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Cholesterol-24-hydroxylase (CYP46), a member of the cytochrome P450 superfamily of enzymes, is selectively expressed in the brain and is mainly responsible for cholesterol turnover in the central nervous system. Although increased cyp46A1 gene expression has been linked to cognitive alterations in aging and observed in neurodegenerative diseases and after traumatic brain injury, a detailed characterization of the brain regions and cell types in which CYP46 is expressed in old individuals has not been performed. Using immunohistochemistry and immunofluorescence, we investigated the specific regions and cell populations in the brain, in which cyp46A1 is expressed in 24-month-old mice. We found that CYP46 is localized in the same neuronal populations in young and old brains, mainly in the hippocampus, in cortical layers, and in Purkinje neurons of the cerebellum. No increase in CYP46 levels was found in astrocytes in old mice brains, in primary astrocyte-neuron cocultures aged in vitro, or in primary cultures of senescent astrocytes. However, interleukin-6 treatment strongly induced cyp46A1 expression in reactive astrocytes characterized by high GFAP levels but had no effect in nonactivated astrocytes. Our data suggest that cholesterol-24-hydroxylase expression is triggered in reactive astrocytes in response to proinflammatory signals, probably as part of a response mechanism to injury.

Amyloid-β (Aβ), a major component of senile plaques, is generated via the proteolysis of amyloid-β protein precursor (AβPP). This cleavage also produces AβPP fragment-derived oligomers which can be highly neurotoxic. AβPP metabolism/processing is affected by many factors, one of which is oxidative stress (OS). Associated with aging, OS is an important risk factor for Alzheimer's disease. In addition, the protein degradation systems, especially those involving cathepsins, are impaired in aging brains. Moreover, cathepsin B (CTSB) is a cysteine protease with potentially specific roles in AβPP proteolysis (β-secretase activity) and Aβ clearance (Aβ degradative activity). The present work examines the effect of OS and the involvement of CTSB in amyloid oligomer formation. The xanthine/xanthine oxidase (X-XOD) free radical generating system induced the partial inhibition of CTSB activity, which was accompanied by an increase in large amyloid oligomers. These were located throughout the cytosol and in endo-lysosomal vesicles. Cells treated with the CTSB inhibitor CA-074Me also showed increased amyloid oligomer levels, whereas those subjected to OS in the presence of the inhibitor showed no such increase. However, CTSB inhibition clearly modulated the AβPP metabolism/processing induced by X-XOD, as revealed by the increase in intracellular AβPP and secreted α-secretase-cleaved soluble AβPP. The present results suggest that CTSB participates in the changes of amyloid oligomer induced by mild OS.

Acid sphingomyelinase deficiency (ASMD) leads to cellular accumulation of sphingomyelin (SM), neurodegeneration, and early death. Here, we describe the downregulation of the endocannabinoid (eCB) system in neurons of ASM knockout (ASM‐KO) mice and a ASMD patient. High SM reduced expression of the eCB receptor CB1 in neuronal processes and induced its accumulation in lysosomes. Activation of CB1 receptor signaling, through inhibition of the eCB‐degrading enzyme fatty acid amide hydrolase (FAAH), reduced SM levels in ASM‐KO neurons. Oral treatment of ASM‐KO mice with a FAAH inhibitor prevented SM buildup; alleviated inflammation, neurodegeneration, and behavioral alterations; and extended lifespan. This treatment showed benefits even after a single administration at advanced disease stages. We also found CB1 receptor downregulation in neurons of a mouse model and a patient of another sphingolipid storage disorder, Niemann–Pick disease type C (NPC). We showed the efficacy of FAAH inhibition to reduce SM and cholesterol levels in NPC patient‐derived cells and in the brain of a NPC mouse model. Our findings reveal a pathophysiological crosstalk between neuronal SM and the eCB system and offer a new treatment for ASMD and other sphingolipidoses., We are grateful to Steven Laffoon and the Wylder Nation Foundation (www.wyldernation.org) for the continuous support. We thank Dr. Melissa Wasserstein at the Children's Hospital at Montefiore for insightful comments and Dr. A. Rábano at the Fundación Cien and Dr. E. Martínez‐Sáez at the Hospital Vall d′Hebron for donating brain samples. We also thank the microscope facility at the CBMSO for their assistance with the confocal imaging and the institutional support of the Fundación Ramón Areces to the CBMSO. This work was funded by the Wylder Nation Foundation and by grants from the Spanish Ministry of Science and Education (SAF2017‐87698‐R) (AEI/FEDER, UE) to M.D.L and a MERIT award from the National Institutes of Health (2R37HD028607) to E.H.S.

Most lysosomal storage disorders (LSDs) cause progressive neurodegeneration leading to early death. While the genetic defects that cause these disorders impact all cells of the body, neurons are particularly affected. This vulnerability may be explained by neuronal cells' critical dependence on the lysosomal degradative capacity, as they cannot use division to eliminate their waste. However, mounting evidence supports the extension of storage beyond lysosomes to other cellular compartments (mitochondria, plasma membrane and synapses) as a key event in pathogenesis. Impaired energy supply, oxidative stress, calcium imbalance, synaptic failure and glial alterations may all contribute to neuronal death and thus could be suitable therapeutic targets for these disorders. Here we review the pathological mechanisms underlying neurodegeneration in Niemann Pick diseases and therapeutic strategies developed in animal models and patients suffering from these devastating disorders. This article is part of the special issue entitled 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

Lignin depolymerisation to simple aromatics was investigated by using a mild microwave-assisted approach. The reaction was catalysed by different supported metal nanoparticles on mesoporous Al-SBA-15 including -nickel (2, 5 and 10 wt.%), palladium (2 wt.%), platinum (2 wt.%) and ruthenium (2 wt.%). Three main products were indentified in the proposed lignin valorisation protocol, namely a bio-oil, a bio-char and a fraction of residual lignin. These have been characterised by means of several techniques including GC–MS, MALDI-TOF, HPSEC and elemental analysis in order to evaluate the extension and mechanism of the selected depolymerisation approach. In this work, the objective has been the maximisation of bio-oil yield as well as its content in phenolic monomeric compounds. All tested catalysts exhibited improved results as compared to the blank depolymerisation (without catalyst), demonstrating a synergetic effect of metal nanoparticles in lignin hydrogenolysis. The most abundant phenolic products observed in most studied catalysts have been solvent derived products such as diethyl phthalate and butyl-octyl phthalate ester. Interestingly, phenolic compounds derived from lignin were also obtained including mesitol and syringaldehyde as well as desaspidinol and aspidinol, depending on the utilised solvent in the systems. The bio-oil obtained was primarily composed of monomers, dimers and trimers. Biochar yield was relatively high in most cases (>35% in some cases) due to existing oligomerisation reactions under the investigated conditions except for the case of the use of formic acid which gave no biochar in the process. Residual lignin content was often high and repolymerisation was observed in some cases. The catalyst containing 10 wt.% nickel was confirmed to achieve the highest lignin depolymerisation degree, with a maximum yield of 30% bio-oil after a short time of reaction (typically 30 min of microwave irradiation).

Base catalyzed depolymerization was studied to revalorize lignin into monomeric phenolic compounds focusing in avoiding repolymerization phenomenon in order to improve oil yield. In this sense, two capping agents were evaluated in the oxidation of organosolv olive tree pruning lignin. Lignin to capping agent ratio was varied in order to establish its influence on phenolic oil yield and composition. The obtained phenolic products (oil) and by-products (char and residual lignin) were characterized to determine their composition and yield. Boric acid and phenol behaviors were completely different concerning their effect on the nature of the obtained products and on products yields. Boric acid avoided repolymerization although the active fragments seemed to prone to char formation instead of increasing oil monomeric compounds yield. Interestingly, phenol capping agent was proved to favor phenolic compounds production and at the same time, to avoid repolymerization phenomenon. The optimum capping agent to lignin ratio depended on the nature of the added capping agent since their action in lignin base catalyzed depolymerization was totally different.

In this work, olive tree pruning has been fractionated into its components to produce ethanol (biofuel) from the cellulose fraction and platform chemicals (biochemicals) from lignin fraction. Organosolv pretreatment has been proved to be an effective process that fractionate and produce intermediates – cellulose and lignin- that can be later transformed. Ethanol was successfully produced from cellulose enriched solid fraction with high yields, 71.9 g L −1 of glucose and 17.1 g of ethanol per 100 g of olive tree pruning. Organosolv pretreatment has been proved to enhance enzymes accessibility to the substrate and so, increased hydrolysis yields. Lignin was depolymerized into interesting compounds such as catechol and 4-methylcatechol. The chemicals obtained from lignin presented promising industrial applications. Repolymerization phenomenon was found to decrease the yields of the proposed lignin revalorization process.

Traditionally, lignin has being considered just for energy generation. 2nd generation bioethanol plants are said to shift this fact since lignin revalorization is one of the key economical points for these plants. Bulk chemicals is one the most interesting applications for lignin. In this work, organosolv lignin was obtained from olive tree pruning under optimized conditions. Base catalyzed lignin depolymerization was achieved changing the applied severity parameter to study the influence of reaction conditions on oil yield and composition. The major difference was the oil composition suggesting that reactions conditions controlled depolymerization mechanism. Catechol and 4-methylcatechol were the main products. Residual lignin contents were very high for all the experiments. Related to this find, it was studied how repolymerization reactions decreased lignin depolymerization degree.

A series of hydrogen-donating solvents have been investigated in lignin depolymerisation practices by using a mild, microwave-assisted, hydrogen-free, hydrogenolytic approach promoted by the use of in situ hydrogen generating reagents with Ni 10 % Al-SBA-15 as a heterogeneous catalyst. Selected solvents were tetralin, isopropanol, glycerol and formic acid. Final identified products, namely bio-oil, biochar and residual lignin were characterised by using GC–MS, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and high-performance size-exclusion chromatography to evaluate the extension of the hydrogenolytic process. Interestingly, the obtained phenolic monomeric products were found to be remarkably affected by the type of hydrogen-donating solvent, with the best results obtained with formic acid, a potentially renewable derived solvent, which unexpectedly provided no biochar as compared to a maximum of 38 % obtained for tetralin. The reported protocol constitutes another step towards the development of fully sustainable and “green” methodologies of low environmental impact for lignin depolymerisation.

Olive tree pruning lignin was studied to be considered as a raw material candidate for biorefinery. Different extraction treatments (organosolv treatment: 60% wt ethanol, 180°C, 90 min; alkali treatment: 90 to 100°C, 7.5% wt NaOH, 90 min; and autohydrolysis process: 180°C, 30 min) were applied to extract lignin. The isolated lignins were deeply characterized to study the effect of the applied extraction conditions on lignin properties. Isolated lignins compositions were measured by determining acid insoluble lignin, acid soluble lignin, sugar content, and ash content. Functional groups (carboxyl groups, carbonyl groups, and OH-phenolic groups) were analyzed to evaluate the reactivity of the different lignins. Nitrobenze oxidation, structure analyses (attenuated-total reflection infrared spectroscopy and heteronuclear single quantum coherence) and high performance size exclusion chromatography analyses were carried out to meet olive tree pruning lignin structure. Organosolv treatment yielded the purest lignin while autohydolyisis process yielded medium purity lignin with low molecular weight. Finally, lignin obtained from alkali treatment was very impure and had high inorganic content and sugar contamination. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1187–1194, 2013

Second generation bioethanol plants are going to produce tones of lignin and its utilisation focuses the interest of the research community. Revalorisation of lignin was studied by proposing an entire process scheme. Agricultural residues are an interesting lignocellulosic raw material due to their high abundance and low price. However, olive tree pruning is undervalorised although it constitutes an attractive raw material. Starting from olive tree pruning, lignin was dissolved by treating the raw material in a water–ethanol mixture. The resulting black liquor was subjected to ultrafiltration in order to fractionate the dissolved lignin by molecular weight using different membrane cut-offs (300, 150, 50, 15 and 5 kDa). Lignin of each permeate was isolated and analysed to evaluate its composition and molecular weight. Afterwards, ultrafiltered lignin fractions were subjected to base catalysed depolymerisation in order to produce high value added products. Obtained products (oil, coke and residual lignin) were analysed in order to determine their composition and yield. Catechol and 4-methylcatechol were the main monomeric products in all ultrafiltrated lignin fractions but other interesting compounds were obtained such as phenol and cresols. Ultrafiltration was proved to produce specific molecular weight lignin fractions that presented different reactivity when applying base catalysed depolymerisation conditions. Furthermore, ultrafiltration process allowed lignin purification by removing hemicellulosic sugars.

The green biorefinery concept relies on economically feasible processing to achieve a complete utilization of most lignocellulosic biomass components using green technologies. Among the main component of lignocellulosic biomass, lignin is one of the most interesting components since its aromatic nature makes lignin unique. The study presented here was focused on the enhancement of the organosolv lignin produced from olive wood from the point of view of not only operational conditions but also taking into account the purity and contamination of the obtained lignin. The results showed that the amount of lignin recovered in the liquor was strongly influenced by the process temperature. The ethanol concentration presented the opposite behavior with lignin, reaching high yields at low concentrations. Then, the obtained lignins under optimized conditions were analyzed in order to verify their purity. Almost all the obtained lignins presented hemicellulose contamination but there were differences between the pol...

Hesperaloe funifera was characterizedin terms of its contents of holocellulose, α-cellulose, and lignin (74.1, 52.3, and 7.9%, respectively). Also, an experimental factor design was used to examine the influence of operational variables in the diethanolamine pulping of this material (viz. diethanolamine concentration (50-80%), cooking temperature (155-185 ºC), and time (30-90 minutes)) on the contents of holocellulose, α-cellulose, and lignin, as well as the yield, kappa number, and viscosity of the resulting pulps, and also on the brightness, tensile index, stretch, burst index, and tear index of paper sheets made from it. The predictions for these dependent variables departed by less than 1, 7, 6, 2, 2, 4, 15, 11, 12, 10, and 37% from their respective experimental values. Black liquors obtained from the pulping runs were characterized by determining pH, density, TDS, (total dissolved solids), MI (inorganic matter), MO (organic matter), and lignin content; lignin samples were characterized by different techniques (FTIR and TGA). Finally, the black liquors were acidified to separate solid fractions that were subjected to pyrolysis and gasification in order to obtain synthesis and fuel gases.

The present work studied the antioxidant capacity of the lignin obtained from Miscanthus sinensis. As the lignin structure is very complex, extraction and separation processes highly influence obtained lignin structure and its properties, including the antioxidant activity. Lignin fractions were obtained from black liquor resulting from different fractionating and autohydrolysis processes of M. sinensis. Different lignin fractions with specific molecular weight were separated by ultrafiltration using different cut-off ceramic membranes (10 and 15 kDa). The physico-chemical properties, phenolic groups content and the antioxidant capacity of each lignin sample were studied. It was found that antiradical activity of the analyzed lignin samples was closely related with the used fractionating process (soda, organosolv and autohydrolysis treatments). The ultrafiltration process allows obtaining lignins with different antioxidant capacity, improving this property as the used cut-off was greater.

The present work presents two different methods to fractionate the lignin resulting from the black liquor of the pulping process of Miscanthus sinensis (7.5% (w/w) NaOH, 90 min, 90 °C). The first method consists of selective precipitation, which is achieved by the gradual acidification of the black liquor, getting different precipitates according to the pH. The second employed technique is the ultrafiltration, which uses ceramic membranes of different cut-off (5, 10 and 15 kDa) to obtain different liquors containing lignins with specific molecular weight. Using both methods, different lignin fractions have been obtained and characterized by the following analysis techniques: FTIR, thermal analysis, GPC and NMR. Obtained results have shown that the fractionation process applied affects the properties of the obtained lignin. Ultrafiltrated fractions are less contaminated by lignin–carbohydrate complex than the fractions obtained by selective precipitation. Ultrafiltration process also allowed controlling the molecular weight of the obtained fractions.

Membrane technology allows the separation from the black liquor of different lignin fractions with a specific molecular weight being able to be used in the synthesis of several high value-added products (chemical reactants, resins and biocomposites, antioxidant agents, etc.). In the present study, black liquor resulting from the alkaline pulping of the Miscanthus sinensis (7.5% NaOH, 90 min and 90 °C) has been subjected to several stages of ultrafiltration, by using ceramics membranes of different cut-offs (5, 10 and 15 kDa). The different permeates obtained have been characterized (density, % TDS, inorganic and organic content and lignin recovery in each fraction), analyzing the effectiveness of the conditions of the pulping and ultrafiltration processes. Subsequently, the lignins have been isolated by acid precipitation and studied by means of different analytical techniques, being able to establish the differences in their chemical structure and thermal behaviour, and subsequently their more adequate commercial application.

In the present work lignin isolation from black liquor resulting from the Miscanthus sinensis pulping with 7.5% soda has been studied. M. sinensis is a raw straw widely studied as energy crop and for cellulose pulp production. Selective precipitation was achieved by decreasing black liquor pH from 12.64 to 0.72 and by adding sulphuric acid (98%, w/w). The precipitate percentage was obtained at each pH, regarding total dissolved solids. A considerable increase in the amount of precipitate was observed while lowering the pH as well as the attenuation in black liquor's colour. All samples along with commercial alkaline lignin were characterized by FT-IR, DSC, TGA, GPC and 1H NMR to determinate the physico-chemical properties and structural features, and the results are reported.

Lignin valorization practices have attracted a great deal of interest in recent years due to the large excess of lignin produced by the pulp and paper industry, together with second-generation bioethanol plants. In this work, a new lignin valorization approach is proposed. It involves ultrafiltration as a fractionation process to separate different molecular weight lignin fractions followed by a hydrogen-free, mild, hydrogenolytic, heterogeneously catalyzed methodology assisted by microwave irradiation to obtain simple phenolic, monomeric products by depolymerization using a nickel-based catalyst. The main products obtained were desaspidinol, syringaldehyde, and syringol; this proves the efficiency of the depolymerization conditions applied. The concentration of these observed compounds increased when the molecular weights of the lignin fractions increased. The applied depolymerization conditions, which take advantage of the use of formic acid as a hydrogen-donating solvent, did not generate any biochar in the systems.