M. Rosário Bronze

Analysis of old brandy and oak extracts by capillary electrophoresis

Abstract Polyphenolic compounds in spirits and ethanolic oak extracts were studied by capillary electrophoresis and results compared with resersed-phase HPLC analysis. Different conditions of analysis were tried in order to set up the best separation conditions, and reproducibility of the migration times was studied with standard mixtures and tested for samples. Compounds usually studied in these samples were well separated with 0.1 M borate buffer with 5% ethanol, pH 9.2. Calibration curves (2.5–50 ppm) were established for some standard compounds. Capillary electrophoresis is a simple and useful method for the analysis of oak extracts and old brandies.

Development of novel sophorolipids with improved cytotoxic activity toward MDA-MB-231 breast cancer cells.

Sophorolipids (SLs) are glycolipid biosurfactants, produced as a mixture of several compounds by some nonpathogenic yeast. In the current study, separation of individual SLs from mixtures with further evaluation of their surface properties and biologic activity on MDA‐MB‐321 breast cancer cell line were investigated. SLs were biosynthesized by Starmerella bombicola in a culture media supplemented with borage oil. A reverse‐phase flash chromatography method with an automated system coupled with a prepacked cartridge was used to separate and purify the main SLs. Compositional analysis of SLs was performed by high‐performance liquid chromatography with electrospray ionization mass spectrometry and tandem mass spectrometry. The following diacetylated lactonic SLs were isolated and purified: C18:0, C18:1, C18:2, and C18:3. The critical micelle concentration (CMC) and surface tension at CMC (γCMC) of the purified SLs showed an increase with the number of double bonds. High cytotoxic effect against MDA‐MB‐231 cells was observed with C18:0 and C18:1 lactonic SLs. The cytotoxic effects of C18:3 lactonic SL on cancerous cells were for the first time studied. This cytotoxic effect was considerably higher than the promoted by acidic SLs; however, it induced a lower effect than the previously mentioned SLs, C18:0 and C18:1. To our knowledge, for the first time, C18:1 lactonic SL, in selected concentrations, proved to be able to inhibit MDA‐MB‐231 cell migration without compromising cell viability and to increase intracellular reactive oxygen species. Copyright

Enzymatic Synthesis of the Flavone Glucosides, Prunin and Isoquercetin, and the Aglycones, Naringenin and Quercetin, with Selective α-L-Rhamnosidase and β-D-Glucosidase Activities of Naringinase

The production of flavonoid glycosides by removing rhamnose from rutinosides can be accomplished through enzymatic catalysis. Naringinase is an enzyme complex, expressing both α-L-rhamnosidase and β-D-glucosidase activities, with application in glycosides hydrolysis. To produce monoglycosylated flavonoids with naringinase, the expression of β-D-glucosidase activity is not desirable leading to the need of expensive methods for α-L-rhamnosidase purification. Therefore, the main purpose of this study was the inactivation of β-D-glucosidase activity expressed by naringinase keeping α-L-rhamnosidase with a high retention activity. Response surface methodology (RSM) was used to evaluate the effects of temperature and pH on β-D-glucosidase inactivation. A selective inactivation of β-D-glucosidase activity of naringinase was achieved at 81.5°C and pH 3.9, keeping a very high residual activity of α-L-rhamnosidase (78%). This was a crucial achievement towards an easy and cheap production method of very expensive flavonoids, like prunin and isoquercetin starting from naringin and rutin, respectively.

Optimization and correlation of HPLC-ELSD and HPLC-MS/MS methods for identification and characterization of sophorolipids.

High-performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD) and HPLC with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) methods were implemented and optimized to separate and identify sophorolipids (SLs) produced by Rhodotorula bogoriensis and Starmerella bombicola. SLs are carbohydrate-based amphiphilic biosurfactants with increased interest in pharmaceutical and environmental areas. Rhodotorula bogoriensis and Starmerella bombicola are mainly producers of respectively C22, and C16 and C18 SLs. Mass fragmentation patterns of SLs produced by both yeasts were investigated by HPLC-ESI-MS/MS in the positive mode for [M+Na]+. Based on the established fragmentation pattern, SLs produced by both yeasts were identified and characterized. A correlation between HPLC-ELSD and HPLC- ESI-MS/MS methods was established and made possible the identification of SLs by the HPLC-ELSD technique. TLC is a common tool for the analysis of SLs mixtures. In this work, TLC scrapped bands were analysed by HPLC-ELSD and HPLC-MS allowing the correlation between R(F) values and the identification of sophorolipids by this technique. Identification of monoacetylated and diacetylated C24:0 hydroxy fatty acids sophorolipids produced by Rhodotorula bogoriensis was for the first time accomplished with this study. Although present in lower quantity these longer chain SLs can assume special importance regarding their biological activity and surface active properties.

Olive paste as vehicle for delivery of potential probiotic Lactobacillus plantarum 33

Use of probiotic bacteria and consumes in large - in novel foods to provide beneficial health effects has attracted an increasing interest by the food industry and fermented olives are an excellent example of a new generation of those foods from plant origin so as to assure maximum viability by the time of ingestion during processing and storage of food products, as well as during transit through the gastrointestinal tract. Our study focused on production, characterization and assessment of efficacy of microencapsulation upon survival of probiotic strains and sensory properties of the final olive paste throughout refrigerated storage. Microencapsulation appears to be an effective technique for strain survival, depending on the operating temperature and experimental results on tolerance to gastrointestinal-like conditions, and ability to adhere to intestinal epithelium is thereby presented and discussed. The sensory panel rated all experienced matrices as good, including overall acceptance without significant preference between them. However, the success of microencapsulation was more limited when incorporated into olive paste. Free cells of Lactobacillus plantarum 33 proved able to survive in olive paste during storage at refrigerated temperatures.

Alternative biomarkers of n-hexane exposure: Characterization of aminoderived pyrroles and thiol-pyrrole conjugates in urine of rats exposed to 2,5-hexanedione

The identification of pyrrole derivatives in urine of rats exposed to 2,5-hexanedione (2,5-HD), was performed to select an adequate peripheral biomarker predictive of 2,5-HD neurotoxicity. Studies on molecular mechanism of 2,5-HD neurotoxicity have revealed that 2,5-hexanedione reacts with free amino groups of lysine in proteins forming primary pyrrole adducts, which may autoxidize and form pyrrole dimers, responsible for protein crosslinking in neurofilaments, or react with sulfhydryl groups of cysteine in peptides and proteins, forming secondary pyrrole adducts, which probably may inhibit the process responsible by 2,5-HD neurotoxicity. In this work, the analysis of excreted 2,5-HD and pyrrole derivatives in urine of rats exposed to 3 doses of 2,5-HD (400mg/kg bw, via ip) was performed using ESI-LC-MS/MS. Several pyrrole compounds were identified, namely dimethylpyrrole norleucine (DMPN), cysteine-pyrrole conjugate (DMPN NAC), glutathione-pyrrole conjugate (DMPN GSH) and 2,5-dimethylpyrrole (2,5-DMP). Additionally, free and total 2,5-HD, DMPN and DMPN NAC were quantified. The observed results suggest that DMPN is a sensitive and specific indicator of repeated exposure to 2,5-HD and its selection as a predictive biomarker of neurotoxic effect, is now under study.

Antiplasmodial drugs in the gas phase: a CID and DFT study of quinolon-4(1H)-imine derivatives.

AbstractThe gas-phase behavior of 12 quinolon-4(1H)-imine derivatives with antiplasmodial activity was investigated using electrospray ionization tandem mass spectrometry together with collision induced dissociation and density functional theory (DFT) calculations. The most probable protonation site was predicted by calculating the proton affinity (PA) values for each possible protonation site and it was found to be the imine nitrogen for all compounds under study. Fragmentation pathways of the protonated molecules were proposed and the assignment of product ion structures was performed taking into account theoretical calculations. The nature of the quinoline substituent was found to influence the gas-phase behavior of the compounds under study. The data acquired allowed to bracket the proton affinity of the quinolin-4-imine scaffold, which can be a useful starting point to choose appropriate references for determining PA values of this scaffold. Figureᅟ