Combination of solid-phase extraction and large-volume stacking with polarity switching in micellar electrokinetic capillary chromatography for the determination of traces of nonsteroidal anti-inflammatory drugs in saliva

A reliable MEKC method for the identification and quantitation of traces of the nonsteroidal anti-inflammatory drugs (NSAIDs) ketoprofen, fenbufen and indomethacin in saliva is proposed. Using CE to analyze biological samples often requires suppressing the interferences and peak broadening typically resulting from high-conductivity sample matrices. We addressed this problem by using Microcon, a centrifugal filter device, to reduce the viscosity of saliva and exclude most higher-molecular-mass substances. This initial pretreatment was followed by the combined used of off-line SPE to isolate and concentrate the analytes, and large-volume stacking with polarity switching (LVSS) in the capillary. These two preconcentration steps allow the determination of NSAIDs at concentrations above 0.1 microg/L; therefore, the proposed SPE/LVSS/MEKC method affords a 500-fold sensitivity enhancement relative to conventional CE injection. The LODs obtained afford the determination of NSAIDs in saliva, where analytes can be present at the microgram-per-liter level.     

Use of physical and chemical properties of commercial tomato (Lycopersicon esculentum Mill.) products for monitoring their quality

Eighteen physical and chemical variables were determined in 25 samples of commercial tomato products: total solids, soluble solids, water activity, lycopene, 5-hydroxymethyl-2-furfural, CIE(L*a*b*) components (L*, a*, b*, a*/b*, C*, H degrees), total acidity, sodium chloride, wet-weight pulp percentage, alcohol insoluble solids, total pectic substances, ascorbic acid, and pH. In order to maximize the variability of products, samples included crushed tomato, tomato puree, tomato paste, and heavy concentrates and were taken from Italy, France, Spain, Portugal, the United States, Mexico, Colombia, and Chile. Correlation analysis and multidimensional data analysis techniques (principal component analysis and hierarchical classifications) were used to describe the products' variability and to study the relationships among variables. Three variables were selected, with the aim of classifying the collection of samples in a way consistent with the classification obtained with the first principal components. These variables were soluble solids content, the CIE(L*a*b*) lightness parameter L*, and total pectic substances content.     

Prospecting fungal ligninases using corncob lignocellulosic fractions

Microorganisms play an important role in the bioconversion of organic residues and have therefore become promising for obtaining value-added enzymes. In an attempt to take advantage of the by-products and residues of bioconversion, this work sought to use lignocellulosic fractions extracted from corncob as fermentation substrate for ligninase induction by Pleurotus sajor-caju. To obtain the corncob lignocellulosic fractions, biomass was submitted to treatment by alkaline extraction (NaOH 0.75 mol L^?1, 55 °C for 2 h) and organosolv (40% ethanol/water, 185 °C for 20 min). The in natura biomass and lignocellulosic fractions were used as substrates in the subsequent fermentation processes: 2% in natura corncob; 2% cellulose–lignin complex fraction; 2% lignin-enriched fraction; 1% lignin-enriched fraction; and synthetic medium fungal (SMF) as standard. Chemical and physical–chemical analyses indicated the effectiveness of the lignocellulosic extraction process. According to the results, the developed system promoted the induction of ligninases by P. sajor-caju. The enzymatic analysis showed laccase production (768 U L^?1) using the 1% lignin-enriched fraction as substrate. Manganese peroxidase production was 1050 U L^?1 with the use of the 2% lignin-enriched fraction. The presence of lignocellulosic fractions extracted from corncob’s lignin-enriched fraction in the culture medium favored the induction of ligninases in comparison to the use of residue alone.     

The energy-constrained quickest path problem

This paper addresses a variant of the quickest path problem in which each arc has an additional parameter associated to it representing the energy consumed during the transmission along the arc while each node is endowed with a limited power to transmit messages. The aim of the energy-constrained quickest path problem is to obtain a quickest path whose nodes are able to support the transmission of a message of a known size. After introducing the problem and proving the main theoretical results, a polynomial algorithm is proposed to solve the problem based on computing shortest paths in a sequence of subnetworks of the original network. In the second part of the paper, the bi-objective variant of this problem is considered in which the objectives are the transmission time and the total energy used. An exact algorithm is proposed to find a complete set of efficient paths. The computational experiments carried out show the performance of both algorithms.     

3-Phenylcoumarins as a Privileged Scaffold in Medicinal Chemistry: The Landmarks of the Past Decade

3-Phenylcoumarins are a family of heterocyclic molecules that are widely used in both organic and medicinal chemistry. In this overview, research on this scaffold, since 2010, is included and discussed, focusing on aspects related to its natural origin, synthetic procedures and pharmacological applications. This review paper is based on the most relevant literature related to the role of 3-phenylcoumarins in the design of new drug candidates. The references presented in this review have been collected from multiple electronic databases, including SciFinder, Pubmed and Mendeley.     

Can Artemisia herba-alba Be Useful for Managing COVID-19 and Comorbidities?

The focus of this roadmap is to evaluate the possible efficacy of Artemisia herba-alba Asso. (Asteraceae) for the treatment of COVID-19 and some of its symptoms and several comorbidities using a combination of in silico (molecular docking) studies, reported ethnic uses, and pharmacological activity studies of this plant. In this exploratory study, we show that various phytochemicals from Artemisia herba-alba can be useful against COVID-19 (in silico studies) and for its associated comorbidities. COVID-19 is a new disease, so reports of any therapeutic treatments against it (traditional or conventional) are scanty. On the other hand, we demonstrate, using Artemisia herba-alba as an example, that through a proper search and identification of medicinal plant(s) and their phytochemicals identification using secondary data (published reports) on the plant’s ethnic uses, phytochemical constituents, and pharmacological activities against COVID-19 comorbidities and symptoms coupled with the use of primary data obtained from in silico (molecular docking and molecular dynamics) studies on the binding of the selected plant’s phytochemicals (such as: rutin, 4,5-di-O-caffeoylquinic acid, and schaftoside) with various vital components of SARS-CoV-2, it may be possible to rapidly identify plants that are suitable for further research regarding therapeutic use against COVID-19 and its associated symptoms and comorbidities.     

Syntheses and characterization of 2‐hydroxy‐N‐(2′‐hydroxyalkyl)acetamides

The reaction of glycolic acid 1 with some β‐aminoalcohols 2–8 without solvent, with temperature and time controlled, led to the syntheses of2‐hydroxy‐N‐(2′‐hydroxyalkyl)acetamides 9–15. All compounds studied in this work were characterized by ¹H, ¹³C, and ¹⁵N NMR, infrared, and mass spectroscopy. The structure of compound 13 was established by a single‐crystal X‐ray diffraction study. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 153–158, 1999     

Variable exponent Hardy spaces associated with discrete Laplacians on graphs

In this paper we develop the theory of variable exponent Hardy spaces associated with discrete Laplacians on infinite graphs. Our Hardy spaces are defined by square integrals, atomic and molecular decompositions. Also we study boundedness properties of Littlewood-Paley functions, Riesz transforms, and spectral multipliers for discrete Laplacians on variable exponent Hardy spaces.     

Analysis of hydroxylated polycyclic aromatic hydrocarbons in urine using comprehensive two-dimensional gas chromatography with a flame ionization detector

The determination of polycyclic aromatic hydrocarbon (PAH) metabolites in human urine is the method of choice for assessing exposure to carcinogenic compounds. The objective of this study was the development of a comprehensive two-dimensional gas chromatography (GC × GC) method using a flame ionisation detector (FID) to simultaneously determine 10 hydroxylated PAH. The method was based on enzymatic deconjugation, liquid–liquid extraction, and trimethylsilyl (TMS) derivatization of the analytes by microwave heating. Satisfactory separation was achieved. The coefficient of variance was 3.8–12.8%. LOD was 0.03–0.18 μg/L, and LOQ was 0.1–0.5 μg/L. The mean recovery was 76%. The method was applied to the analysis of urine from smokers and non-smokers.     

Incorporating boundary conditions in a stochastic volatility model for the numerical approximation of bond prices

In this paper, we consider a two-factor interest rate model with stochastic volatility, and we assume that the instantaneous interest rate follows a jump-diffusion process. In this kind of problems, a two-dimensional partial integro-differential equation is derived for the values of zero-coupon bonds. To apply standard numerical methods to this equation, it is customary to consider a bounded domain and incorporate suitable boundary conditions. However, for these two-dimensional interest rate models, there are not well-known boundary conditions, in general. Here, in order to approximate bond prices, we propose new boundary conditions, which maintain the discount function property of the zero-coupon bond price. Then, we illustrate the numerical approximation of the corresponding boundary value problem by means of an alternative direction implicit method, which has been already applied for pricing options. We test these boundary conditions with several interest rate pricing models.