Synthesis, biological, and theoretical evaluations of new 1,2,3-triazoles against the hemolytic profile of the Lachesis muta snake venom

Bioactive 1,2,3-Triazoles: An Account on their Synthesis, Structural Diversity and Biological Applications

The triazole heterocycle is a privileged scaffold in medicinal chemistry, since its structure is present in a large number of biologically active molecules, including several drugs currently in the market. Due to their vast applications, a wide variety of methods are described for their preparation, such as the 1,3-dipolar cycloaddition and processes involving diazo compounds and diazo transfer reactions. Considering the significant number of contributions from our research group to this chemistry in recent decades, in this account we discuss both the development of new methods for the synthesis of 1,2,3-triazoles and the preparation of new triazole-functionalized biologically active molecules using classical approaches.

Experimental Lachesis muta rhombeata envenomation and effects of soursop (Annona muricata) as natural antivenom

Background

In the Atlantic forest of the North and Northeast regions of Brazil, local population often uses the fruit juice and the aqueous extract of leaves of soursop (Annona muricata L.) to treat Lachesis muta rhombeata envenomation. Envenomation is a relevant health issue in these areas, especially due to its severity and because the production and distribution of antivenom is limited in these regions. The aim of the present study was to evaluate the relevance of the use of soursop leaf extract and its juice against envenomation by Lachesis muta rhombeata.

Methods

We evaluated the biochemical, hematological and hemostatic parameters, the blood pressure, the inflammation process and the lethality induced by Lachesis muta rhombeata snake venom. We also assessed the action of the aqueous extract of leaves (AmL) and juice (AmJ) from A. muricata on the animal organism injected with L. m. rhombeata venom (LmrV) in the laboratory environment.

Results

LmrV induced a decrease of total protein, albumin and glucose; and increase of creatine kinase, aspartate aminotransferase, and urea concentrations. It provoked hemoconcentration followed by reduction of hematocrit, an increase in prothrombin time and partial thromboplastin time and a decrease of the blood pressure. LmrV induced the release of interleukin-6, an increase in neutrophils and changes in the serum protein profile, characteristic of the acute inflammatory process. LD₅₀ values were similar for the groups injected with LmrV and treated or untreated with AmJ and AmL. Both treatments play a role on the maintenance of blood glucose, urea and coagulation parameters and exert a protective action against the myotoxicity. However, they seem to worsen the hypotension caused by LmrV.

Conclusion

The treatments with AmJ and AmL present some beneficial actions, but they might intensify some effects of the venom. Therefore, additional studies on A. muricata are necessary to enable its use as natural antivenom for bushmaster snakebite.

Synthesis and characterization of poly(N-vinyl-1,2,3-triazole)s derived from monomers obtained by highly efficient Wolff's cyclocondensation

High-efficiency synthetic access to poly(N-vinyl-1,2,3-triazole)s has been described via modified Wolff's cyclocondensation.

Virtual analysis of structurally diverse synthetic analogs as inhibitors of snake venom secretory phospholipase A2

Due to the toxic pathophysiological role of snake venom phospholipase A2 (PLA2 ), its compelling limitations to anti-venom therapy in humans and the need for alternative therapy foster considerable pharmacological interest towards search of PLA2 specific inhibitors. In this study, an integrated approach involving homology modeling, molecular dynamics and molecular docking studies on VRV-PL-V (Vipera russellii venom phospholipase A2 fraction-V) belonging to Group II-B secretory PLA2 from Daboia russelli pulchella is carried out in order to study the structure-based inhibitor design. The accuracy of the model was validated using multiple computational approaches. The molecular docking study of this protein was undertaken using different classes of experimentally proven, structurally diverse synthetic inhibitors of secretory PLA2 whose selection is based on IC50 value that ranges from 25 μM to 100 μM. Estimation of protein-ligand contacts by docking analysis sheds light on the importance of His 47 and Asp 48 within the VRV-PL-V binding pocket as key residue for hydrogen bond interaction with ligands. Our virtual analysis revealed that compounds with different scaffold binds to the same active site region. ADME analysis was also further performed to filter and identify the best potential specific inhibitor against VRV-PL-V. Additionally, the e-pharmacophore was generated for the best potential specific inhibitor against VRV-PL-V and reported here. The present study should therefore play a guiding role in the experimental design of VRV-PL-V inhibitors that may provide better therapeutic molecular models for PLA2 recognition and anti-ophidian activity.

Accessing Brominated Natural Product Motifs Using Phosphoramidite Catalysis

This article describes the application of a first-generation phosphoramidite catalyst to the construction of the most commonly encountered subunits of bromine-containing natural products. The process is compared with previous efforts, and is found to be complementary to existing methods. Application of the process enables bromocarbocyclisations, bromoetherifications, and bromoallene formation using the common laboratory reagent N-bromosuccinimide.

Synthesis of a new class of naphthoquinone glycoconjugates and evaluation of their potential as antitumoral agents

A novel series of carbohydrate-based naphthoquinones was synthesized and evaluated for cytotoxicity against different human cancer cell lines (HCT-116, A-549 and MDA-MB 435). The compounds derived from juglone showed better cytotoxicity profiles.

A simple hydrated salt with a complex hydrogen-bonding network: tetrakis(5-amino-3-carboxy-4H-1,2,4-triazol-1-ium) hexachloridocadmate(II) tetrahydrate

In the title cadmium chloride salt, (C3H5N4O2)4[CdCl6]·4H2O, the asymmetric unit comprises two N-protonated 5-amino-3-carboxy-4H-1,2,4-triazol-1-ium cations, half a [CdCl6](4-) anion and two molecules of water. The Cd(2+) cation is located on a centre of inversion and is coordinated by six chloride anions, forming a distorted octahedron. In the crystal structure, alternating layers of cations and anions are arranged along the [101] direction, forming a three-dimensional supramolecular network via a combination of hydrogen-bonding and aromatic stacking interactions.

In vitro comparison of enzymatic effects among Brazilian Bothrops spp. venoms

In various types of snake venom, the major toxic components are proteinases and members of the phospholipase A2 family, although other enzymes also contribute to the toxicity. In this study, we evaluated the proteolytic, phospholipase, and L-Amino acid oxidase activities in the venom of five Bothrops species-Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni, Bothrops neuwiedi, and Bothrops alternatus-all of which are used in the production of commercial antivenom, prepared in horses. The enzymatic activities of each species' venom were classified as high, moderate, or low. B. moojeni venom demonstrated the highest enzymatic activity profile, followed by the venom of B. neuwiedi, B. jararacussu, B. jararaca, and B. alternatus. To our knowledge, this is the first study to compare all of these enzymes from multiple species, which is significant in view of the activity of L-amino acid oxidase across Bothrops species.

Antivenom effects of 1,2,3-triazoles against Bothrops jararaca and Lachesis muta snakes

Snake venoms are complex mixtures of proteins of both enzymes and nonenzymes, which are responsible for producing several biological effects. Human envenomation by snake bites particularly those of the viperid family induces a complex pathophysiological picture characterized by spectacular changes in hemostasis and frequently hemorrhage is also seen. The present work reports the ability of six of a series of 1,2,3-triazole derivatives to inhibit some pharmacological effects caused by the venoms of Bothrops jararaca and Lachesis muta. In vitro assays showed that these compounds were impaired in a concentration-dependent manner, the fibrinogen or plasma clotting, hemolysis, and proteolysis produced by both venoms. Moreover, these compounds inhibited biological effects in vivo as well. Mice treated with these compounds were fully protected from hemorrhagic lesions caused by such venoms. But, only the B. jararaca edema-inducing activity was neutralized by the triazoles. So the inhibitory effect of triazoles derivatives against some in vitro and in vivo biological assays of snake venoms points to promising aspects that may indicate them as molecular models to improve the production of effective antivenom or to complement antivenom neutralization, especially the local pathological effects, which are partially neutralized by antivenoms.

Analysis of phospholipase A2, L-amino acid oxidase, and proteinase enzymatic activities of the Lachesis muta rhombeata venom

The study of venom components is an important step toward understanding the mechanism of action of such venoms and is indispensable for the development of new therapies. This work aimed to investigate the venom of Lachesis muta rhombeata and evaluate enzymes related to its toxicity. Phospholipase A2 (PLA(2)), L-amino acid oxidase (LAAO), and proteinase activities were measured, and the molecular weights were estimated. We found the venom to contain one PLA(2) (17 kDa), one LAAO (132 kDa), and three serine proteinases (40, 31, and 20 kDa). Although only serine proteinases were observed in the zymogram, metalloproteinases were found to contribute more to the total proteolytic activity than did serine proteinases. The work confirmed the presence of highly active enzymes; and, moreover, we proposed a novel method for confirming the presence of LAAOs by zymography. We also suggested a simple step to increase the sensitivity of proteinase assays.

Intramolecular hydrogen bonding-assisted cyclocondensation of α-diazoketones with various amines: a strategy for highly efficient Wolff 1,2,3-triazole synthesis

A catalytic and highly efficient Wolff's cyclocondensation of α-diazoketones with aromatic and aliphatic amines has been realized for the first time by utilizing the strategy of an intramolecular hydrogen bonding-activating carbonyl group. This approach successfully solved the challenging problem of poor condensation efficiency in Wolff 1,2,3-triazole synthesis, and constitutes a powerful method for the synthesis of highly functionalized 1,2,3-triazoles.

A Facile Synthesis of Novel Spiro Indoline-Based Heterocycles through 1,3-Dipolar Cycloaddition Reactions

A simple and efficient one-pot route for the synthesis of novel spiro [indolin–3,3'-1,2,4-triazol] derivatives by 1,3-dipolar cycloaddition reaction of nitrilimines and isatin imines under classical or microwave irradiation conditions is described. Spiro heterocyclic compounds possess pharmacological properties such as antimicrobial, analgesic, anti-inflammatory, antimycobacterial, antifungal, antitumor and antiviral activities.

Synthesis and anti-HSV-1 activity of new 1,2,3-triazole derivatives

In this work, a new series of arysulfonylhydrazine-1H-1,2,3-triazole derivatives were synthesized, and their ability to inhibit the in vitro replication of HSV-1 was evaluated. Among the 1,2,3-triazole derivatives, 1-[(5″-methyl-1″-(4‴-fluorophenylamino)-1H-1,2,3-triazol-4″-yl)carbonyl]-2-(4'-methylphenylsulfonyl)hydrazine and 1-[(5'-methyl-1'-(2″,5″-dichlorophenylamino)-1H-1,2,3-triazol-4'-yl)carbonyl]-2-(phenylsulfonyl)hydrazine, with IC(50) values of 1.30 and 1.26 μM, respectively, displayed potent activity against HSV-1. Because these compounds have low cytotoxicity, their selectivity indices are high. Under the assay conditions, they have better performance than does the reference compound acyclovir. The structures of all of the compounds were confirmed by one- and two-dimensional NMR techniques ((1)H, (13)C-APT, COSY-(1)H×(1)H and HETCOR (1)J(CH)) and by elemental analysis.

Synthesis, characterization and antifungal evaluation of 5-substituted-4-amino-1,2,4-triazole-3-thioesters

A series of 5-substituted-4-amino-1,2,4-triazole-3-thioesters was synthesized by converting variously substituted organic acids successively into the corresponding esters, hydrazides, 5-substituted-1,3,4-oxadiazole-2-thiols, 5-substituted-1,2,4-triazole-2-thiols and 5-substituted-1,3,4-oxadiazole-2-thioesters. Finally the target compounds were obtained by refluxing 5-substituted-1,3,4-oxadiazole-2-thioesters in the presence of hydrazine hydrate and absolute alcohol. The structures of the synthesized compounds were established by physicochemical and spectroscopic methods. The synthesized compounds were evaluated for their in vitro antifungal activity. Some of the evaluated compounds possessed significant antifungal activity as compared to a terbinafine standard.

WITHDRAWN: Antiophidian properties of a dolastane diterpene isolated from the marine brown alga Canistrocarpus cervicornis

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.bionut.2011.06.021. The duplicate article has therefore been withdrawn.