Identification of FTY720 and COH29 as novel topoisomerase I catalytic inhibitors by experimental and computational studies.

The development of novel topoisomerase I (TOP1) inhibitors is crucial for overcoming the drawbacks and limitations of current TOP1 poisons. Here, we identified two potential TOP1 inhibitors, namely, FTY720 (a sphingosine 1-phosphate antagonist) and COH29 (a ribonucleotide reductase inhibitor), through experimental screening of known active compounds. Biological experiments verified that FTY720 and COH29 were nonintercalative TOP1 catalytic inhibitors that did not induce the formation of DNA-TOP1 covalent complexes. Molecular docking revealed that FTY720 and COH29 interacted favorably with TOP1. Molecular dynamics simulations revealed that FTY720 and COH29 could affect the catalytic domain of TOP1, thus resulting in altered DNA-binding cavity size. The alanine scanning and interaction entropy identified Arg536 as a hotspot residue. In addition, the bioinformatics analysis predicted that FTY720 and COH29 could be effective in treating malignant breast tumors. Biological experiments verified their antitumor activities using MCF-7 breast cancer cells. Their combinatory effects with TOP1 poisons were also investigated. Further, FTY720 and COH29 were found to cause less DNA damage compared with TOP1 poisons. The findings provide reliable lead compounds for the development of novel TOP1 catalytic inhibitors and offer new insights into the potential clinical applications of FTY720 and COH29 in targeting TOP1.

QSAR prediction, synthesis, anticancer evaluation, and mechanistic investigations of novel sophoridine derivatives as topoisomerase I inhibitors.

Sophoridine, which is derived from the Leguminous plant Sophora alopecuroides L., has certain pharmacological activity as a new anticancer drug. Herein, a series of novel N-substituted sophoridine derivatives was designed, synthesized and evaluated with anticancer activity. Through QSAR prediction models, it was discovered that the introduction of a benzene ring as a main pharmacophore and reintroduced into a benzene in para position on the phenyl ring in the novel sophoridine derivatives improved the anticancer activity effectively. In vitro, 28 novel compounds were evaluated for anticancer activity against four human tumor cell lines (A549, CNE-2, HepG-2, and HEC-1-B). In particular, Compound 26 exhibited remarkable inhibitory effects, with an IC50 value of 15.6 µM against HepG-2 cells, surpassing cis-Dichlorodiamineplatinum (II). Molecular docking studies verified that the derivatives exhibit stronger binding affinity with DNA topoisomerase I compared to sophoridine. In addition, 26 demonstrated significant inhibition of DNA Topoisomerase I and could arrest cells in G0/G1 phase. This study provides valuable insights into the design and synthesis of N-substituted sophoridine derivatives with anticancer activity.

Design, Synthesis, and Investigation of the Pharmacokinetics and Anticancer Activities of Indenoisoquinoline Derivatives That Stabilize the G-Quadruplex in the MYC Promoter and Inhibit Topoisomerase I.

G-quadruplexes are noncanonical four-stranded DNA secondary structures. MYC is a master oncogene and the G-quadruplex formed in the MYC promoter functions as a transcriptional silencer and can be stabilized by small molecules. We have previously revealed a novel mechanism of action for indenoisoquinoline anticancer drugs, dual-downregulation of MYC and inhibition of topoisomerase I. Herein, we report the design and synthesis of novel 7-aza-8,9-methylenedioxyindenoisoquinolines based on desirable substituents and π-π stacking interactions. These compounds stabilize the MYC promoter G-quadruplex, significantly lower MYC levels in cancer cells, and inhibit topoisomerase I. MYC targeting was demonstrated by differential activities in Raji vs CA-46 cells and cytotoxicity in MYC-dependent cell lines. Cytotoxicities in the NCI-60 panel of human cancer cell lines were investigated. Favorable pharmacokinetics were established, and in vivo anticancer activities were demonstrated in xenograft mouse models. Furthermore, favorable brain penetration, brain pharmacokinetics, and anticancer activity in an orthotopic glioblastoma mouse model were demonstrated.

Design, synthesis, and biological evaluation of novel benzo[6,7]indolo[3,4-c]isoquinolines as anticancer agents with topoisomerase I inhibition.

A novel series of benzo[6,7]indolo[3,4-c]isoquinolines 3a-3f was designed by scaffold hopping of topoisomerase I inhibitor benzo[g][1]benzopyrano[4,3-b]indol-6(13H)-ones (BBPIs), which were developed by structural modification of the natural marine product lamellarin. The unconventional pentacycle was constructed by Bischler-Napieralski-type condensation of amide 11 and subsequent intramolecular Heck reaction. In vitro anticancer activity of the synthesized benzo[6,7]indolo[3,4-c]isoquinolines was evaluated on a panel of 39 human cancer cell lines (JFCR39). Among the compounds tested, N-(3-morpholinopropyl) derivative 3e showed the most potent antiproliferative activity, with a mean GI50 value of 39 nM. This compound inhibited topoisomerase I activity by stabilizing the enzyme-DNA complex.

Synthesis of hybrid phosphorated indenoquinolines and biological evaluation as topoisomerase I inhibitors and antiproliferative agents.

This work describes the first synthesis of diethyl 6,6a,7,11b-tetrahydro-5H-indeno[2,1-c]quinolinylphosphonates 5, diethyl 7H-indeno[2,1-c]quinolinylphosphonates 6 and diethyl 7-oxo-7H-indeno[2,1-c]quinolinylphosphonates 7, which were prepared in good to high overall yields. The synthetic route involves a multicomponent reaction of 2-phosphonateaniline, aldehydes and indene as olefin and allows the selective generation of three stereogenic centres in a short, efficient and reliable manner. The selective dehydrogenation of 1,2,3,4-tetrahydroindenoquinolines leads to the formation of corresponding indenoquinolines, and subsequent oxidation of methylene group of the indenoquinolines allows the access to indenoquinolinones.

Identification of potential antileishmanial 1,3-disubstituted-4-hydroxy-6-methylpyridin-2(1H)-ones, in vitro metabolic stability, cytotoxicity and molecular modeling studies.

We report the synthesis and in vitro evaluation of 1,3-disubstituted-4-hydroxy-6-methylpyridin-2(1H)-one derivatives against Leishmania donovani. Amongst the compound library synthesized, molecules 3d, 3f, 3h, 3i, 3l, and 3m demonstrated substantial dose-dependent killing of the promastigotes. Their IC50 values range from 55.0 to 77.0 µg/ml, with 3m (IC50 55.75 µg/ml) being equipotent with amphotericin B (IC50 50.0 µg/ml, used as standard). The most active compound 3m, is metabolically stable in rat liver microsomes. Furthermore, the molecules are highly specific against leishmania as shown by their weak antibacterial and antifungal activity. In vitro cytotoxicity studies show the compounds lack any cytotoxicity. Furthermore, molecular modeling studies show plausibility of binding to Leishmania donovani topoisomerase 1 (LdTop1). Structure activity relationships reveal bulky substitutions on the pyridone nitrogen are well-tolerated, and such compounds have better binding affinity. Intramolecular hydrogen bonds confer some rigidity to the molecules, rendering a degree of planarity akin to topotecan. Taken together, we emphasis the merits of molecules possessing the 1,3-disubstituted-4-hydroxy-6-methylpyridin-2(1H)-one skeleton as potential antileishmanial agents warranting further investigation.

Ruthenium(II) Diphosphine Complexes with Mercapto Ligands That Inhibit Topoisomerase IB and Suppress Tumor Growth In Vivo.

Ruthenium(II) complexes (Ru1-Ru5), with the general formula [Ru(N-S)(dppe)2]PF6, bearing two 1,2-bis(diphenylphosphino)ethane (dppe) ligands and a series of mercapto ligands (N-S), have been developed. The combination of these ligands in the complexes endowed hydrophobic species with high cytotoxic activity against five cancer cell lines. For the A549 (lung) and MDA-MB-231 (breast) cancer cell lines, the IC50 values of the complexes were 288- to 14-fold lower when compared to cisplatin. Furthermore, the complexes were selective for the A549 and MDA-MB-231 cancer cell lines compared to the MRC-5 nontumor cell line. The multitarget character of the complexes was investigated by using calf thymus DNA (CT DNA), human serum albumin, and human topoisomerase IB (hTopIB). The complexes potently inhibited hTopIB. In particular, complex [Ru(dmp)(dppe)2]PF6 (Ru3), bearing the 4,6-diamino-2-mercaptopyrimidine (dmp) ligand, effectively inhibited hTopIB by acting on both the cleavage and religation steps of the catalytic cycle of this enzyme. Molecular docking showed that the Ru1-Ru5 complexes have binding affinity by active sites on the hTopI and hTopI-DNA, mainly via π-alkyl and alkyl hydrophobic interactions, as well as through hydrogen bonds. Complex Ru3 displayed significant antitumor activity against murine melanoma in mouse xenograph models, but this complex did not damage DNA, as revealed by Ames and micronucleus tests.

Design and synthesis of novel conformationally constrained 7,12-dihydrodibenzo[b,h][1,6] naphthyridine and 7H-Chromeno[3,2-c] quinoline derivatives as topoisomerase I inhibitors: In vitro screening, molecular docking and ADME predictions.

Novel non-camptothecin (non-CPT) class of conformationally constrained, hitherto unknown 7,12-dihydrodibenzo[b,h][1,6] naphthyridine and 7H-Chromeno[3,2-c] quinoline derivatives have been designed, synthesized and evaluated for anti-cancer activity. In vitro anti-proliferation evaluation against human cancer cell lines (A549 and MCF-7) exhibited significant cytotoxicity. Among the derivatives (8-24), 8 (IC50 0.44 µM and IC50 0.62 µM) and 12 (IC50 0.69 µM and IC50 0.54 µM) were identified as the most promising candidate against A-549 and MCF-7 cancer cell lines respectively. Topo I inhibitory activity of 8 and 12 suggested that, they may be developed as potential anti-cancer molecules in future and rationalized by docking analysis with effective binding modes. Further, in silico ADME prediction studies of all derivatives were found promising, signifying the drug like properties. In precise, the present investigation displays a new strategy to synthesize and emphasis on anticancer activities of conformationally constrained dibenzo[b,h][1,6] naphthyridine derivatives and Chromeno[3,2-c] quinoline derivatives in the context of cancer drug development and refinement.

Fused chromeno and quinolino[1,8]naphthyridines: Synthesis and biological evaluation as topoisomerase I inhibitors and antiproliferative agents.

The synthesis of 1,8-naphthyridine derivatives fused with other heterocycles, such as chromenes and quinolines, as well as their behaviour as topoisomerase I inhibitors is studied. The preparation is carried out through a direct and simple process as an intramolecular [4 + 2] cycloaddition reaction between functionalized aldimines, obtained by the condensation of 2-aminopyridine and unsaturated aldehydes, and olefins. In particular, while no clear inhibitory activity is observed for chromeno[4,3-b][1,8]naphthyridine fused heterocycles, a very different result is observed for quinolino[4,3-b][1,8]naphthyridine derivatives. Experimental assays indicated that quinolino[4,3-b][1,8]naphthyridines inhibited the topoisomerase I enzymatic reaction behaving like a poison, as occurs with the natural TopI inhibitor, camptothecin. Furthermore, the cytotoxic effect on cell lines derived from human lung adenocarcinoma (A549), human ovarian carcinoma (SKOV3), and on non-cancerous lung fibroblasts cell line (MRC5) was also screened.

Synthesis of Methoxy-, Methylenedioxy-, Hydroxy-, and Halo-Substituted Benzophenanthridinone Derivatives as DNA Topoisomerase IB (TOP1) and Tyrosyl-DNA Phosphodiesterase 1 (TDP1) Inhibitors and Their Biological Activity for Drug-Resistant Cancer.

As a recently discovered DNA repair enzyme, tyrosyl-DNA phosphodiesterase 1 (TDP1) removes topoisomerase IB (TOP1)-mediated DNA protein cross-links. Inhibiting TDP1 can potentiate the cytotoxicity of TOP1 inhibitors and overcome cancer cell resistance to TOP1 inhibitors. On the basis of our previous study, herein we report the synthesis of benzophenanthridinone derivatives as TOP1 and TDP1 inhibitors. Seven compounds (C2, C4, C5, C7, C8, C12, and C14) showed a robust TOP1 inhibitory activity (+++ or ++++), and four compounds (A13, C12, C13, and C26) showed a TDP1 inhibition (half-maximal inhibitory concentration values of 15 or 19 µM). We also show that the dual TOP1 and TDP1 inhibitor C12 induces both cellular TOP1cc, TDP1cc formation and DNA damage, resulting in cancer cell apoptosis at a sub-micromolar concentration. In addition, C12 showed an enhanced activity in drug-resistant MCF-7/TDP1 cancer cells and was synergistic with topotecan in both MCF-7 and MCF-7/TDP1 cells.

Design and synthesis of C-aryl angular luotonins via a one-pot aza-Nazarov-Friedlander sequence and their Topo-I inhibition studies along with C-aryl vasicinones and luotonins.

A facile one-pot synthesis of C-ring substituted angular luotonins has been realized via a methanesulfonic acid mediated aza-Nazarov-Friedlander condensation sequence on quinazolinonyl enones. Topoisomerase I (topo-I) inhibition studies revealed that the angular luotonin library (7a-7l) and their regioisomeric analogs (linear luotonins, 8a-8l) are weak negative modulators, compared to camptothecin. These results would fare well for the design of topo-I-inert luotonins for non-oncological applications such as anti-fungal and insecticide lead developments. Surprisingly, the tricyclic vasicinones (9h, 9i, and 9j) showed better topo-I inhibition compared to pentacyclic C-aryl luotonins providing a novel pharmacophore for further explorations.

Synthesis, molecular modeling and biological evaluation of new benzo[4,5]thieno[3,2-b]pyran derivatives as topoisomerase I-DNA binary complex poisons.

A series of new benzo[b]thiophenes 2a-f and benzo[4,5]thieno[3,2-b]pyran derivatives 3a-f and 4a-f were synthesized and their structures were confirmed by elemental analyses and spectral data. All synthesized compounds were evaluated by the National Cancer Institute (NCI, USA) against 60 human tumor cell lines. Compounds 3a-f and 4a-f showed potent cytotoxic effects in one dose assay with mean growth inhibition ranging from 62% to 80%. Six compounds 3a, 3d, 3e, 3f, 4d and 4e were selected by NCI, USA for five dose evaluation against 60 human tumor cell lines. Compounds 3a, 3d, 3e and 3f exhibited very potent and broad spectrum cytotoxicity against almost all cancer cell lines with mean concentration that yield 50% growth inhibition (MG-MID GI50) of 0.1-0.58 µM and mean concentration that produce 100% growth inhibition (MG-MID TGI) of 6.03-10.00 µM. Compounds 4d and 4e exhibited very potent and selective cytotoxic activity against MDA-MB-435 subpanel (melanoma cancer) with GI50 of 0.45 µM and 0.59 µM, respectively. The mechanism of antiproliferative activity was determined for the most active compounds 3a, 3d, 3e, 3f, 4d, and 4evia measuring their half maximal inhibitory concentration (IC50) against topoisomerase I enzyme at different concentrations. Compounds 3a and 3e exhibited excellent activity compared with reference drugs with IC50 of 0.295 µM and 0.219 µM, respectively. Plasmid DNA nicking assay verified that these compounds are topoisomerase I poisons not suppressors. The active compound 3e induced a significant disruption in the cell cycle profile parallel to its effect on apoptosis induction.

Synthesis, biological evaluation, and correlation of cytotoxicity versus redox potential of 1,4-naphthoquinone derivatives.

A series of 1,4-naphthoquinone derivatives of lawsone (1), 6-hydroxy-1,4-naphthoquinone (2), and juglone (3) were synthesized by alkylation, acylation, and sulfonylation reactions. The yields of lawsone derivatives 1a-1k (type A), 6-hydroxy-1,4-naphthoquinone derivatives 2a-2j (type B), and juglone derivatives 3a-3h (type C) were 52-99%, 53-96%, and 28-95%, respectively. All compounds were tested in vitro for the cytotoxicity against human oral epidermoid carcinoma (KB) and cervix epithelioid carcinoma (HeLa) cells and their structure-activity relationship was studied. Compound 3c was found to be most potent in KB cell line (IC50 = 1.39 µM). Some compounds were evaluated for DNA topoisomerase I inhibition. Compounds 2c, 3, 3a, and 3d showed topoisomerase inhibition activity with IC50 values of 8.3-91 µM. Standard redox potentials (E°) of all naphthoquinones in phosphate buffer at pH 7.2 were examined by means of cyclic voltammetry. A definite correlation has been found between the redox potentials and inhibitory effects of type A compounds.

Structural simplification of evodiamine: Discovery of novel tetrahydro-ß-carboline derivatives as potent antitumor agents.

Natural products (NPs) have played a crucial role in the discovery and development of antitumor drugs. However, the high structural complexity of NPs generally results in unfavorable physicochemical profiles and poor drug-likeness. A powerful strategy to tackle this obstacle is the structural simplification of NPs by truncating nonessential structures. Herein, a series of tetrahydro-ß-carboline derivatives were designed by elimination of the D ring of NP evodiamine. Structure-activity relationship studies led to the discovery of compound 45, which displayed highly potent antitumor activity against all the tested cancer cell lines and excellent in vivo antitumor activity in the HCT116 xenograft model with low toxicity. Further mechanistic research indicated that compound 45 acted by dual Top1/2 inhibition and induced caspase-dependent cell apoptosis coupled with G2/M cell cycle arrest. This proof-of-concept study validated the effectiveness of structural simplification in NP-based drug development, discovered compound 45 as a potent antitumor lead compound and enriched the structure-activity relationships of evodiamine.

3,7-bis-benzylidene hydrazide ciprofloxacin derivatives as promising antiproliferative dual TOP I & TOP II isomerases inhibitors.

We report herein design and synthesis of a new series of 3,7-bis-benzylidenes of ciprofloxacin. Most of the target compounds revealed good cytotoxic activity; the most potent 4e and 4i achieved strong broad spectrum antiproliferative activity with comparable activity to Doxorubicin with IC50 (µM) of 1.21 ± 0.02, 0.87 ± 0.04, 1.21 ± 0.02; 0.41 ± 0.02, 0.57 ± 0.06, 1.31 ± 0.04 and 1.26 ± 0.01, 1.79 ± 0.04, 0.63 ± 0.01 against leukemia cancer cell line HL-60 (TB), colon cancer cell line HCT-116 and breast cancer cell line MCF7, respectively. Moreover, the most potent derivative 4i induced apoptosis at G2/M phase Investigating the mechanism of action of compounds 4e, 4 h and 4i exhibited promising dual TOP Iα and TOP IIB % inhibition comparable to Camptothecin and Etoposide; respectively. Docking of 4e, 4 h and 4i into the active site of topo I and II proteins compared to Camptothein and Etoposide revealed acceptable binding score and augmented enzyme assay data. Hence, 4e and 4i are promising targeted antiproliferative dual acting TOP Iα TOP IIB inhibitors that require further optimization.

Discovery of 4-alkoxy-2-aryl-6,7-dimethoxyquinolines as a new class of topoisomerase I inhibitors endowed with potent in vitro anticancer activity.

In our attempt to develop potential anticancer agents targeting Topoisomerase I (TOP1), two novel series of 4-alkoxy-2-arylquinolines 14a-p and 19a-c were designed and synthesized based on structure activity relationships of the reported TOP1 inhibitors and structural features required for stabilization of TOP1-DNA cleavage complexes (TOP1ccs). The in vitro anticancer activity of these two series of compounds was evaluated at one dose level using NCI-60 cancer cell lines panel. Compounds 14e-h and 14m-p, with p-substituted phenyl at C2 and propyl linker at C4, were the most potent and were selected for assay at five doses level in which they exhibited potent anticancer activity at sub-micromolar level against diverse cancer cell lines. Compound 14m was the most potent with full panel GI50 MG-MID 1.26 µM and the most sensitive cancers were colon cancer, leukemia and melanoma with GI50 MG-MID 0.875, 0.904 and 0.926 µM, respectively. Melanoma (LOX IMVI) was the most sensitive cell line to all tested compounds displaying GI50 from 0.116 to 0.227 µM, TGI from 0.275 to 0.592 µM and LC50 at sub-micromolar concentration against almost of the tested compounds. Compounds 14e-h and 14m-p were assayed using TOP1-mediated DNA cleavage assay to evaluate their ability to stabilize TOP1ccs resulting in cancer cell death. The morpholino analogs 14h and 14p exhibited moderate TOP1 inhibitory activity compared to 1 µM camptothecin suggesting their use as lead compounds that can be optimized for the development of more potent anticancer agents with potential TOP1 inhibitory activity. Finally, Swiss ADME online web tool predicted that compounds 14h and 14p possessed good oral bioavailability and druglikeness characteristics.

Design, Synthesis and Structure-Activity Relationship Studies of Glycosylated Derivatives of Marine Natural Product Lamellarin D.

Lamellarin D, a marine natural product, acts as a potent inhibitor of DNA topoisomerase I (Topo I). To modify its physicochemical property and biological activity, a series of mono- and di-glycosylated derivatives were designed and synthesized through 22-26 multi-steps. Their inhibition of human Topo I was evaluated, and most of the glycosylated derivatives exhibited high potency in inhibiting Topo I activity as well as lamellarin D. All the 15 target compounds were evaluated for their cytotoxic activities against five human cancer cell lines. The typical lamellarin derivative ZL-3 exhibited the best activity with IC50 values of 3 nM, 10 nM, and 15 nM against human lung cancer A549 cells, human colon cancer HCT116 cells and human hepatocellular carcinoma HepG2 cells. Compound ZL-1 exhibited anti-cancer activity with IC50 of 14 nM and 24 nM against human colon cancer HCT116 cells and human hepatocellular carcinoma HepG2 cells, respectively. Cell cycle analysis in MDA-MB-231 suggested ZL-3 inhibited cell growth through arresting cells at the G2/M phase of the cell cycle. Further tests showed a significant improvement in aqueous solubility of ZL-1 and ZL-7. This study suggested that glycosylation could be utilized as a useful strategy to optimize lamellarin D derivatives as Topo I inhibitors and anticancer agents.

Concise synthesis and in vitro anticancer activity of benzo[g][1]benzopyrano[4,3-b]indol-6(13H)-ones (BBPIs), topoisomerase I inhibitors based on the marine alkaloid lamellarin.

Benzo[g][1]benzopyrano[4,3-b]indol-6(13H)-ones (BBPIs) are potent anticancer compounds having unique BBPIs ring system designed on the basis of the marine natural product lamellarin D. In this study, we describe an alternative synthesis of a 2-demethoxy series of BBPIs, employing van Leusen pyrrole synthesis and an intramolecular Heck reaction as the key reactions. Cytotoxicity of the derivatives against several cancer and normal cell lines is reported.

Copper(I)-Catalyzed Nitrile-Addition/N-Arylation Ring-Closure Cascade: Synthesis of 5,11-Dihydro-6H-indolo[3,2-c]quinolin-6-ones as Potent Topoisomerase-I Inhibitors.

In this paper, we present a copper(I)-catalyzed nitrile-addition/N-arylation ring-closure cascade for the synthesis of 5,11-dihydro-6H-indolo[3,2-c]quinolin-6-ones from 2-(2-bromophenyl)-N-(2-cyanophenyl)acetamides. Using CuBr and t-BuONa in dimethylformamide (DMF) as the optimal reaction conditions, the cascade reaction gave the target products, in high yields, with a good substrate scope. Application of the cascade reaction was demonstrated on the concise total syntheses of alkaloid isocryptolepine. Further optimization of the products from the cascade reaction led to 3-chloro-5,12-bis[2-(dimethylamino)ethyl]-5,12-dihydro-6H-[1,3]dioxolo[4',5':5,6]indolo[3,2-c]quinolin-6-one (2k), which exhibited the characteristic DNA topoisomerase-I inhibitory mechanism of action with potent in vitro anticancer activity. Compound 2k actively inhibited ARC-111- and SN-38-resistant HCT-116 cells and showed in vivo activity in mice bearing human HCT-116 and SJCRH30 xenografts. The interaction of 2k with the Top-DNA cleavable complex was revealed by docking simulations to guide the future optimization of 5,11-dihydro-6H-indolo[3,2-c]quinolin-6-ones as topoisomerase-I inhibitors.

Design and Synthesis of Arylnaphthalene Lignan Lactone Derivatives as Potent Topoisomerase Inhibitors.

BACKGROUND: Arylnaphthalene lignan lactones are a class of natural products containing the phenyl-naphthyl skeleton. Some arylnaphthalene lignan lactones have been used in clinical practice as antitumor agents, due to their cytotoxicity and inhibitory activities against DNA topoisomerase I (Topo I) and topoisomerase II (Topo II). OBJECTIVE: This study presents the design and synthesis of arylnaphthalene lignan lactones derivatives. The inhibitory activities against Topo I and Topo IIα and antitumor activities of these compounds were assayed. METHODS: A series of arylnaphthalene lignan lactones derivatives have been designed and synthesized, using the Diels-Alder reaction and Suzuki reaction as the key steps. Their antiproliferation activities were evaluated by sulforhodamine B assay on human breast cancer MDAMB-231, MDA-MB-435 and human cervical cancer HeLa cells. DNA relaxation assays were employed to examine the inhibitory activity of compounds 1-22 on Topo I and Topo IIα in vitro. Flow cytometry analysis was performed to study the drug effects on cell cycle progressions. RESULTS: Seven compounds exhibited the modest anti-proliferation activity with IC50 values between 1.36 and 20 µM. Compounds 3, 19 and 22 showed potent inhibitory activities with IC50 values less than 1 µM. DNA relaxation assay revealed that compound 22 showed potent inhibitory activity against Topo IIα in vitro. Compound 22 also induced DNA breaks in MDA-MB-435 cells evidenced by comet tails and the accumulation of γ-H2AX foci. The ability of 22 in inducing DNA breaks mediated by Topo IIα resulted in G2/M phase arrest and apoptosis. CONCLUSION: This work indicates that arylnaphthalene lignan lactones derivatives represent a novel type of Topo IIα inhibitory scaffold for developing new antitumor chemotherapeutic agents.