-multicellular tumor spheroid model. Bioinformatics research of the hTop1 gene revealed that the TP53 cell proliferative gene is in the network of hTop1. The finding is confirmed empirically using the gene expression assay that proved the increase in p53 expression. The impact of structure simplification on compound 12 profile, characterized by the absence of acute oral liver toxicity when compared to Doxorubicin as a standard inhibitor, the lethal dose measured on Swiss Albino female mice and reported at LD50 = 250 mg/kg, and therapeutic significance in reducing colon adenocarcinoma tumor volume by 75.36 % after five weeks of treatment with compound 12. The molecular docking solutions of the active CPT-based derivative 12 and the inactive congener 14 into the active site of hTop1 and the activity cliffing of such MMP directed us to recommend the addition of HBD and HBA variables to compound 12 imidazoquinazoline core scaffold to enhance the potency via hydrogen bond formation with the major groove amino acids (Asp533, Lys532) as well as maintaining the hydrogen bond with the minor groove amino acid Arg364.