The antimicrobial activity of lapachol and its thiosemicarbazone and semicarbazone derivatives

Lapachol was chemically modified to obtain its thiosemicarbazone and semicarbazone derivatives. These compounds were tested for antimicrobial activity against several bacteria and fungi by the broth microdilution method. The thiosemicarbazone and semicarbazone derivatives of lapachol exhibited antimicrobial activity against the bacteria Enterococcus faecalis and Staphylococcus aureus with minimal inhibitory concentrations (MICs) of 0.05 and 0.10 µmol/mL, respectively. The thiosemicarbazone and semicarbazone derivatives were also active against the pathogenic yeast Cryptococcus gattii (MICs of 0.10 and 0.20 µmol/mL, respectively). In addition, the lapachol thiosemicarbazone derivative was active against 11 clinical isolates of Paracoccidioides brasiliensis, with MICs ranging from 0.01-0.10 µmol/mL. The lapachol-derived thiosemicarbazone was not cytotoxic to normal cells at the concentrations that were active against fungi and bacteria. We synthesised, for the first time, thiosemicarbazone and semicarbazone derivatives of lapachol. The MICs for the lapachol-derived thiosemicarbazone against S. aureus, E. faecalis, C. gattii and several isolates of P. brasiliensis indicated that this compound has the potential to be developed into novel drugs to treat infections caused these microbes.     

Dual on-off and off-on switchable oligoaziridine biosensor

A water-soluble biocompatible aziridine-based biosensor with pendant anthracene units was synthesized by radicalar polymerization of N-substituted aziridines in supercritical carbon dioxide. The binding ability of the sensor towards a series of metal ions was examined by comparing the fluorescence intensities of the solutions before and after the addition of 100 equivalents of a solution of the metal ion chloride salt. A fast, simple and highly optical sensitive dual behavior, "off-on" and "on-off" response, was observed after the biosensor was exposed to the metal cations in aqueous solution. Zinc presented the highest fluorescence enhancement (turn-on) and copper presented the highest fluorescence quenching (turn-off). The response time was found to be instantaneous and the detection limit was achieved even in the presence of excess metal cation competitors. By using immunofluorescence microscopy it was also shown that oligoaziridine acts as an "on-off" probe through highly sensitive (detection limit of 1.6nM), selective and reversible binding to copper anions under physiologic conditions using living Human Fibroblast cells. The stoichiometry for the reaction of the biosensor with Cu(2+) was determined by a Job plot and indicates the formation of an oligoaziridine-Cu(2+) 1:2 adduct.     

Richness and composition of Calliphoridae in an Atlantic Forest fragment: implication for the use of dipteran species as bioindicators

Studies measuring the damage in degraded environments have increased, and it is necessary to obtain reliable biological and ecological indicators for the recovery of such degraded environments and subsequent preservation. This study aimed to conduct a survey of local insects and evaluate their utility in monitoring forest restoration in a degraded area in the Atlantic Forest biome in Ribeirao Grande, State of São Paulo, Brazil. Collections with Shuey traps were conducted from 2006 to 2011 in four distinct forest fragments characterized by environmental impacts, human actions, and phytophysiognomic profiles: Forest (FO), a preserved area with native plant species; “Capoeira” (CA), an area in the natural regeneration process; Planting (PL), an area reforested with native plants; and Pasture (PA), an area with only shrubs. A total of 2,456 specimens of Calliphoridae (Diptera) were collected. Mesembrinella bellardiana was the most abundant (n = 1,884) and dominant species in all environments sampled. The relative abundance of M. bellardiana in the most preserved environment (60.2 % FO, 24.4 % CA, 8.6 % PL, and 6.7 % PA) and other ecological parameters showed that it could be a bioindicator species, i.e., data on its presence or absence directly reflected the status of local preservation. Information on Neotropical dipterans associated with the forested environment is very scarce in the literature. To our knowledge, this is the first study describing the occurrence of Calliphora lopesi (Calliphoridae) in the State of São Paulo.     

Poor Immune Reconstitution in HIV-Infected Patients Associates with High Percentage of Regulatory CD4+ T Cells

CD4⁺ regulatory T cells (Tregs) are essential for the maintenance of the immune system''s equilibrium, by dampening the activation of potential auto-reactive T cells and avoiding excessive immune activation. To correctly perform their function, Tregs must be maintained at the right proportion with respect to effector T cells. Since this equilibrium is frequently disrupted in individuals infected with the human immunodeficiency virus (HIV), we hypothesize that its deregulation could hamper immune reconstitution in patients with poor CD4⁺ T cell recovery under highly active antiretroviral therapy (HAART). We analysed Tregs percentages amongst CD4⁺ T cells in 53 HIV-infected patients under HAART, with suppression of viral replication and distinct levels of immune reconstitution. As controls, 51 healthy individuals were also analysed. We observed that amongst the patients with Nadir values (the lowest CD4⁺ T cell counts achieved) <200 cells/µL, the individuals with high Tregs percentages (≥10% of total CD4⁺ T cells) had the worse CD4⁺ T cell reconstitution. In accordance, the well-described direct correlation between the Nadir value and CD4⁺ T cell reconstitution is clearly more evident in individuals with high Tregs proportions. Furthermore, we observed a strong negative correlation between Tregs percentages and CD4⁺ T cell recovery among immunological non-responder HIV⁺ individuals. All together, this work shows that high Tregs frequency is an important factor associated with sub-optimal CD4⁺ T cell recovery. This is particularly relevant for immunological non-responders with low Nadir values. Our results suggest that the Tregs proportion might be of clinical relevance to define cut-offs for HAART initiation.     

Evaluation of the Activity of the Essential Oil from an Ornamental Flower against Aedes aegypti: Electrophysiology,Molecular Dynamics and Behavioral Assays

Dengue fever has spread worldwide and affects millions of people every year in tropical and subtropical regions of Africa, Asia, Europe and America. Since there is no effective vaccine against the dengue virus, prevention of disease transmission depends entirely on regulating the vector (Aedes aegypti) or interrupting human-vector contact. The aim of this study was to assess the oviposition deterrent activity of essential oils of three cultivars of torch ginger (Etlingera elatior, Zingiberaceae) against the dengue mosquito. Analysis of the oils by gas chromatography (GC)—mass spectrometry revealed the presence of 43 constituents, of which α-pinene, dodecanal and n-dodecanol were the major components in all cultivars. Solutions containing 100 ppm of the oils exhibited oviposition deterrent activities against gravid Ae. aegypti females. GC analysis with electroantennographic detection indicated that the oil constituents n-decanol, 2-undecanone, undecanal, dodecanal, trans-caryophyllene, (E)-β-farnesene, α-humulene, n-dodecanol, isodaucene and dodecanoic acid were able to trigger antennal depolarization in Ae. aegypti females. Bioassays confirmed that solutions containing 50 ppm of n-dodecanol or dodecanal exhibited oviposition deterrent activities, while a solution containing the alcohol and aldehyde in admixture at concentrations representative of the oil presented an activity similar to that of the 100 ppm oil solution. Docking and molecular dynamics simulations verified that the interaction energies of the long-chain oil components and Ae. aegypti odorant binding protein 1 were quite favorable, indicating that the protein is a possible oviposition deterrent receptor in the antenna of Ae. aegypti.     

Effective and Low-Cost Saccharification of Pineapple Peel by <Emphasis Type="Italic">Trichoderma viride</Emphasis> Crude Extract with Enhanced β-Glucosidase Activity

Efficient, low-cost enzymatic hydrolysis of lignocellulosic biomass is essential for cost-effective production of bioethanol. The aim of this study was to establish a fungal fermentation-based strategy for the economic enzymatic conversion of pineapple peel into fermentable sugars. Trichoderma viride was grown on passion fruit peel in order to improve its β-glucosidase production, and a crude extract was then used to hydrolyze pineapple peel. The effects of medium pH, cultivation time, and passion fruit peel concentration on β-glucosidase production were evaluated using a central composite rotational design (CCRD) combined with response surface methodology (RSM). Optimal β-glucosidase activity of 2.40 U mL^?1 was found after 6.5 days of cultivation in medium at pH 6.0, containing 2.0 % passion fruit peel. Saccharification of pineapple peel was also optimized by RSM and CCRD with respect to pH, temperature, β-glucosidase concentration, and reaction time and proceeded optimally at pH 4.0, 55 °C, with a β-glucosidase loading of 31.25 U g^?1 dry feedstock and 75 h of reaction. Under these conditions, T. viride crude extract hydrolyzed pineapple peel with a glucose yield of 65.3 %. This study therefore presents passion fruit peel as an attractive raw material for the production of β-glucosidases. In addition, it describes an improved, effective, and low-cost enzymatic method for the production of fermentable sugars from pineapple peel, an abundant and inexpensive agro-industrial waste.     

Diversity of gene cassettes and the abundance of the class 1 integron-integrase gene in sediment polluted by metals

The integron-gene cassette system has typically been associated with antibiotic-resistant pathogens. However, the diversity of gene cassettes and the abundance of class 1 integrons outside of the clinical context are not fully explored. Primers targeting the conserved segments of attC recombination sites were used to amplify gene cassettes from the sediment of the Mina stream, which exhibited a higher degree of stress to metal pollution in the dry season than the rainy season. Of the 143 total analyzed sequences, 101 had no matches to proteins in the database, where cassette open reading frames could be identified by homology with database entries. There was a predominance of sequences encoding essential cellular functions. Each season that was sampled yielded a specific pool of gene cassettes. Real-time PCR revealed that 8.5 and 41.6 % of bacterial cells potentially harbored a class 1 integron in the rainy and dry seasons, respectively. In summary, our findings demonstrate that most of the gene cassettes have no ascribable function and, apparently, historically metal-contaminated sediment favors the maintenance of bacteria containing the intI1 gene. Thus, the diversity of gene cassettes is far from being fully explored deserving further attention.