Synthetic Naphthoquinones Research Articles

Synthetic Naphthoquinone Inhibits Herpes Simplex Virus Type-1 Replication Targeting Na+, K+ ATPase.

Since 1970 acyclovir (ACV) has been the reference drug in treating herpes simplex virus (HSV) infections. However, resistant herpes simplex virus type 1 (HSV-1) strains have emerged, narrowing the treatment efficacy. The antiviral activity of classical Na+, K+ ATPase enzyme (NKA) inhibitors linked the viral replication to the NKA's activity. Herein, we evaluated the anti-HSV-1 activity of synthetic naphthoquinones, correlating their antiviral activity with NKA inhibition. We tested seven synthetic naphthoquinones initially at 50 μM on HSV-1-infected African green monkey kidney cells (VERO cells). Only one compound, 2-hydroxy-3-(2-thienyl)-1,4-naphthoquinone (AN-06), exhibited higher antiviral activity with a low cytotoxicity. AN-06 reduced the viral titer of 9 (log10) to 1.32 (log10) and decreased the steps of attachment and penetration. The addition of AN-06 up to 20 h postinfection (hpi) interfered with the viral cycle. The viral infection alone increases NKA activity 3 h postinfection (hpi), scaling up to 6 hpi. The addition of AN-06 in a culture infected with HSV-1 decreased NKA activity, suggesting that its antiviral action is linked to NKA inhibition. Also, docking results showed that this compound binds at the same site of NKA in which adenosine triphosphate (ATP) binds. AN-06 exhibited promising pharmacokinetic and toxicology properties. Thus, we postulate that AN-06 may be a good candidate for antiviral compounds with a mechanism of action targeting NKA activity.

Synthetic naphthoquinone derivatives suppressed nitric oxide and prostaglandin E2 production

Objectives: To synthesize and evaluate the anti-inflammatory potential of fifteen naphthoquinones (NQs), determining their ability to inhibitory nitric oxide (NO•) and prostaglandin E2 (PGE2) production. Methods: NQs were screened for their inhibitory effect on NO• and PGE production using LPS-activated RAW 264.7 macrophages. Results: Three linear furanonaphthoquinones (4-6) were identified as potent inhibitors of NO• and PGE2 production, with IC50 values ranging from 0.45 to 2.86 μM (NO•) and 0.38 to 1.65 (PGE2), highlighting the potent activity showed by compound 5 with IC50 values lower than one and high selectivity indices. Conclusions: Synthesized furanonaphthoquinones constitute leading compounds for the design of new anti-inflammatory agents and provide a valuable tool for designing new NQs that might be useful to treat inflammation. The evaluation of compounds 4-6 using in vivo models is warranted.

Naphthoquinones as a Promising Class of Compounds for Facing the Challenge of Parkinson's Disease.

Parkinson's disease (PD) is a degenerative disease that affects approximately 6.1 million people and is primarily caused by the loss of dopaminergic neurons. Naphthoquinones have several biological activities explored in the literature, including neuroprotective effects. Therefore, this review shows an overview of naphthoquinones with neuroprotective effects, such as shikonin, plumbagin and vitamin K, that prevented oxidative stress, in addition to multiple mechanisms. Synthetic naphthoquinones with inhibitory activity on the P2X7 receptor were also found, leading to a neuroprotective effect on Neuro-2a cells. It was found that naphthazarin can act as inhibitors of the MAO-B enzyme. Vitamin K and synthetic naphthoquinones hybrids with tryptophan or dopamine showed inhibition of the aggregation of α-synuclein. Synthetic derivatives of juglone and naphthazarin were able to protect Neuro-2a cells against neurodegenerative effects of neurotoxins. In addition, routes for producing synthetic derivatives were also discussed. With the data presented, 1,4-naphthoquinones can be considered as a promising class in the treatment of PD and this review aims to assist the scientific community in the application of these compounds. The derivatives presented can also support further research that explores their structures as synthetic platforms, in addition to helping to understand the interaction of naphthoquinones with biological targets related to PD.

Synthetic Naphthoquinone Derivatives as Anticancer Agents in Ovarian Cancer: Cytotoxicity Assay and Investigation of Possible Biological Mechanisms Action.

In this study, eight naphthoquinone derivatives were synthesized in yields ranging from 52 to 96% using easy, fast, and low-cost methodologies. All naphthoquinone derivatives were screened for their in vitro anti-proliferative activities against OVCA A2780 cancer cell lines. Amongst all analysed compounds, derivatives 3-5 presented the most prominent cytotoxic potential. Naphthoquinones 3 and 4, bearing sulfur-containing groups, were identified as having high potential for ROS production, in particular the superoxide anion. Furthermore, 3 and 4 compounds caused a decrease in the cell population in G0/G1 and induced more than 90% of the cell population to apoptosis. Compound 5 did not act in any of these processes. Finally, compounds 3-5 were tested for their inhibitory ability against PI3K and MAPK. Compounds 3 and 4 do not inhibit the PI3K enzyme. On the other hand, the naphthoquinone-polyphenol 5 was only able to inhibit the percentage of cells expressing pERK.

Role of synthetical amynoquinone ethyl 2-(1,4-dioxo-1,4-dihydronaphthalen-2-ylamino) acetate in inhibition of Ehrlich’s tumor

Quinones are naturally or synthetically occurring secondary metabolites that have various bio-dynamics, highlighting their antitumor potential. This has been explored through their selective cytotoxicity, and studies in medicinal chemistry about the relation between biological activity versus chemical structure may lead to the solution of the toxicity problems associated with quinones. In this context, the antitumor effect of a synthetic naphthoquinone, named Ethyl 2-(1,4-Dioxo-1,4-Dihydronaphthalen-2-Ylamino) Acetate, was tested using mice transplanted with Ehrlich ascitic tumor as an experimental model. The acute toxicity test was performed using 30 mice that received the aminoquinone at doses of 100, 200, 300, and 600mg/kg. After evaluation of the clinical findings in the spontaneous activity tests, the LD50 calculation for the test substance showed low levels of toxicity at doses lower than 244.11±23.29mg/kg. Thus, three experimental groups were established, where animals transplanted with tumor cells received NaCl vehicle solution (control, n=6), and the others were treated with 71.7mg/kg of Methotrexate (n=6) or 20mg/kg of Aminoquinone (n=6). All administrations were intraperitoneal, in a single dose. Three days after the implantation of the tumor cells the animals were weighed daily and evaluated for tumor biometry and development. The treatments occurred five days after the implantation of the tumor cells and were extended for 7 more days. At the end of the 12-day experimental period, all animals were euthanized for biochemical and histopathological analyses of the tumors and vital organs. The spontaneous activity test showed that the amount of responses associated with the nervous system tends to increase with the increase in dosage, highlighting the excitatory effect on the central nervous system in almost all dosages employed, followed by depressant activities on this system. There was a significant tumor reduction, both in animals treated with methotrexate (71.7 %) and in those treated with aminoquinone (91.6 %) in the control group. There was no significant difference in tumor volume between the animals treated with aminoquinone or methotrexate. The histopathological analysis revealed that in both treatments there were fewer mitoses in the tumor mass compared to the control group. However, there was apparent toxicity to the liver, heart, and left kidney in the treatment with methotrexate compared to aminoquinone. The significant capacity for tumor reduction presented by aminoquinone allows pointing it as a promising alternative for the development of a more efficient drug to control tumor development, being necessary for the development of new studies to deepen the knowledge about its mechanisms of action.

Natural naphthoquinones and their derivatives as potential drug molecules against trypanosome parasites.

Over the past decades, a number of 1,4-naphthoquinones have been isolated from natural resources and several of naphthoquinone derivatives with diverse structural motif have been synthesized; they possess a multitude of biochemical properties and modulate numerous pharmacological roles that offer new targets for addressing the challenges pertaining to novel drug developments. Among natural naphthoquinones, lapachol, α-lapachone, β-lapachone, lawsone, juglone, and plumbagin have been evaluated for its potential as antitrypanosomal activities. The chemotherapeutic drugs available for combating human trypanosomiasis, that is, American trypanosomiasis and African trypanosomiasis caused by Trypanosoma cruzi and Trypanosoma brucei, respectively, and animal tripanosomosis caused by Trypanosoma evansi have a problem of drug resistance and several toxic effect. Therefore, search of alternative effective drug molecules, without toxic effects, have enthused the researchers for searching new drug entity with potential clinical efficacy. In the search for new antitrypanosomal compound, this review focuses on different natural quinones and their synthetic derivatives associated with antitrypanosomal studies. In this context, this review will be useful for the development of new antitrypanosomal drugs mainly based on different structural modification of natural and synthetic naphthoquinones.

Naphthoquinone-induced arylation inhibits Sirtuin 7 activity.

Natural or synthetic naphthoquinones have been identified to interfere with biological systems and, in particular, exhibit anticancer properties. As redox cyclers, they generate reactive oxygen species in cells and, as electrophiles, they react with nucleophiles, mainly thiols, and form covalent adducts. To further decipher the molecular mechanism of action of naphthoquinones in human cells, we analyzed their effects in HeLa cells. First, we demonstrated that the naphthoquinones menadione and plumbagin inhibited the nucleolar NAD+-dependent deacetylase Sirtuin 7 in vitro. As assessed by their inhibition of rDNA transcription, pre-rRNA processing and formation of etoposide-induced 53BP1 foci, menadione and plumbagin also inhibited Sirtuin 7 catalytic activity in vivo. Second, we established that when sulfhydryl arylation by menadione or plumbagin was prevented by the thiol reducing agent N-acetyl-L-cysteine, the inhibition of Sirtuin 7 catalytic activity was also blocked. Finally, we discuss how inhibition of Sirtuin 7 might be crucial in defining menadione or plumbagin as anti-tumor agents that can be used in combination with other anti-tumor strategies.

Menadione: a platform and a target to valuable compounds synthesis.

Naphthoquinones are important natural or synthetic compounds belonging to the general class of quinones. Many compounds in this class have become drugs that are on the pharmaceutical market for the treatment of various diseases. A special naphthoquinone derivative is menadione, a synthetic naphthoquinone belonging to the vitamin K group. This compound can be synthesized by different methods and it has a broad range of biological and synthetic applications, which will be highlighted in this review.

Synthetic Naphthoquinone Derivatives as Anticancer Agents in Ovarian Cancer: Synthesis, Cytotoxicity Assay, and Investigation of the Mechanism of Action

Synthetic Naphthoquinone Derivatives as Anticancer Agents in Ovarian Cancer: Synthesis, Cytotoxicity Assay, and Investigation of the Mechanism of Action

Synthetic enamine naphthoquinone derived from lawsone as cytotoxic agents assessed by in vitro and in silico evaluations

We synthesized ten enamine naphthoquinones with yields ranging from 43 to 76%. These compounds were screened for their in vitro antiproliferative activities by MTT assay against four types of human cancer cell lines: HCT116, PC3, HL60 and SNB19. The naphthoquinones bearing the picolylamine (7) and quinoline (12) moieties were the most actives (IC50 < 24 μM for all the cell lines), which were comparable or better to the values obtained for the control drugs. In silico evaluations allowed us to develop a qualitative Structure-Activity Relationship which suggest that electrostatic features, particularly the C2–C3 internuclear repulsion and the molecular dipole moment, relate to the biological response. Furthermore, Molecular Docking simulations indicate that the synthetic compounds have the potential to act as anticancer molecules by inhibiting topoisomerase-II and thymidylate synthase.

Natural and Synthetic Naphthoquinones as Potential Anti-Infective Agents.

Naphthoquinones are a class of aromatic compounds relevant for their chemical characteristics, structural properties, and biological activity. These compounds are found in nature with a wide range of effects, highlighting their antibacterial, antifungal, and antiprotozoal properties. Additionally, naphthoquinones are used as a scaffold to obtain new derivatives with pharmacological potential, mainly compounds against parasitic diseases. The purpose of this work was to carry out a comprehensive review of naphthoquinones and their derivatives obtained from both natural and synthetic sources, also, to analyze their biological activity against Leishmania spp. (Leishmaniasis), Trypanosoma cruzi (Chagas disease), Plasmodium falciparum (Malaria), Toxoplasma gondii (Toxoplasmosis), and Toxocara canis (Toxocariasis). All of these agents are responsible for relevant diseases worldwide. Natural naphthoquinones, such as plumbagin, diospyrin, burmanin, lapachol, lawsone and psychorubrin, show an antiprotozoal activity similar or enhanced antiprotozoal activity to reference drugs. Some naphthoquinones obtained by synthesis or semi-synthesis showed better biological activity or less toxic effects than natural compounds. In this review, natural and synthetic naphthoquinones showed antiparasitic activity, in most cases, with improved results than current drugs currently used in clinical trials. A modification of their structure with different functional groups can enhance their biological effects, improve solubility, and reduce undesirable side effects. Therefore, naphthoquinones are important molecules in the development of new chemotherapeutic agents against parasitic diseases.

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.

Liposomes containing 3-arylamino-nor-β-lapachone derivative: Development, characterization, and in vitro evaluation of the cytotoxic activity

This study aimed to encapsulate the novel synthetic naphthoquinone ENSJ39 in liposomes, characterize them, and evaluate their in vitro cytotoxic activity in different cancer cell lines. Liposomes were obtained by the dried-lipid film hydration method, and characterizations included thermogravimetric analysis, differential scanning calorimetry, dynamic light scattering technique, and atomic force microscopy. Simulation of storage conditions, in vitro cytotoxicity by MTT, Trypan blue exclusion assay, and evaluation of morphological changes in tumor cell lines were also analyzed. Liposomes containing ENSJ39 (LE39) exhibited an average size of 31 ± 5.81 nm, zeta potential of +53.5 mV, polydispersity index of 0.24, and high encapsulation efficiency (96.58 ± 0.09%). They were thermally stable up to 250 °C and able to preserve the mass loss of the free drug. After four months of storage, they maintained excellent physical-chemical characteristics. The encapsulated drug showed less cytotoxic activity than the free drug only in HCT-116 and SNB-19 cells and caused cytoplasmic vacuolization plus an increase in the number of non-viable HCT-116 cells. ENSJ39 encapsulation method was effective in obtaining stable liposomes that presented substantial cytotoxicity activity against tumor cell lines.

Synthetic naphthoquinones thioglucosides as potential candidates to antivirals

Background: Human alphaherpesvirus 1 (HSV-1) is a one of a widespread human pathogen with Herpes labialis as most common clinical form. The nucleoside inhibitors of DNA polymerase are available for treatment of HSV-1 infection but their undesirable adverse effects and emergence of drug-resistant strains highlight the need to search new effective antivirals. The aim of our study was to improve solubility of structural analogues of naphthoquinonoid pigment of sea urchins echinochrome A (Ech) which antiviral activity against HSV-1 have been demonstrated previously. Methods and materials: The conjugation of naphthoquinones with non-toxic carbohydrate, thioglucose, have resulted in a number of compounds distinguished by presence of methyl-, ethyl, or hydroxyl-groups in defined position. Anti-HSV-1 activity of six thioglucosides (TGs) was analyzed on the different stages of L-2 strain of HSV-1 replication in the Vero E cells with help of MTT-test and calculation of half maximal inhibitory concentrations (IC50) and selectivity indexes. Acyclovir and echinochrome A were used as reference drugs. Results: Cytotoxity of new hydroxy- and alkyl dithioglucoside structures was 1.5–2 times less than the cytotoxity of Ech. When mode of TG action was studied, in simultaneous treatment of cells by virus + TG mixture, the TG-Et showed lowest among all TG and Ech value of IC50 (219.0 ± 46.0 vs. 246.8 ± 44.5 of Ech) and highest SI (1.9 ± 0.3 vs. 0.8 ± 0.1 of Ech). TG-Et also has more significant virulicidal effect with IC50 = 86.2 ± 12.9 and SI = 2.7 ± 0.5, compare with echinochrome (214.7 ± 36.6 and 0.9 ± 0.2, respectively). However, the pretreatment of uninfected cells and treatment of HSV-1-infected cells by TG-Et, TG-Me, and TG-OH has now effect, whereas when one Et-group was added to TG-Et, or Et-group was substituted by phenyl-group, the modified compounds became permeable to infected cells and showed good antiviral toward infected cells. Conclusion: Thus, we suggest that main anti-HSV-1 effect of new synthetic thioglucoside derivates of natural naphthoquinones is related to their virulicidal action, and TG with a lipophilic ethyl substituent more easily penetrate to virus envelope. The additional increase of lipophilic capacity improves the permeability into infected cells and such modifications may be very useful for development of new effective drugs with broad spectrum of antiviral activity.

Antioxidant, antiproliferative, and acetylcholinesterase inhibition activity of amino alcohol derivatives from 1,4-naphthoquinone

Natural and synthetic naphthoquinones have demonstrated numerous biological activities; therefore, they provide an interesting scaffold for medicinal chemists in the search for new drugs. A series of amino alcohol derivatives from 1,4-naphthoquinone with a free (2a–e) and acetylated (3a–d) hydroxyl group were synthesized, characterized, and evaluated as antioxidant agents employing 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2-2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS·+) assays, as acetylcholinesterase (AChE) inhibitors and antiproliferative compounds. In the DPPH assay, compound 3d showed the better result with 51.52% of antioxidant activity at 1 mg/mL, while in ABTS·+ was 2e (47.12%). The antiproliferative activity was evaluated against six different tumor cell lines, where the particular best results were for products 2a, 2c, and 2e against cervix line HeLa, with 50% growth inhibition (GI50) of 5.6, 15.0, and 17.0 μM, respectively. All synthesized compounds presented varying degrees of response, some of them with similar results compared with the positive control 5-fluorouracil. AChE inhibition of the products was not as strong as the positive control galantamine; the most potent compound was 2e with a 50% inhibitory concentration (IC50) of 0.0586 mM, followed by 2a (0.0902 mM). No inhibition in the evaluated concentrations was observed for products 2d and 3a-d. Docking of 2a and 2e was realized against AChE in order to gain insight into the interactions made between them and the enzyme residues in its catalytic gorge. In silico calculations for all synthesized products showed their drug-like properties. Alcohol derivatives, specially 2a and 2e, could be further derivatized in the search for new and improved drugs.

Synthesis and characterization of Mannich bases of lawsone and their anticancer activity

Natural and synthetic naphthoquinones are known for a large number of biological activities. Lawsone (2-hydroxy-1, 4-naphthoquinone) is a simplest naturally occurring compound obtained from dried henna (Lawsonia inermis) leaves. In literature, some lawsone derivatives have been reported to exhibit anticancer activity. Hence, a clean and facile one-pot protocol was developed for the synthesis of new aminonaphthoquinones derived from lawsone by three-component Mannich reaction, at room temperature for potential anti-cancer application. Herein we present a small library of Mannich bases with different amines and aromatic aldehydes with moderate to high yield. Synthesized compounds were characterized using various spectroscopic techniques. The anticancer activity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay) along with nuclear morphology assessment (4′,6-diamidino-2-phenylindole or DAPI staining), apoptosis assessment (acridine orange/ ethidium bromide staining), hemolysis and DNA ladder assay evaluated on human liver carcinoma cell line HepG2 are presented.

The Antifungal Activity of Naphthoquinones: An Integrative Review.

Naphthoquinones are the most commonly occurring type of quinones in nature. They are a diverse family of secondary metabolites that occur naturally in plants, lichens and various microorganisms. This subgroup is constantly being expanded through the discovery of new natural products and by the synthesis of new compounds via innovative techniques. Interest in quinones and the search for new biological activities within the members of this class have intensified in recent years, as evidenced by the evaluation of the potential antimicrobial activities of quinones. Among fungi of medical interest, yeasts of the genus Candida are of extreme importance due to their high frequency of colonization and infection in humans. The objective of this review is to describe the development of naphthoquinones as antifungals for the treatment of Candida species and to note the most promising compounds. By using certain criteria for selection of publications, 68 reports involving both synthetic and natural naphthoquinones are discussed. The activities of a large number of substances were evaluated against Candida albicans as well as against 7 other species of the genus Candida. The results discussed in this review allowed the identification of 30 naphthoquinones with higher antifungal activities than those of the currently used drugs.

Antioxidant and Antifungal Activity of Naphthoquinones Dimeric Derived from Lawsone

This article reports the evaluation of antioxidant and antifungal activity from synthetic naphthoquinones derived from lawsone. The antifungal activity was carried out through the inhibition of exoenzymes produced by Candida albicans. The inhibition of phospholipase and the proteinase production by Candida was similar in all derivatives tested; however, the difference between the enzyme production of the control and test does not show statistical difference in any of the studied strains. Furthermore, the antioxidant activity using DPPH radical-scavenging assay showed an important activity for all naphtoquinone derivatives.

Sarqaquinoic acid and related synthetic naphthoquinones inhibit the function of Hsp90

Sarqaquinoic acid and related synthetic naphthoquinones inhibit the function of Hsp90

Synthesis and studies of the antifungal activity of 2-anilino-/2,3-dianilino-/2-phenoxy- and 2,3-diphenoxy-1,4-naphthoquinones

Several synthetic and natural naphthoquinone derivatives have been associated with antifungal activity. Candida albicans is a fungus that is known to exist in the normal human flora, but under certain conditions it can cause mild to fatal infections. Its pathogenicity has been associated with fungus conversion from cellular yeast to filamentous form Y–M. Inhibition of this process by several anilino-, dianilino-, phenoxy-, and diphenoxy-1,4-naphthoquinones was investigated in order to find some correlation between structure, redox properties and biological activity.