Evaluation of the antimicrobial activity of silver nanoparticles biosynthesized from the aqueous extract of Schinus terebinthifolius Raddi leaves.

Silver nanoparticles (AgNPs) synthesized from green synthesis using medicinal plants are presented as an option for the development of new antimicrobial agents. In this context, this study aims to evaluate the antimicrobial activity of silver nanoparticles synthesized from the aqueous extract of Schinus terebinthifolius Raddi leaves, popularly known as "aroeira." A 23 factorial design was used to assess the statistical significance of the studied factors, and Box-Behnken design was used to define the optimal conditions for the green synthesis of AgNPs. The studied factors were significant for the synthesis of nanoparticles, and the optimal conditions were pH 9.5, reaction time of 180 min, and 10 g of S. terebinthifolius Raddi leaves. The samples were characterized using UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. Antimicrobial activity was evaluated using the broth microdilution method and through the minimum microbicidal concentration. AgNPs showed greater antimicrobial efficacy compared to the extract, both for bacteria and fungi: bacteriostatic activity against all tested bacteria and bactericidal against Pseudomonas aeruginosa, besides fungistatic action against Candida albicans and Candida glabrata. Finally, the aqueous extract of "aroeira" leaves was effective in the synthesis of AgNPs, with greater antimicrobial potential than the extract.

Characterization of the chemical composition (mineral, lead and centesimal) in pine nut (Araucaria angustifolia (Bertol.) Kuntze) using exploratory data analysis.

In this study, mineral composition, centesimal composition and lead were evaluated in pine nut seeds (raw and cooked) from five Brazilian states. Mineral composition was determined by ICP OES and lead by GF AAS. The results for minerals were evaluated by Boxplot, PCA and HCA, using the R software. Average minerals in raw and cooked samples (mg 100 g-1) were: 15.2 and 10.8 (Ca), 0.168 and 0.113 (Cu), 0.506 and 0.330 (Fe), 536 and 420 (K), 51.3 and 40.6 (Mg), 0.373 and 0.208 (Mn), 132 and 102 (P) and 0.746 and 0.520 (Zn). The average centesimal composition (raw and cooked) was: 53.5 and 47.2% (moisture), 1.76 and 1.26% (ash), 3.90 and 3.53% (protein), 40.8 and 48.0% (carbohydrate) and 179 and 206 kcal/100 g (total caloric value) and Pb was not detected. The chemometric analysis showed a distinction of raw and cooked samples due to significant nutrient losses after thermal processing.

Evaluation of multielement/proximate composition and bioactive phenolics contents of unconventional edible plants from Brazil using multivariate analysis techniques.

Unconventional edible plants (UEP) are potential supplementary sources of minerals and bioactive compounds. However, there is still a gap in the literature on UEP composition. In this study, the multielement/proximate composition of ten UEP from Brazil was evaluated by ICP OES. Furthermore, phenolic bioactives were quantified by HPLC-UV-DAD. The UEP showed high moisture content (84.85-95.27%) and elements (in mg Kg-1): Al (122-657), Ca (145-14,229), Cu (8.3-18.81), Fe (177-586), K (12.46-34.50%), Mg (157-1,552), Mn (16.85-84.96), Na (1,107-23,775), P (2,535-6,127), Si (189-1,695), Sr (25.56-104.63) and Zn (0.3-72.31). Nine phenolic bioactive compounds (1-2,147) and three flavonoids (1-2,042 mg Kg-1) were determined. PCA and HCA grouped samples (Java ginseng, Coriander, Spearmint and Indian borage) rich in minerals. Spearmint showed high levels of transcinamic acid, kaempferol and quercetin. This study contributes to the scientific development and use of UEP.

Multivariate optimization of a goat meat alkaline solubilization procedure using tetramethylammonium hydroxide for metals determination using FAAS.

In the present work, multivariate designs were used to optimize an alkaline dissolution, assisted by ultrasound energy, procedure of goat meat using tetramethylammonium hydroxide (TMAH) aiming to determine Ca, Cu, Fe, K, Mg, Na and Zn by flame atomic absorption (FAAS) and emission (FAES) spectrometry. The optimal conditions found for the dissolution were in the following ranges: 0.4-0.5 g for the sample mass, 12-15 min of sonication and using 700-1000 µL of 25% TMAH at a temperature of 50 °C. The obtained limits of quantification varied between 0.221 (Mg) and 7.60 (Ca) µg g-1. Accuracy was assessed by comparing the results obtained by applying the proposed method with the digestion in an acid medium using a digesting block and by analyzing bovine liver certified reference material. The application of a t-test revealed that, at a 95% confidence level, there were no significant differences between the values obtained.

Screening of Mangifera indica L. functional content using PCA and neural networks (ANN).

A method using reversed-phase high-performance liquid chromatography with diode array detection (HPLC-DAD) was applied after extraction with acidified methanol, to determine 12 bioactive phenolic compounds in the peel and pulp of the mango fruit (Mangifera indica L.) cultivated in the Bahia, state of Brazil. The proposed methodology was previously fully validated and proven successful in the analysis of methanolic extracts of lyophilized samples. The limits of quantification ranged between 0.78 and 3.14 mg L-1 and the individual recovery values obtained for the spiked samples ranged from 80% to 120%. The results were evaluated using PCA and ANN. The results indicate that the fruits are rich in polyphenols, mainly: ellagic acid, gallic acid, rutin and catechin, which contribute to their greater use as functional foods, natural antioxidants and in the pharmaceutical industry, as well as other applications.

Multielementar/centesimal composition and determination of bioactive phenolics in dried fruits and capsules containing Goji berries (Lycium barbarum L.).

The elemental/centesimal composition of dried fruits and capsules containing Goji berries (Lycium barbarum L.) was evaluated by ICP OES after two digestion procedures. Furthermore, phenolic acid compounds and flavonoids were quantified by HPLC-UV-DAD. Precision, accuracy, LOD and LOQ were evaluated. The samples showed similar contents of proteins, lipids and carbohydrates. The metal contents in the samples were found at different levels (minimum-maximum, in mg kg-1), as follows: Ca (181.1-200.2); Cu (1.703-2.145); Fe (7.420-7.852); K (81.78-83.59); Mg (92.58-95.12); Mn (1.630-2.570); Na (587.9-590.7); P (3.124-3.360); Se (2.812-3.345); V (0.055-0.062) and Zn (2.325-2.610). Al, As, Ba Cd, Co, Ni, P, Pb, Sb, Sn and Sr showed values below the LOD. Accuracy was assessed by analysis of tomato leaves (NIST 1573a). Eight bioactive phenolic compounds (caffeic, chlorogenic, ellagic, ferulic, gallic, p-coumaric, syringic and vanillic acids) and two flavonoids [(+)-catequin and rutin] were determined, in levels of 55.5-83.700 and 172.3-2982.4 mg kg-1, respectively.

Simultaneous determination of mercury and selenium in fish by CVG AFS.

In this work, an analytical method was proposed for the simultaneous determination of mercury and selenium in fish samples using Atomic Fluorescence Spectrometry (AFS). Multivariate designs were performed to evaluate the variables and optimize the best condition of chemical vapor generation (CVG) and simultaneous determination of mercury and selenium by AFS. Fish samples were prepared via acid digestion in digester block with cold finger reflux system, which ensured that the elements were not lost by volatility. The proposed analytical method was validated, and excellent figures of merit have been achieved, such as detection limits of 0.33 and 9.18 ng g-1 for mercury and selenium, respectively. The method was applied for simultaneous determination of mercury and selenium in canned sardines. Mercury concentrations ranged from 0.057 to 0.203 µg g-1 and selenium concentration from 1.76 to 2.21 µg g-1, providing a mean molar ratio (Se:Hg) equivalent to 36.

Multivariate analysis of the composition of bioactive in tea of the species Camellia sinensis.

This study deals with the development of a separation and quantification method by high performance liquid chromatography with a diode array detector (HPLC- DAD), for the determination of phenolic acids and methylxanthines in tea (Camellia Sinensis) samples. Six phenolic acids (Gallic, trans-cinnamic, caffeic, ferulic and p-coumaric acids) and two methylxanthines (caffeine, theobromine) were studied, according to the principles of green chemistry, with the goal of comparing teas with different processing level. After development and validation of separation and extraction methods was applied to 11 extracts obtained by infusions of green and black tea samples in commercial areas of the city of Salvador-BA, showing feasible and efficient. Was employed multivariate data analysis and the Tukey test to correlate the chromatographic profile with the different samples. Principal component and analysis and hierarchical cluster analysis were used for the chromatographic analysis, allowing the visualization of two groups, formed by green and black tea samples.

Doehlert design in the optimization of ultrasound assisted dissolution of fish fillet samples with tetramethyl ammonium hydroxide for metals determination using FAAS.

Doehlert design and desirability function were used in the optimization of an ultrasound assisted dissolution method of fish fillet samples with tetramethyl ammonium hydroxide (TMAH) for the determination of Ca, Fe, Zn and Mg by flame atomic absorption spectrometry. The variables values after optimization were 620 µL (volume of TMAH), 25 min (sonication time) and 46 °C (bath temperature). The quantification limits for Ca, Mg, Fe and Zn were 56, 107, 23 and 2.9 µg g-1, respectively. Accuracy was evaluated by comparing the results generated from the analysis of the samples treated by the proposed method and by wet digestion. Additionally, accuracy for Fe and Zn was assessed by the analysis of certified reference materials Tort-3 (Lobster hepatopancreas), ERM-CE 278 (mussel tissue) and Dolt-4 (Fish liver). There were no significant differences between the results obtained at a 95% confidence level when results were evaluated by t-test application.

Statistical designs and response surface techniques for the optimization of chromatographic systems.

This paper describes fundamentals and applications of multivariate statistical techniques for the optimization of chromatographic systems. The surface response methodologies: central composite design, Doehlert matrix and Box-Behnken design are discussed and applications of these techniques for optimization of sample preparation steps (extractions) and determination of experimental conditions for chromatographic separations are presented. The use of mixture design for optimization of mobile phases is also related. An optimization example involving a real separation process is exhaustively described. A discussion about model validation is presented. Some applications of other multivariate techniques for optimization of chromatographic methods are also summarized.