Studies on quinones. Part 45: novel 7-aminoisoquinoline-5,8-quinone derivatives with antitumor properties on cancer cell lines

Synthesis of 6-bromo-7-arylaminoisoquinoline-5,8-quinones and its effects on Piscirickettsia salmonis infection in vitro

Among the most important aquaculture resources for our country, salmon and trout stand out. Their production has increased significantly in recent decades, making them two of the most valuable resources in economic terms. However, high aquaculture production has allowed many pathogens to proliferate, causing infectious diseases and significant production losses. Piscirickettsia salmonis is a gram-negative, facultative intracellular bacterium that is responsible for causing severe disease in a variety of salmonid fish species. Despite the significant impact of P. salmonis on aquaculture, effective treatments for this disease remain limited. Current prevention and control strategies often include antibiotics and vaccines. However, these treatments have shown varying degrees of efficacy. A promising approach involves synthesizing bioactive analog compounds with antibacterial properties. Quinones, secondary metabolites that are abundant in nature, have become a focal point of interest due to their diverse physiological activities, including antibiotic, insecticidal, antifungal, and anticancer properties. In this study, it is shown the synthesis of series 6-bromo-7-arylaminoisoquinoline-5,8-quinones, the characterization of these compounds using classical spectroscopic methods such as one-dimensional nuclear magnetic resonance (NMR), FT-IR (infrared), mass spectrometry, and the biological activity against Piscirickettsia salmonis. The brominated derivative compounds showed no cytotoxicity at any concentration evaluated. Furthermore, the infectivity of P. salmonis after treatment with the analog compounds indicated that derivatives methyl 6-bromo-7-((4-methoxyphenyl)amino)-1,3-dimethy-5,8-dioxo-5,8-dihydroisoquinoline-4-carboxylate (4b) and methyl 7-((4'-amino-[1,1'-biphenyl]-4-yl)amino)-6-bromo-1,3-dimethy-5,8-dioxo-5,8-dihydroisoquinoline-4-carboxylate (4g) reduced the bacterial load at 25 μg/mL concentration.

Discovery of Potent Isoquinolinequinone N-Oxides to Overcome Cancer Multidrug Resistance

Multidrug resistance (MDR) of human tumors has resulted in an immediate need to develop appropriate new drugs. This work outlines the development of 20 potent IQQ N-oxide derivatives in two isomeric families, both exhibiting nanomolar GI50 against human tumor cell lines. Preliminary NCI-60 tumor screening sees the C(6) isomers achieve a mean GI50 > 2 times lower than the corresponding C(7) isomers. MDR evaluation of nine selected compounds reveals that each presents lower GI50 concentrations in two MDR tumor cell lines. Four of the series display nanomolar GI50 values against MDR cells, having selectivity ratios up to 2.7 versus the sensitive (parental) cells. The most potent compound 25 inhibits the activity of drug efflux pumps in MDR cells, causes significant ROS accumulation, and potently inhibits cell proliferation, causing alterations in the cell cycle profile. Our findings are confirmed by 3D spheroid models, providing new candidates for studies against MDR cancers.

The study on QSAR and relations between molecular descriptors of 5, 8-quinoline quinones derivatives

Abstract In this study, some electronic, hydrophobic and thermochemical parameters of 28 different 5,8-quinolinequinone derivatives having diverse substituents have been calculated by using DFT (B3LYP)/6-31G(d, p) method and basis set. Relationships between different molecular descriptors have been studied by using molecular polarizability (α), dipole moment (μ), EHOMO, ELUMO, molecular volume (Vm), ionization potential (IP), electron affinity (EA), electronegativity (χ), molecular hardness (η), molecular softness (S), electrophilic index (ω), molar refractivity (MR), octanol–water partition coefficient (log P), thermochemical properties (entropy (Se), capacity of heat (C)); as to investigate activity relationships with molecular structure. In addition, the QSAR/QSPR between molecular properties and biological activity (anti-proliferative and anti-inflammatory activity) has been investigated, where R, R2, F, P and RMSE have taken into account in order to find a statistically correct model in QSAR studies. The dependence of the electronegativity parameter on both electronic and thermochemical parameters is found to be the most correlated parameter.

Phenoxy- and Phenylamino-Heterocyclic Quinones: Synthesis and Preliminary Anti-Pancreatic Cancer Activity

The successful application of fragment-based drug discovery strategy for the efficient synthesis of phenoxy- or phenylamino-2-phenyl-benzofuran, -benzoxazole and -benzothiazole quinones is described. Interestingly, in the final step of the synthesis of the target compounds, unusual results were observed on the regiochemistry of the reaction of bromoquinones with phenol and aniline. A theoretical study was carried out for better understanding the factors that control the regiochemistry of these reactions. The substituted heterocyclic quinones were evaluated in vitro to determine their cytotoxicity by the MTT method in three pancreatic cancer cell lines (MIA-PaCa-2, BxPC-3, and AsPC-1). Phenoxy benzothiazole quinone 26a showed potent cytotoxic activity against BxPC-3 cell lines, while phenylamino benzoxazole quinone 20 was the most potent on MIA-PaCa-2 cells. Finally, electrochemical properties of these quinones were determined to correlate with a potential mechanism of action. All these results, indicate that the phenoxy quinone fragment led to compounds with increased activity against pancreatic cancer cells.

Benzo[f]indole-4,9-dione Derivatives Effectively Inhibit the Growth of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with poor clinical outcome, and currently no effective targeted therapies are available. Indole compounds have been shown to have potential antitumor activity against various cancer cells. In the present study, we found that new four benzo[f]indole-4,9-dione derivatives reduce TNBC cell viability by reactive oxygen species (ROS) accumulation stress in vitro. Further analyses showed that LACBio1, LACBio2, LACBio3 and LACBio4 exert cytotoxic effects on MDA-MB 231 cancer cell line by inducing the intrinsic apoptosis pathway, activating caspase 9 and Bax/Bcl-2 pathway in vitro. These results provide evidence that these new four benzo[f]indole-4,9-dione derivatives could be potential therapeutic agents against TNBC by promoting ROS stress-mediated apoptosis through intrinsic-pathway caspase activation.

Selective AMPK activator leads to unfolded protein response downregulation and induces breast cancer cell death and autophagy

AIMS

AMPK plays a critical role regulating cell metabolism, growth and survival. Interfering with this enzyme activity has been extensively studied as putative mechanism for cancer therapy. The present work aims to identify a specific AMPK activator for cancer cells among a series of novel heterocyclic compounds.

MATERIALS AND METHODS

A series of novel hybrid heterocyclic compounds, namely naphtoquinone-4-oxoquinoline and isoquinoline-5,8-quinone-4-oxoquinoline derivatives, were synthesized via Michael reaction and their structures confirmed by spectral data: infrared; ¹H and ¹³C NMR spectroscopy (COSY, HSQC, HMBC); and high-resolution mass spectrometry (HRMS). The novel compounds were screened and tested for antitumoral activity and have part of their mechanism of action scrutinized.

KEY FINDINGS

Here, we identified a selective AMPK activator among the new hybrid heterocyclic compounds. This new compound presents selective cytotoxicity on breast cancer cells but not on non-cancer counterparts. We identified that by specifically activating AMPK in cancer cells, the drug downregulates unfolded protein response pathway, as well as inhibits mTOR signaling.

SIGNIFICANCE

These effects, that are selective for cancer cells, lead to activation of autophagy and, ultimately, to cancer cells death. Taken together, our data support the promising anticancer activity of this novel compound which is a strong modulator of metabolism.

Isoquinolinequinone N-oxides as anticancer agents effective against drug resistant cell lines

The isoquinolinequinone (IQQ) pharmacophore is a privileged framework in known cytotoxic natural product families, caulibugulones and mansouramycins. Exploiting both families as a chemical starting point, we report on the structured development of an IQQ N-oxide anticancer framework which exhibits growth inhibition in the nM range across melanoma, ovarian and leukaemia cancer cell lines. A new lead compound (16, R6 = benzyl, R7 = H) exhibits nM GI50 values against 31/57 human tumour cell lines screened as part of the NCI60 panel and shows activity against doxorubicin resistant tumour cell lines. An electrochemical study highlights a correlation between electropositivity of the IQQ N-oxide framework and cytotoxicity. Adduct binding to sulfur based biological nucleophiles glutathione and cysteine was observed in vitro. This new framework possesses significant anticancer potential.

Green Synthesis and Electrochemical Properties of Mono- and Dimers Derived from Phenylaminoisoquinolinequinones

In the search for new quinoid compounds endowed with potential anticancer activity, the synthesis of novel heterodimers containing the cytotoxic 7-phenylaminoisoquinolinequinone and 2-phenylaminonaphthoquinone pharmacophores, connected through methylene and ethylene spacers, is reported. The heterodimers were prepared from their respective isoquinoline and naphthoquinones and 4,4'-diaminodiphenyl alkenes. The access to the target heterodimers and their corresponding monomers was performed both through oxidative amination reactions assisted by ultrasound and CeCl3·7H2O catalysis "in water". This eco-friendly procedure was successfully extended to the one-pot synthesis of homodimers derived from the 7-phenylaminoisoquinolinequinone pharmacophore. The electrochemical properties of the monomers and dimers were determined by cyclic and square wave voltammetry. The number of electrons transferred during the oxidation process, associated to the redox potential EI1/2, was determined by controlled potential coulometry.

Half-Wave Potentials and In Vitro Cytotoxic Evaluation of 3-Acylated 2,5-Bis(phenylamino)-1,4-benzoquinones on Cancer Cells

A broad range of 3-acyl-2,5-bis(phenylamino)-1,4-benzoquinones were synthesized and their voltammetric values, as well as in vitro cancer cell cytotoxicities, were assessed. The members of this series were prepared from acylbenzoquinones and phenylamines, in moderate to good yields (47–74%), through a procedure involving a sequence of two in situ regioselective oxidative amination reactions. The cyclic voltammograms of the aminoquinones exhibit two one-electron reduction waves to the corresponding radical-anion and dianion, and two quasi-reversible oxidation peaks. The first and second half-wave potential values (E_1/2) of the members of the series were sensitive to the push-pull electronic effects of the substituents around the benzoquinone nucleus. The in vitro cytotoxic activities of the 3-acyl-2,5-bis(phenylamino)-1,4-benzoquinones against human cancer cells (bladder and prostate) and non-tumor human embryonic kidney cells were measured using the MTT colorimetric method. The substitution of both aniline groups, by either methoxy (electron donating effect) or fluorine (electron withdrawal effect), decreased the cytotoxicity in the aminoquinones. Among the members of the unsubstituted phenylamino series, two of the 18 compounds showed interesting anti-cancer activities. A preliminary assay, looking for changes in the expression of selected genes, was performed. In this context, the two compounds increased TNF gene expression, suggesting an association with an inflammatory-like response.

1,4-Naphthoquinone Analogues: Potent Antibacterial Agents and Mode of Action Evaluation

1,4-Naphthoquinones have antibacterial activity and are a promising new class of compound that can be used to treat bacterial infections. The goal was to improve effective antibacterial agents; therefore, we synthesized a new class of naphthoquinone hybrids, which contain phenylamino-phenylthio moieties as significant counterparts. Compound 4 was modified as a substituted aryl amide moiety, which enhanced the antibacterial activity of earlier compounds 3 and 4. In this study, five bacterial strains Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae) were used to evaluate the antibacterial potency of synthesized naphthoquinones using the minimal inhibitory concentration (MIC) method. Most of the studied naphthoquinones demonstrated major antibacterial activity with a MIC of 15.6 µg/mL–500 µg/mL. Selected compounds (5a, 5f and 5x) were studied for the mode of action, using intracellular ROS generation, determination of apoptosis by the Annexin V-FITC/PI assay, a bactericidal kinetic study and in silico molecular modelling. Additionally, the redox potentials of the specified compounds were confirmed by cyclic voltammetry (CV).

Quinone-Fused Pyrazoles through 1,3-Dipolar Cycloadditions: Synthesis of Tricyclic Scaffolds and in vitro Cytotoxic Activity Evaluation on Glioblastoma Cancer Cells

A novel and straightforward synthesis of highly substituted isoquinoline-5,8-dione fused tricyclic pyrazoles is reported. The key step of the synthetic sequence is a regioselective, Ag₂ CO₃ promoted, 1,3-dipolar cycloaddition of C-heteroaryl-N-aryl nitrilimines and substituted isoquinoline-5,8-diones. The broad functional group tolerability and mild reaction conditions were found to be suitable for the preparation of a small library of compounds. These scaffolds were designed to interact with multiple biological residues, and two of them, after brief synthetic elaborations, were analyzed by molecular docking studies as potential anticancer drugs. In vitro studies confirmed the potent anticancer effects, showing promising IC₅₀ values as low as 2.5 μm against three different glioblastoma cell lines. Their cytotoxic activity was finally positively correlated to their ability to inhibit PI3K/mTOR kinases, which are responsible for the regulation of diverse cellular processes in human cancer cells.

Synthesis and antitumor evaluation of hybrids of 5,8-dioxo-5,8-dihydroisoquinoline-4-carboxylates and carbohydrates

Aim: Cancer has emerged as a growing public health problem in many parts of the world. Methodology: We describe the synthesis of a series of carbohydrate-based isoquinoline-5,8-diones through the 1,4-addition reaction between 5,8-dioxo-5,8-dihydroisoquinoline and aminocarbohydrates. Halogenated quinones were also synthesized. Their inhibitory effects on the proliferation of human cancer cell lines were studied. Results & conclusion: The most promising compound, derived from isoquinoline-5,8-dione, containing ribofuranosidyl ring, was selectively active in vitro against H1299 cancer cells, with 1.7-fold higher activity than that of vinorelbine tartrate. This result suggests that the glycoconjugate in question may constitute a valuable lead compound to design and synthesize a more active and less toxic derivative with respect to the development of a new antitumor substance.

Preparation of Novel Homodimers Derived from Cytotoxic Isoquinolinequinones. A Twin Drug Approach

The synthesis of five novel homodimers is reported based on the anilinoisoquinolinequinone scaffold. In these twin-drug derivatives, two units of the anilinoquinone pharmacophores are linked through a methylene spacer. The formation of dimers was achieved by reaction of isoquinolinequinones with 4, 4'-diaminodiphenylmethane via a sequence of two oxidative amination reactions. A preliminary in vitro screening of the homodimers reveals moderate to high cytotoxic activities against MDA-MB-21 breast adenocarcinoma and B16-F10 murine metastatic melanoma cell lines. The asymmetrical homodimer 15 stands out due to its cytotoxic potencies at submicromolar concentrations and high selectivity index (mean IC₅₀ = 0.37 μM; SI = 6.97) compared to those of etoposide (mean IC₅₀ = 3.67; SI = 0.32) and taxol (mean IC₅₀ = 0.35; SI = 0.91) employed as reference anticancer drugs.

Synthesis and antimicrobial evaluation of promising 7-arylamino-5,8-dioxo-5,8-dihydroisoquinoline-4-carboxylates and their halogenated amino compounds for treating Gram-negative bacterial infections

In this work we described the synthesis and antimicrobial evaluation of 7-arylamino-5,8-dioxo-5,8-dihydroisoquinoline-4-carboxylates derivatives that exhibited remarkable activity against two Gram-negative strains of clinical importance.

Analysis of quinolinequinone reactivity, cytotoxicity, and anti-HIV-1 properties

We have analyzed a set of quinolinequinones with respect to their reactivities, cytotoxicities, and anti-HIV-1 properties. Most of the quinolinequinones were reactive with glutathione, and several acted as sulfhydryl crosslinking agents. Quinolinequinones inhibited binding of the HIV-1 matrix protein to RNA to varying degrees, and several quinolinequinones showed the capacity to crosslink HIV-1 matrix proteins in vitro, and HIV-1 structural proteins in virus particles. Cytotoxicity assays yielded quinolinequinone CC₅₀ values in the low micromolar range, reducing the potential therapeutic value of these compounds. However, one compound, 6,7-dichloro-5,8-quinolinequinone potently inactivated HIV-1, suggesting that quinolinequinones may prove useful in the preparation of inactivated virus vaccines or for other virucidal purposes.

Synthesis, half-wave potentials and antiproliferative activity of 1-aryl-substituted aminoisoquinolinequinones

The synthesis of a variety of 1-aryl-7-phenylaminoisoquinolinequinones from 1,4-benzoquinone and arylaldehydes via the respective 1-arylisoquinolinequinones is reported. The cyclic voltammograms of the new compounds exhibit two one-electron reduction waves to the corresponding radical-anion and dianion and two quasi-reversible oxidation peaks. The half-wave potential values (EI½) of the members of the series have proven sensitive to the electron-donor effect of the aryl group (phenyl, 2-thienyl, 2-furyl) at the 1-position as well as to the phenylamino groups (anilino, p-anisidino) at the 7-position. The antiproliferative activity of the new compounds was evaluated in vitro using the MTT colorimetric method against one normal cell line (MRC-5 lung fibroblasts) and two human cancer cell lines: AGS human gastric adenocarcinoma and HL-60 human promyelocytic leukemia cells in 72-h drug exposure assays. Among the series, compounds 5a, 5b, 5g, 5h, 6a and 6d exhibited interesting antiproliferative activities against human gastric adenocarcinoma. The 1-arylisoquinolinequinone 6a was found to be the most promising active compound against the tested cancer cell lines in terms of IC50 values (1.19; 1.24 µM) and selectivity index (IS: 3.08; 2.96), respect to the anti-cancer agent etoposide used as reference (IS: 0.57; 0.14).

On-Water Reactivity and Regioselectivity of Quinones in C–N Coupling with Amines: Experimental and Theoretical Study

A study about the oxidative coupling of some representative carbo- and heterocyclic non-symmetrical quinones with aryl- and alkylamines, was carried out comparing dichloromethane and water as reaction mediums. We found that the on-water reactions gave better or, at worst, the same results as a conventional organic medium like dichloromethane. Descriptors derived from conceptual density functional theory and approaches of electrostatic nature, such as the molecular electrostatic potential, were used to explain the observed chemical reactivity and regioselectivity. Further, the on-water conditions were used to obtain 24 new aminoquinones with potential biological activity.

Synthesis and in vitro antiproliferative activity of new phenylaminoisoquinolinequinones against cancer cell lines

A variety of phenylaminoisoquinolinequinones were synthesized and tested for their antiproliferative activity against three human-tumor derived cancer cell lines. The new aminoquinones were prepared from 4-methoxycarbonyl-3-methylisoquinoline-5,8-quinone (1) via acid-induced amination and bromination reactions. Remarkable differences in antiproliferative activity were observed depending upon the location and donor capacity of the substituted phenylamino group at the quinone nucleus. The effect of the substituents on the biological activity is discussed in terms of the donor-acceptor interactions which were evaluated through the redox properties of the aminoquinones.

Synthesis and in vitro cytotoxic evaluation of aminoquinones structurally related to marine isoquinolinequinones

The synthesis of 4-methoxycarbonyl-3-methylisoquinolinequinone (1) and a variety of its substitution products with amino-, alkylamino and halogen groups on the quinone nucleus is reported. The series of 6-, 7- and 6,7-subtituted isoquinolinequinones were evaluated in vitro for their cytotoxic activity using the MTT colorimetric method. All the newly synthesized compounds showed moderate to high potency against MRC-5 healthy lung fibroblasts and four human tumor cell lines: AGS gastric adenocarcinoma, SK-MES-1 lung, J82 bladder carcinoma, and HL-60 leukemia cells. Among the series, compounds 4b, 12 and 13 exhibited interesting antitumor activity against human gastric adenocarcinoma, human lung and human bladder carcinoma cancer cells. 7-Amino-6-bromoisoquinoline-5,8-quinone (13) was found to be the most promising active compound against the tested cancer cell lines, with IC₅₀ values in the 0.21−0.49 μM range, lower than the anti-cancer agent etoposide used as reference.

Sanguisorba minor extract suppresses plasmin-mediated mechanisms of cancer cell migration

BACKGROUND

Sanguisorba minor, as well as several other edible herbs and vegetables, has been used extensively in traditional medicine. The observed beneficial effects can be attributed at least in part to the direct modulation of several enzymatic activities by its polyphenolic constituents.

METHODS

The ethanol extract of Sanguisorba minor was characterized by reversed-phase liquid chromatography, and most relevant analytes were identified by multiple stage mass spectrometry. The whole extract and the most relevant isolated constituents were tested for their ability to modulate the activity of human plasmin both toward a synthetic substrate and in human breast cancer cell culture models. Kinetic and equilibrium parameters were obtained by a concerted spectrophotometric and biosensor-based approach.

RESULTS

Quercetin-3-glucuronide was recognized as the compound mainly responsible for the in vitro plasmin inhibition by S. minor extract, with an inhibition constant in the high nanomolar range; in detail, our approach based on bioinformatic, enzymatic and binding analyses classified the inhibition as competitive. Most interestingly, cell-based assays showed that this flavonoid was effective in suppressing plasmin-induced loss of cancer cell adhesion.

GENERAL SIGNIFICANCE

Our results show that the extract from Sanguisorba minor limits plasmin-mediated tumor cell motility in vitro, mostly due to quercetin-3-glucuronide. This glucuronated flavonoid is a promising template for rational designing of anticancer drugs to be used in the treatment of pathological states involving the unregulated activity of plasmin.

Studies on quinones. Part 46. Synthesis and in vitro antitumor evaluation of aminopyrimidoisoquinolinequinones

In the search of structure-activity relationship studies and to explore the antitumor effect associated with the pyrimidoisoquinolinequinone scaffold, several diversily substituted 8-aminopyrimido[4,5-c]isoquinolinequinones were regioselectively synthesized. Variation in the structure of the nitrogen substituent bonded to the 8-position of the pyrimidoisoquinolinequinone system led to a set of alkylamino-, phenylamino- and alkyphenylamino derivatives. The cytotoxic activity of the aminoquinone derivatives was evaluated in vitro using the MTT colorimetric method against one normal cell line (MRC-5 lung fibroblasts) and four human cancer cell lines (AGS human gastric adenocarcinoma; SK-MES-1 human lung cancer cells, and J82 human bladder carcinoma; HL-60 human leukemia) in 72-h drug exposure assays. Among the series, five compounds exhibited interesting antitumor activity against AGS human gastric adenocarcinoma and human lung cancer cells. The SAR studies revealed that both the nature of the nitrogen substituent into the quinone ring and the methyl group at the 6-position play key roles in the antitumor activity.

Lipophilicity of novel antitumour and analgesic active 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-dione derivatives determined by reversed-phase HPLC and computational methods

Eight novel antitumour and analgesic active 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-diones (1-8) have been obtained as a bioactive set of substances and their lipophilicity has been studied. The logk values of fifteen reference compounds and eight newly synthesised imidazotriazine-3,4-dione derivatives were determined by reversed-phase high performance liquid chromatography (RP-HPLC) using mixtures of methanol and water as mobile phases with different methanol concentrations. The relationships between logk values of a set of reference compounds (fifteen compounds) and investigated ones (eight compounds) and concentration of methanol was used for determination of the logkwater values by extrapolation. The partition coefficients (logP) values for reference compounds measured experimentally were taken from the literature. The calibration equation was then obtained for the standards of known lipophilicity (logPHPLC) and logkwater. In next step the partition coefficients of new synthesised solutes were calculated from the calibration equation. For the comparison purpose, additionally the partition coefficients (logPcalc.) of the examined imidazotriazine-3,4-diones were calculated by means of the Pallas 3.1.1.2. software. It was found that logkwater values as a lipophilicity measure of derivatives correlate well with partition coefficients measured experimentally (logPHPLC). Correlation between the logPHPLC and the logarithm of partition coefficient calculated by Pallas software (logPcalc.) is not so satisfactory as that for values determined experimentally. Furthermore, it has been found that the lipophilicity variation of investigated imidazotriazine-3,4-diones (1-8) correlates well with their acute toxicity expressed as log(1/LD50). The drug-likeness of all the bioactive 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-diones was assessed on the basis of their structural properties by applying Lipniski's rule of five. The solutes have all four parameters important for the favourable pharmacokinetics in the human body that would make them likely orally active drugs in humans.

Synthesis and antitumor evaluation of 8-phenylaminopyrimido[4,5-c]isoquinolinequinones

A series of 8-phenylaminopyrimido[4,5-c]isoquinoline-7,10-quinone derivatives were prepared by regioselective amination reaction of pyrimido[4,5-c]isoquinoline-7,10-quinones with arylamines in the presence of a Lewis acid catalyst. Preliminary evaluation of the members of the series against cancer cell lines and assays of activation of their cytotoxic activity on K562 cells with ascorbic acid are reported.