Trace analysis of environmental matrices by large-volume injection and liquid chromatography-mass spectrometry

The time-honored convention of concentrating aqueous samples by solid-phase extraction (SPE) is being challenged by the increasingly widespread use of large-volume injection (LVI) liquid chromatography–mass spectrometry (LC–MS) for the determination of traces of polar organic contaminants in environmental samples. Although different LVI approaches have been proposed over the last 40 years, the simplest and most popular way of performing LVI is known as single-column LVI (SC-LVI), in which a large-volume of an aqueous sample is directly injected into an analytical column. For the purposes of this critical review, LVI is defined as an injected sample volume that is ≥10% of the void volume of the analytical column. Compared with other techniques, SC-LVI is easier to set up, because it requires only small hardware modifications to existing autosamplers and, thus, it will be the main focus of this review. Although not new, SC-LVI is gaining acceptance and the approach is emerging as a technique that will render SPE nearly obsolete for many environmental applications.In this review, we discuss: the history and development of various forms of LVI; the critical factors that must be considered when creating and optimizing SC-LVI methods; and typical applications that demonstrate the range of environmental matrices to which LVI is applicable, for example drinking water, groundwater, and surface water including seawater and wastewater. Furthermore, we indicate direction and areas that must be addressed to fully delineate the limits of SC-LVI

Extraction of polyphenols and synthesis of new activated carbon from spent coffee grounds

A valorization process of spent coffee grounds (SCG) was studied. Thus, a two-stage process, the first stage of polyphenols extraction and synthesis of a carbonaceous precursor and a subsequent stage of obtaining activated carbon (AC) by means of a carbonization process from the precursor of the previous stage, was performed. The extraction was carried out with a hydro-alcoholic solution in a pressure reactor, modifying time, temperature and different mixtures EtOH:HO. To optimize the polyphenols extraction, a two-level factorial experimental design with three replicates at the central point was used. The best results were obtained by using a temperature of 80 °C during 30 min with a mixture of EtOH:HO 50:50 (v/v). Caffeine and chlorogenic acid were the most abundant compounds in the analysed extracts, ranging from 0.09 to 4.8 mg∙g and 0.06 to 9.7 mg∙g, respectively. Similarly, an experimental design was realized in order to analyze the influence of different variables in the AC obtained process (reaction time, temperature and KOH:precursor ratio). The best results were 1 h, 850 °C, and a mixture of 2.5:1. The obtained activated carbons exhibit a great specific surface (between 1600 m∙g and 2330 m∙g) with a microporous surface. Finally, the adsorption capacity of the activated carbons was evaluated by methylene blue adsorption.To the Technical Research Support Unit of the Institute of Catalysis and Petroleum Chemistry (CSIC) for support in the textural characterization of activated carbon. Mª Eugenia Léon-González and Noelia Rosales-Conrado thank the Spanish Commission of Science and Technology (CTQ2017-83569-C2-1-R) and the Comunidad of Madrid and European funding from FSE and FEDER programs for financial support (project S2018/BAA-4393, AVANSECAL-II-CM)

Discovery of 7-aminophenanthridin-6-one as a new scaffold for matrix metalloproteinase inhibitors with multitarget neuroprotective activity

Matrix metalloproteinases (MMPs) are zinc-dependent hydrolytic enzymes of great biological relevance, and some of them are key to the neuroinflammatory events and the brain damage associated to stroke. Non-zinc binding ligands are an emerging trend in drug discovery programs in this area due to their lower tendency to show off-target effects. 7-Amino-phenanthridin-6-one is disclosed as a new framework able to inhibit matrix metalloproteinases by binding to the distal part of the enzyme S1’ site, as shown by computational studies. A kinetic study revealed inhibition to be noncompetitive. Some of the compounds showed some degree of selectivity for the MMP-2 and MMP-9 enzymes, which are crucial for brain damage associated to ischemic stroke. Furthermore, some compounds also had a high neuroprotective activity against oxidative stress, which is also very relevant aspect of ischaemic stroke pathogenesis, both decreasing lipid peroxidation and protecting against the oxidative stress-induced reduction in cell viability. One of the compounds, bearing a 2-thienyl substituent at C-9 and a 4-methoxyphenylamino at C-7, had the best-balanced multitarget profile and was selected as a lead on which to base future structural manipulation