Naphthoquinone-Quinolone Hybrids with Antitumor Effects on Breast Cancer Cell Lines-From the Synthesis to 3D-Cell Culture Effects.

Breast cancer stands as one of the foremost cause of cancer-related deaths globally, characterized by its varied molecular subtypes. Each subtype requires a distinct therapeutic strategy. Although advancements in treatment have enhanced patient outcomes, significant hurdles remain, including treatment toxicity and restricted effectiveness. Here, we explore the anticancer potential of novel 1,4-naphthoquinone/4-quinolone hybrids on breast cancer cell lines. The synthesized compounds demonstrated selective cytotoxicity against Luminal and triple-negative breast cancer (TNBC) cells, which represent the two main molecular types of breast cancer that depend most on cytotoxic chemotherapy, with potency comparable to doxorubicin, a standard chemotherapeutic widely used in breast cancer treatment. Notably, these derivatives exhibited superior selectivity indices (SI) when compared to doxorubicin, indicating lower toxicity towards non-tumor MCF10A cells. Compounds 11a and 11b displayed an improvement in IC50 values when compared to their precursor, 1,4-naphthoquinone, for both MCF-7 and MDA-MB-231 and a comparable value to doxorubicin for MCF-7 cells. Also, their SI values were superior to those seen for the two reference compounds for both cell lines tested. Mechanistic studies revealed the ability of the compounds to induce apoptosis and inhibit clonogenic potential. Additionally, the irreversibility of their effects on cell viability underscores their promising therapeutic utility. In 3D-cell culture models, the compounds induced morphological changes indicative of reduced viability, supporting their efficacy in a more physiologically relevant model of study. The pharmacokinetics of the synthesized compounds were predicted using the SwissADME webserver, indicating that these compounds exhibit favorable drug-likeness properties and potential as antitumor agents. Overall, our findings underscore the promise of these hybrid compounds as potential candidates for breast cancer chemotherapy, emphasizing their selectivity and efficacy.

Exploring the Antimicrobial and Antitumoral Activities of Naphthoquinone-Grafted Chitosans.

Biopolymers obtained from natural macromolecules are noteworthy among materials presenting high biocompatibility and adequate biodegradability, as is the case of chitosan (CS), making this biopolymeric compound a suitable drug delivery system. Herein, chemically-modified CS were synthetized using 2,3-dichloro-1,4-naphthoquinone (1,4-NQ) and the sodium salt of 1,2-naphthoquinone-4-sulfonic acid (1,2-NQ), producing 1,4-NQ-CS and 1,2-NQ-CS by three different methods, employing an ethanol and water mixture (EtOH:H2O), EtOH:H2O plus triethylamine and dimethylformamide. The highest substitution degree (SD) of 0.12 was achieved using water/ethanol and triethylamine as the base for 1,4-NQ-CS and 0.54 for 1,2-NQ-CS. All synthesized products were characterized by FTIR, elemental analysis, SEM, TGA, DSC, Raman, and solid-state NMR, confirming the CS modification with 1,4-NQ and 1,2-NQ. Chitosan grafting to 1,4-NQ displayed superior antimicrobial activities against Staphylococcus aureus and Staphylococcus epidermidis associated with improved cytotoxicity and efficacy, indicated by high therapeutic indices, ensuring safe application to human tissue. Although 1,4-NQ-CS inhibited the growth of human mammary adenocarcinoma cells (MDA-MB-231), it is accompanied by cytotoxicity and should be considered with caution. The findings reported herein emphasize that 1,4-NQ-grafted CS may be useful in protecting injured tissue against bacteria, commonly found in skin infections, until complete tissue recovery.

Synthesis, Biological Evaluation and Molecular Modeling Studies of Naphthoquinone Sulfonamides and Sulfonate Ester Derivatives as P2X7 Inhibitors.

ATP acts in the extracellular environment as an important signal, activating a family of receptors called purinergic receptors. In recent years, interest in the potential therapeutics of purinergic components, including agonists and antagonists of receptors, has increased. Currently, many observations have indicated that ATP acts as an important mediator of inflammatory responses and, when found in high concentrations in the extracellular space, is related to the activation of the P2X7 purinergic receptor. In this sense, the search for new inhibitors for this receptor has attracted a great deal of attention in recent years. Sulfonamide derivatives have been reported to be potent inhibitors of P2X receptors. In this study, ten naphthoquinone sulfonamide derivatives and five naphthoquinone sulfonate ester derivatives were tested for their inhibitory activity on the P2X7 receptor expressed in peritoneal macrophages. Some compounds showed promising results, displaying IC50 values lower than that of A740003. Molecular docking and dynamic studies also indicated that the active compounds bind to an allosteric site on P2X7R. The binding free energy indicates that sulfonamides have an affinity for the P2X7 receptor similar to A740003. Therefore, the compounds studied herein present potential P2X7R inhibition.

Antitumoral effect of novel synthetic 8-hydroxy-2-((4-nitrophenyl)thio)naphthalene-1,4-dione (CNN16) via ROS-mediated DNA damage, apoptosis and anti-migratory effect in colon cancer cell line.

Colorectal cancer (CRC) is estimated as the third most incident cancer and second in mortality worldwide. Moreover, CRC metastasis reduces patients' survival rates. Thus, the study and identification of new compounds with anticancer activity selectively to tumor cells are encouraged in the CRC treatment. Naphtoquinones are compounds with several pharmacologic activities, including antitumoral properties. Therefore, this study aimed to investigate the anticancer mechanism of synthetic 8-Hydroxy-2-(P-Nitrothiophenol)-1,4-Naphthoquinone (CNN16) in colon cancer cell line HCT-116. CNN16 showed an IC50 of 5.32 µM in HCT-116, and 9.36, 10.77, and 24.57 µM in the non-cancerous cells MRC-5, MNP-01, and PMBC, respectively, evaluated by the MTT assay. CNN16 showed an anticlonogenic effect in HCT-116 and induced cell fragmentation identified by flow cytometry analysis. Furthermore, we observed that CNN16 presented genotoxicity and induces reactive oxygen species (ROS) after 3 h of treatment visualized by alkaline comet assay and DCFH-DA dye fluorescence, respectively. Furthermore, CNN16 caused cellular membrane disruption, reduction in the mitochondrial membrane polarization, and the presence of apoptotic bodies and chromatin condensation was visualized by differential stained (HO/FD/PI) in fluorescent microscopy along with PARP1, TP53, BCL-2, and BAX analyzed by RT-qPCR. Results also evidenced inhibition in the migratory process analyzed by wound healing assay. Therefore, CNN16 can be considered as a potential new leader molecule for CRC treatment, although further studies are still necessary to comprehend the effects of CNN16 in in vivo models to evaluate the anti-migratory effect, and toxicology and assure compound safety and selectively.

Pro-Apoptotic Antitumoral Effect of Novel Acridine-Core Naphthoquinone Compounds against Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) is a global public health problem with high incidence and mortality. The chemotherapeutic agents used in the clinic, alone or in combination, usually lead to important side effects. Thus, the discovery and development of new antineoplastic drugs are essential to improve disease prognosis and reduce toxicity. In the present study, acridine-core naphthoquinone compounds were synthesized and evaluated for their antitumor activity in OSCC cells. The mechanism of action, pharmacokinetics, and toxicity parameters of the most promising compound was further analyzed using in silico, in vitro, and in vivo methods. Among the derivatives, compound 4e was highly cytotoxic (29.99 µM) and selective (SI 2.9) at levels comparable and generally superior to chemotherapeutic controls. Besides, compound 4e proved to be non-hemolytic, stable, and well tolerated in animals at all doses tested. Mechanistically, compound 4e promoted cell death by apoptosis in the OSCC cell, and molecular docking studies suggested this compound possibly targets enzymes important for tumor progression, such as RSK2, PKM2, and topoisomerase IIα. Importantly, compound 4e presented a pharmacological profile within desirable parameters for drug development, showing promise for future preclinical trials.

Chitosans and Nanochitosans: Recent Advances in Skin Protection, Regeneration, and Repair.

Chitosan displays a dual function, acting as both an active ingredient and/or carrier for pharmaceutical bioactive molecules and metal ions. Its hydroxyl- and amino-reactive groups and acetylation degree can be used to adjust this biopolymer's physicochemical and pharmacological properties in different forms, including scaffolds, nanoparticles, fibers, sponges, films, and hydrogels, among others. In terms of pharmacological purposes, chitosan association with different polymers and the immobilization or entrapment of bioactive agents are effective strategies to achieve desired biological responses. Chitosan biocompatibility, water entrapment within nanofibrils, antioxidant character, and antimicrobial and anti-inflammatory properties, whether enhanced by other active components or not, ensure skin moisturization, as well as protection against bacteria colonization and oxidative imbalance. Chitosan-based nanomaterials can maintain or reconstruct skin architecture through topical or systemic delivery of hydrophilic or hydrophobic pharmaceuticals at controlled rates to treat skin affections, such as acne, inflammatory manifestations, wounds, or even tumorigenesis, by coating chemotherapy drugs. Herein, chitosan obtention, physicochemical characteristics, chemical modifications, and interactions with bioactive agents are presented and discussed. Molecular mechanisms involved in chitosan skin protection and recovery are highlighted by overlapping the events orchestrated by the signaling molecules secreted by different cell types to reconstitute healthy skin tissue structures and components.

Synthesis, characterization and utilization of a new series of 1,2,3-triazole derivatives to neutralize some toxic activities of Bothrops jararaca snake venom

Abstract Snake envenomation is a public health problem, and while serum therapy prevents death, the local effects of venoms can lead to amputations or morbidities. Thus, alternative treatments deserve attention. In this study, we tested eight derivatives of 1,2,3-triazole against some toxic activities of Bothrops jararaca venom. The derivatives were synthesized, and their structures analyzed by infrared and nuclear magnetic resonance. After that, the ability of compounds to inhibit hemolysis, coagulation, proteolysis, hemorrhaging, edema, and lethal activities of B. jararaca venom was investigated. The derivatives were incubated with B. jararaca venom (incubation protocol), administered before (prevention protocol) or after (treatment protocol) injecting venom into the mice. Then, hemorrhaging assay occurred. As a result, most of the derivatives inhibited the activities, even if they were incubated, injected before or after B. jararaca venom. However, the derivatives TRI 07 and TRI 18 seemed to be the most efficient in impairing hemorrhaging. The derivatives showed a low drug score of toxicity based on an in silico technique. Therefore, the derivatives fulfilled physicochemical and biological requirements to become drugs, and they may be a brand new initiative for designing antivenom molecules to complement antivenom therapy to efficiently block tissue necrosis or any other local effects.

(3,3'-Methylene)bis-2-hydroxy-1,4-naphthoquinones induce cytotoxicity against DU145 and PC3 cancer cells by inhibiting cell viability and promoting cell cycle arrest.

We developed a novel method for the synthesis of bis-naphthoquinones (BNQ), which are hybrids of lawsone (2-hydroxy-1,4-naphthoquinone) and 3-hydroxy-juglone (3,5-dihydroxy-1,4-naphthoquinone). The anticancer activity of three synthesized compounds, named 4 (RC10), 5 (RCDFC), and 6 (RCDOH) was evaluated in vitro against two metastatic prostate cancer (PCa) cell lines, DU145 and PC3, using MTT assays. We found that 4 (RC10) and 5 (RCDFC) induced cytotoxicity against DU145 and PC3 cells. Flow cytometry analysis revealed that these two compounds promoted cell cycle arrest in G1/S and G2/M phases, increased Sub-G1 peak and induced inhibition in cell viability. We also showed that these effects are cell-type context dependent and more selective for these tested PCa cells than for HUVEC non-tumor cells. The two BNQ compounds 4 (RC10) and 5 (RCDFC) displayed promising anticancer activity against the two tested metastatic PCa cell lines, DU145 and PC3. Their effects are mainly associated with inhibition of cell viability, possibly through apoptotic cell death, besides altering the SubG1, G1/S and G2/M phases of cell cycle. 5 (RCDFC) compound was found to be more selective than 4 (RC10), when comparing their cytotoxic effects in relation to HUVEC non-tumoral cells. Future work should also test these compounds in combination with other chemotherapeutic drugs to evaluate their effects on further sensitizing drug-resistant metastatic PCa cells.

A new synthetic antitumor naphthoquinone induces ROS-mediated apoptosis with activation of the JNK and p38 signaling pathways.

Quinones are plant-derived secondary metabolites that present diverse pharmacological properties, including antibacterial, antifungal, antiviral, anti-inflammatory, antipyretic and anticancer activities. In the present study, we evaluated the cytotoxic effect of a new naphthoquinone 6b,7-dihydro-5H-cyclopenta [b]naphtho [2,1-d]furan-5,6 (9aH)-dione) (CNFD) in different tumor cell lines. CNFD displayed cytotoxic activity against different tumor cell lines, especially in MCF-7 human breast adenocarcinoma cells, which showed IC50 values of 3.06 and 0.98 µM for 24 and 48 h incubation, respectively. In wound-healing migration assays, CNFD promoted inhibition of cell migration. We have found typical hallmarks of apoptosis, such as cell shrinkage, chromatin condensation, phosphatidylserine exposure, increase of caspases-9 and-3 activation, increase of internucleosomal DNA fragmentation without affecting the cell membrane permeabilization, increase of ROS production, and loss of mitochondrial membrane potential induced by CNFD. Moreover, gene expression experiments indicated that CNFD increased the expression of the genes CDKN1A, FOS, MAX, and RAC1 and decreased the levels of mRNA transcripts of several genes, including CCND1, CDK2, SOS1, RHOA, GRB2, EGFR and KRAS. The CNFD treatment of MCF-7 cells induced the phosphorylation of c-jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs) and inactivation of extracellular signal-regulated protein kinase 1/2 (ERK1/2). In a study using melanoma cells in a murine model in vivo, CNFD induced a potent anti-tumor activity. Herein, we describe, for the first time, the cytotoxicity and anti-tumor activity of CNFD and sequential mechanisms of apoptosis in MCF-7 cells. CNFD seems to be a promising candidate for anti-tumor therapy.

P2X7 receptor inhibition by 2-amino-3-aryl-1,4-naphthoquinones.

Extracellular ATP activates purinergic receptors such as P2X7, cationic channels for Ca2+, K+, and Na+. There is robust evidence of the involvement of these receptors in the immune response, so P2X7 receptors (P2X7R) are considered a potential therapeutic target for the development of anti-inflammatory drugs. Although there are many studies of the anti-inflammatory properties of naphthoquinones, these molecules have not yet been explored as P2X7 antagonists. In previous work, our group prepared 3-substituted (halogen or aryl) 2-hydroxy-1,4-naphthoquinones and studied their action on P2X7R. In this paper, eight 2-amino-3-aryl-1,4-naphthoquinones were evaluated to identify the inhibitory activity on P2X7R and the toxicological profile. Three analogues (AD-4CN, AD-4Me, and AD-4F) exhibited reduced toxicity for mammalian cells with CC50 values higher than 500 µM. These three 3-substituted 2-amino-1,4-naphthoquinones inhibited murine P2X7R (mP2X7R) in vitro. However, the analogues AD-4CN and AD-4Me showed low selectivity index values. AD-4F inhibited both mP2X7R and human P2X7R (hP2X7R) with IC50 values of 0.123 and 0.93 µM, respectively. Additionally, this analogue exhibited higher potency than BBG at inhibiting the ATP-induced release of IL-1ß in vitro. Carrageenan-induced paw edema in vivo was reversed for AD-4F with an ID50 value of 11.51 ng/kg. Although AD-4F was less potent than previous 3-substituted (halogen or aryl) 2-hydroxy-1,4-naphthoquinones such as AN-04in vitro, this 3-substituted 2-amino-1,4-naphthoquinone revealed higher potency in vivo to reduce the edematogenic response. In silico analysis suggests that the binding site of the novel 2-amino-3-aryl-1,4-naphthoquinone derivatives, including all the tautomeric forms, is located in the pore area of the hP2X7R model. Based on these results, we considered AD-4F to be a satisfactory P2X7R inhibitor. AD-4F might be used as a scaffold structure to design a novel series of inhibitors with potential inhibitory activity on murine (mP2X7R) and human (hP2X7R) P2X7 receptors.

NQO1 induction mediated by photodynamic therapy synergizes with ß-Lapachone-halogenated derivative against melanoma.

The elevated expression of NQO1 in many human solid tumors along with its ability to activate quinone-based anticancer agents makes it an excellent target for enzyme-directed drug development. NQO1 plays an important role in melanogenesis and given its correlation with a poor patient outcome we propose this enzyme as an intriguing target for molecular-based therapeutic regimen against melanoma. Unfortunately, the natural product ß-Lapachone (ß-Lap), whose antitumor activity is based on NQO1, reported dose-limiting toxicity which hampered its pre-clinical and clinical use. Therefore, new effective and safe therapeutic NQO1-bioactivatable agents for melanoma treatment are desirable. Regarding NQO1, we demonstrated that halogenated ß-Lap derivative named PFB is an excellent substrate and effective tumor-selective anticancer compound. In addition, PFB resulted more attractive than the parent ß-Lap for treating metastatic-derived melanoma cells. In this context, it would be interesting to design strategies to induce NQO1 activity in cancer cells as a promising combinatorial approach with bioreductive drugs. In this sense, we had reported that photodynamic therapy (PDT) significantly upregulated NQO1 expression. Based on this event, here we demonstrated that the cytotoxic regimen consisting of PFB plus PDT improved synergistic therapeutic combination on melanoma cells. In conclusion, our contribution provides a strong rationale for using therapies that associate photo- and chemotherapy to effectively treat melanoma with modular NQO1 status.

Synthesis and evaluation of the cytotoxic activity of Furanaphthoquinones tethered to 1H-1,2,3-triazoles in Caco-2, Calu-3, MDA-MB231 cells.

Naphthoquinones and 1,2,3-triazoles are structural pharmacophore that is known to impart several cancer cells. This work shows a synthetic methodology to obtain hybrid molecules involving naphthoquinone and triazol scaffold as multiple ligands. A simple and efficient synthetic route was used to prepare a series of sixteen compounds being eight 2-(1-aryl-1H-1,2,3-triazol-4-yl)-2,3-dihydronaphtho[1,2 b]furan-4,5-diones and eight 2-(1-aryl-1H-1,2,3-triazol-4-yl)-2,3-dihydronaphtho[2,3-b]furan-4,9-diones. These compounds were tested in MDA-MB231, Caco-2 and Calu-3 human cancer cells, and among them 7a was the most selective compound on Caco-2 cells, the most sensitized cell line in this study. In silico study suggest that the blockage of topoisomerase I and IIα may be one of the mechanisms of action responsible for the cytotoxic effect of 7a in Caco-2 cells.

Antileishmanial Activity of 2-Methoxy-4H-spiro-[naphthalene-1,2'-oxiran]-4-one (Epoxymethoxy-lawsone): A Promising New Drug Candidate for Leishmaniasis Treatment.

Epoxymethoxylawsone is a naphthoquinone derivative promising as drug candidate for the treatment of leishmaniases. In the present work the effectiveness of epoxymethoxylawsone, and meglumine antimoniate on Leishmania (Leishmania) amazonensis parasites and on mice paw lesions of infected BALB/c mice was assessed. In an intracellular amastigotes assay, the half-maximal inhibitory concentration (IC50) value for epoxymethoxylawsone was slightly higher (1.7-fold) than that found for meglumine antimoniate. The efficacy of both drugs became more evident after 48 h of exposure when either the oxirane compound and reference drug reached 18-fold and 7.4-fold lower IC50 values (0.40 ± 0.001 µM and 0.60 ± 0.02 µM), respectively. Promastigotes were also affected by epoxymethoxylawsone after 24 h of incubation (IC50 = 45.45 ± 5.0 µM), but with IC50 6-fold higher than those found for intracellular amastigotes. Cytotoxicity analysis revealed that epoxymethoxylawsone (CC50 = 40.05 ± µM) has 1.7-fold higher effects than meglumine antimoniate (CC50 = 24.14 ± 2.6 µM). Treatment of the paw lesion in infected BALB/c mice with epoxymethoxy-lawsone led to a significant 27% reduction (p < 0.05) of the lesion size, for all administrated doses, compared to the control group. Lesion reduction was also detected after mice treatment with meglumine antimoniate, reaching 31.0% (0.23 mg of Sb(V)/Kg/day and 2.27 mg of Sb(V)/Kg/day) and 64.0% (22.7 mg of Sb(V)/Kg/day). In addition, mice lesion ultrastructural changes were evidenced in amastigotes. The set of data gathered here indicate that epoxymethoxylawsone has pronounced effects on parasites and merits furthering to the preclinical stage.

Insights into cytochrome bc1 complex binding mode of antimalarial 2-hydroxy-1, 4-naphthoquinones through molecular modelling

BACKGROUND Malaria persists as a major public health problem. Atovaquone is a drug that inhibits the respiratory chain of Plasmodium falciparum, but with serious limitations like known resistance, low bioavailability and high plasma protein binding. OBJECTIVES The aim of this work was to perform molecular modelling studies of 2-hydroxy-1,4-naphthoquinones analogues of atovaquone on the Qo site of P. falciparum cytochrome bc1 complex (Pfbc1) to suggest structural modifications that could improve their antimalarial activity. METHODS We have built the homology model of the cytochrome b (CYB) and Rieske iron-sulfur protein (ISP) subunits from Pfbc1 and performed the molecular docking of 41 2-hydroxy-1,4-naphthoquinones with known in vitro antimalarial activity and predicted to act on this target. FINDINGS Results suggest that large hydrophobic R2 substituents may be important for filling the deep hydrophobic Qo site pocket. Moreover, our analysis indicates that the H-donor 2-hydroxyl group may not be crucial for efficient binding and inhibition of Pfbc1 by these atovaquone analogues. The C1 carbonyl group (H-acceptor) is more frequently involved in the important hydrogen bonding interaction with His152 of the Rieske ISP subunit. MAIN CONCLUSIONS Additional interactions involving residues such as Ile258 and residues required for efficient catalysis (e.g., Glu261) could be explored in drug design to avoid development of drug resistance by the parasite.

Strategies for Increasing the Solubility and Bioavailability of Anticancer Compounds: ß-Lapachone and Other Naphthoquinones.

Quinones are among the most studied natural and synthetic products in the literature because they have considerable biological potential. These compounds exhibit activity against many microorganisms and are able to eliminate tumor cells through several mechanisms of action. Some of these compounds have become drugs that are used clinically. However, they also have problems with respect to solubility, stability and toxicity. The alternative of using controlled-release systems has been applied to quinones, with good results in some cases, indicating that these formulations may be a strategy for improving the pharmacological profile of this class of compounds.

Novel o-naphthoquinones induce apoptosis of EL-4 T lymphoma cells through the increase of reactive oxygen species.

Novel ß-lapachone analogs 2-phenyl-3,4-dihydro-2H-benzo[h]chromene-5,6-dione (NQ1), 2-p-tolyl-3,4-dihydro-2H-benzo[h]chromene-5,6-dione (NQ3) and 2-methyl-2-phenyl-3,4-dihydro-2H-benzo[h]chromene-5,6-dione (NQ7), which have trypanocidal activity, were assayed for cytotoxic effects on murine EL-4 T lymphoma cells. The NQs inhibited the proliferation of EL-4 cells at concentrations above 1µM. Nuclear staining of the EL-4 cells revealed chromatin condensation and a nuclear morphology compatible with the induction of apoptosis. Flow cytometry assays with annexin V-FITC and propidium iodide confirmed the cell death by apoptosis. Using electron paramagnetic resonance (EPR), a semiquinone radical was detected in EL-4 cells treated with NQs. In addition, a decrease in the GSH level in parallel with reactive oxygen species (ROS) production was observed. Preincubation with n-acetyl-l-cysteine (NAC) was able to reverse the inhibitory effects of the NQs on cell proliferation, indicating that ROS generation is involved in NQ-induced apoptosis. In addition, the NQs induced a decrease in the mitochondrial membrane potential and increased the proteolytic activation of caspases 9 and 3 and the cleavage of Poly (ADP-Ribose) Polymerase (PARP). In conclusion, these results indicate that redox cycling is induced by the NQs in the EL-4 cell line, with the generation of ROS and other free radicals that could inhibit cellular proliferation as a result of the induction of the intrinsic apoptosis pathway.

Synergistic enhancement of antitumor effect of ß-Lapachone by photodynamic induction of quinone oxidoreductase (NQO1).

ß-Lapachone is a phytochemotherapeutic originally isolated from Lapacho tree whose extract has been used medicinally for centuries. It is well known that NAD(P)H:quinone oxidoreductase (NQO1) activity is the principal determinant of ß-Lapachone cytotoxicity. As NQO1 is overexpressed in most common carcinomas, recent investigations suggest its potential application against cancer. Photodynamic therapy (PDT) is a clinically approved and rapidly developing cancer treatment. PDT involves the administration of photosensitizer (PS) followed by local illumination with visible light of specific wavelength. In the presence of oxygen molecules, the light illumination of PS can lead to a series of photochemical reactions and consequently the generation of cytotoxic reactive oxygen species (ROS). It has been reported that ß-Lapachone synergistically interacts with ionizing radiation, hyperthermia and cisplatin and that the sensitivity of cells to ß-Lapachone is closely related to the activity of NQO1. So, the present study aimed to investigate the feasibility of PDT to increase the anticancer effect of ß-Lapachone by up-regulating NQO1 expression on breast cancer MCF-7c3 cells. NQO1 expression was evaluated by Western blot analysis at different times after PDT using ME-ALA as PS. The cytotoxicity of the photodynamic treatment and ß-Lapachone alone or in combination was determined by MTT assay and the combination index (CI)-isobologram method and the dose reduction index (DRI) analysis were used to assess the effect of drug combinations. Our studies for the first time demonstrated that the expression of NQO1 is induced 24h after photodynamic treatment. The sensitivity of cancer cells to ß-Lapachone treatment increased 24h after PDT and a synergistic inhibitory effect on MCF-7c3 cells was showed. Taken together, these results lead us to conclude that the synergistic interaction between ß-Lapachone and PDT in killing cells was consistent with the up-regulation of NQO1. The combination of ß-Lapachone and PDT is a potentially promising modality for the treatment of cancer.

Synthesis and anticancer activities of some novel 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones.

A series of 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones (3a-g) have been synthesized and evaluated for their in vitro antiproliferative activities against four human cancer cell lines: MDA-MB-435 (breast), HL-60 (leukemia), HCT-8 (colon) and SF-295 (central nervous system). The results showed that the compounds 3b (2-(benzo[d]thiazol-2-yl)-8-methyl-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) and 3c (2-(benzo[d]thiazol-2-yl)-8-bromo-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) exhibited good cytotoxicity for three cell lines with IC(50) values lower than 5 µg/mL. Analysis of theoretical toxicity risks have shown medium tumorigenic and irritant risks related to 3b and 3c in contrast to doxorubicin, the positive control.