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.

Isocyanide-based multicomponent reactions for the synthesis of benzopyran derivatives with biological scaffolds

Benzopyrans (BZPs) are among the most privileged and influential small O-heterocycles that form the core of many natural compounds, commercial drugs, biological compositions, agrochemicals, and functional materials. BZPs are divided into six general categories including coumarins, chromans, 2H-chromenes, 4H-chromenes, chromones, and 4-chromanones, each of which is abundant in many plants and foods. These oxygenated heterocyclic compounds are fascinating motifs and have extensive applications in biology and materials science. Hence, numerous efforts have been made to develop innovative approaches for their extraction and synthesis. However, most of them are step-by-step or multi-step strategies that suffer from waste material generation and a tedious extraction process. Isocyanide-based multicomponent reactions (I-MCRs) offer a highly efficient method for overcoming these problems. The I-MCR is a simple and environmentally friendly one-pot domino procedure that does not require intermediate isolation or workup and is generally more efficient in material usage. This review covers all research articles related to I-MCRs for synthesizing BZP derivatives from the beginning to the middle of the year 2023. This strategy will be useful for organic and pharmaceutical chemists to design new drugs and optimize the synthesis steps of biological compounds and commercial drugs with benzopyran cores.

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

Several low molecular weight naphthoquinones are very useful in organic synthesis. These compounds have given rise to thousands of other naphthoquinones that have been tested against various microorganisms and pharmacological targets, including being used in the preparation of several drugs that are on the pharmaceutical market. Among these naphthoquinones, the series of compounds prepared from 1,2-naphthoquinone-4-sulfonic acid salts (β-NQS) stands out. In addition to being used in organic synthesis, they are excellent analytical derivatization reagents to spectrophotometrically determine drugs containing primary and secondary amino groups. This review summarizes the literature involving β-NQS.

One-pot synthesis of indole-fused nitrogen heterocycles via the direct C(sp2)–H functionalization of naphthoquinones; accessibility for deep red emitting materials

A convenient one-pot, two-step methodology was developed for the transformation of readily available planar naphthoquinone derivatives into structurally complex indole-fused nitrogen heterocycles under aerobic conditions.

Characterization and trypanocidal activity of a β-lapachone-containing drug carrier

The treatment of Chagas disease (CD), a neglected parasitic condition caused by Trypanosoma cruzi, is still based on only two drugs, nifurtimox (Nif) and benznidazole (Bz), both of which have limited efficacy in the late chronic phase and induce severe side effects. This scenario justifies the continuous search for alternative drugs, and in this context, the natural naphthoquinone β-lapachone (β-Lap) and its derivatives have demonstrated important trypanocidal activities. Unfortunately, the decrease in trypanocidal activity in the blood, high toxicity to mammalian cells and low water solubility of β-Lap limit its systemic administration and, consequently, clinical applications. For this reason, carriers as drug delivery systems can strategically maximize the therapeutic effects of this drug, overcoming the above mentioned restrictions. Accordingly, the aim of this study is to investigate the in vitro anti-T. cruzi effects of β-Lap encapsulated in2-hydroxypropyl-β-cyclodextrin (2HP-β-CD) and its potential toxicity to mammalian cells.

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-1β 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.

Synthesis of quinones with highlighted biological applications: A critical update on the strategies towards bioactive compounds with emphasis on lapachones

Naphthoquinones are of key importance in organic synthesis and medicinal chemistry. In the last few years, various synthetic routes have been developed to prepare bioactive compounds derived or based on lapachones. In this sense, this review is mainly focused on the synthetic aspects and strategies used for the design of these compounds on the basis of their biological activities for the development of drugs against the neglected diseases leishmaniases and Chagas disease and also cancer. Three strategies used to develop bioactive quinones are discussed and categorized: (i) C-ring modification, (ii) redox centre modification and (iii) A-ring modification. Framed within these strategies for the development of naphthoquinoidal compounds against T. cruzi. Leishmania and cancer, reactions including copper-catalyzed azide-alkyne cycloaddition (click chemistry), palladium-catalysed cross couplings, C-H activation reactions, Ullmann couplings and heterocyclisations reported up to July 2019 will be discussed. The aim of derivatisation is the generation of novel molecules that can potentially inhibit cellular organelles/processes, generate reactive oxygen species and increase lipophilicity to enhance penetration through the plasma membrane. Modified lapachones have emerged as promising prototypes for the development of drugs against leishmaniases, Chagas disease and cancer.

Site-selectivity control in hetero-Diels-Alder reactions of methylidene derivatives of lawsone through modification of the reactive carbonyl group: an experimental and theoretical study

A new perspective on the reactivity of hydroxyquinones was revealed as an acetal derivative of lawsone was synthesized, isolated, and used in tandem Knoevenagel/hetero-Diels-Alder reactions catalyzed by S-proline. The intermediate alkylidene-1,3-diones that were formed in situ reacted with electron rich alkenes to predominantly afford pyrano-1,2-naphthoquinone (β-lapachone) derivatives along with the isomeric pyrano-1,4-naphthoquinone (α-lapachone) derivatives in high to excellent total yields. Interestingly, the highly reactive arylidene-1,3-dione derivatives were found to be stable and isolable. DFT calculations suggest that these hetero-Diels-Alder reactions have a high polar character, taking place through a two-stage one-step mechanism. An analysis of the conceptual DFT indices allows explaining the remarkable site-selectivity observed.

Efficient Catalytic Oxidation of 3-Arylthio- and 3-Cyclohexylthio-lapachone Derivatives to New Sulfonyl Derivatives and Evaluation of Their Antibacterial Activities

New sulfonyl-lapachones were efficiently obtained through the catalytic oxidation of arylthio- and cyclohexylthio-lapachone derivatives with hydrogen peroxide in the presence of a Mn(III) porphyrin complex. The antibacterial activities of the non-oxidized and oxidized lapachone derivatives against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus were evaluated after their incorporation into polyvinylpyrrolidone (PVP) micelles. The obtained results show that the PVP-formulations of the lapachones 4b–g and of the sulfonyl-lapachones 7e and 7g reduced the growth of S. aureus.

Synthetic methodologies leading to porphyrin-quinone conjugates

This review focuses on synthetic strategies that have been established for the preparation of porphyrin-quinone conjugates of potential biological significance and as donor–acceptor compounds for electron transfer processes.

Synthesis, characterization and biological activities of 3-aryl-1,4-naphthoquinones – green palladium-catalysed Suzuki cross coupling

Antifungal and trypanocidal aryl-1,4-naphthoquinones were prepared through an aqueous Suzuki protocol with reflux or microwave irradiation.

Catalyst-free microwave-assisted arylglyoxal-based multicomponent reactions for the synthesis of fused pyrans

A simple and straight forward method has been reported for the synthesis of fused pyrans from the three component reactions of arylglyoxals, cyclic 1,3-dicarbonyls and malononitrile under microwave and catalyst free conditions.

Coumarin heterocyclic derivatives: chemical synthesis and biological activity

This review highlights the broad range of science that has arisen from the synthesis of coumarin-linked and fused heterocycle derivatives. Specific topics include their synthesis and biological activity.

A new and efficient procedure for the synthesis of hexahydropyrimidine-fused 1,4-naphthoquinones

A new and efficient method for the synthesis of hexahydropyrimidine-fused 1,4-naphthoquinones in one step with high yields from the reaction of lawsone with 1,3,5-triazinanes was developed.

Antifungal Activity of Pyranonaphthoquinones Obtained from Cipura paludosa Bulbs

Previous studies with the bulbs of Cipura paludosa (Iridaceae) showed the presence of pyranonaphthoquinones, including eleutherine, isoeleutherine and eleutherol. The aim of this study was to evaluate the antifungal properties of these compounds. The activity was tested against the clinically relevant yeasts Candida albicans, C. tropicalis, Saccharomyces cerevisiae and Cryptococcus neoformans with the microbroth dilution method, following the guidelines of CLSI. Eleutherine, isoeleutherine and eleutherol all presented significant antifungal activity, especially the first two, the major components, with MIC values between 7.8 and 250 μg/mL. In conclusion, these results demonstrate that C. paludosa bulbs produce active principles with relevant antifungal potential, contributing, at least in part, to the antimicrobial effect evidenced for this plant and justifying its popular use against infections.

Identification of unusual C–Cl⋯π contacts in 2-(alkylamino)-3-chloro-1,4-naphthoquinones: effect of N-substituents on crystal packing, fluorescence, redox and anti-microbial properties

XRD study demonstrates the opening of unusual C–Cl⋯π synthon in 2-(alkylamino)-3-chloro-1,4-naphthoquinone. Notably, compound holding N-pyridylmethyl exhibits enhanced activity against S. aureus and proved to be more potent than ciprofloxacin.

Antifungal activity of synthetic naphthoquinones against dermatophytes and opportunistic fungi: preliminary mechanism-of-action tests

This study evaluated the antifungal activities of synthetic naphthoquinones against opportunistic and dermatophytic fungi and their preliminary mechanisms of action. The minimum inhibitory concentrations (MICs) of four synthetic naphthoquinones for 89 microorganisms, including opportunistic yeast agents, dermatophytes and opportunistic filamentous fungi, were determined. The compound that exhibited the best activity was assessed for its action against the cell wall (sorbitol test), for interference associated with ergosterol interaction, for osmotic balance (K+ efflux) and for membrane leakage of substances that absorb at the wavelength of 260 nm. All tested naphthoquinones exhibited antifungal activity, and compound IVS320 (3a,10b-dihydro-1H-cyclopenta [b] naphtho [2,3-d] furan-5,10-dione)-dione) demonstrated the lowest MICs across the tested species. The MIC of IVS320 was particularly low for dermatophytes (values ranging from 5-28 μg/mL) and Cryptococcus spp. (3-5 μg/mL). In preliminary mechanism-of-action tests, IVS320 did not alter the fungal cell wall but did cause problems in terms of cell membrane permeability (efflux of K+ and leakage of substances that absorb at 260 nm). This last effect was unrelated to ergosterol interactions with the membrane.

Simple access to 5-carboalkoxy-2,3-dihydro-4H-pyran-4-ones via domino acylative electrocyclization: the first three step total synthesis of the dihydronaphthopyran-4-one class of natural products

5-Carboalkoxy-2,3-dihydropyran-4-ones synthesised via domino C-acylation/6π-oxaelectrocyclization protocol was employed as a starting material for the first three step total synthesis of dihydronaphthopyran-4-one class of natural products.

Synthetic 1,4-pyran naphthoquinones are potent inhibitors of dengue virus replication

Dengue virus infection is a serious public health problem in endemic areas of the world where 2.5 billion people live. Clinical manifestations of the Dengue infection range from a mild fever to fatal cases of hemorrhagic fever. Although being the most rapidly spreading mosquito-borne viral infection in the world, until now no strategies are available for effective prevention or control of Dengue infection. In this scenario, the development of compounds that specifically inhibit viral replication with minimal effects to the human hosts will have a substantial effect in minimizing the symptoms of the disease and help to prevent viral transmission in the affected population. The aim of this study was to screen compounds with potential activity against dengue virus from a library of synthetic naphthoquinones. Several 1,2- and 1,4-pyran naphthoquinones were synthesized by a three-component reaction of lawsone, aldehyde (formaldehyde or arylaldehydes) and different dienophiles adequately substituted. These compounds were tested for the ability to inhibit the ATPase activity of the viral NS3 enzyme in in vitro assays and the replication of dengue virus in cultured cells. We have identified two 1,4-pyran naphthoquinones, which inhibited dengue virus replication in mammal cells by 99.0% and three others that reduced the dengue virus ATPase activity of NS3 by two-fold in in vitro assays.

Synthesis of quinoidal molecules: strategies towards bioactive compounds with an emphasis on lapachones

Naphthoquinoidal compounds are of great interest in medicinal chemistry. In recent years, several synthetic routes have been developed to obtain bioactive molecules derived from lapachones. In this mini-review, we focus on the synthetic aspects and strategies used to design these compounds and on the biological activities of these substances for the development of drugs against the neglected diseases leishmaniasis and Chagas disease as well as malaria, tuberculosis and cancer. Three strategies used to develop bioactive naphthoquinoidal compounds are discussed: (i) C-ring modification, (ii) redox centre modification and (iii) A-ring modification. Among these strategies, reactions such as copper-catalysed azide-alkyne cycloaddition (click chemistry), palladium-catalysed cross couplings, and heterocyclisations will be discussed for the development of naphthoquinoidal compounds against Trypanosoma cruzi, Leishmania and cancer. The aim of derivatisation is the generation of novel molecules that inhibit cellular organelles/processes, generate reactive oxygen species (ROS) and increase lipophilicity to enhance penetration through the plasma membrane. Modified lapachones have emerged as promising prototypes for the development of drugs against neglected diseases and cancer.

Mimicking P450 processes and the use of metalloporphyrins

Metalloporphyrins (MPs) are known to catalyze in vitro a broad range of cytochrome P450-mediated reactions occurring in vivo. Most of the biomimetic research using MPs in oxidative catalysis has been directed towards the oxidation of organic compounds presenting significant reactivity features in one functional group. Much less effort has been made to imitate the oxidation of more complex molecules, with a range of functionalities, such as drugs or other xenobiotics. By varying the structure of the porphyrin, the metal ion, the oxidant, and the reaction conditions, it is possible to modulate the regioselectivity of the oxidation reactions. Recently, and along with studies on the synthesis and reactivity of porphyrins, chlorins, and phthalocyanines, our group was able to develop an interesting line of research in the field of biomimetic oxidation of organic compounds using environmentally benign hydrogen peroxide as oxidant and Mn(III) or Fe(III) porphyrin complexes as catalysts. The more up to date results obtained in such work are reviewed here.

Populene D analogues: design, concise synthesis and antiproliferative activity

An efficient and concise synthesis of nine populene D analogues was performed using an iodine-catalyzed Prins cyclization as the key transformation. The antiproliferative activity of these new pyrans against several cancer cell lines was then investigated. Among them, an isochromene with moderate activity (mean logGI₅₀ = 0.91) was found. Additionally, compounds with selectivity toward the tumor cell lines NCI-ADR/RES, OVCAR-3, and HT29 were discovered.

New oxirane derivatives of 1,4-naphthoquinones and their evaluation against T. cruzi epimastigote forms

New oxirane derivatives were synthesized using six naphthoquinones as the starting materials. Our biological results showed that these oxiranes acted as trypanocidal agents against Trypanosoma cruzi with minimal cytotoxicity in the VERO cell line compared to naphthoquinones. In particular, oxirane derivative 14 showed low cytotoxicity in a mammalian cell line and exhibited better activity against epimastigote forms of T.cruzi than the current drug used to treat Chagas disease, benznidazole.

Preclinical genotoxicology of nor-β-lapachone in human cultured lymphocytes and Chinese hamster lung fibroblasts

Nor-β-lapachone has shown several biological properties. Regarding cytotoxic activity against cancer cell lines, it has been recognized as an important prototype. However, quinonoid drugs present a major challenge because of their toxicity. In this study, we evaluated the cytotoxicity and genetic toxicity of nor-β-lapachone in human lymphocytes and HL-60 leukemia cells and murine V79 fibroblasts, to shed some light on its selectivity toward cancer cells. As measured by MTT test, exposure of V79 cells to nor-β-lapachone resulted in a weak cytotoxicity (IC(50) = 13.41 μM), and at a concentration up to 21.9 μM, no cytotoxic effect was observed in lymphocytes, while in HL-60 cells, nor-β-lapachone elicited significantly greater cytotoxicity (IC(50) = 1.89 μM). Cultures coexposed to GSH-OEt showed an increased viability, which may indicate a neutralization of ROS generated by quinonoid treatment. In fact, only the highest concentrations of nor-β-lapachone (10 or 20 μM) caused an increase in oxidative stress in nontumor levels cells as measured by TBARS and nitrite/nitrate detection. This was accompanied by an alteration in intracellular thiol content. However, NAC pre-exposure restored the redox equilibrium of the cells and the concentration of thiol levels to control values. Nor-β-lapachone at 2.5 and 5 μM failed to induce DNA damage in nontumor cells, but at the highest concentrations tested, it induced single and double DNA strand breaks and increased the frequency of chromosomal aberrations. Interestingly, these damages were prevented by NAC pretreatment or exacerbated by prior exposure to the GSH-depleting agent 1-bromoheptane. In electrochemical experiments, nor-β-lapachone at the same concentrations as those used in genotoxic tests did not damage DNA directly, but at the highest concentration tested (200 μM), it caused a very weak DNA interaction. Corroborating electrochemical data, oxidative modifications of DNA bases were observed, as checked by DNA repair enzymes EndoIII and FPG, which reinforced the indirect actions caused by nor-β-lapachone through ROS generation and not via DNA intercalation. The DNA repair capacities were higher for nontumor cells than for leukemia cells, which may be related to the selective cytoxicity of nor-β-lapachone toward cancer cells. Our data suggest that ROS play an important role in nor-β-lapachone toxicity and that its DNA-damaging effect occurs only at concentrations several times higher than that needed for its antiproliferative effect on cancer cells.