Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen "Neglected Tropical Diseases" (NTDs) defined as such by WHO due to the neglect of financial investment into research and development of new drugs by a large part of pharmaceutical industry and neglect of public awareness in high income countries. Another major tropical protozoan disease is malaria (caused by various Plasmodium species), which -although not mentioned currently by the WHO as a neglected disease- still represents a major problem, especially to people living under poor circumstances in tropical countries. Malaria causes by far the highest number of deaths of all protozoan infections and is often (as in this review) included in the NTDs. The mentioned diseases threaten many millions of lives world-wide and they are mostly associated with poor socioeconomic and hygienic environment. Existing therapies suffer from various shortcomings, namely, a high degree of toxicity and unwanted effects, lack of availability and/or problematic application under the life conditions of affected populations. Development of new, safe and affordable drugs is therefore an urgent need. Nature has provided an innumerable number of drugs for the treatment of many serious diseases. Among the natural sources for new bioactive chemicals, plants are still predominant. Their secondary metabolism yields an immeasurable wealth of chemical structures which has been and will continue to be a source of new drugs, directly in their native form and after optimization by synthetic medicinal chemistry. The current review, published in two parts, attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs.

The purpose of this study was to prepare various 4-substituted N-phenyl-1,2,3-triazole derivatives using click chemistry. The derivatives were screened in vitro for antimicrobial activity against Mycobacterium tuberculosis strain H37Rv (ATCC 27294) using the Alamar Blue susceptibility test. The activity was expressed as the minimum inhibitory concentration (MIC) in μg/mL (μM). Derivatives of isoniazid (INH), (E)-N'-[(1-aryl)-1H-1,2,3-triazole-4-yl)methylene] isonicotinoyl hydrazides, exhibited significant activity with MIC values ranging from 2.5 to 0.62 μg/mL. In addition, they displayed low cytotoxicity against liver cells (hepatoma HepG2) and kidney cells (BGM), thereby providing a high therapeutic index. The results demonstrated the potential and importance of developing new INH derivatives to treat mycobacterial infections.

A class of drugs in use for treating type II diabetes mellitus (T2D), typified by the pseudotetrasaccharide acarbose, act by inhibiting the alpha-glucosidase activity present in pancreatic secretions and in the brush border of the small intestine. Herein, we report the synthesis of a series of 4-substituted 1,2,3-triazoles conjugated with sugars, including D-xylose, D-galactose, D-allose, and D-ribose. Compounds were screened for alpha-glucosidase inhibitory activity using yeast maltase (MAL12) as a model enzyme. Methyl-2,3-O-isopropylidene-beta-D-ribofuranosides, such as the 4-(1-cyclohexenyl)-1,2,3-triazole derivative, were among the most active compounds, showing up to 25-fold higher inhibitory potency than the complex oligosaccharide acarbose. Docking studies on a MAL12 homology model disclosed a binding mode consistent with a transition-state-mimicking mechanism. Finally, the actual pharmacological potential of this triazole series was demonstrated by the reduction of postprandial blood glucose levels in normal rats. These compounds could represent new chemical scaffolds for developing novel drugs against T2D.

de todas as unidades que utilizam produtos químicos em suas rotinas de trabalho, têm sido confrontados, ao longo de muitos anos, com o problema relacionado ao tratamento e à disposição final dos resíduos gerados em seus laboratórios de ensino e pesquisa. Esses resíduos diferenciam-se daqueles gerados em unidades industriais por apresentarem baixo volume, mas grande diversidade de composições, o que dificulta a tarefa de estabelecer um tratamento químico e/ou uma disposição final padrão para todos. De maneira geral, esse problema atinge graves proporções e tem sido relegado a um plano secundário. Na maioria dos casos os resíduos são estocados de forma inadequada e ficam aguardando um destino final, isso quando são estocados. Infelizmente, a cultura ainda dominante é de descartá-los na pia do laboratório, já que a maioria das instituições públicas brasileiras de ensino e pesquisa não tem uma política institucional clara que permita um tratamento global do problema. A Química é uma das ciências básicas que mais benefícios trouxe à humanidade ao longo dos últimos tempos. Com os seus vários segmentos, ela permeia a vida de todas as pessoas que vivem em uma sociedade moderna e de alto grau tecnológico (p. ex., fármacos, materiais especiais, defensivos agrícolas, insumos para vários segmentos industriais, materiais de limpeza, higiene pessoal, beleza, etc.). Infelizmente, esse quadro, como uma moeda, não tem um lado só. O mau uso dessa Ciência tem causado graves problemas à humanidade e vem sendo responsável pela percepção negativa da Química. Dentro desse quadro, pode-se dizer que um dos problemas mais graves relacionado ao mau uso da Química refere-se aos danos ambientais. Para contornar essa situação, as legislações ambientais de todos os países do mundo, inclusive a do Brasil, vêm evoluindo e se adaptando às novas realidades, visando coibir severamente os abusos. Essas legislações vêm também incorporando novas exigências no monitoramento das emissões de voláteis no ar e no lançamento de resíduos industriais nos corpos aqüíferos.

para‐Quinone methides (p‐QMs) are naturally occurring molecules that have been finding increasing synthetic applications in the last few years. The presence of two electronically different exocyclic conjugate substituents in their structure, carbonyl and methylidene, leads to a pronounced reactivity owing to the polarization of the molecule. In this sense, those are prone to undergo the attack of nucleophiles in the terminal carbon exocyclic double bond, behaving as vinylogous electrophiles and generating 1,6‐addition products. In this context, in the last few years the development of catalytic approaches for 1,6‐nucleophilic addition reactions involving p‐QMs has attracted considerable attention. Considering the extensive applications that such molecules have found in the last decades in 1,6‐addition reactions, in this review we comprehensively discuss the historical development of this field, starting with early approaches on natural product synthesis, going through seminal non‐stereoselective processes and progressing to cutting‐edge asymmetric‐catalyzed approaches.

In this article a mild, simple, safe, and chemoselective synthesis and reduction of o-quinone methides to the corresponding 3-alkyl-2-hydroxy-1,4-naphthoquinones, compounds with interesting biological activity, mediated by the formic acid-water system is described. This new one-pot methodology was applied to the synthesis of lapachol and constitutes an efficient and inexpensive alternative for the preparation of this natural bioactive compound

Naphthoquinones are the most commonly occurring type of quinones in nature. They are a diverse family of secondary metabolites that occur naturally in plants, lichens and various microorganisms. This subgroup is constantly being expanded through the discovery of new natural products and by the synthesis of new compounds via innovative techniques. Interest in quinones and the search for new biological activities within the members of this class have intensified in recent years, as evidenced by the evaluation of the potential antimicrobial activities of quinones. Among fungi of medical interest, yeasts of the genus Candida are of extreme importance due to their high frequency of colonization and infection in humans. The objective of this review is to describe the development of naphthoquinones as antifungals for the treatment of Candida species and to note the most promising compounds. By using certain criteria for selection of publications, 68 reports involving both synthetic and natural naphthoquinones are discussed. The activities of a large number of substances were evaluated against Candida albicans as well as against 7 other species of the genus Candida. The results discussed in this review allowed the identification of 30 naphthoquinones with higher antifungal activities than those of the currently used drugs.

This review intends to explore synthetic methodologies for the preparation of 2H‐chromenes and their analog chromanes through ortho‐quinone methide (o‐QM) intermediates associated with inter and intramolecular hetero‐Diels‐Alder and electrocyclization reactions. J. Heterocyclic Chem., (2009).