The cariogenic processes are mainly caused by the bacterium Streptococcus mutans (S. mutans) and consist of the demineralization of the tooth that occurs when the acid production overcomes the natural repair or if a problem occurs in the last one. In this work, we performed the synthesis of twenty-one 1,4-naphthoquinones tethered to 1,2,3-1H-triazoles (8a-8k and 9a-9j), antibacterial evaluation against the S. mutans in vitro and the acute toxicity of the better ones in vivo. We observed strong inhibition results in the disc diffusion test ranging, the halos of inhibitions, from 18.66 (± 0.57) to 29 (± 2.64) mm, and good values in the minimum inhibitory concentration (5 to 50 μg), for the compounds 9e, 9h, 9i and 9j: Furthermore, they do not have a cytotoxic effect at the concentrations tested. Besides that, in the in vivo test, they show some slight alteration in the histopathological analyses and the biochemistry. Thus, we found four potential candidates to become instruments for the treatment of cavities.

The death of professor Rolf Huisgen (1920-2020) was announced on March 26th 2020, in the midst of the COVID-19 pandemic. Professor Huisgen was professor emeritus at the University of Munich in Germany, and studied in detail the mechanism of the 1,3-dipolar cycloaddition reaction, significantly expanding its scope. Even though he did not discover this reaction, it was through his studies that it became important in organic synthesis. Indeed, in honor of his work, the reaction became known as Huisgen’s cycloaddition and it has been consolidated as a useful method for the preparation of five-membered heterocyclic compounds. Considering these facts, in this review we provide an overview on the applications of 1,3-dipolar cycloaddition reactions, starting with the seminal examples in the field and further discussing the most recent applications.

Zika virus (ZIKV) is a mosquito-borne pathogen which is a current global public health concern. There are currently no approved vaccines or antivirals against ZIKV infection. Taking into account that naphthoquinones have shown promising antiviral activity, the aim of this study was to describe the screening of two bis-naphthoquinones series against ZIKV. Twenty seven compounds were evaluated against ZIKV using Vero cells. The findings showed that among the compounds analyzed four were promising. Compound 3,3’-((2-nitrophenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione) containing the nitro group at the ortho position showed the best selectivity index, followed by compound 3,3’-(4-chlorophenylmethylene)bis(naphthalene-1,2,4-triyl triacetate) with the chlorophenylmethylene radical. These results demonstrate that these bis-naphthoquinones are largely effective in inhibiting the replication of ZIKV.

The crystal structures of (Z)-1-phenyl-4-[((2-phenylhydrazono)methyl)]-1H-1,2,3-triazole, (Z)-4-[(2-(2,4-dimethylphenyl)hydrazono)methyl]-2-phenyl-2H-1,2,3-triazole, (E)-4-[(2-(2,4-dinitrophenyl)hydrazono)methyl]-2-phenyl-2H-1,2,3-triazole, and (E)-N'-((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)isonicotinohydrazide dihydrate are reported. The formations of (Z)- configurations about the C=N bonds in the first two compounds arise from the stabilizing presence of intramolecular N-H···N hydrogen bonds, while in the third compound, the presence of intramolecular N-H···O hydrogen bonds promotes an (E) geometry. The arrangement about the CONHC=N fragment in the hydrated acylhydrazone is EC(O)NH/EC=N. Also present in (E)-N'-((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)isonicotinohydrazide is an interesting R44(8) ring formed from hydrogen bonds generated from four water molecules. Significant π···π stacking interactions are exhibited in three compounds, but not in the least planar first compound, in which the dominant intermolecular interactions are C-H···π interactions. Other intermolecular interactions in one of the compounds are C-H···π interactions, in another compound are C-H···O hydrogen bonds and N-O···π interactions, and in the last compound are O-H···X (X = O and N), N-H···O and C-H···O hydrogen bonds.

As isatinas e os 1H-1,2,3-triazóis são duas classes de compostos com grande destaque na síntese orgânica e na química medicinal uma vez que são núcleos heterociclos com elevada reatividade, que permitem a obtenção de diversos compostos com importantes propriedades biológicas. Neste artigo, a síntese de novos 5`-(4-alquil/aril-1H-1,2,3-triazóis)-isatina via reação de cicloadição 1,3-dipolar catalisada por ácido acético é descrita.

Isatin and 1H-1,2,3-triazoles are two classes of compounds with great prominence in organic synthesis and medicinal chemistry as they are heterocycle nuclei with a high reactivity allowing to obtain several compounds with important biological properties. Herein, the synthesis of novel 5'-(4-alquil/aril-1H-1,2,3-triazole)-isatin via reaction of 1,3-dipolar cycloaddition catalyzed by acetic acid is reported.

Plant extracts of Eugenia punicifolia (Kunth) DC., Myrtaceae, are used in Amazon region of Brazil to treat diarrhea and stomach disturbances, and as hypoglycemic medicine. We have recently shown that an aqueous extract of E. punicifolia augmented cholinergic neurotransmission in a rat phrenic nerve-diaphragm preparation. In this study, we investigated the effects of an E. punicifolia dichloromethane extract (EPEX) in a neuronal model of cholinergic neurotransmission, the bovine adrenal chromaffin cell. EPEX augmented the release of catecholamine triggered by acetylcholine (ACh) pulses but did not enhance ACh-evoked inward currents, which were inhibited by 30%. Since EPEX did not cause a blockade of acetylcholinesterase or butyrylcholinesterase, it seems that EPEX is not directly activating the cholinergic system. EPEX also augmented K+-elicited secretion without enhancing the whole-cell inward calcium current. This novel and potent effect of EPEX in enhancing exocytosis might help to identify the active component responsible for augmenting exocytosis. When elucidated, the molecular structure of this active principle could serve as a template to synthesise novel compounds to regulate the exocytotic release of neurotransmitters.