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

Exploring the dual effect of novel 1,4-diarylpyranopyrazoles as antiviral and anti-inflammatory for the management of SARS-CoV-2 and associated inflammatory symptoms

COVID-19 and associated substantial inflammations continue to threaten humankind triggering death worldwide. So, the development of new effective antiviral and anti-inflammatory medications is a major scientific goal. Pyranopyrazoles have occupied a crucial position in medicinal chemistry because of their biological importance. Here, we report the design and synthesis of a series of sixteen pyranopyrazole derivatives substituted with two aryl groups at N-1 and C-4. The designed compounds are suggested to show dual activity to combat the emerging Coronaviruses and associated substantial inflammations. All compounds were evaluated for their in vitro antiviral activity and cytotoxicity against SARS-CoV infected Vero cells. As well, the in vitro assay of all derivatives against the SARS-CoV M^pro target was performed. Results revealed the potential of three pyranopyrazoles (22, 27, and 31) to potently inhibit the viral main protease with IC₅₀ values of 2.01, 1.83, and 4.60 μM respectively compared with 12.85 and 82.17 μM for GC-376 and lopinavir. Additionally, in vivo anti-inflammatory testing for the most active compound 27 proved its ability to reduce levels of two cytokines (TNF-α and IL-6). Molecular docking and dynamics simulation revealed consistent results with the in vitro enzymatic assay and indicated the stability of the putative complex of 27 with SARS-CoV-2 M^pro. The assessment of metabolic stability and physicochemical properties of 27 have also been conducted. This investigation identified a set of metabolically stable pyranopyrazoles as effective anti-SARS-CoV-2 M^pro and suppressors of host cell cytokine release. We believe that the new compounds deserve further chemical optimization and evaluation for COVID-19 treatment.

Contemporary exploitation of natural products for arthropod-borne pathogen transmission-blocking interventions

An integrated approach to innovatively counter the transmission of various arthropod-borne diseases to humans would benefit from strategies that sustainably limit onward passage of infective life cycle stages of pathogens and parasites to the insect vectors and vice versa. Aiming to accelerate the impetus towards a disease-free world amid the challenges posed by climate change, discovery, mindful exploitation and integration of active natural products in design of pathogen transmission-blocking interventions is of high priority. Herein, we provide a review of natural compounds endowed with blockade potential against transmissible forms of human pathogens reported in the last 2 decades from 2000 to 2021. Finally, we propose various translational strategies that can exploit these pathogen transmission-blocking natural products into design of novel and sustainable disease control interventions. In summary, tapping these compounds will potentially aid in integrated combat mission to reduce disease transmission trends.

Imidazoles and Oxazoles from Lapachones and Phenanthrene-9,10-dione: A Journey through their Synthesis, Biological Studies, and Optical Applications

Diverse structural frameworks are found in natural compounds and are well known for their chemical and biological properties; such compounds include the imidazoles and oxazoles. Researchers worldwide are continually working on the development of methods for synthesizing new molecules bearing these basic moiety and evaluating their properties and applications. To expand the knowledge related to azoles, this review summarizes important examples of imidazole and oxazole derivatives from 1,2-dicarbonyl compounds, such as lapachones and phenanthrene-9,10-diones, not only regarding their synthesis and biological applications but also their photophysical properties and uses. The data concerning the latter are particularly scarce in the literature, which leads to underestimation of the potential applications that can be envisaged for these compounds.

Evaluation of the Toxicity on Lung Cells of By-Products Present in Naphthalene Secondary Organic Aerosols

In 2018, seven million people died prematurely due to exposure to pollution. Polycyclic aromatic hydrocarbons (PAHs) are a significant source of secondary organic aerosol (SOA) in urban areas. We investigated the toxic effects of by-products of naphthalene SOA on lung cells. These by-products were 1,4-naphthoquinone (1,4-NQ), 2-hydroxy-1,4-naphthoquinone (2-OH-NQ), phthalic acid (PA) and phthaldialdehyde (OPA). Two different assessment methodologies were used to monitor the toxic effects: real-time cell analysis (RTCA) and the Holomonitor, a quantitative phase contrast microscope. The chemicals were tested in concentrations of 12.5 to 100 µM for 1,4-NQ and 1 to 10 mM for 2-OH-NQ, PA and OPA. We found that 1,4-NQ is toxic to cells from 25 to 100 µM (EC50: 38.7 µM ± 5.2); 2-OH-NQ is toxic from 1 to 10mM (EC50: 5.3 mM ± 0.6); PA is toxic from 5 to 10 mM (EC50: 5.2 mM ± 0.3) and OPA is toxic from 2.5 to 10 mM (EC50: 4.2 mM ± 0.5). Only 1,4-NQ and OPA affected cell parameters (migration, motility, motility speed and optical volume). Furthermore, 1,4-NQ is the most toxic by-product of naphthalene, with an EC50 value that was one hundred times higher than those of the other compounds. RTCA and Holomonitor analysis showed a complementarity when studying the toxicity induced by chemicals.

Copper-Catalyzed Cascade 1,4-Addition/Annulation/Hydrolysis of Propargylamines with 2-Hydroxynaphthalene-1,4-diones: Direct Formation of 12-Phenacyl-11H-benzo[b]xanthenes

A novel and versatile approach to construct 12-phenacyl-11H-benzo[b]xanthene-6,11(12H)-dione derivatives through copper-catalyzed cascade reaction of propargylamines with 2-hydroxynaphthalene-1,4-diones has been developed. The procedure is proposed to go through a sequence of 1,4-conjugate addition, intramolecular nucleophilic addition/dehydration, and hydrolysis of alkyne followed by an enol-ketone tautomerization. The reaction provides a new and highly efficient method for the synthesis of 12-phenacyl-11H-benzo[b]xanthene-6,11(12H)-diones by formation of three new bonds and one heterocycle from readily available starting materials in good to high yields (70-88%) with broad functional group compatibility in a single step.

Naphthoquinone derivatives exhibit apoptosis-like effect and anti-trypanosomal activity against Trypanosoma evansi

Trypanosoma evansi is an extracellular flagellate blood protozoan parasite and an etiological agent of animal trypanosomosis. Presently, only a few drugs are registered and have been used for the treatment of animal trypanosomosis, but they show severe toxic effects and also face the problem of drug resistance. Naphthoquinones (NTQ) are considered as fortunate structures in the field of medicinal chemistry as they have been reported for their antitrypanosomal potential against other trypanosomes-T. brucei and T. cruzi. In the present study, six naphthoquinones (NTQ1-NTQ6) derivatives were evaluated for anti-trypanosomal activity by demonstrating their growth inhibitory effect against T. evansi. All NTQs significantly (p < 0.001) exhibited activity against parasite growth and multiplication with IC₅₀ values of 11.48 μM, 373.6 μM, 12.97 μM, 21.97 μM, 18.19 μM and 5.758 μM but NTQ1, NTQ3 and NTQ6 were selected based on their IC₅₀ value for further studies. The dose-and time-dependent morphological effect on parasite was evaluated including the measurement of reactive oxygen species (ROS) by spectrofluorometery and measurement of apoptosis by flow cytometry. The selected NTQs exhibited a significant production of ROS and displayed a significant AV⁺ and PI⁺ labelled cells in the axenic culture of T. evansi than quinapyramine methyl sulphate (QPS), as reference control. NTQs also showed more cytotoxic effect on horse peripheral blood mononuclear cells as compare to QPS. Therefore, we confirmed the antitrypanosomal activity and apoptotic-like mechanism of NTQs in an axenic culture of T. evansi.

Hetero-Diels-Alder Reactions of Quinone Methides: The Origin of the α-Regioselectivity of 3-Methylene-1,2,4-naphthotriones

The regioselective formation of α- and β-lapachone via hetero-Diels-Alder reactions was investigated by experimental and computational approaches. The experimentally observed α-selectivity was explored in detail, revealing that the lower energy barrier for the formation of α-lapachone is a result of lower Pauli repulsion throughout the reaction path, when compared to the β-isomer. By comparing equivalent points on both α- and β-lapachone potential energy surfaces (PES), according to the activation strain model (ASM) and energy decomposition analysis (EDA), we were able to demonstrate that the Pauli repulsion term increases more significantly when going from reactants to TS_β than to TS_α, resulting in lower interaction energy in the early stages of the reaction path and in a later transition state for β-lapachone. Moreover, we confirmed that regio- and diastereoselectivity trends previously reported for other quinone methide intermediates are also observed for 3-methylene-1,2,4-naphthotriones, such as small endo/exo diastereoselectivity, as well as pronounced ortho/meta regioselectivity for reactions performed with dienophile containing electron-releasing groups. The results presented here provide a deeper understanding of the reactivity of quinone methide derivatives, aiding the future rational design of the reaction condition, structural modification of possible quinone methide intermediates, and the development of more selective synthetic routes for quinone derivatives.

Discovery of Dengue Virus Inhibitors

To date, there is still no approved anti-dengue agent to treat dengue infection in the market. Although the only licensed dengue vaccine, Dengvaxia is available, its protective efficacy against serotypes 1 and 2 of dengue virus was reported to be lower than serotypes 3 and 4. Moreover, according to WHO, the risk of being hospitalized and having severe dengue increased in seronegative individuals after they received Dengvaxia vaccination. Nevertheless, various studies had been carried out in search of dengue virus inhibitors. These studies focused on the structural (C, prM, E) and non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5) of dengue virus as well as host factors as drug targets. Hence, this article provides an overall up-to-date review of the discovery of dengue virus inhibitors that are only targeting the structural and non-structural viral proteins as drug targets.

Dengue Virus

Dengue virus (DENV) belongs to the family Flaviviridae, genus Flavivirus. It is a single-stranded positive-sense ribonucleic acid virus with 10,700 bases. The genus Flavivirus includes other arthropod borne viruses such as yellow fever virus, West Nile virus, Zika virus, tick-borne encephalitis virus. It infects ~50–200 million people annually, putting over 3.6 billion people living in tropical regions at risk and causing ~20,000 deaths annually. The expansion of dengue is attributed to factors such as the modern dynamics of climate change, globalization, travel, trade, socioeconomics, settlement, and also viral evolution. There are four antigenically different serotypes of DENV based on the differences in their viral structural and nonstructural proteins. DENV infection causes a spectrum of illness ranging from asymptomatic to dengue fever to severe dengue shock syndrome. Infection with one serotype confers lifelong immunity against that serotype, but heterologus infection leads to severe dengue hemorrhagic fever due to antibody-dependent enhancement. Diagnosis of dengue infections is based mainly on serological detection of either antigen in acute cases or antibodies in both acute and chronic infection. Viral detection and real-time PCR detection though helpful is not feasible in resource poor setup. Treatment of dengue depends on symptomatic management along with fluid resuscitation and may require platelet transfusion. Although vaccine development is in late stages of development, developing a single vaccine against four serotypes often causes serious challenges to researchers; hence, the main stay of prevention is vector control and management.

Efficient Synthesis and Antibacterial Profile of Bis(2-hydroxynaphthalene- 1,4-dione)

BACKGROUND

Antibacterial resistance is a serious public health problem infecting millions in the global population. Currently, there are few antimicrobials on the market against resistant bacterial infections. Therefore, there is an urgent need for new therapeutic options against these strains.

OBJECTIVE

In this study, we synthesized and evaluated ten Bis(2-hydroxynaphthalene-1,4-dione) against Gram-positive strains, including a hospital Methicillin-resistant (MRSA), and Gram-negative strains.

METHODS

The compounds were prepared by condensation of aldehydes and lawsone in the presence of different L-aminoacids as catalysts in very good yields. The compounds were submitted to antibacterial analysis through disk diffusion and Minimal Inhibitory Concentration (MIC) assays.

RESULTS

L-aminoacids have been shown to be efficient catalysts in the preparation of Bis(2- hydroxynaphthalene-1,4-dione) from 2-hydroxy-1,4-naphthoquinones and arylaldehydes in excellent yields of up to 96%. The evaluation of the antibacterial profile against Gram-positive strains (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. epidermidis ATCC 12228) also including a hospital Methicillin-resistant S. aureus (MRSA) and Gram-negative strains (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Klebsiella pneumoniae ATCC 4352), revealed that seven compounds showed antibacterial activity within the Clinical and Laboratory Standards Institute (CLSI) levels mainly against P. aeruginosa ATCC 27853 (MIC 8-128 µg/mL) and MRSA (MIC 32-128 µg/mL). In addition, the in vitro toxicity showed all derivatives with no hemolytic effects on healthy human erythrocytes. Furthermore, the derivatives showed satisfactory theoretical absorption, distribution, metabolism, excretion, toxicity (ADMET) parameters, and a similar profile to antibiotics currently in use. Finally, the in silico evaluation pointed to a structure-activity relationship related to lipophilicity for these compounds. This feature may help them in acting against Gram-negative strains, which present a rich lipid cell wall selective for several antibiotics.

CONCLUSION

Our data showed the potential of this series for exploring new and more effective antibacterial activities in vivo against other resistant bacteria.

Anti-Herpetic, Anti-Dengue and Antineoplastic Activities of Simple and Heterocycle-Fused Derivatives of Terpenyl-1,4-Naphthoquinone and 1,4-Anthraquinone

Quinones are secondary metabolites of higher plants associated with many biological activities, including antiviral effects and cytotoxicity. In this study, the anti-herpetic and anti-dengue evaluation of 27 terpenyl-1,4-naphthoquinone (NQ), 1,4-anthraquinone (AQ) and heterocycle-fused quinone (HetQ) derivatives was done in vitro against Human Herpesvirus (HHV) type 1 and 2, and Dengue virus serotype 2 (DENV-2). The cytotoxicity on HeLa and Jurkat tumor cell lines was also tested. Using plaque forming unit assays, cell viability assays and molecular docking, we found that NQ 4 was the best antiviral compound, while AQ 11 was the most active and selective molecule on the tested tumor cells. NQ 4 showed a fair antiviral activity against Herpesviruses (EC₅₀: <0.4 µg/mL, <1.28 µM) and DENV-2 (1.6 µg/mL, 5.1 µM) on pre-infective stages. Additionally, NQ 4 disrupted the viral attachment of HHV-1 to Vero cells (EC₅₀: 0.12 µg/mL, 0.38 µM) with a very high selectivity index (SI = 1728). The in silico analysis predicted that this quinone could bind to the prefusion form of the E glycoprotein of DENV-2. These findings demonstrate that NQ 4 is a potent and highly selective antiviral compound, while suggesting its ability to prevent Herpes and Dengue infections. Additionally, AQ 11 can be considered of interest as a leader for the design of new anticancer agents.

Design, Synthesis and Biological Evaluation of 1H-1,2,3-Triazole-Linked-1H-Dibenzo[b,h]xanthenes as Inductors of ROS-Mediated Apoptosis in the Breast Cancer Cell Line MCF-7

BACKGROUND

Low molecular weight 1,2,3-triazoles and naphthoquinones are endowed with various types of biological activity, such as against cancer, HIV and bacteria. However, in some cases, the conjugation of these two nuclei considerably increases their biological activities.

OBJECTIVE

In this work, we decided to study the synthesis and screening of bis-naphthoquinones and xanthenes tethered to 1,2,3-triazoles against cancer cell lines, specifically the human breast cancer cell line MCF-7.

RESULTS

Starting from lawsone and aryl-1H-1,2,3-triazole-4-carbaldehydes (10a-h) several new 7- (1-aryl-1H-1,2,3-triazol-4-yl)-6H-dibenzo[b,h]xanthene-5,6,8,13(7H)-tetraones (12a-h) and 3,3'- ((1-aryl-1H-1,2,3-triazol-4-yl)methylene)bis(2-hydroxynaphthalene-1,4-diones) 11a-h were synthesized and evaluated for their cytotoxic activities using the human breast cancer cell line MCF-7 and the non-tumor cell line MCF10A as control. We performed test of cell viability, cell proliferation, intracellular ATP content and cell cytometry to determine reactive oxygen species (ROS) formation.

CONCLUSIONS

Based on these results, we found that compound 12a promotes ROS production, interfering with energy metabolism, cell viability and proliferation, and thus promoting whole cell damage.

Dengue virus nonstructural 3 protein interacts directly with human glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and reduces its glycolytic activity

Dengue is an important mosquito-borne disease and a global public health problem. The disease is caused by dengue virus (DENV), which is a member of the Flaviviridae family and contains a positive single-stranded RNA genome that encodes a single precursor polyprotein that is further cleaved into structural and non-structural proteins. Among these proteins, the non-structural 3 (NS3) protein is very important because it forms a non-covalent complex with the NS2B cofactor, thereby forming the functional viral protease. NS3 also contains a C-terminal ATPase/helicase domain that is essential for RNA replication. Here, we identified 47 NS3-interacting partners using the yeast two-hybrid system. Among those partners, we highlight several proteins involved in host energy metabolism, such as apolipoprotein H, aldolase B, cytochrome C oxidase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH directly binds full-length NS3 and its isolated helicase and protease domains. Moreover, we observed an intense colocalization between the GAPDH and NS3 proteins in DENV2-infected Huh7.5.1 cells, in NS3-transfected BHK-21 cells and in hepatic tissue from a fatal dengue case. Taken together, these results suggest that the human GAPDH-DENV NS3 interaction is involved in hepatic metabolic alterations, which may contribute to the appearance of steatosis in dengue-infected patients. The interaction between GAPDH and full-length NS3 or its helicase domain in vitro as well as in NS3-transfected cells resulted in decreased GAPDH glycolytic activity. Reduced GAPDH glycolytic activity may lead to the accumulation of metabolic intermediates, shifting metabolism to alternative, non-glycolytic pathways. This report is the first to identify the interaction of the DENV2 NS3 protein with the GAPDH protein and to demonstrate that this interaction may play an important role in the molecular mechanism that triggers hepatic alterations.

Antivirus effectiveness of ivermectin on dengue virus type 2 in Aedes albopictus

Background

Dengue fever is the most rapidly spreading mosquito-borne viral disease over the past 50 years, with a 30-fold increase in global incidence. Dengue vector control is a key component for the dengue control strategy, since no absolutely effective vaccine or drug is available yet. However, the rapid rise and spread of mosquito insecticide resistance have become major threats to the efficiency of insecticide-based vector control activities. Thus, innovative vector control tools are badly needed. This study aims to confirm the antivirus effectiveness of ivermectin on dengue virus type 2 (DENV-2) in Aedes albopictus (Skuse, 1894), then to explore its potential use in the combating to the dengue epidemics.

Methods

Aedes albopictus were first infected with DENV-2 in human whole blood, and at the fourth day after infectious blood feeding, they were divided into eight groups. Seven of them were held for six days with access to 0, 2, 4, 8, 16, 32 and 64 ng/ml ivermectin, respectively, and the last one was set as a historical control group, which was stored at -80°C until being detected at the same time with the other groups. Each mosquito was detected using real-time fluorescent RT-PCR kit. DENV-2 RNA concentration (copies/ml) and infection rate in each group were compared.

Results

Both of quantitatively and qualitatively inhibiting effects of ivermectin have been detected in this study. Generally, DENV-2 replicated well in Aedes albopictus without ivermectin intervention, whose virus loads exhibited significantly higher when the mosquitoes were holding from 4 days to 10 days after infectious blood feeding. In contrast, with the treatment of ivermectin, the infection rate was reduced by as much as 49.63%. The regression equation between infection rates (Y₂) and ivermectin concentration log₂ values (X₂) was obtained as Y₂ = 91.41–7.21*X₂ with R² = 0.89.

Conclusion

Ivermectin can directly or indirectly inhibit DENV-2 multiplication in Aedes albopictus. Moreover, the actual concentration for application in zooprophylaxis needs to be confirmed in the further field trials.

Dengue fever is one of neglected vector-borne tropical diseases with a 30-fold increase in global incidence recently. In 2012, World Health Organization set a goal to reduce dengue mortality by at least 50% by 2020. Being faced with more challenges in the dengue control programs, such as the increase of dengue outbreaks, lacking absolutely effective vaccine, rise of vector insecticide resistance and so on; innovative vector control tools are urgently needed for current control programs on dengue fever. To find a new avenue in vector control, we for the first time assessed the inhibiting effectiveness of ivermectin on dengue virus type 2 (DENV-2) inside Aedes mosquitoes. We found that about 80% Aedes albopictus mosquitoes were effectively infected with DENV-2 without treatment of ivermectin. But in the groups of ivermectin treatment, the infection rate of DENV-2 and the median of virus loads were significantly reduced by up to 49.63% and 99.99%, respectively. Both quantitatively and qualitatively inhibiting effects of ivermectin were detected. We found out that ivermectin was able to effectively inhibit the DENV-2 multiplication in Aedes albopictus, which may gave us a hint that using ivermectin in some control programs as a zooprophylaxis to block dengue epidemic through inhibiting DENV-2 in field Aedes mosquitoes.

Characterizing the ligand-binding landscape of Zika NS3 helicase-promising lead compounds as potential inhibitors

Aim: This study aims to provide insight into the binding features of the ATPase and ssRNA sites of the NS3 helicase. Methods: Clinically approved Flavivirus inhibitors were docked to the corresponding active sites of the protein, and the three best compounds were validated with molecular dynamic simulations. Result: Binding of Ivermectin to ssRNA site and Lapachol and HMC-HO1α to the ATPase site allowed for conformational rigidity of the Zika NS3 helicase, thus stabilizing residue fluctuations and allowing for protein stability. Favorable free binding energies were also noted between compounds and the helicase, thus supporting the intermolecular forces at the helicase active site. Conclusion: The pharmacophoric characteristics found in Lapachol, HMC-HO1α and Ivermectin may be utilized in the design of a potent hybrid drug that is able to show efficient inhibition of a multitude of diseases including the detrimental co-infection of Zika virus, dengue and chikungunya.

Aromatase inhibitory activity of 1,4-naphthoquinone derivatives and QSAR study

A series of 2-amino(chloro)-3-chloro-1,4-naphthoquinone derivatives (1-11) were investigated for their aromatase inhibitory activities. 1,4-Naphthoquinones 1 and 4 were found to be the most potent compounds affording IC₅₀ values 5.2 times lower than the reference drug, ketoconazole. A quantitative structure-activity relationship (QSAR) model provided good predictive performance (R²_CV = 0.9783 and RMSE_CV = 0.0748) and indicated mass (Mor04m and H8m), electronegativity (Mor08e), van der Waals volume (G1v) and structural information content index (SIC2) descriptors as key descriptors governing the activity. To investigate the effects of structural modifications on aromatase inhibitory activity, the model was employed to predict the activities of an additional set of 39 structurally modified compounds constructed in silico. The prediction suggested that the 2,3-disubstitution of 1,4-naphthoquinone ring with halogen atoms (i.e., Br, I and F) is the most effective modification for potent activity (1a, 1b and 1c). Importantly, compound 1b was predicted to be more potent than its parent compound 1 (11.90-fold) and the reference drug, letrozole (1.03-fold). The study suggests the 1,4-naphthoquinone derivatives as promising compounds to be further developed as a novel class of aromatase inhibitors.

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.

Cytotoxicity, hemolysis and in vivo acute toxicity of 2-hydroxy-3-anilino-1,4-naphthoquinone derivatives

The 1,4-naphthoquinones, important members of the family of quinones are used as both crude extracts and as compound manipulated by the pharmaceutical industry. They have gained great emphasis by presenting different pharmacological properties as antibacterial, antiviral, antiprotozoal and anthelmintic, and has antitumor activity. Our aim was to evaluate the cytotoxicity, hemolytic activity and in vivo acute toxicity of three derivatives of 2-hydroxy-1,4-naphthoquinones. The cell viability in vitro against RAW Cell Line displayed IC₅₀ ranging of 483.5–2044.8 μM, whereas in primary culture tests using murine macrophages, IC₅₀ were 315.8–1408.0 μM for naphthoquinones derivatives 4a and 4c respectively, besides no hemolysis was observed at the dose tested. The in vivo acute toxicity assays exhibited a significant safety margin indicated by a lack of systemic and behavioral toxicity up to 300 mg/kg, and at a dose of 1000 mg/kg the derivatives not triggering signs of toxicity although the compound 4a have promoted hepatic steatosis and hyperemia in kidney tissue. Thereby, these modifications decrease the toxicity of the tested derivatives naphthoquinones, providing a high potential for the development of news drugs.

Goulart MO, Cavalcanti BC, Pessoa C, Bruno MP, Corrêa JR, Emery FS, da Silva Júnior EN. Novel fluorescent lapachone-based BODIPY: synthesis, computational and electrochemical aspects, and subcellular localisation of a potent antitumour hybrid quinone

A fully characterized fluorescent lapachone-based BODIPY, a specific mitochondrial-staining agent, is reported.

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.

Lawsone in organic synthesis

Lawsone has been used as the starting material for the synthesis of a variety of biologically active compounds and materials.