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.

The preparation of 1H-1,2,3-, 2H-1,2,3-, 1H-1,2,4- and 4H-1,2,4-triazole derivatives brings to light several issues. There is a need to find new, more efficient preparations for these triazoles that take into consideration current issues in green chemistry, energy saving and sustainability. New diseases are discovered and new viruses and bacteria continue to challenge mankind, so it is imperative to find new prototypes for these new diseases. Of great urgency is finding prototypes against bacteria that continue to increase resistance and for neglected diseases that affect a large part of humanity, especially the poor and vulnerable.

The reaction of carbohydrate-substituted α-diazoacetates with meso-tetrakis(pentafluorophenyl)porphyrinatozin(II) allows the synthesis of new glyco-hydroporphyrin derivatives.

In this study we compared the effects of naphthoquinones (α-lapachone, β-lapachone, nor-β-lapachone and Epoxy-α-lap) on growth of Trypanosoma cruzi epimastigotes forms, and on viability of VERO cells. In addition we also experimentally analyzed the most active compounds inhibitory profile against T. cruzi serine- and cysteine-proteinases activity and theoretically evaluated them against cruzain, the major T. cruzi cysteine proteinase by using a molecular docking approach. Our results confirmed β-lapachone and Epoxy-α-lap with a high trypanocidal activity in contrast to α-lapachone and nor-β-lapachone whereas Epoxy-α-lap presented the safest toxicity profile against VERO cells. Interestingly the evaluation of the active compounds effects against T. cruzi cysteine- and serine-proteinases activities revealed different targets for these molecules. β-Lapachone is able to inhibit the cysteine-proteinase activity of T. cruzi proteic whole extract and of cruzain, similar to E-64, a classical cysteine-proteinase inhibitor. Differently, Epoxy-α-lap inhibited the T. cruzi serine-proteinase activity, similar to PMSF, a classical serine-proteinase inhibitor. In agreement to these biological profiles in the enzymatic assays, our theoretical analysis showed that E-64 and β-lapachone interact with the cruzain specific S2 pocket and active site whereas Epoxy-α-lap showed no important interactions. Overall, our results infer that β-lapachone and Epoxy-α-lap compounds may inhibit T. cruzi epimastigotes growth by affecting T. cruzi different proteinases. Thus the present data shows the potential of these compounds as prototype of protease inhibitors on drug design studies for developing new antichagasic compounds.

Siphoneugena Berg (Myrtaceae) é um pequeno gênero eugenióide segregado de Eugenia por Berg. A investigação fitoquímica de Siphoneugena densiflora foi realizada com o objetivo de se descobrir metabólitos secundários que possam ser considerados marcadores quimiotaxonômicos e auxiliar na distinção entre os dois gêneros. Cinco taninos hidrolisáveis inéditos foram isolados do extrato metanólico da casca da raiz e caracterizados como 4-O-α-L-2"-O-e seu isômero 4-O-α-L-3"-O-acetilramnopiranosídeo do ácido elágico, siphoneugenina, constituído por uma nova aglicona de estrutura dibenzo-1,4-dioxínica, 4-O-β-D-6"-e 4-O-β-D-3",6"-di-O-acetilglucopiranosídeo do ácido 3,4'-di-O-metilelágico, juntamente com o 4-O-α-L-4"-O-acetilramnopiranosídeo do ácido elágico, eschweilenol C, sitosterol, daucosterol, ramnose, casuarinina, castalagina e ácidos elágico, gálico e siríngico. Do extrato metanólico das folhas, além dos compostos conhecidos como a quercetina, quercitrina, guiajaverina, reinoutrina, chebulosídeo II, ácidos terminólico, madecássico e asiático, lupeol, α-e β-amirina, foi isolado um novo triterpeno pentacíclico nomeado como 2α,3β,6β-triidroxiolean-12-en-28-ato de β-D-glucopiranosila. Todas as substâncias foram identificadas através da análise dos dados espectrais e químicos obtidos, além da comparação com dados relatados na literatura.Siphoneugena Berg (Myrtaceae) is a small eugenioid genus segregated from Eugenia by Berg. The phytochemical survey of Siphoneugena densiflora was carried out in order to find secondary metabolites which may be considered as chemotaxonomic characters and help to distinguish between the two genera. Five novel hydrolysable tannins were isolated from the methanolic extract of root bark and were characterized as ellagic acid 4-O-α-L-2"-O-and its isomer 4-O-α-L-3"-O-acetylrhamnopyranoside, siphoneugenin, that supports a new aglycone with a dibenzo-1,4-dioxin structure, 3,4'-di-O-methylellagic acid 4-O-β-D-6"-O-and 4-O-β-D-3",6"-diacetylglucopyranoside, accompanied by ellagic acid 4-O-α-L-4"-O-acetylrhamnopyranoside, eschweilenol C, sitosterol, daucosterol, rhamnose, casuarinin, castalagin, ellagic, gallic and syringic acids. From methanolic extract of leaves, in addition to the well known compounds quercetin, quercitrin, guiajaverin, reynoutrin, chebuloside II, terminolic, madecassic and asiatic acids, lupeol, α-and β-amyrin, a new pentacyclic triterpene was isolated and named as β-D-glucopyranosyl-2α,3β,6β-trihydroxyolean-12-en-28-ate. Structures were established on the basis of spectroscopic and chemical evidence, along with the comparison of the data reported in the literature. Keywords:Siphoneugena densiflora, Myrtaceae, chemotaxonomy, hydrolysable tannin, pentacyclic triterpene IntroductionThe genus Siphoneugena comprises only eight species and belongs to Myrtaceae family. It is one of the specialized genera segregated from Eugenia by Berg. 1 Siphoneugena densiflora Berg, commonly known as Uvatinga, occurs in montane grasslands ("campos rupestres"), deciduous forests ("cerradões") and gall...