Comparative Analysis of a Secondary Metabolite Profile from Roots and Leaves of Iostephane heterophylla by UPLC-MS and GC-MS.

Iostephane heterophylla is a traditional Mexican medicinal plant and is an important source of secondary metabolites with antimicrobial and cytotoxic activity. The aim of this work was to conduct a comparative analysis of secondary metabolites of different roots and leaf extracts of I. heterophylla from two zones in Mexico using ultraperformance liquid chromatography (UPLC) and gas chromatography (GC) coupled with mass spectrometry (MS). Twelve secondary metabolites from roots were identified in the leaves. Five new molecular weight secondary metabolites not previously reported were found. Six bioactive metabolites were quantified (quercetin ≤0.151 mg/mL in root and ≤0.041 mg/mL in leaf; hesperidin ≤0.66 mg/mL in root and ≤0.173 mg/mL in leaf; epicatechin ≤0. 163 mg/mL in root and ≤0.664 mg/mL in leaf; caffeic acid ≤0.372 mg/mL in root and ≤0.393 mg/mL in leaf; chlorogenic acid ≤0.234 mg/mL in root and ≤0.328 mg/mL in leaf; and xanthorrhizol ≤0.667 mg/mL in root), and a selective extraction method was established: quercetin in root and leaf by reflux; hesperidin in leaf by Soxhlet and in leaf by reflux; chlorogenic acid in root by Soxhlet and in leaf by reflux; chlorogenic acid ≤0.234 mg/mL in root and ≤0.328 mg/mL in leaf by ultrasound-assisted extraction; epicatechin in root by ultrasound-assisted extraction; caffeic acid in root by reflux and in leaf by Soxhlet. The most efficient solvent was methanol. This study provides a new secondary metabolite profile found in the leaves of I. heterophylla, highlighting it is an essential source of three bioactive compounds: epicatechin, hesperidin, and quercetin.

Repositioning FDA-Approved Drug Against Chagas Disease and Cutaneous Leishmaniosis by Structure-Based Virtual Screening.

BACKGROUND: Chagas disease and cutaneous leishmaniasis, two parasitic diseases caused by Trypanosoma cruzi (T. cruzi) and Leishmania mexicana (L. mexicana), respectively, have a major global impact. Current pharmacological treatments for these diseases are limited and can cause severe side effects; thus, there is a need for new antiprotozoal drugs. METHODS: Using molecular docking, this work describes a structure-based virtual screening of an FDA-approved drug library against Trypanosoma cruzi and Leishmania mexicana glycolytic enzyme triosephosphate isomerase (TIM), which is highly conserved in these parasites. The selected compounds with potential dual inhibitory activity were tested in vitro to confirm their biological activity. RESULTS: The study showed that five compounds: nilotinib, chlorhexidine, protriptyline, cyproheptadine, and montelukast, were more active against T. cruzi, than the reference drugs, nifurtimox and benznidazole while chlorhexidine and protriptyline were the most active against L. mexicana. CONCLUSIONS: The analysis of these compounds and their structural characteristics may provide the basis for the development of new antiprotozoal agents.

Advances in the Development of Carbonic Anhydrase Inhibitors as New Antiprotozoal Agents.

BACKGROUND: Parasitic diseases are a public health problem despite the existence of drugs for their treatment. These treatments have variable efficacy and, in some cases, serious adverse effects. There has been interest in the enzyme carbonic anhydrase (CA) in the last two decades since it is essential in the life cycle of various parasites due to its important participation in processes such as pyrimidine synthesis, HCO3- transport across cell membranes, and the maintenance of intracellular pH and ion transport (Na+, K+, and H+), among others. OBJECTIVE: In this review, CA was analyzed as a pharmacological target in etiological agents of malaria, American trypanosomiasis, leishmaniasis, amoebiasis, and trichomoniasis. The CA inhibitors´ design, binding mode, and structure-activity relationship are also discussed. CONCLUSION: According to this review, advances in discovering compounds with potent inhibitory activity suggest that CA is a candidate for developing new antiprotozoal agents.

Triose Phosphate Isomerase Structure-Based Virtual Screening and In Vitro Biological Activity of Natural Products as Leishmania mexicana Inhibitors.

Cutaneous leishmaniasis (CL) is a public health problem affecting more than 98 countries worldwide. No vaccine is available to prevent the disease, and available medical treatments cause serious side effects. Additionally, treatment failure and parasite resistance have made the development of new drugs against CL necessary. In this work, a virtual screening of natural products from the BIOFACQUIM and Selleckchem databases was performed using the method of molecular docking at the triosephosphate isomerase (TIM) enzyme interface of Leishmania mexicana (L. mexicana). Finally, the in vitro leishmanicidal activity of selected compounds against two strains of L. mexicana, their cytotoxicity, and selectivity index were determined. The top ten compounds were obtained based on the docking results. Four were selected for further in silico analysis. The ADME-Tox analysis of the selected compounds predicted favorable physicochemical and toxicological properties. Among these four compounds, S-8 (IC50 = 55 µM) demonstrated a two-fold higher activity against the promastigote of both L. mexicana strains than the reference drug glucantime (IC50 = 133 µM). This finding encourages the screening of natural products as new anti-leishmania agents.

Phenothiazine-based virtual screening, molecular docking, and molecular dynamics of new trypanothione reductase inhibitors of Trypanosoma cruzi.

Phenothiazine derivatives can unselectively inhibit the trypanothione-dependent antioxidant system enzyme trypanothione reductase (TR). A virtual screening of 2163 phenothiazine derivatives from the ZINC15 and PubChem databases docked on the active site of T. cruzi TR showed that 285 compounds have higher affinity than the natural ligand trypanothione disulfide. 244 compounds showed higher affinity toward the parasite's enzyme than to its human homolog glutathione reductase. Protein-ligand interaction profiling predicted that the main interactions for the top scored compounds were with residues important for trypanothione disulfide binding: Phe396, Pro398, Leu399, His461, Glu466, and Glu467, particularly His461, which participates in catalysis. Two compounds with the desired profiles, ZINC1033681 (Zn_C687) and ZINC10213096 (Zn_C216), decreased parasite growth by 20 % and 50 %, respectively. They behaved as mixed-type inhibitors of recombinant TR, with Ki values of 59 and 47 µM, respectively. This study provides a further understanding of the potential of phenothiazine derivatives as TR inhibitors.

Molecular docking and dynamic simulations of quinoxaline 1,4-di-N-oxide as inhibitors for targets from Trypanosoma cruzi, Trichomonas vaginalis, and Fasciola hepatica.

CONTEXT: Quinoxaline 1,4-di-N-oxide is a scaffold with a wide array of biological activities, particularly its use to develop new antiparasitic agents. Recently, these compounds have been described as trypanothione reductase (TR), triosephosphate isomerase (TIM), and cathepsin-L (CatL) inhibitors from Trypanosoma cruzi, Trichomonas vaginalis, and Fasciola hepatica, respectively. METHODS: Therefore, the main objective of this work was to analyze quinoxaline 1,4-di-N-oxide derivatives of two databases (ZINC15 and PubChem) and literature by molecular docking, dynamic simulation and complemented by MMPBSA, and contact analysis of molecular dynamics' trajectory on the active site of the enzymes to know their potential effect inhibitory. Interestingly, compounds Lit_C777 and Zn_C38 show preference as potential TcTR inhibitors over HsGR, with favorable energy contributions from residues including Pro398 and Leu399 from Z-site, Glu467 from γ-Glu site, and His461, part of the catalytic triad. Compound Lit_C208 shows potential selective inhibition against TvTIM over HsTIM, with favorable energy contributions toward TvTIM catalytic dyad, but away from HsTIM catalytic dyad. Compound Lit_C388 was most stable in FhCatL with a higher calculated binding energy by MMPBSA analysis than HsCatL, though not interacting with catalytic dyad, holding favorable energy contribution from residues oriented at FhCatL catalytic dyad. Therefore, these kinds of compounds are good candidates to continue researching and confirming their activity through in vitro studies as new selective antiparasitic agents.

Advances in Protozoan Epigenetic Targets and Their Inhibitors for the Development of New Potential Drugs.

Protozoan parasite diseases cause significant mortality and morbidity worldwide. Factors such as climate change, extreme poverty, migration, and a lack of life opportunities lead to the propagation of diseases classified as tropical or non-endemic. Although there are several drugs to combat parasitic diseases, strains resistant to routinely used drugs have been reported. In addition, many first-line drugs have adverse effects ranging from mild to severe, including potential carcinogenic effects. Therefore, new lead compounds are needed to combat these parasites. Although little has been studied regarding the epigenetic mechanisms in lower eukaryotes, it is believed that epigenetics plays an essential role in vital aspects of the organism, from controlling the life cycle to the expression of genes involved in pathogenicity. Therefore, using epigenetic targets to combat these parasites is foreseen as an area with great potential for development. This review summarizes the main known epigenetic mechanisms and their potential as therapeutics for a group of medically important protozoal parasites. Different epigenetic mechanisms are discussed, highlighting those that can be used for drug repositioning, such as histone post-translational modifications (HPTMs). Exclusive parasite targets are also emphasized, including the base J and DNA 6 mA. These two categories have the greatest potential for developing drugs to treat or eradicate these diseases.

Virtual Screening of Benzimidazole Derivatives as Potential Triose Phosphate Isomerase Inhibitors with Biological Activity against Leishmania mexicana.

Leishmania mexicana (L. mexicana) is a causal agent of cutaneous leishmaniasis (CL), a "Neglected disease", for which the search for new drugs is a priority. Benzimidazole is a scaffold used to develop antiparasitic drugs; therefore, it is interesting molecule against L. mexicana. In this work, a ligand-based virtual screening (LBVS) of the ZINC15 database was performed. Subsequently, molecular docking was used to predict the compounds with potential binding at the dimer interface of triosephosphate isomerase (TIM) of L. mexicana (LmTIM). Compounds were selected on binding patterns, cost, and commercial availability for in vitro assays against L. mexicana blood promastigotes. The compounds were analyzed by molecular dynamics simulation on LmTIM and its homologous human TIM. Finally, the physicochemical and pharmacokinetic properties were determined in silico. A total of 175 molecules with docking scores between -10.8 and -9.0 Kcal/mol were obtained. Compound E2 showed the best leishmanicidal activity (IC50 = 4.04 µM) with a value similar to the reference drug pentamidine (IC50 = 2.23 µM). Molecular dynamics analysis predicted low affinity for human TIM. Furthermore, the pharmacokinetic and toxicological properties of the compounds were suitable for developing new leishmanicidal agents.

Recent advances in the development of methyltransferase (MTase) inhibitors against (re)emerging arboviruses diseases dengue and Zika.

Emerging and/or re-emerging viral diseases such as dengue and Zika are a worldwide concern. Therefore, new antiviral therapeutics are necessary. In this sense, a non-structural protein with methyltransferase (MTase) activity is an attractive drug target because it plays a crucial role in dengue and Zika virus replication. Different drug strategies such as virtual screening, molecular docking, and molecular dynamics have identified new inhibitors that bind on the MTase active site. Therefore, in this review, we analyze MTase inhibitors, including S-adenosyl-L-methionine (SAM), S-adenosyl-l-homocysteine (SAH) and guanosine-5'-triphosphate (GTP) analogs, nitrogen-containing heterocycles (pyrimidine, adenosine, and pyridine), urea derivatives, and natural products. Advances in the design of MTase inhibitors could lead to the optimization of a possible single or broad-spectrum antiviral drug against dengue and Zika virus.

In Vitro and In Silico Analysis of New n-Butyl and Isobutyl Quinoxaline-7-carboxylate 1,4-di-N-oxide Derivatives against Trypanosoma cruzi as Trypanothione Reductase Inhibitors.

American trypanosomiasis is a worldwide health problem that requires attention due to ineffective treatment options. We evaluated n-butyl and isobutyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives against trypomastigotes of the Trypanosoma cruzi strains NINOA and INC-5. An in silico analysis of the interactions of 1,4-di-N-oxide on the active site of trypanothione reductase (TR) and an enzyme inhibition study was carried out. The n-butyl series compound identified as T-150 had the best trypanocidal activity against T. cruzi trypomastigotes, with a 13% TR inhibition at 44 µM. The derivative T-147 behaved as a mixed inhibitor with Ki and Ki' inhibition constants of 11.4 and 60.8 µM, respectively. This finding is comparable to the TR inhibitor mepacrine (Ki = 19 µM).

Ligand-Based Virtual Screening and Molecular Docking of Benzimidazoles as Potential Inhibitors of Triosephosphate Isomerase Identified New Trypanocidal Agents.

Trypanosoma cruzi (T. cruzi) is a parasite that affects humans and other mammals. T. cruzi depends on glycolysis as a source of adenosine triphosphate (ATP) supply, and triosephosphate isomerase (TIM) plays a key role in this metabolic pathway. This enzyme is an attractive target for the design of new trypanocidal drugs. In this study, a ligand-based virtual screening (LBVS) from the ZINC15 database using benzimidazole as a scaffold was accomplished. Later, a molecular docking on the interface of T. cruzi TIM (TcTIM) was performed and the compounds were grouped by interaction profiles. Subsequently, a selection of compounds was made based on cost and availability for in vitro evaluation against blood trypomastigotes. Finally, the compounds were analyzed by molecular dynamics simulation, and physicochemical and pharmacokinetic properties were determined using SwissADME software. A total of 1604 molecules were obtained as potential TcTIM inhibitors. BP2 and BP5 showed trypanocidal activity with half-maximal lytic concentration (LC50) values of 155.86 and 226.30 µM, respectively. Molecular docking and molecular dynamics simulation analyzes showed a favorable docking score of BP5 compound on TcTIM. Additionally, BP5 showed a low docking score (-5.9 Kcal/mol) on human TIM compared to the control ligand (-7.2 Kcal/mol). Both compounds BP2 and BP5 showed good physicochemical and pharmacokinetic properties as new anti-T. cruzi agents.

Synthesis and biological evaluation in vitro and in silico of N-propionyl-N'-benzeneacylhydrazone derivatives as cruzain inhibitors of Trypanosoma cruzi.

An N-acylhydrazone scaffold has been used to develop new drugs with diverse biological activities, including trypanocidal activity against different strains of Trypanosoma cruzi. However, their mechanism of action is not clear, although in T. cruzi it has been suggested that the enzyme cruzain is involved. The aim in this work was to obtain new N-propionyl-N'-benzeneacylhydrazone derivatives as potential anti-T. cruzi agents and elucidate their potential mechanism of action by a molecular docking analysis and effects on the expression of the cruzain gene. Compounds 9 and 12 were the most active agents against epimastigotes and compound 5 showed better activity than benznidazole in T. cruzi blood trypomastigotes. Additionally, compounds 9 and 12 significantly increase the expression of the cruzain gene. In summary, the in silico and in vitro data presented herein suggest that compound 9 is a cruzain inhibitor.

Recent Advances in the Development of Triose Phosphate Isomerase Inhibitors as Antiprotozoal Agents.

BACKGROUND: Parasitic diseases caused by protozoa, such as Chagas disease, leishmaniasis, malaria, African trypanosomiasis, amoebiasis, trichomoniasis, and giardiasis, are considered serious public health problems in developing countries. Drug resistance among parasites justifies the search for new therapeutic drugs, and the identification of new targets becomes a valuable approach. In this scenario, the glycolysis pathway, which converts glucose into pyruvate, plays an important role in the protozoa energy supply, and it is therefore considered a promising target. In this pathway, triose phosphate isomerase (TIM) plays an essential role in efficient energy production. Furthermore, protozoa TIM shows structural differences with human enzyme counterparts, suggesting the possibility of obtaining selective inhibitors. Therefore, TIM is considered a valid approach to develop new antiprotozoal agents, inhibiting the glycolysis in the parasite. OBJECTIVE: In this review, we discuss the drug design strategies, structure-activity relationship, and binding modes of outstanding TIM inhibitors against Trypanosoma cruzi, Trypanosoma brucei, Plasmodium falciparum, Giardia lamblia, Leishmania mexicana, Trichomonas vaginalis, and Entamoeba histolytica. RESULTS: TIM inhibitors have mainly shown aromatic systems and symmetrical structure, where the size and type of heteroatom are important for enzyme inhibition. This inhibition is mainly based on the interaction with i) the interfacial region of TIM inducing changes on the quaternary and tertiary structure or ii) with the TIM catalytic region, the main pathways that disable the catalytic activity of the enzyme. CONCLUSION: Benzothiazole, benzoxazole, benzimidazole, and sulfhydryl derivatives stand out as TIM inhibitors. In silico and in vitro studies have demonstrated that the inhibitors bind mainly at the TIM dimer interface. In this review, the development of new TIM inhibitors as antiprotozoal drugs is demonstrated as an important pharmaceutical strategy that may lead to new therapies for these ancient parasitic diseases.

Recent Advances in the Medicinal Chemistry of Phenothiazines, New Anticancer and Antiprotozoal Agents.

BACKGROUND: Molecules with a phenothiazine scaffold have been considered versatile organic structures with a wide variety of biological activities, such as antipsychotic, anticancer, antibacterial, antifungal, antiviral, anti-inflammatory, antimalarial, and trypanocidal, etc. It was first discovered in the 19th century as a histochemical dye, phenothiazine methylene blue. Since then, its derivatives have been studied, showing new activities; moreover, they have also been repurposed. OBJECTIVE: This review aims to describe the main synthetic routes of phenothiazines and, particularly, the anticancer and antiprotozoal activities reported during the second decade of the 2000s (2010 - 2020). RESULTS: Several studies on phenothiazines against cancer and protozoa have revealed that these compounds show IC50 values in the micromolar and near nanomolar range. The structural analyses have revealed that compounds bearing halogens or electron-withdrawing groups at 2-position have favorable anticancer activity. Phenothiazine dyes have shown a photosensitizing activity against trypanosomatids at a micromolar range. Tetra and pentacyclic azaphenothiazines are structures with a high broad-spectrum anticancer activity. CONCLUSION: The phenothiazine scaffold is favorable for developing anticancer agents, especially those bearing halogens and electron-withdrawing groups bound at 2-position with enhanced biological activities through a variety of aromatic, aliphatic and heterocyclic substituents in the thiazine nitrogen. Further studies are warranted along these investigation lines to attain more active anticancer and antiprotozoal compounds with minimal to negligible cytotoxicity.

Analysis of the effect of methyl 2-acetamide-3-methylquinoxaline-7-carboxylate 1,4-di-N-oxide on the relative expression of the trypanothione reductase gene in Trypanosoma cruzi epimastigotes.

In recent decades, some quinoxaline 1,4-di-N-oxide derivatives have been shown to have better trypanocidal activity than the reference drugs; however, their mechanism of action is not yet clear, although it is suggested that they mainly produce reactive oxygen species that cause oxidative stress and parasite death. Trypanosoma cruzi relies on the enzyme trypanothione reductase, among others, to defend itself against oxidative stress. With the aim of contributing to the elucidation of the mechanism of action of quinoxaline 1,4-di-N-oxide derivatives on Trypanosoma cruzi, this study was carried out to evaluate the effect of methyl 2-amide-3-methylquinoxaline-7-carboxylate 1,4-di-N-oxide (compound M-8) on the expression of the trypanothione reductase gene in an in vitro model on Trypanosoma cruzi epimastigotes of the CL-Brener strain. The results show that compound M-8 does not cause a significant effect on the trypanothione reductase gene, suggesting a mechanism of action not related to oxidative stress.

Effect of 4-amino-3-nitrobenzoic acid on the expression level of the trans-sialidase gene in Trypanosoma cruzi epimastigotes.

Trans-sialidase of Trypanosoma cruzi (TcTS) is a key enzyme in the infection process from parasite to host; therefore, it has been considered an important target for developing new anti-Chagas drugs. Different compounds with trypanocidal activity and/or inhibition of TcTS have been reported; however, some benzoic acid derivatives have shown high enzymatic inhibition but low trypanocidal activity and viceversa. These results show that each compound may possess a different mechanism of action. Based on the above, the compound 4-amino-3-nitrobenzoic acid (16), a potent TcTS inhibitor (77% inhibition in enzymatic assays) was selected to evaluate its effects on the expression level of the TS gene in T. cruzi epimastigotes and determine its involvement in the mechanism of action. Results showed an increase in the expression level of the TcTS gene, which confirmed that compound 16, has a direct effect on TcTS.