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

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

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

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

1,4-Naphthoquinone (CNN1) Induces Apoptosis through DNA Damage and Promotes Upregulation of H2AFX in Leukemia Multidrug Resistant Cell Line.

The multidrug resistance (MDR) phenotype is one of the major obstacles in the treatment of chronic myeloid leukemia (CML) in advantage stages such as blast crisis. In this scenario, more patients develop resistance mechanisms during the course of the disease, making tyrosine kinase inhibitors (TKIs) target therapies ineffective. Therefore, the aim of the study was to examine the pharmacological role of CNN1, a para-naphthoquinone, in a leukemia multidrug resistant cell line. First, the in vitro cytotoxic activity of Imatinib Mesylate (IM) in K-562 and FEPS cell lines was evaluated. Subsequently, membrane integrity and mitochondrial membrane potential assays were performed to assess the cytotoxic effects of CNN1 in K-562 and FEPS cell lines, followed by cell cycle, alkaline comet assay and annexin V-Alexa Fluor® 488/propidium iodide assays (Annexin/PI) using flow cytometry. RT-qPCR was used to evaluate the H2AFX gene expression. The results demonstrate that CNN1 was able to induce apoptosis, cell membrane rupture and mitochondrial membrane depolarization in leukemia cell lines. In addition, CNN1 also induced genotoxic effects and caused DNA fragmentation, cell cycle arrest at the G2/M phase in leukemia cells. No genotoxicity was observed on peripheral blood mononuclear cells (PBMC). Additionally, CNN1 increased mRNA levels of H2AFX. Therefore, CNN1 presented anticancer properties against leukemia multidrug resistant cell line being a potential anticancer agent for the treatment of resistant CML.

Synthesis of new N,S-acetal analogs derived from juglone with cytotoxic activity against Trypanossoma cruzi.

A series of 11 new N,S-acetal juglone derivatives were synthesized and evaluated against T. cruzi epimastigote forms. These compounds were obtained in good to moderate yields using a microwave irradiation protocol. Among all compounds, two N,S-acetal analogs, showed significant trypanocidal activity. Notably, one compound 11g exhibited selectivity index 10-fold higher than the reference drug benznidazole for epimastigote. The compound 11h was more effective for amastigote forms. Both prototypes exhibited S.I. higher than the benznidazole description. Thus, both compounds proving to be useful candidate molecules to further studies in infected animals.

In silico and pharmacological study of N,S-acetal juglone derivatives as inhibitors of the P2X7 receptor-promoted in vitro and in vivo inflammatory response.

Purinergic receptors are transmembrane proteins responsive to extracellular nucleotides and are expressed by several cell types throughout the human body. Among all identified subtypes, the P2×7 receptor has emerged as a relevant target for the treatment of inflammatory disease. Several clinical trials have been conducted to evaluate the effectiveness of P2×7R antagonists. However, to date, no selective antagonist has reached clinical use. In this work, we report the pharmacological evaluation of eleven N, S-acetal juglone derivatives as P2×7R inhibitors. Using in vitro assays and in vivo experimental models, we identified one derivative with promising inhibitory activity and low toxicity. Our in silico studies indicate that the 1,4-naphthoquinone moiety might be a valuable molecular scaffold for the development of novel P2×7R antagonists, as suggested by our previous studies.

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.

Semisynthetic triterpenes led to the generation of selective antitrypanosomal lead compounds.

Triterpenes α,ß-amyrin are naturally occurring molecules that can serve as building blocks for synthesizing new chemical entities. This study synthesized acyl, carboxyesther, NSAID, and nitrogenous derivatives and evaluated their antimicrobial activity. A cyclodextrin complexation method was developed to improve the solubility of the derivatives. Of the 17 derivatives tested, five exhibited activity against Trypanosoma cruzi, T. brucei, Leishmania infantum, Candida albicans, Staphylococcus aureus, and Escherichia coli. The 9a/9b mixture showed weak activity against the parasites (IC50 24.45-40.32 µM). However, it showed no activity for the other microorganisms. Derivatives 14a/14b exhibited potent activity against T. cruzi (IC50 2.0 nM) in this tested concentration did not show activity to the other microorganisms and were not cytotoxic. Derivatives 15a/15b and 16a/16b demonstrated relevant activity against the parasites (IC50 2.24-5.44 µM), but were also cytotoxic. Derivatives 17a/17b showed low activity against the tested parasites (IC50 21.70-22.79 µM), but they were selective since they did not show activity against other microorganisms. In docking studies, in general, all derivatives showed complementarity with the CYP51 binding site of the trypanosomatid mainly by hydrophobic interactions; thus, it is not conclusive that the molecules act by inhibiting this enzyme. Our results showed that triterpenes derivatives with antitrypanosomal activity could be synthesized by an inexpensive and rapid method.

Evaluation of 5-hydroxy-1,4-naphthoquinone-cobalt(III) complexes for hypoxia-activated drug delivery.

Three novel Py2N2-cobalt(III) complexes with the 5-hydroxy-1,4-naphthoquinone nuclei (NQ) were evaluated as potential hypoxia-activated anticancer prodrugs. The complexes were synthesized and fully characterized by IR and UV-Visible spectroscopies, ESI mass spectrometry and CHN elemental analysis. Structural information was obtained from density functional theory (DFT) calculations. Cyclic voltammetry analysis in acetonitrile indicates that the ligand substituents (H, CH3 and p-tolylthio) do not have a relevant effect on the Co3+/Co2+ redox potential. Reactions with ascorbic acid in phosphate buffers were performed to simulate redox activation of the complexes in biological media. Fast and irreversible dissociation of the NQ ligands was observed for all complexes upon Co3+/Co2+ reduction. Cytotoxic activity of complexes 1 and 3 was evaluated in tumor cells (HT-29 and HCT-116) under hypoxic and normoxic conditions.