Exploring the origin of the catalytic power and product specificity of SET domain protein methyltransferase.

Herein, we used computer simulation to evaluate the free energy activation barriers of the first and second methyl transfer for native SET8 PKMT and its Y334F mutant. The results suggest that the origin of SET8 catalytic power is mainly due to electrostatic preorganization.

Avaliação do efeito antifúngico do óleo resina e do óleo essencial de copaíba (Copaifera multijuga Hayne) / Evaluation of the antifungal effect of oleoresin and essential oil of copaiba (Copaifera multijuga Hayne)

Óleo de Copaifera multijuga Hayne, in natura e as frações foram avaliados quanto às suas atividades fungitóxicas, frente a cinco espécies de fungos filamentosos do gênero Aspergillus e três espécies de leveduras do gênero Candida. Concentrações de óleo resina e de óleo essencial na faixa de 0,08 mg mL-1a 1,6 mg mL-1 foram usadas para as análises qualitativa e quantitativas. As amostras foram dispostas sobre discos de papel de 5 mm de diâmetro e distribuídos sobre o meio Saboraud em placas de Petri, inoculadas com esporos dos microrganismos e incubadas a 28ºC durante 10 dias. Utilizou-se uma solução com 1,6 mg mL-1 de nitrato de miconazol como controle positivo. Os resultados qualitativos mostraram que o óleo resina apresentou boa atividade, porém uma das frações do óleo essencial se mostrou altamente efetivo contra C. parapsilosis IOC - 2882, A.flavus IOC-3874 e A. tamarii IOC-187 com halos de inibição de 16,0±1,4 mm, 19,5±2,1 mm e 12,5±3,5 mm, respectivamente. Já a avaliação quantitativa mostrou que 0,3 mg mL-1 do óleo resina inibiu o crescimento de A. flavus e C. parapsilosis, enquanto que 0,08 mg mL-1 da fração do óleo essencial atingiu esta mesma atividade.

Copaifera multijuga Hayne oil in natura and its fractions were evaluated as to their fungitoxic activities against five filamentous fungus species belonging to the genus Aspergillus and three yeast species of the genus Candida. Oleoresin and essential oil concentrations ranging from 0.08 mg mL-1 to 1.6 mg mL-1 were used for qualitative and quantitative analyses. The samples were placed onto 5mm-diameter paper discs distributed on Sabouraud's medium in Petri dishes inoculated with spores of the microorganisms and incubated at 28ºC for 10 days. A solution containing 1.6 mg mL-1 miconazole nitrate was used as positive control. Qualitative results showed that the oleoresin presented good activity, while a fraction of the essential oil was highly effective against Candida parapsilosis IOC-2882, Aspergillus flavus IOC-3874 and A tamarii IOC-187 with 16.0±1.4 mm, 19.5±2.1 mm and 12.5±3.5 mm inhibition halos, respectively. The quantitative evaluation showed that 0.3 mg mL-1 oleoresin inhibited the growth of Aspergillus flavus and Candida parapsilosis, while 0.08 mg mL-1 of the essential oil fraction reached this same activity.

Structure-activity relationship study of flavone compounds with anti-HIV-1 integrase activity: a density functional theory study.

Human immunodeficiency virus type-1 integrase (HIV-1 IN) is an essential enzyme for effective viral replication. Flavone compounds have been very much studied due to their activity during the inhibition process of HIV-1 IN. In this study, we employed density functional theory (DFT) using the B3LYP hybrid functional to calculate a set of molecular properties for 32 flavonoid compounds with anti-HIV-1 IN activity. The stepwise discriminant analysis (SDA), principal component analysis (PCA) and hierarchical cluster analysis (HCA) methods were employed to reduce dimensionality and investigate possible relationship between the calculated properties and the anti-HIV-1 IN activity. These analyses showed that the molecular hydrophobicity (ClogP), charge on atom 11 and electrophilic index (omega) are responsible for the separation between anti-HIV-1 IN active and inactive compounds.

A density functional study of flavonoid compounds with anti-HIV activity.

Quantum chemical calculations at the DFT/B3LYP theory level, with the 6-31G* basis set, was employed to calculate a set of molecular properties of 26 flavonoid compounds with anti-HIV activity. The correlation between biological activity and structural properties was obtained by using the multiple linear regression method. The model obtained showed not only statistical significance but also predictive ability. We demonstrate in this paper that the anti-HIV activity of compounds can be related with the molecular hydrophobicity (ClogP), the electronegativity (chi) and the charges on some key atoms, while that the toxicity can be related with the electronic affinities (EA), ClogP and charge on atom 8.

Evaluation of total mercury concentrations in fish consumed in the municipality of Itaituba, Tapajós River Basin, Pará, Brazil.

The environmental exposure to mercury by riverine and Indian communities can occur through the ingestion of fish and products contaminated by mercury compounds. The present study aims to evaluate the total mercury concentration in the different fish species most consumed in the municipality of Itaituba, Tapajós river basin, where there are intense gold-mining activities. These fish samples were analyzed by atomic absorption spectrophotometry by cold vapor technique, Automatic Mercury Analyzer HG-3500. The largest mercury concentrations were found in the carnivorous species ranging from 112.4 to 2250 microg/g, while the detritivorous, herbivorous and omnivorous species presented total mercury levels ranging from 3.2 to 309.8 microg/g, which is below the limit established by the World Health Organization. This paper also reports and identifies which species are more polluted and present a statistical relationship among concentration and weight of the carnivorous species studied in detail, Brachyplatystoma flavicans (dourada) (r2 = 0.691) and Pseudoplatystoma sp. (surubim) (r2 = 0.654).

Determination of total mercury in workers' urine in gold shops of Itaituba, Pará State, Brazil.

Gold extraction and its commercialization in the Amazon region is mainly by rudimentary procedures. Therefore, during the process of extraction and recovery of this precious metal, large amounts of mercury vapors are thrown into the environment. This paper is an attempt to establish a correlation between the concentration of total mercury in the urine of workers at the gold shop in the Municipality of Itaituba, Pará, and the information related to the lifestyles of each individual studied. Through statistical analysis, it was possible to divide the workers into three groups: people with normal mercury concentrations, [Hg] < or = 10 ppb, (29%); with concentrations at the biological limit of tolerance, [Hg] up to 50 ppb, (49%); and contaminated people, [Hg] > or = 50 ppb (22%). It may be concluded that fish consumption, time of alcohol consumption, number of amalgam fillings, as well as working hours, are important variables when evaluating mercurial contamination of people who are occupationally exposed to mercury vapors.