Novel diindoloazepinone derivatives as DNA minor groove binding agents with selective topoisomerase I inhibition: Design, synthesis, biological evaluation and docking studies

Structure-based drug design of DNA minor groove binders and evaluation of their antibacterial and anticancer properties

Antimicrobial and chemotherapy resistance are escalating medical problem of paramount importance. Yet, research for novel antimicrobial and anticancer agents remains lagging behind. With their reported medical applications, DNA minor groove binders (MGBs) are worthy of exploration. In this study, the approach of structure-based drug design was implemented to generate 11 MGB compounds including a novel class of bioactive alkyne-linked MGBs. The NCI screening protocol was utilized to evaluate the antitumor activity of the target MGBs. Furthermore, a variety of bactericidal, cytopathogenicity, MIC90, and cytotoxicity assays were carried out using these MGBs against 6 medically relevant bacteria: Salmonella enterica, Escherichia coli, Serratia marcescens, Bacillus cereus, Streptococcus pneumoniae and Streptococcus pyogenes. Moreover, molecular docking, molecular dynamic simulations, DNA melting, and isothermal titration calorimetry (ITC) analyses were utilized to explore the binding mode and interactions between the most potent MGBs and the DNA duplex d(CGACTAGTCG)2. NCI results showed that alkyne-linked MGBs (26 & 28) displayed the most significant growth inhibition among the NCI-60 panel. In addition, compounds MGB3, MGB4, MGB28, and MGB32 showed significant bactericidal effects, inhibited B. cereus and S. enterica-mediated cytopathogenicity, and exhibited low cytotoxicity. MGB28 and MGB32 demonstrated significant inhibition of S. pyogenes, whereas MGB28 notably inhibited S. marcescens and all four minor groove binders significantly inhibited B. cereus. The ability of these compounds to bind with DNA and distort its groove dimensions provides the molecular basis for the allosteric perturbation of proteins-DNA interactions by MGBs. This study shed light on the mechanism of action of MGBs and revealed the important structural features for their antitumor and antibacterial activities, which are important to guide future development of MGB derivatives as novel antibacterial and anticancer agents.

Hydrazyl hydroxycoumarins as new potential conquerors towards Pseudomonas aeruginosa

A class of unique hydrazyl hydroxycoumarins (HHs) as novel structural scaffold was developed to combat dreadful bacterial infections. Some HHs could effectively suppress bacterial growth at low concentrations, especially, pyridyl HH 7 exhibited a good inhibition against Pseudomonas aeruginosa 27853 with a low MIC value of 0.5 μg/mL, which was 8-fold more active than norfloxacin. Furthermore, pyridyl HH 7 with low hemolytic activity and low cytotoxicity towards NCM460 cells showed much lower trend to induce the drug-resistant development than norfloxacin. Preliminarily mechanism exploration indicated that pyridyl HH 7 could eradicate the integrity of bacterial membrane, result in the leakage of intracellular proteins, and interact with bacterial DNA gyrase via non-covalent binding, and ADME analysis manifested that compound 7 gave good pharmacokinetic properties. These results suggested that the newly developed hydrazyl hydroxycoumarins as potential multitargeting antibacterial agents should be worthy of further investigation for combating bacterial infection.

Overview of the New Bioactive Heterocycles as Targeting Topoisomerase Inhibitors Useful Against Colon Cancer

Colorectal cancer (CRC) is the third most common cancer globally, with high mortality. Metastatic CRC is incurable in most cases, and multiple drug therapy can increase patients' life expectancy by 2 to 3 years. Efforts are being made to understand the relationship between topoisomerase enzymes and colorectal cancer. Some studies have shown that higher expression of these enzymes is correlated to a poor prognosis for this type of cancer. One of the primary drugs used in the treatment of CRC is Irinotecan, which can be used in monotherapy or, more commonly, in therapeutic schemes such as FOLFIRI (Fluorouracil, Leucovorin, and Irinotecan) and CAPIRI (Capecitabine and Irinotecan). Like Camptothecin, Irinotecan and other compounds have a mechanism of action based on the formation of a ternary complex with topoisomerase I and DNA providing damage to it, therefore leading to cell death. Thus, this review focused on the principal works published in the last ten years that demonstrate a correlation between the inhibition of different isoforms of topoisomerase and in vitro cytotoxic activity against CRC by natural products, semisynthetic and synthetic compounds of pyridine, quinoline, acridine, imidazoles, indoles, and metal complexes. The results revealed that natural compounds, semisynthetic and synthetic derivatives showed potential in vitro cytotoxicity against several colon cancer cell lines, and this activity was often accompanied by the ability to inhibit both isoforms of topoisomerase (I and II), highlighting that these enzymes can be promising targets for the development of new chemotherapy against CRC. Pyridine analogs were considered the most promising for this study, while the evaluation of the real potential of natural products was limited by the lack of information in their work. Moreover, the complexes, although promising, presented as the main limitation the lack of selectivity.

Design, synthesis, and antitumor evaluation of morpholine substituted bisnaphthalimides as DNA targeting agents

A series of mono- and bisnaphthalimides derivatives containing 3-nitro and 4-morpholine moieties were designed, synthesized, and evaluated for their in vitro anticancer activities against four cancer cell lines. Some compounds exhibited relatively good antiproliferative activity on the cell lines tested, in comparison with mitonafide and amonafide. It is noteworthy that bisnaphthalimide A6 was identified as the most potent compound in anti-proliferation against MGC-803 cells, with an IC₅₀ lowered to 0.09 μM, a far greater potency than that of mono-naphthalimide A7, mitonafide, and amonafide. A gel electrophoresis assay revealed that DNA and Topo I were the potential targets of compounds A6 and A7. The treatment of CNE-2 cells with compounds A6 and A7 resulted in an S phase cell cycle arrest, accompanied by the upregulation of the expression levels of the antioncogene p27 and the down-regulation of the expression levels of CDK2 and cyclin E. In addition, compounds A6 and A7-induced apoptosis was further confirmed by flow cytometry, ROS generation assay, and Hoechst 33,258 staining. In particular, in vivo antitumor assay results revealed that bisnaphthalimide A6 exhibited potent anticancer efficiency in an MGC-803 xenograft tumor model, in comparison with mitonafide, and had lower toxicity than mono-naphthalimide A7. In brief, the results suggested that bisnaphthalimide derivatives containing 3-nitro and 4-morpholine moieties might serve as DNA binding agents for the development of new antitumor agents.

An inorganic-organic-polymeric nanovehicle for targeting delivery of doxorubicin: Rational assembly, pH-stimulus release, and dual hyperthermia/chemotherapy of hepatocellular carcinoma

Efficiently synergistic therapy of hepatocellular carcinoma (HCC) by chemotherapeutic drug and photothermal agent remains a considerable challenge. Here, we report a nanodrug that integrates specific hepatoma-targeted delivery, pH-triggered drug release, and cooperative photothermal-chemotherapy function. By grafting the easily self-assembled CuS@polydopamine (CuS@PDA) nanocapsulation with polyacrylic acid (PAA), an inorganic-organic-polymeric hybrid nanovehicle was developed as a dual photothermal agent and carrier for loading antitumor drug-doxorubicin (DOX) through electrostatic adsorption and chemical linking antibody against GPC3 commonly overexpressed in HCC, resulting in the nanodrug, CuS@PDA/PAA/DOX/GPC3. The multifunctional nanovehicle had excellent biocompatibility, stability, and high photothermal conversion efficiency, due to the rationally designed binary CuS@PDA photothermal agent. The 72-h accumulative drug release in pH 5.5 tumor microenvironment can reach up to 84%, far higher than 15% measured in pH 7.4 condition. Notably, in contrast to the merely 20% survival rate of H9c2 and HL-7702 cells exposed to free DOX, their viabilities in the nanodrug circumstance can maintain 54% and 66%, respectively, suggesting the abated toxicity to the normal cell lines. When exposed to the hepatoma-targeting nanodrug, the viability of HepG2 cells was found to be 36%, which further drastically declined to 10% plus 808-nm NIR irradiation. Moreover, the nanodrug is potent to cause tumor ablation in HCC-modeled mice, and the therapeutic efficacy can be greatly enhanced under NIR stimulus. Histology analyses reveal that the nanodrug can effectively alleviate the chemical damage to heart and liver, as compared to free DOX. This work thus offers a facile strategy for design of targeting anti-HCC nanodrug toward combined photothermal-chemotherapy.

Synthesis and biological evaluation of 1-phenyl-4,6-dihydrobenzo[b]pyrazolo[3,4-d]azepin-5(1H)-one/thiones as anticancer agents

Cancer is associated with uncontrolled cell proliferation invading adjoining tissues and organs. Despite the availability of several chemotherapeutic agents, the constant search for newer approaches and drugs is necessitated owing to the ever-growing challenge of resistance. Over the years, DNA has emerged as an important druggable therapeutic drug due to its role in critical cellular processes such as cell division and maintenance. Further, evading apoptosis stands out as a hallmark of cancer. Hence, designing new compounds that would target DNA and induce apoptosis plays an important role in cancer therapy. In the current work, we carried out the synthesis and anticancer evaluation of 1-aryl-4,6-dihydrobenzo[b]pyrazolo[3,4-d]azepin-5(1H)-ones/thiones (26 compounds) against selected human cancer cell lines. Among these, compounds 8ae, 8ad, 8cf, 10ad and Kenpaullone have shown good inhibitory properties against HeLa cells (IC₅₀ < 2 µM) with good selectivity over the non-cancerous human embryonic kidney (Hek293T) cells. In cell cycle analysis, the compounds 8ad and 8cf have exhibited G₂/M cell cycle arrest in HeLa cells. In addition, the compounds 8ad and 8cf induced apoptosis in a dose-dependent manner in the Annexin-V FITC staining assay. The DAPI staining clearly demonstrated the condensed and fragmented nuclei in 8ad, 8cf, 8ae and Kenpaullone-treated HeLa cells. In addition, these compounds strongly suppressed the healing after 48 h in in vitro cell migration assay. The DNA binding experiments indicated that compounds 8ae, 8cf, and 8ad as well as Kenpaullone interact with double-stranded DNA by binding in grooves which may interrupt the DNA replication and kill fast-growing cells. Molecular docking studies revealed the binding pose of 8ad and Kenpaullone at HT1 binding pocket of double-stranded DNA. Compounds 8ad and 8cf demonstrated moderate topo II inhibition which could be a possible reason for their anticancer properties. Compounds 8ad and 8cf may cause the topo II and DNA covalent complex, which leads to the inhibition of DNA replication and transcription. This eventually increases the DNA damage in cells and promotes cell apoptosis. With the above interesting biological profile, the new 1-aryl-2,6-dihydrobenzo[b]pyrazolo[3,4-d]azepin-5(4H)-one/thione derivatives have emerged as promising leads for the discovery of new anticancer agents.

Electrochemical detection of the oxidative damage of a potential pyrimido[5,4-g]pteridine-derived antitumor agent toward DNA

In this work, we design and synthesize 2,2'-(7,9-dimethyl-2,4,6,8-tetraoxo-6,7,8,9-tetrahydropyrimido[5,4-g]pteridine-1,3(2H,4H)-diyl)bis(N,N-bis(2-chloroethyl)acetamide) (PT-MCA) as a novel DNA intercalator and potential antitumor agent. Electrochemical analysis reveals the redox process of PT-MCA on the electrode surface. The bioelectrochemical sensors are obtained by modifying the surface of GCE with calf thymus DNA (ctDNA), poly (dG), poly (dA), and G-quadruplex, respectively. The DNA oxidative damage induced by PT-MCA is investigated by comparing the peak intensity change of dGuo and dAdo and monitoring the peaks of the oxidation products of guanine and/or adenine (8-oxoGua and/or 2,8-oxoAde). UV-vis absorption and fluorescence spectra and gel electrophoresis are further employed to understand the intercalation of PT-MCA into DNA base pairs. Moreover, PT-MCA is proved to exhibit stronger anti-proliferation activity than mitoxantrone against both 4T1 and B16-F10 cancer cells. At last, the oxidative damage of PT-MCA toward ctDNA is not interfered by the coexistence of ions and also can be detected in real serums.

Synthesis, biological evaluation, and in silico studies of indole-tethered pyrazoline derivatives as anticancer agents targeting topoisomerase IIα

We herein report a new series of indole-tethered pyrazoline derivatives as potent anticancer agents. A total of 12 compounds were designed and synthesized by conventional as well as microwave-irradiated synthesis methods. The latter method results in a significant reduction in the duration of reaction along with improved yields. All synthesized derivatives (7a-7l) were evaluated for their cytotoxic activity against A431, HeLa, and MDAMB-231 cell lines. Compounds 7a and 7b were found most potent in the series and demonstrated an IC₅₀ value of 3.17 and 5.16 µM against the A431 cell line, respectively, compared to the standard drug doxorubicin. Compounds 7a and 7b significantly suppress colony formation, migration, and S phase cell cycle arrest of A431 cells. Furthermore, compound 7a regulated the expression of apoptotic proteins causing the downregulation of procaspase 3/9, antiapoptotic protein Bcl-xL, and upregulation of proapoptotic protein Bax in a dose-dependent manner. Topoisomerase enzyme inhibition assay confirmed that compounds 7a and 7b can significantly inhibit topoisomerase IIα. In vivo oral acute toxicity of compounds 7a and 7b revealed that both compounds are safe compared to doxorubicin; cardiomyopathy studies showed normal architecture of cardiomyocytes and myofibrils. In addition, molecular docking studies revealed the possible interaction of compounds 7a and 7b within the active binding site of the topoisomerase enzyme. The 100 ns molecular dynamic simulation of compounds 7a and 7b proved that both compounds validate all screening parameters.

Synthesis of Azepinoindoles via Pd-Catalyzed C(sp2)-H Imidoylative Cyclization Reactions

An efficient and convenient method for the construction of diverse free (N-H)-benzazepinoindoles by Pd-catalyzed C(sp²)-H imidoylative cyclization of 3-(2-isocyanobenzyl)-1H-indoles was developed. The reaction shows a wide substrate scope and can be scaled up, providing a practical route to valuable bioactive azepinoindoles.

Exploration of mercaptoacetamide-linked pyrimidine-1,3,4-oxadiazole derivatives as DNA intercalative topo II inhibitors: Cytotoxicity and apoptosis induction

The design and synthesis of a new series of mercaptoacetamide-linked pyrimidine-1,3,4-oxadiazole hybrids was accomplished. The in vitro cytotoxic potential of these new compounds was evaluated against lung cancer (A549), prostate cancer (PC-3, DU-145) and human embryonic kidney (HEK) cell lines. Compound 9p showed the highest potency on A549 cells with an IC₅₀ value of 3.8 ± 0.02 μM. Moreover, 9p was found to be 25-fold more selective towards cancer cell lines than the non-cancerous (HEK) cell line. The target-based assay revealed the inhibition of the topoisomerase II enzyme by compound 9p. UV-visible spectroscopy, fluorescence, circular dichroism (CD), and viscosity studies inferred the intercalative property and effective binding of compound 9p with CT-DNA. Apoptosis induced by the compound 9p was observed by various morphological staining assays, i.e, DAPI, EtBr/AO. Further, the molecular modeling studies revealed the binding of compound 9p at the active site of the DNA-topoisomerase II complex while the physicochemical properties were in the recommended range. Finally, mercaptoacetamide-linked pyrimidine-1,3,4-oxadiazole derivatives can be considered as a promising scaffold for development as effective anticancer agents and topoisomerase II inhibitors.

Biological properties of aqueous extract and pyranocoumarins obtained from the bark of Brosimum alicastrum tree

ETHNOPHARMACOLOGICAL RELEVANCE

Brosimum alicastrum is a tree used in Mexican traditional medicine for the treatment of several diseases, including uterine cancer.

AIM OF THE STUDY

In this study, the cytotoxic activity of aqueous extract of B. alicastrum bark and isolated compounds xanthyletin (1), luvangetin (2), and 8-hydroxyxanthyletin (3) on three human cancer cell lines was determined. Moreover, the biological effects of 8-hydroxyxanthyletin (3) were investigated.

MATERIALS AND METHODS

The aqueous extract was prepared according to the ethnomedical information reported from the bark. The compounds were purified using chromatographic methods and their structures were elucidated by spectroscopic techniques. The antiproliferative effect of aqueous extract and isolates was determined in three human tumor cell lines: HeLa, A2780, and MSTO-211H, and evaluated by trypan blue exclusion assay. The cell cycle and the mitochondrial transmembrane potential (ΔΨ) were measured by flow cytometry, while Reactive Oxygen Species (ROS) levels were determined using 2',7'-dichlorofluorescein diacetate (DCFH-DA) probe. The effect on the relaxation activity, mediated by topoisomerase I and II, was evaluated by electrophoresis, and docking studies were performed using Autodock 4.2 to analyze the interactions.

RESULTS

Aqueous extract of B. alicastrum bark showed significant antiproliferative effect on the evaluated cancer cell lines (IC₅₀ = 1.6, 8.5, and 21.4 μg/ml). Four coumarins were identified in the extract and three of them were also evaluated. A2780 cell line exhibited higher sensitivity against pyranocoumarins with IC₅₀ values ranging from 32 to 47 μmol/l. 8-hydroxyxanthyletin (3) exerts an interesting effect on human topoisomerases I and II, by inhibiting the enzymes at concentrations comparable to those obtained in antiproliferative assay. Moreover, 8-hydroxyxanthyletin (3) arrests the cell cycle at G₀/G₁ phase and induces in A2780 cells a concentration-dependent increase in ROS levels. The results of molecular docking suggest the participation of the hydroxyl group in the interaction between 8-hydroxyxanthyletin (3) and topoisomerase I and II.

CONCLUSION

This is the first report that demonstrates the cytotoxic activity of the aqueous extract of B. alicastrum bark, and determines the main metabolites.

Design and synthesis of Aza-boeravinone derivatives as potential novel topoisomerase I inhibitors

Based on the structural skeleton of natural products boeravinones, two types of 6H-chromeno[3,4-b]quinoline derivatives were designed and synthesized by nitrogen atom substitution strategy. Then, their cytotoxic activities were evaluated against six human tumor cell lines including HepG2 (hepatocellular carcinoma), A2780 (ovarian cancer), Hela (cervical cancer), HCT116 (colorectal cancer), SW1990 (pancreatic cancer), and MCF7 (breast cancer). The results showed that compounds ZML-8 and ZML-14 exhibited robust inhibitory activities against HepG2 cells with IC₅₀ values of 0.58 and 1.94 μM, respectively. In addition, ZML-8 and ZML-14 showed higher selectivity against HepG2 and L-02 cells than Topotecan. Mechanistically, ZML-8 and ZML-14 not only induced cell cycle arrest in the G2/M phase and cell apoptosis, but also dose-dependently inhibited topoisomerase I activity and induced DNA damage in HepG2 cells. Molecular docking showed that ZML-8 and ZML-14 could interact with topoisomerase I-DNA complex with a similar binding mode to Topotecan. Inhibitory activities of these two compounds on topoisomerase I were then confirmed in both cell-free systems and in whole-cell lysates. Taken together, compounds ZML-8 and ZML-14 merit further development as a new generation of non-camptothecin topoisomerase I inhibitors for the treatment of cancer.

A facile reaction to access novel structural sulfonyl-hybridized imidazolyl ethanols as potential DNA-targeting antibacterial agents

A novel type of sulfonyl-hybridized imidazolyl ethanols as potential DNA-targeting antibacterial agents was constructed via the unique ring-opened reaction of oxiranes by imidazoles for the first time. Some developed target hybrids showed potential antimicrobial potency against the tested microbes. Especially, imidazole derivative 5f could strongly suppressed the growth of MRSA (MIC = 4 μg/mL), which was 2-fold and 16-fold more potent than the positive control sulfathiazole and norfloxacin. This compound exhibited quite low propensity to induce bacterial resistance. Antibacterial mechanism exploration indicated that compound 5f could embed in MRSA DNA to form steady 5f-DNA complex, which possibly hinder DNA replication to exert antimicrobial behavior. Molecular docking showed that molecule 5f could bind with dihydrofolate synthetase through hydrogen bonds. These results implied that imidazole derivative 5f could be served as a promising molecule for the exploration of novel antibacterial candidates.

Molecular design and preparation of 2-aminothiazole sulfanilamide oximes as membrane active antibacterial agents for drug resistant Acinetobacter baumannii

A series of 2-aminothiazole sulfanilamide oximes were developed as new membrane active antibacterial agents to conquer the microbial infection. Benzoyl derivative 10c was preponderant for the treatment of drug-resistant A. baumannii infection in contrast to norfloxacin and exerted excellent biocompatibility against mammalian cells including erythrocyte and LO2 cell line. Meanwhile, it had ability to eradicate established biofilm to alleviate the resistance burden. Mechanism investigation elucidated that compound 10c was able to disturb the membrane effectively and inhibit lactic dehydrogenase, which led to cytoplasmic content leakage. The cellular redox homeostasis was interfered via the production of reactive oxygen and nitrogen species (RONS), which further contributed to respiratory pathway inactivation and reduction of GSH activity. This work indicated that 2-aminothiazole sulfanilamide oximes could be a promising start for the exploitation of novel antibacterial agents against pathogens.

Fused-azepinones: Emerging scaffolds of medicinal importance

Hymenialdisine an alkaloid of oroidin class has drawn the attention of researchers owing to its unique structural features and interesting biological properties. Hymenialdisine exhibited promising inhibitory activity against a number of therapeutically important kinases viz., CDKs, GSK-3β etc., and showed anti-cancer, anti-inflammatory, anti-HIV, neuroprotective, anti-fouling, anti-plasmodium properties. Hymenialdisine and other structurally related oroidin alkaloids such as dibromo-hymenialdisine, stevensine, hymenin, axinohydantoin, spongicidines A-D, latonduines and callyspongisines contain pyrrolo[2,3-c] azepin-8-one core in common. Keeping in view of the interesting structural and therapeutic features of HMD, several structural modifications were carried around the fused-azepinone core which resulted in a number of diverse structural motifs like indolo-azepinones, paullones, aza-paullones, darpones and 5,7-dihydro-6H-benzo[b]pyrimido[4,5-d] azepin-6-one. In this review, an attempt is made to collate and review the structures of diverse hymenialdisine and related fused-azepinones of synthetic/natural origin and their biological properties.

Unique para-aminobenzenesulfonyl oxadiazoles as novel structural potential membrane active antibacterial agents towards drug-resistant methicillin resistant Staphylococcus aureus

A class of structurally unique para-aminobenzenesulfonyl oxadiazoles as new potential antimicrobial agents was designed and synthesized from acetanilide. Some target para-aminobenzenesulfonyl oxadiazoles showed antibacterial potency. Noticeably, hexyl derivative 8b (MIC = 1 μg/mL) was more active than norfloxacin against drug resistant MRSA. Compound 8b was able to disturb the membrane effectively and intercalate into deoxyribonucleic acid (DNA) to form a steady 8b-DNA complex, which might be responsible for bacterial metabolic inactivation. Molecular docking indicated that 8b could interact with DNA topoisomerase IV through noncovalent interactions to form a supramolecular complex and hinder the function of this enzyme. These results indicated that hexyl derivative 8b deserved further investigation as a new lead compound.

Syntheses and medicinal chemistry of azepinoindolones: a look back to leap forward

Nitrogen-containing heterocyclic scaffolds constitute nearly 75% of small molecules which favorably act as drug candidates. For the past few decades, numerous natural and synthetic indole-based scaffolds have been reported for their diverse pharmacological profiles. In particular, indole-fused azepines, termed azepinoindolones, have come under the radar of medicinal chemists owing to their synthetic and pharmacological importance. A plethora of literature reports has been generated thereof, which calls for the need for the compilation of information to understand their current status in drug discovery. Accumulating reports of evidence suggest that compounds containing this privileged scaffold display their cytotoxic effects via inhibition of kinase, topoisomerase I, mitochondrial malate dehydrogenase (mMDH), and tubulin polymerization and as DNA minor groove binding agents. Herein, we endeavor to present a closer look at the advancements of various synthetic and derivatization methods of azepinoindolone-based compounds. We have further extended our efforts to discuss the pharmacological effects of azepinoindolones in the whole range of medicinal chemistry as anti-Alzheimer, anticancer, anti-inflammatory, antidiabetic, antileishmanial, and antipyranosomal agents and as drug delivery vectors. Our analysis of recent advances reveals that azepinoindolones will continue to serve as potential pharmaceutical modalities in the years to come and their substantial pool of synthetic methods will be ever expanding.

Novel urea linked ciprofloxacin-chalcone hybrids having antiproliferative topoisomerases I/II inhibitory activities and caspases-mediated apoptosis

A novel series of urea-linked ciprofloxacin (CP)-chalcone hybrids 3a-j were synthesized and screened by NCI-60 cancer cell lines as potential cytotoxic agents. Interestingly, compounds 3c and 3j showed remarkable antiproliferative activities against both colon HCT-116 and leukemia SR cancer cells compared to camptothecin, topotecan and staurosporine with IC₅₀ = 2.53, 2.01, 17.36, 12.23 and 3.1 μM for HCT-116 cells, respectively and IC₅₀ = 0.73, 0.64, 3.32, 13.72 and 1.17 μM for leukemia SR cells, respectively. Also, compounds 3c and 3j exhibited inhibitory activities against Topoisomerase (Topo) I with % inhibition = 51.19% and 56.72%, respectively, compared to camptothecin (% inhibition = 60.05%) and Topo IIβ with % inhibition = 60.81% and 60.06%, respectively, compared to topotecan (% inhibition = 71.09%). Furthermore, compound 3j arrested the cell cycle of leukemia SR cells at G2/M phase. It induced apoptosis both intrinsically and extrinsically via activation of proteolytic caspases cascade (caspases-3, -8, and -9), release of cytochrome C from mitochondria, upregulation of proapoptotic Bax and down-regulation of Bcl-2 protein level. Thus, the new ciprofloxacin derivative 3j could be considered as a potential lead for further optimization of antitumor agent against leukemia and colorectal carcinoma.