Olive Oil Waste as a Source of Functional Food Ingredients: Assessing Polyphenolic Content and Antioxidant Activity in Olive Leaves

Around two million tons of olive oil are produced in Europe annually, with Portugal being among the top five European olive oil-producing countries. Olive oil production results in a substantial amount of waste in the form of olive leaves. These discarded olive leaves contain valuable phenolic compounds with antioxidant, anti-inflammatory, hypoglycaemic, neuroprotective, and antiproliferative properties. Due to their richness in polyphenols with health-promoting properties, olive leaves can be considered a potential functional food ingredient. Thus, sustainable practices for reusing olive leaf waste are in demand. In this study, the polyphenolic content in olive leaves from different Portuguese locations was determined using HPLC-UV-Vis after defining the best fit-for-purpose liquid extraction strategy. The differences in the in vitro antioxidant activity in these samples were determined by several methodologies based on radical scavenging (against 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-2-picrylhydrazyl (DPPH), and peroxyl radical (ORAC)) and on reducing properties (cupric-reducing antioxidant capacity (CUPRAC), and Folin-Ciocalteu assay (FC)), to unveil the relationship between the profile and quantity of polyphenols with antioxidant mechanisms and their capacity. At last, the stability of extracted compounds upon lyophilization and exposition to surrogate biological fluids was assessed, envisioning the future incorporation of olive leaves extracted compounds in food products.

Assessing the differences of two vineyards soils' by NIR spectroscopy and chemometrics

Soil properties influence greatly the status of vine plants which consequently influences the quality of wine. Therefore, in the context of viticulture management, it is extremely important to assess the physical and chemical parameters of vineyards soils. In this study, the soils of two vineyards were analysed by near-infrared (NIR) spectroscopy and established analytical reference procedures. The main objective of this study was to verify if NIR spectroscopy is a potential tool to discriminate the soils of both vineyards as well as to quantify differences of soil's parameters. For that, a total of eight sampling spots were selected at each vineyard taking into consideration the soil type and sampled at different depths. The data analysis was performed using analysis of variance (ANOVA), principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) and partial least squares (PLS) regression. The ANOVA results revealed that 12 out of the 18 parameters analysed through the reference procedures can be considered statistically different (p < 0.05). Regarding PCA, the obtained results revealed a clear separation between the scores of both vineyards either considering NIR spectra or the chemical parameters. The PLS-DA model was able to obtain 100 % of correct predictions for the discrimination of both vineyards. PLS regression analysis using NIR spectra revealed R2P and RER values higher than 0.85 and 10, respectively, for 8 (pH (H2O), N, Ca2+, Mg2+, SB, CEC, ECEC and GSB) of the 18 chemical parameters evaluated. Concluding, these results demonstrate that it is possible to discriminate the soils of the different vineyards through NIR spectroscopy as well as to quantify several chemical parameters through soils NIR spectra in a rapid, accurate, cost-effective, simple and environmentally friendly way when compared to the reference procedures.

Total analysis system for the determination of uremic toxins in human plasma based on bead injection solid phase extraction hyphenated to mass spectrometry

Indoxyl sulfate (INDS) and p-cresol sulfate (pCS) are two of the most relevant uremic toxins that are recognized to have an essential role in chronic kidney disease (CKD) progression and associated cardiovascular risk. Thus, it is crucial to accurately assess their circulating levels in the body. Aiming at establishing an analytical strategy for quantification of INDS and pCS in human plasma, an automatic on-line micro-solid-phase extraction (μSPE) procedure hyphenated to tandem mass spectrometry (MS/MS) detection without previous chromatographic separation was herein developed. The bead injection (BI) concept was used to implement the μSPE procedure in the lab-on-valve (LOV) format. After studying the extraction conditions, the anion-exchange OASIS WAX sorbent beads (10 mg) and 99% ACN-H2O (15:85, v/v)-1% (v/v) NH4OH were chosen as sorbent and eluent, respectively, as they provided the highest analyte recoveries. Subsequently, the μSPE-BI-LOV system was hyphenated on-line to a MS/MS detector and the full analytical cycle, comprising sample preparation and analytes detection, was completed in <20 min. The developed μSPE-BI-LOV-MS methodology presented good linearity (r2 > 0.999) for quantification of the target analytes at concentrations ranging from 18 to 360 μg mL-1 in plasma. LOQ values were 2 μg mL-1 for INDS and 7 μg mL-1 for pCS in plasma. Human plasma samples from healthy subjects and individuals with CKD were successfully analyzed using the developed approach. The proposed automatic methodology can be described as an eco-friendly strategy, with a favorable score of 0.64 after greenness evaluation using the AGREE metric.

Lab-on-Valve Automated and Miniaturized Assessment of Nanoparticle Concentration Based on Light-Scattering

Nanoparticles (NPs) concentration directly impacts the dose delivered to target tissues by nanocarriers. The evaluation of this parameter is required during NPs developmental and quality control stages, for setting dose-response correlations and for evaluating the reproducibility of the manufacturing process. Still, faster and simpler procedures, dismissing skilled operators and post-analysis conversions are needed to quantify NPs for research and quality control operations, and to support result validation. Herein, a miniaturized automated ensemble method to measure NPs concentration was established under the lab-on-valve (LOV) mesofluidic platform. Automatic NPs sampling and delivery to the LOV detection unit were set by flow programming. NPs concentration measurements were based on the decrease in the light transmitted to the detector due to the light scattered by NPs when passing through the optical path. Each analysis was accomplished in 2 min, rendering a determination throughput of 30 h^-1 (6 samples h^-1 for n = 5) and only requiring 30 μL (≈0.03 g) of NPs suspension. Measurements were performed on polymeric NPs, as these represent one of the major classes of NPs under development for drug-delivery aims. Determinations for polystyrene NPs (of 100, 200, and 500 nm) and for NPs made of PEGylated poly-d,l-lactide-co-glycolide (PEG-PLGA, a biocompatible FDA-approved polymer) were accomplished within 10⁸-10¹² particles mL^-1 range, depending on the NPs size and composition. NPs size and concentration were maintained during analysis, as verified for NPs eluted from the LOV by particle tracking analysis (PTA). Moreover, concentration measurements for PEG-PLGA NPs loaded with an anti-inflammatory drug, methotrexate (MTX), after their incubation in simulated gastric and intestinal fluids were successfully achieved (recovery values of 102-115%, as confirmed by PTA), showing the suitability of the proposed method to support the development of polymeric NPs targeting intestinal delivery.

Rapid and sustainable HPLC method for the determination of uremic toxins in human plasma samples

Protein-bound uremic toxins, mainly indoxyl sulfate (3-INDS), p-cresol sulfate (pCS), and indole-3-acetic acid (3-IAA) but also phenol (Pol) and p-cresol (pC), are progressively accumulated during chronic kidney disease (CKD). Their accurate measurement in biomatrices is demanded for timely diagnosis and adoption of appropriate therapeutic measures. Multianalyte methods allowing the establishment of a uremic metabolite profile are still missing. Hence, the aim of this work was to develop a rapid and sensitive method based on high-performance liquid chromatography with fluorescence detection for the simultaneous quantification of Pol, 3-IAA, pC, 3-INDS, and pCS in human plasma. Separation was attained in 12 min, using a monolithic C18 column and isocratic elution with acetonitrile and phosphate buffer containing an ion-pairing reagent, at a flow rate of 2 mL min^-1. Standards were prepared in plasma and quantification was performed using the background subtraction approach. LOQ values were ≤ 0.2 µg mL^-1 for all analytes except for pCS (LOQ of 2 µg mL^-1). The method proved to be accurate (93.5-112%) and precise (CV ≤ 14.3%). The multianalyte application of the method, associated to a reduced sample volume (50 µL), a less toxic internal standard (eugenol) in comparison to the previously applied 2,6-dimethylphenol and 4-ethylphenol, and a green extraction solvent (ethanol), resulted in the AGREE score of 0.62 which is in line with the recent trend of green and sustainable analytical chemistry. The validated method was successfully applied to the analysis of plasma samples from control subjects exhibiting normal levels of uremic toxins and CKD patients presenting significantly higher levels of 3-IAA, pC, 3-INDS, and pCS that can be further investigated as biomarkers of disease progression.

Sample preparation and chromatographic methods for the determination of protein-bound uremic retention solutes in human biological samples: An overview

Protein-bound uremic retention solutes, such as indole-3-acetic acid, indoxyl sulfate, p-cresol and p-cresol sulfate, are associated with the development of several pathologies, namely renal, cardiovascular, and bone toxicities, due to their potential accumulation in the human body, thus requiring analytical methods for monitoring and evaluation. The present review addresses conventional and advanced sample treatment procedures for sample handling and the chromatographic analytical methods developed for quantification of these compounds in different biological fluids, with particular focus on plasma, serum, and urine. The sample preparation and chromatographic methods coupled to different detection systems are critically discussed, focusing on the different steps involved for sample treatment, namely elimination of interfering compounds present in the sample matrix, and the evaluation of their environmental impact through the AGREEprep tool. There is a clear trend for the application of liquid-chromatography coupled to tandem mass spectrometry, which requires protein precipitation, solid-phase extraction and/or dilution prior to analysis of biological samples. Furthermore, from a sustainability point of view, miniaturized methods resorting to microplate devices are highly recommended.

Miniaturized Fluorimetric Method for Quantification of Zinc in Dry Dog Food

Zinc is an essential trace element for animals in several biological processes, particularly in energy production, and it is acquired from food ingestion. In this context, a microplate-based fluorimetric assay was developed for simple, fast, and low-cost determination of zinc in pet food using 2,2'-((4-(2,7-difluoro-3,6-dihydroxy-4aH-xanthen-9-yl)-3-methoxyphenyl)azanediyl)diacetic acid (FluoZin-1) as fluorescent probe. Several aspects were studied, namely, the stability of the fluorescent product over time, the FluoZin-1 concentration, and the pH of reaction media. The developed methodology provided a limit of detection of 1 μg L-1 in sample acid digests, with a working range of 10 to 200 μg L-1, corresponding to 100-2000 mg of Zn per kg of dry dog food samples. Intraday repeatability and interday repeatability were assessed, with relative standard deviation values < 3.4% (100 μg L-1) and <11.7% (10 μg L-1). Sample analysis indicated that the proposed fluorimetric assay provided results consistent with ICP-MS analysis. These results demonstrated that the developed assay can be used for rapid determination of zinc in dry dog food.

Characterization of phospholipid vesicles containing lauric acid: physicochemical basis for process and product development

Lauric acid (LAH) strongly inhibits the growth of acne-causing bacteria. LAH is essentially water-insoluble and the solubility of laurate (LA) salts are medium and temperature dependent. Hence, LAH/LA preparations are difficult to formulate. Here we fully characterized phospholipid vesicles containing up to 50 mol% LAH. Vesicles of dipalmitoylphosphatidylcholine (DPPC) containing LAH, at pHs 7.4 and 5.0, were characterized measuring size, charge, bilayer phase transition temperature (Tm) and permeability of water-soluble probes. Small angle X-ray scattering and cryotransmission electron microscopy showed multilamellar vesicles at low LAH %. Increasing LAH % had a negligible effect on particle size. An internal aqueous compartment in all vesicle's preparations, even at equimolar DPPC: LAH fractions, was demonstrated using water-soluble probes. At pH 5.0, the interaction between DPPC and LAH increased the Tm and phase transition cooperativity showing a single lipid phase formed by hydrogen-bonded DPPC: LAH complexes. At pH 7.4, vesicles containing 50 mol% LAH exhibited distinct phases, ascribed to complex formation between LAH and LA or LAH and DPPC. LAH incorporated in the vesicles minimally permeated a skin preparation at both pHs, indicating that the primary sites of LAH solubilization were the skin layers. These results provide the foundations for developing processes and products containing DPPC: LAH.

Chemistry, bioactivities, extraction and analysis of azadirachtin: State-of-the-art

Azadirachta indica A. Juss. (Neem) is an Indian tree recognized for its activity as pesticide, as well as several pharmacological properties. Among the various compounds already isolated and studied from Neem tree, azadirachtin (AZA) was identified as the main bioactive compound. Azadirachtin can be found at different parts of the Neem plant but assumes its maximum concentration at the seed level. This compound features a quite complex chemical structure, which justifies the 20-plus-year difficulty to identify the synthetic pathway that subsequently permitted to carry out its artificial synthesis. Azadirachtin is widely used as a basis for production of biopesticides; nevertheless, other properties have been recognized for this substance, among which the anticancer and antimalarial activity stand out. The methods available for azadirachtin extraction are diverse, including solid-liquid extraction and extraction with solvents at high or low temperatures. Alcohol based solvents are associated with higher extraction yields and are therefore preferred for the isolation of azadirachtin from plant parts. Clean-up of the extracts is generally required for further purification. The highest azadirachtin levels have been obtained from Neem seeds but concentration values present a large variation between batches. Therefore, in addition to extraction procedures, it is essential to establish routine methods for azadirachtin identification and quantification. Chromatography-based techniques are preferably selected for detection and quantification of azadirachtin in plant matrices. Overall, this process will guarantee a future reproducible, safe and effective use of the extracts in formulations for commercial applications.

Noncovalent PEG Coating of Nanoparticle Drug Carriers Improves the Local Pharmacokinetics of Rectal Anti-HIV Microbicides

Antiretroviral drug nanocarriers hold great promise for developing anti-human immunodeficiency virus (HIV) rectal microbicides. However, challenges remain, namely, concerning which properties are more suited for enhancing colorectal distribution and retention of microbicide compounds. In this work, we developed and assessed the in vitro and in vivo performance of poly(lactic- co-glycolic acid) (PLGA)-based nanoparticles (NPs) as carriers for the model drug efavirenz (EFV). We particularly focused on the effect of noncovalent poly(ethylene glycol) coating of PLGA NPs (PEG-PLGA NPs) conferring a mucus-diffusive behavior on the pharmacokinetics (PK) of EFV following rectal administration to mice. Drug-loaded PLGA NPs and PEG-PLGA NPs (200-225 nm) were obtained by nanoprecipitation. Both types of systems were able to retain native antiretroviral activity of EFV in vitro, while featuring lower cytotoxicity against different epithelial cell lines and HIV target cells. Also, PLGA NPs and PEG-PLGA NPs were readily taken up by colorectal cell lines and mildly reduced EFV permeation while increasing membrane retention in Caco-2 and Caco-2/HT29-MTX cell monolayer models. When administered intrarectally to CD-1 mice in phosphate-buffered saline (pH 7.4), EFV-loaded PEG-PLGA NPs consistently provided higher drug levels in colorectal tissues and lavages, as compared to free EFV or drug-loaded PLGA NPs. Mean values for the area-under-the-curve between 15 min and 12 h following administration were particularly higher for PEG-PLGA NPs in distal and middle colorectal tissues, with relative bioavailability values of 3.7 and 29, respectively, as compared to free EFV (2.2 and 6.0 over PLGA NPs, respectively). Systemic exposure to EFV was reduced for all treatments. NPs were further shown safe after once-daily administration for 14 days, as assessed by histological analysis of colorectal tissues and chemokine/cytokine assay of rectal lavages. Overall, PEG-PLGA NPs demonstrated to be safe carriers for rectal microbicide drug delivery and able to provide enhanced local PK that could be valuable in preventing rectal HIV transmission.

Photocatalytic ozonation of urban wastewater and surface water using immobilized TiO2 with LEDs: Micropollutants, antibiotic resistance genes and estrogenic activity

Photocatalytic ozonation was employed for the first time in continuous mode with TiO2-coated glass Raschig rings and light emitting diodes (LEDs) to treat urban wastewater as well as surface water collected from the supply area of a drinking water treatment plant (DWTP). Different levels of contamination and types of contaminants were considered in this work, including chemical priority substances (PSs) and contaminants of emerging concern (CECs), as well as potential human opportunistic antibiotic resistant bacteria and their genes (ARB&ARG). Photocatalytic ozonation was more effective than single ozonation (or even than TiO2 catalytic ozonation) in the degradation of typical reaction by-products (such as oxalic acid), and more effective than photocatalysis to remove the parent micropollutants determined in urban wastewater. In fact, only fluoxetine, clarithromycin, erythromycin and 17-alpha-ethinylestradiol (EE2) were detected after photocatalytic ozonation, by using solid-phase extraction (SPE) pre-concentration and LC-MS/MS analysis. In surface water, this treatment allowed the removal of all determined micropollutants to levels below the limit of detection (0.01-0.20 ng L(-1)). The efficiency of this process was then assessed based on the capacity to remove different groups of cultivable microorganisms and housekeeping (16S rRNA) and antibiotic resistance or related genes (intI1, blaTEM, qnrS, sul1). Photocatalytic ozonation was observed to efficiently remove microorganisms and ARGs. Although after storage total heterotrophic and ARB (to ciprofloxacin, gentamicin, meropenem), fungi, and the genes 16S rRNA and intI1, increased to values close to the pre-treatment levels, the ARGs (blaTEM, qnrS and sul1) were reduced to levels below/close to the quantification limit even after 3-days storage of treated surface water or wastewater. Yeast estrogen screen (YES), thiazolyl blue tetrazolium reduction (MTT) and lactate dehydrogenase (LDH) assays were also performed before and after photocatalytic ozonation to evaluate the potential estrogenic activity, the cellular metabolic activity and the cell viability. Compounds with estrogenic effects and significant differences concerning cell viability were not observed in any case. A slight cytotoxicity was only detected for Caco-2 and hCMEC/D3 cell lines after treatment of the urban wastewater, but not for L929 fibroblasts.

Epifluorescence microscope methods for bacterial enumeration in a 4-chlorophenol degrading consortium

Epifluorescence microscope methods, namely BacLight, direct epifluorescence filter technique and Rhodamine 123, consistently underestimated plate bacterial counts in a 4-chlorophenol degrading consortium. Cells capable of passing through 0.2 microm filters, referred as 'ultramicrocells', were found. Although cell counts were higher when traditional methods were used, BacLight and direct epifluorescence filter technique were convenient techniques for the systematic monitoring of bacteria involved in biodegradation processes, as results were consistent and available within a short time.