Topoisomerase IIα Inhibitory Activity Research Articles

4-Flourophenyl-substituted 5H-indeno[1,2-b]pyridinols with enhanced topoisomerase IIα inhibitory activity: Synthesis, biological evaluation, and structure–activity relationships

A series of fluorinated and hydroxylated 2,4-diphenyl indenopyridinols were designed and synthesized using l-proline-catalyzed and microwave-assisted synthetic methods for the development of new anticancer agents. Adriamycin and etoposide were used as reference compounds for the evaluation of topo IIα inhibitory and anti-proliferative activity of the synthesized compounds. Exploring the structure–activity relationships of 36 prepared compounds and biological results, most of the compounds with ortho- and para-fluorophenyl at 4-position of indenopyridinol ring displayed strong topo IIα inhibition. In addition, the majority of the ortho- and meta-fluorophenyl substituted compounds 1–24 displayed strong anti-proliferative activity against DU145 prostate cancer cell line compared to the positive controls. Interestingly, compound 4 possessing ortho-phenolic and ortho-fluorophenyl group at 2- and 4-position, respectively of the central pyridine ring showed high anti-proliferative activity (IC50 = 0.82 μM) against T47D human breast cancer cell line, while para-phenolic and para-fluorophenyl substituted compound 36 exhibited potent topo IIα inhibitory activity with 94.7% and 88.6% inhibition at 100 μM and 20 μM concentration, respectively. A systematic comparison between the results of this study and the previous study indicated that minor changes in the position of functional groups in the structure affect the topo IIα inhibitory activity and anti-proliferative activity of the compounds. The findings from this study will provide valuable information to the researchers working on the medicinal chemistry of topoisomerase IIα-targeted anticancer agents.

Anticancer Activity of Indeno[1,2-b]-Pyridinol Derivative as a New DNA Minor Groove Binding Catalytic Inhibitor of Topoisomerase IIα

Topoisomerase IIα has been a representative anti-cancer target for decades thanks to its functional necessity in highly proliferative cancer cells. As type of topoisomerase IIα targeting drugs, topoisomerase II poisons are frequently in clinical usage. However, topoisomerase II poisons result in crucial consequences resulted from mechanistically induced DNA toxicity. For this reason, it is needed to develop catalytic inhibitors of topoisomerase IIα through the alternative mechanism of enzymatic regulation. As a catalytic inhibitor of topoisomerase IIα, AK-I-191 was previously reported for its enzyme inhibitory activity. In this study, we clarified the mechanism of AK-I-191 and conducted various types of spectroscopic and biological evaluations for deeper understanding of its mechanism of action. Conclusively, AK-I-191 represented potent topoisomerase IIα inhibitory activity through binding to minor groove of DNA double helix and showed synergistic effects with tamoxifen in antiproliferative activity.

Development of 13H-benzo[f]chromeno[4,3-b][1,7]naphthyridines and their salts as potent cytotoxic agents and topoisomerase I/IIα inhibitors

A novel series of 35 angularly fused pentacyclic 13H-benzo[f]chromeno[4,3-b][1,7]naphthyridines and 13H-benzo[f]chromeno[4,3-b][1,7]naphthyridin-5-ium chlorides were designed and synthesized. Their cytotoxic activities were investigated against six human cancer cell lines (NCIH23, HCT15, NUGC-3, ACHN, PC-3, and MDA-MB-231). Among all screened compounds; 28, 30, 34, 35, 46, 48, 52, and 53 compounds exhibited potent cytotoxic activities against all tested human cancer cell lines. Further, these potent lead cytotoxic agents were evaluated against human Topoisomerase I and IIα inhibition. Among them, the compound 48 exhibited dual Topoisomerase I and IIα inhibition especially at 20 μM concentrations the compound 48 exhibited 1.25 times more potent Topoisomerase IIα inhibitory activity (38.3%) than the reference drug etoposide (30.6%). The compound 52 also exhibited excellent (88.4%) topoisomerase I inhibition than the reference drug camptothecin (66.7%) at 100 μM concentrations. Molecular docking studies of the compounds 48 and 52 with topo I discovered that they both intercalated into the DNA single-strand cleavage site where the compound 48 have van der Waals interactions with residues Arg364, Pro431, and Asn722 whilst the compound 52 have with Arg364, Thr718, and Asn722 residues. Both the compounds 48 and 52 have π–π stacking interactions with the stacked DNA bases. The docking studies of the compound 48 with topo IIα explored that it was bound to the topo IIα DNA cleavage site where etoposide was situated. The benzo[f]chromeno[4,3-b][1,7]naphthyridine ring of the compound 48 was stacked between the DNA bases of the cleavage site with π–π stacking interactions and there were no hydrogen bond interactions with topo IIα.

Synthesis and biological evaluation of N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-β-benzyl ester derivatives as potent topoisomerase IIα inhibitors

A new series of thirteen N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-β-benzyl ester compounds were synthesized and evaluated for antiproliferative activity against four different human cancer cell lines: cervical cancer (HeLa), lung cancer (A549), gastric cancer (MGC-803) and breast cancer (MCF-7) as well as topoisomerase I and IIα inhibitory activity. Compounds (5a, 5b, 5e, 8a, 8b) showed significant antiproliferative activity with low IC50 values against the four cancer cell lines. Equally, compounds 5a, 5b, 5e, 5f, 8a, 8d, 8e and 8f showed topoisomerase IIα inhibitory activity at 100μM with 5b, 5e, 8f exhibiting potential topoisomerase IIα inhibitory activity compared to positive control at 100μM and 20μM, respectively. Conversely compounds 5e, 5f, 5g and 8a showed weaker topoisomerase I inhibitory activity compared to positive control at 100μM. Compound 5b exhibited the most potent topoisomerase IIα inhibitory activity at low concentration and better antiproliferative activity against the four human cancer cell lines. The molecular interactions between compounds 5a–5g, 8a–8f and the topoisomerase IIα (PDB ID: 1ZXM) were further investigated through molecular docking. The results indicated that these compounds could serve as promising leads for further optimization as novel antitumor agents.

Inhibition of Topoisomerase IIα and Induction of Apoptosis in Gastric Cancer Cells by 19-Triisopropyl Andrographolide

Gastric cancer is the most common cancer in Eastern Asia. Increasing chemoresistance and general systemic toxicities have complicated the current chemotherapy leading to an urgent need of more effective agents. The present study reported a potent DNA topoisomerase IIα inhibitory activity of an andrographolide analogue (19-triisopropyl andrographolide, analogue-6) in gastric cancer cells; MKN-45, and AGS cells. The analogue was potently cytotoxic to both gastric cancer cell lines with the half maximal inhibitory concentration (IC50 values) of 6.3±0.7 μM, and 1.7±0.05 μM at 48 h for MKN-45, and AGS cells, respectively. It was more potent than the parent andrographolide and the clinically used, etoposide with the IC50 values of >50 μM in MKN-45 and 11.3±2.9 μM in AGS cells for andrographolide and 28.5±4.4 μM in MKN-45 and 4.08±0.5 μM in AGS cells for etoposide. Analogue-6 at 2 μM significantly inhibited DNA topoisomerase IIα enzyme in AGS cells, induced DNA damage, activated cleaved PARP-1, and Caspase3 leading to late cellular apoptosis. Interestingly, the expression of tumor suppressor p53 was not activated. These results show the importance of 19-triisopropyl-andrographolide in its emerging selectivity to primary target on topoisomerase IIα enzyme, inducing DNA damage and apoptosis by p53- independent mechanism. Thereby, the results provide insights of the potential of 19-triisopropyl andrographolide as an anticancer agent for gastric cancer. The chemical transformation of andrographolide is a promising strategy in drug discovery of a novel class of anticancer drugs from bioactive natural products.

Design, synthesis, cytotoxicity, HuTopoIIα inhibitory activity and molecular docking studies of pyrazole derivatives as potential anticancer agents

In an attempt to find potential anticancer agents, a series of novel ethyl 4-(3-(aryl)-1-phenyl-1H-pyrazol-4-yl)-2-oxo-6-(pyridin-3-yl)cyclohex-3-enecarboxylates 5a-i and 5-(3-(4-fluorophenyl)-1-phenyl-1H-pyrazol-4-yl)-3-(pyridin-3-yl)-4,5-dihydropyrazole-1-carbothioamides 6a-i were designed, synthesized and evaluated for their topoisomerase IIα inhibitory activity and in vitro cytotoxicity against a panel of cancerous cell lines (MCF-7, NCI-H460, HeLa) and a normal cell line (HEK-293T). Molecular docking studies of all the synthesized compounds into the binding site of topoisomerase IIα protein (PDB ID: 1ZXM) were performed to gain a comprehensive understanding into plausible binding modes. These compounds were also screened for in silico drug-likeliness properties on the basis of the absorption, distribution, metabolism and excretion (ADME) prediction. Among all the synthesized compounds, analogue 5d showed superior cytotoxicity with an IC50 value of 7.01±0.60μM for HeLa, 8.55±0.35μM for NCI-H460 and 14.31±0.90 for MCF-7 cancer cell lines. Further, compound 5d showed 70.82% inhibition of topoisomerase IIα at a concentration of 100μM with maximum docking score of −8.24. Results of ADME prediction revealed that most of these compounds showed in silico drug-likeliness properties within the ideal range.

Synthesis and biological evaluation of C1-O-substituted-3-(3-butylamino-2-hydroxy-propoxy)-xanthen-9-one as topoisomerase IIα catalytic inhibitors

Topoisomerase II poison blocks the transitorily generated DNA double-strand breaks (DSBs) from religation, thereby causes severe DNA damage and gene toxicity. While topoisomerase II catalytic inhibitor does not form cleavable DNA-enzyme complex because its function attributes to inhibition of the catalytic steps of the enzyme such as before generating DNA DSBs or in the last step of the catalytic cycle after religation. It has been reported that the stabilizing effect of etoposide on transient cleavable DNA-topoisomerase IIβ complex attributes to its secondary malignancy. Therefore, topoisomerase IIα has been considered as more attractive target than topoisomerase IIβ for the development of chemotherapeutic agents. In the previous work, we reported compounds I and II as novel topoisomerase IIα catalytic inhibitors targeting for ATP binding site of human topoisomerase IIα ATP-binding domain. As a continuous work, we have designed and synthesized 43 compounds of C1-O-alkyl and arylalkyl substitiuted compounds with or without methoxy group on ring A. In the topoisomerase IIα inhibitory test, among the tested C1-O-4-chlorophenethyl substituted compounds 37 and 47 were more active than others, and compound 37 showed strongest topoisomerase IIα inhibitory activity with 94.4% and 23.0% inhibition, respectively, at 100 and 20 μM. Compounds 37 and 47 have also showed much enhanced cytotoxic activity against T47D cells; IC50 (μM): 0.63 ± 0.01 and 0.19 ± 0.02, respectively, which are stronger than reference drugs. Band depletion assay and cleavage complex assay results showed compounds 37 and 47 were potential topoisomerase IIα catalytic inhibitor with low DNA damage.

New spiro-acridines: DNA interaction, antiproliferative activity and inhibition of human DNA topoisomerases

Two new spiro-acridines were synthesized by introducing cyano-N-acylhydrazone between the acridine and phenyl rings followed by spontaneous cyclization. The final compounds (E)-1⿲-(benzylideneamino)-5⿲-oxo-1⿲,5⿲-dihydro-10H-spiro[acridine-9,2⿲-pyrrole]-4⿲-carbonitrile (AMTAC-01) and (E)-1⿲-((4-methoxybenzylidene)amino)-5⿲-oxo-1⿲,5⿲-dihydro-10H-spiro[acridine-9,2⿲-pyrrole]-4⿲-carbonitrile (AMTAC-02) were evaluated for their interactions with calf thymus DNA, antiproliferative and human topoisomerase I and IIα inhibitory activities. Both compounds presented ability to bind DNA. The binding constant determined by UV⿿vis spectroscopy was found to be 104M⿿1. Antiproliferative assay demonstrated that AMTAC-01 and AMTAC-02 were most active against prostate and melanoma tumor cell lines, respectively. The compound did not present Topo I inhibitory activity. However, both derivatives displayed topoisomerase IIα inhibitory activity comparable to amsacrine, and AMTAC-02 was more potent than AMTAC-01 with methoxy substituent group on phenyl ring. This study demonstrates that the new derivatives are promising molecules with topoisomerase IIα inhibitory and antiproliferative activities.

Synthesis of friedelan triterpenoid analogs with DNA topoisomerase IIα inhibitory activity and their molecular docking studies

Five highly oxygenated friedelan derivatives (3a, 3b, 4, 5a and 5b) were synthesized. The structures of these compounds were established on the basis of spectral (IR, 1D and 2D NMR, MS etc.) and chemical data. The molecules, including the parent compounds were screened for three-dimensional (3D) molecular docking on the crystal structure of topoisomerase IIα (1 bgw for topoisomerase IIα, PDB). Compounds 3a and 5a showed a dose dependent inhibition of catalytic activity of human topoisomerase IIα.