Henrique Faccin

Study of ion suppression for phenolic compounds in medicinal plant extracts using liquid chromatography–electrospray tandem mass spectrometry

A systematic study on the various sources of ion suppression in UHPLC-MS-MS analysis was carried out for 24 phenolic antioxidants in 6 different extracts of medicinal plants from Amazonia. The contributions of matrix effects, mobile-phase additives, analyte co-elution and electric charge competition during ionization to the global ion suppression were evaluated. Herein, the influence of mobile-phase additives on the ionization efficiency was found to be very pronounced, where ion suppression of approximately 90% and ion enhancement effects greater than 400% could be observed. The negative effect caused by the wrong choice of internal standard (IS) on quantitative studies was also evaluated and discussed from the perspective of ion suppression. This work also shows the importance of performing studies with this approach even for very similar matrices, such as varieties of medicinal plants from the same species, because different effects were observed for the same analyte.

A liquid chromatographyatmospheric pressure photoionization tandem mass spectrometric method for the determination of organosulfur compounds in petroleum asphalt cements

We present a sensitive liquid chromatography-atmospheric pressure photoionization tandem mass spectrometric (UHPLC-APPI-MS/MS) method for the determination of selected organosulfur compounds in Brazilian asphalt cements. It was possible to detect 14 organosulfur compounds of different classes where sulfoxides and sulfones presented higher sensibility in ionization than thiophenes and aromatic sulfides. A dopant-assisted APPI method was also tested, however, when chromatographic flow rate was optimized a decrease in signal was observed for all compounds. PAHs were tested and ruled out as possible interfering compounds and the matrix effect of asphalt cements was within an acceptable range for the quantification of organosulfur compounds. The proposed method was found to have satisfactory linearity and accuracy with recoveries between 83.85 and 110.28% for thianaphthene and 3-methylbenzothiophene, respectively. Therefore, the method allowed the characterization of organosulfur compounds in Brazilian asphalt cements and demonstrated changes in the amount quantified in asphaltenic and maltenic fractions after the RTFOT+SUNTEST aging process.

Metal and metalloid distribution in different environmental compartments of the middle Xingu River in the Amazon, Brazil

Concentrations of As, Cd, Cu, Cr, Pb, Hg, and Ni were analyzed during rainy and dry seasons in water, sediment, soil, and two fish species. The analysis took place at four points in the Xingu River, one point in the Fresco River, and two mining pits in the southeastern area of the Eastern Amazon, Brazil. In the water, the total concentration of As (>0.14μg/L) was higher than the local reference values at all sampling points and in both seasons. Ordination analysis (PCA) highlighted As and Cu elements in the water. PERMANOVA showed that the metals behaved differently in the water throughout the monitored season and between sampling points. The sites with mining activity were the regions that were the most contaminated by metals. Samples of sediment (Ni>18mg/kg and Cr>37.30mg/kg) and soil (Pb>72mg/kg, Cr>75mg/kg and Ni>30mg/Kg) showed concentrations above the recommended by local legislation. Metal values in the muscle of both fish species were relatively low at all sampling points and in both monitored seasons. Concentrations in water, sediment, and soil showed that some points of the Xingu River, Fresco River and mining pits are contaminated by trace elements, mainly As, Hg, Cr, Pb, and Ni. This was the first study about trace elements in the Middle Xingu River, which leads us to conclude that rainfall and cassiterite mining activities strongly influence the mobilization of metals, especially in abiotic compartments. However, the fish analyzed did not exhibit relevant levels of contamination. This indicates low risk for human consumption. Additionally, results highlight the need to establish local criteria to define contamination limits for different metals while taking into account local geochemistry particularities and biome diversity.

Substrate-free Determination of the Radical Scavenging Activity of Phenolic Compounds by Photochemical Generation of Hydroxyl Radicals and HPLC-UV Detection

This paper describes the study of the radical scavenging activity of the natural antioxidants rutin, quercetin, caffeic acid, ferulic acid, and resveratrol by using a substrate-free chromatographic method based on the generation of •OH radicals by the photolysis of H2O2 in a photochemical reactor. The comparative studies permitted the classification of some phenolic compounds regarding their in vitro radical scavenging properties (rutin > caffeic acid ≈ quercetin>ferulic acid > resveratrol). The results obtained by the proposed HPLC-UV/H2O2 photolysis method could be well corroborated by the other methods, which employ the generation of free radicals with different reactivity (ROO•, , and DPPH•). Furthermore, the reverse-phase chromatographic separation of the antioxidants from their sub-products generated after attacking with HO• radicals improved advantageously the selectivity of the measured signal used for calculating the radical scavenging activity.

Determination of phenolic compounds in extracts of Amazonian medicinal plants by liquid chromatography-electrospray tandem mass spectrometry

A method for the separation, identification and quantification of 24 phenolic compounds using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. Six species of traditional medicinal plants from the Brazilian Amazon region were studied (Mansoa alliacea, Bauhinia variegata var. variegata, Bauhinia variegata var. alboflava, Connarus perrottetii var. angustifolius, Cecropia obtusa and Cecropia palmata). The analytes were separated by a reversed-phase SB-C18 column (2.1 × 50 mm, 1.8 μm) using a gradient elution of 7 min composed of 0.1% acetic acid in water (v/v) and acetonitrile, at a constant flow rate of 0.8 mL min−1. The limit of detection for the analytes ranged between 0.5 and 130.3 μg L−1. Intra- and inter-day precision showed satisfactory results and the recoveries obtained for the 24 analytes varied between 91.7 and 111.9% for most of the evaluated matrices. Quantifications were performed with the standard addition method (r > 0.99) using the data acquired in a multiple reaction monitoring (MRM) mode. Rutin, apigenin, vanillic acid, caffeic acid, ferulic acid, p-coumaric acid and trans-cinnamic acid were found in all the studied plants. However, we highlight the high contents of rutin in varieties of Bauhinia variegata (up to 2.52 mg g−1 of plant), chlorogenic acid in species of genus Cecropia (up to 0.57 mg g−1 of plant) and catechin in Connarus perrottetii var. angustifolius (1.77 mg g−1 of plant).

Salting-out assisted liquid-liquid extraction and partial least squares regression to assay low molecular weight polycyclic aromatic hydrocarbons leached from soils and sediments

A novel method was developed to determine low molecular weight polycyclic aromatic hydrocarbons in aqueous leachates from soils and sediments using a salting-out assisted liquid-liquid extraction, synchronous fluorescence spectrometry and a multivariate calibration technique. Several experimental parameters were controlled and the optimum conditions were: sodium carbonate as the salting-out agent at concentration of 2molL-1, 3mL of acetonitrile as extraction solvent, 6mL of aqueous leachate, vortexing for 5min and centrifuging at 4000rpm for 5min. The partial least squares calibration was optimized to the lowest values of root mean squared error and five latent variables were chosen for each of the targeted compounds. The regression coefficients for the true versus predicted concentrations were higher than 0.99. Figures of merit for the multivariate method were calculated, namely sensitivity, multivariate detection limit and multivariate quantification limit. The selectivity was also evaluated and other polycyclic aromatic hydrocarbons did not interfere in the analysis. Likewise, high performance liquid chromatography was used as a comparative methodology, and the regression analysis between the methods showed no statistical difference (t-test). The proposed methodology was applied to soils and sediments of a Brazilian river and the recoveries ranged from 74.3% to 105.8%. Overall, the proposed methodology was suitable for the targeted compounds, showing that the extraction method can be applied to spectrofluorometric analysis and that the multivariate calibration is also suitable for these compounds in leachates from real samples.

Vitis vinifera L. cv Pinot noir pomace and lees as potential sources of bioactive compounds

Abstract Food and agricultural industries generate substantial quantities of phenolic-rich by-products that could be valuable natural sources of antioxidants. The aim of this study was to identify and quantify the phenolic compounds and radical scavenging activities of two by-products (pomace and lees) from Vitis vinifera L. cv Pinot noir. We found a different distribution of phenolic classes (flavanols, flavonols, phenolic acids and stilbenes) and singular scavenging activity against free radicals (hydroxyl, superoxide and peroxyl radicals). The major class of phenolics in pomace was flavanols and in lees was flavonols, with catechin (117.9 ± 2.5 μg g−1) and quercetin (42.4 ± 1.2 μg g−1) being the most abundant individual compounds. We also found high potential on scavenging activity against superoxide radicals in pomace (80% of scavenging activity) and radical peroxyl (67% scavenging activity). These results show the possibility of using Pinot noir by-products as promising additives or as a source for the development of new products in different segments of the food and cosmetic industries.

Antinociceptive and antidepressant-like effects of the crude extract of Vitex megapotamica in rats

ETHNOPHARMACOLOGICAL RELEVANCE Vitex megapotamica (Spreng) Moldenke has been used in South American folk medicine to treat inflammatory diseases. However, the effects of V. megapotamica on animal models of nociception and depression have not been evaluated. AIM OF THE STUDY This study investigated whether the crude leaf extract of V. megapotamica exhibits antinociceptive and antidepressant-like effects in a Freunds adjuvant-induced chronic inflammation and depression model. MATERIALS AND METHODS Chronic inflammation was induced in rats by the intraplantar administration of complete Freunds adjuvant (CFA; 100μl). The effect of oral crude extract of V. megapotamica (VmE; 3-30mg/kg, p.o.) on nociception (thermal hyperalgesia, mechanical allodynia and arthritis score), inflammation (edema, myeloperoxidase activity), immobility (forced swimming test), locomotor activity (open field), gastrointestinal transit, hyperalgesia and naloxone-precipitated morphine withdrawal syndrome was evaluated. Naloxone (0.4mg/kg, i.p.) was used to investigate the involvement of opioid system in the currently described effects of VmE. RESULTS Crude extract caused antinociceptive/antidepressant-like effects in the CFA-induced chronic inflammation model, which was prevented by naloxone. The VmE extract (10mg/kg, p.o.) did not alter the locomotor activity, gastrointestinal function and inflammatory parameters and did not cause hyperalgesia. CONCLUSION V. megapotamica induces opioid-dependent antinociception and antidepressant-like effect, without anti-inflammatory activity. The results support the use of VmE as analgesic and antidepressant.