Synthesis and in vitro and in vivo biological evaluation of substituted nitroquinoxalin-2-ones and 2,3-diones as novel trichomonacidal agents

Functionalized quinoxalinones as privileged structures with broad-ranging pharmacological activities

Quinoxalinones are a class of heterocyclic compounds which attract extensive attention owing to their potential in the field of organic synthesis and medicinal chemistry. During the past few decades, many new synthetic strategies toward the functionalization of quinoxalinone based scaffolds have been witnessed. Regrettably, there are only a few reports on the pharmacological activities of quinoxalinone scaffolds from a medicinal chemistry perspective. Therefore, herein we intend to outline the applications of multifunctional quinoxalinones as privileged structures possessing various biological activities, including anticancer, neuroprotective, antibacterial, antiviral, antiparasitic, anti-inflammatory, antiallergic, anti-cardiovascular, anti-diabetes, antioxidation, etc. We hope that this review will facilitate the development of quinoxalinone derivatives in medicinal chemistry.

Current status of quinoxaline and quinoxaline 1,4-di-N-oxides derivatives as potential antiparasitic agents

Parasitic diseases are a public health problem, especially in developing countries where millions of people are affected every year. Current treatments have several drawbacks: emerging resistance to the existing drugs, lack of efficacy, and toxic side effects. Therefore, new antiparasitic drugs are urgently needed to treat and control diseases that affect human health, such as malaria, Chagas disease, leishmaniasis, amebiasis, giardiasis schistosomiasis, and filariasis, among others. Quinoxaline is a compound containing a benzene ring and a pyrazine ring. The oxidation of both pyrazine ring nitrogens allows the obtention of quinoxaline 1,4-di-N-oxides (QdNOs) derivatives. By modifying the chemical structure of these compounds, it is possible to obtain a wide variety of biological properties. This review investigated the activity of quinoxaline derivatives and QdNOs against different protozoan parasites and helminths. We also cover the structure-activity relationship (SAR) and summarize the main findings related to their mechanisms of action from published works in recent years. However, further studies are needed to determine specific molecular targets. This review aims to highlight the new development of antiparasitic drugs with better pharmacological profiles than current treatments.

Wasp venom peptide as a new antichagasic agent

Chagas disease is caused by Trypanosoma cruzi and affects approximately 10 million people a year worldwide. The only two treatment options, benznidazole and nifurtimox, have low efficacy and high toxicity towards human cells. Mastoporan peptide (MP) a small cationic AMP from the venom of the wasp Polybia paulista has been reported as a potent trypanocidal agent. Thus, we evaluated the antichagasic effect of another AMP from the venom of the same wasp Polybia paulista, polybia-CP (ILGTILGLLSKL-NH₂), and investigated its mechanism of action against different stages of the trypanosomal cells life cycle. Polybia-CP was tested against the epimastigote, trypomastigote and amastigote forms of the T. cruzi Y strain (benznidazole-resistant strain) and inhibited the development of these forms. We also assessed the selectivity of the AMP against mammalian cells by exposing LLC-MK2 cells to polybia-CP, the peptide presented a high selectivity index (>106). The mechanism of action of polybia-CP on trypanosomal cells was investigated by flow cytometry, scanning electron microscopy (SEM) and enzymatic assays with T. cruzi GAPDH (tcGAPDH), enzyme that catalyzes the sixth step of glycolysis. Polybia-CP induced phosphatidylserine exposure, it also increased the formation of reactive species of oxigen (ROS) and reduced the transmembrane mitochondrial potential. Polybia-CP also led to cell shrinkage, evidencing apoptotic cell death. We did not observe the inhibition of tcGAPDH or autophagy induction. Altogether, polybia-CP has shown the features of a promising template for the development of new antichagasic agents.

Evolution in medicinal chemistry of sorafenib derivatives for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Traditional chemotherapy drugs are hard to reach a satisfactory therapeutic effect since advanced HCC is highly chemo-resistant. Sorafenib is an oral multikinase inhibitor that can suppress tumor cell proliferation, angiogenesis and induce cancer cell apoptosis. However, the poor solubility, rapid metabolism and low bioavailability of sorafenib greatly restricted its further clinical application. During the past decade, numerous sorafenib derivatives have been designed and synthesized to overcome its disadvantages and improve its clinical performance. This article focuses on the therapeutic effects and mechanisms of various sorafenib derivatives with modifications on the N-methylpicolinamide group, urea group, central aromatic ring or others. More importantly, this review summarizes the current status of the structure-activity relationship (SAR) of reported sorafenib derivatives, which can provide some detailed information of future directions for further structural modifications of sorafenib to discovery new anti-tumor drugs with improved clinical performance.

Chemotherapeutic options for the treatment of human trichomoniasis

Trichomonas vaginalis is the causative agent of the most common non-viral sexually transmitted disease worldwide. The infection may be associated with severe complications, including infertility, preterm labour, cancer and an increased risk of human immunodeficiency virus (HIV) transmission. Treatment remains almost exclusively based on 5-nitroimidazoles, but resistance is on the rise. This article provides an overview of clinically evaluated systemic and topical treatment options for human trichomoniasis and summarises the current state of knowledge on various herbal, semisynthetic and synthetic compounds evaluated for their anti-Trichomonas efficacy in vitro.

Synthesis and cytotoxic evaluation of some novel quinoxalinedione diarylamide sorafenib analogues

A series of novel sorafenib analogues containing a quinoxalinedione ring and amide linker were synthesized. A total of 9 novel compounds in 6 synthetic steps were synthesized. Briefly, the amino group of p-aminophenol was first protected which then followed by O-arylation with 5-chloro-2-nitroaniline to provide compound d. Reduction of the nitro group of compound d and cyclization of the diamine group of compound e with oxalic acid afforded compound f which on deacetylation yeilded compound g. Then compound g was reacted with different acyl halides to afford the target compounds 1h-1p. Chemical structures of synthesized compounds were confirmed by 1H NMR and FT-IR analysis. All compounds were evaluated at 1, 10, 50 and 100 μM concentrations for their cytotoxicity against HeLa and MCF-7 cancer cell lines. Some of the compounds showed good cytotoxic activity, especially compounds 1i and 1k-1n with the IC50 values of 19, 16, 22, 18, and 16 μM against MCF-7 cell line and 20, 18, 25, 20, and 18 μM against HeLa cell line, respectively.

2-Methyl-4/5-nitroimidazole derivatives potentiated against sexually transmitted Trichomonas: Design, synthesis, biology and 3D-QSAR study

Trichomoniasis is the most prevalent, non-viral sexually transmitted diseases (STD) caused by amitochondriate protozoan Trichomonas vaginalis. Increased resistance of T. vaginalis to the marketed drug Metronidazole necessitates the development of newer chemical entities. A library of sixty 2-methyl-4/5-nitroimidazole derivatives was synthesized via nucleophilic ring opening reaction of epoxide and the efficacies against drug-susceptible and -resistant Trichomonas vaginalis were evaluated. All the molecules except two were found to be active against both susceptible and resistant strains with MICs ranging 8.55-336.70 μM and 28.80-1445.08 μM, respectively. Most of the compounds were remarkably more effective than the standard Metronidazole. This study analyzes the in vitro and in vivo activities of the new 5-nitroimidazoles, which were found to be safe against human cervical HeLa cells with good selectivity index. The exploration of SAR by the synthesis of four different prototypes and 3D-QSAR study has shown the importance of prototype 1 over other prototypes.

In vitro trichomonacidal activity and preliminary in silico chemometric studies of 5-nitroindazolin-3-one and 3-alkoxy-5-nitroindazole derivatives

A selection of 1,2-disubstituted 5-nitroindazolin-3-ones (1–19) and 3-alkoxy-5-nitroindazoles substituted at positions 1 (20–24) or 2 (25–39) from our in-house compound library were screened in vitro against the most common curable sexually transmitted pathogen, Trichomonas vaginalis. A total of 41% of the studied molecules (16/39) achieved a significant activity of more than 85% growth inhibition at the highest concentration assayed (100 µg mL−1). Among these compounds, 3-alkoxy-5-nitroindazole derivatives 23, 24, 25 and 27 inhibited parasite growth by more than 50% at 10 µg mL−1. In addition, the first two compounds (23, 24) still showed remarkable activity at the lowest dose tested (1 µg mL−1), inhibiting parasite growth by nearly 40%. Their specific activity towards the parasite was corroborated by the determination of their non-specific cytotoxicity against mammalian cells. The four mentioned compounds exhibited non-cytotoxic profiles at all of the concentrations assayed, showing a fair antiparasitic selectivity index (SI > 7·5). In silico studies were performed to predict pharmacokinetic properties, toxicity and drug-score using Molinspiration and OSIRIS computational tools. The current in vitro results supported by the virtual screening suggest 2-substituted and, especially, 1-substituted 3-alkoxy-5-nitroindazoles as promising starting scaffolds for further development of novel chemical compounds with the main aim of promoting highly selective trichomonacidal lead-like drugs with adequate pharmacokinetic and toxicological profiles.