Analysis of oxidised and glycated aminophospholipids: complete structural characterisation by C30 liquid chromatography-high resolution tandem mass spectrometry

The aminophospholipids (APL), phosphatidylethanolamine (PE) and phosphatidylserine (PS) are widely present in cell membranes and lipoproteins. Glucose and reactive oxygen species (ROS), such as the hydroxyl radical (•OH), can react with APL leading to an array of oxidised, glycated and glycoxidised derivatives. Modified APL have been implicated in inflammatory diseases and diabetes, and were identified as signalling molecules regulating cell death. However, the biological relevance of these molecules has not been completely established, since they are present in very low amounts, and new sensitive methodologies are needed to detect them in biological systems. Few studies have focused on the characterisation of APL modifications using liquid chromatography-tandem mass spectrometry (LC-MS/MS), mainly using C5 or C18 reversed phase (RP) columns. In the present study, we propose a new analytical approach for the characterisation of complex mixtures of oxidised, glycated and glycoxidised PE and PS. This LC approach was based on a reversed-phase C30 column combined with high-resolution MS, and higher energy C-trap dissociation (HCD) MS/MS. C30 RP-LC separated short and long fatty acyl oxidation products, along with glycoxidised APL bearing oxidative modifications on the glucose moiety and the fatty acyl chains. Functional isomers (e.g. hydroxy-hydroperoxy-APL and tri-hydroxy-APL) and positional isomers (e.g. 9-hydroxy-APL and 13-hydroxy-APL) were also discriminated by the method. HCD fragmentation patterns allowed unequivocal structural characterisation of the modified APL, and are translatable into targeted MS/MS fingerprinting of the modified derivatives in biological samples.publishe

Isolamento e caracterização estrutural de polissacarídeos pécticos da pêra passa de Viseu.

polissacarídeos constituídos, essencialmente, por uma longa cadeia de resíduos de ácido galacturónico (GalA). Estes compostos podem ser encontrados nas paredes celulares primárias dos frutos e vegetais, apresentando um papel importante na determinação da força e flexibilidade dos tecidos. Os polissacarídeos das paredes celulares da pêra de S. Bartolomeu obtida em fresco e das peras secadas foram fraccionados e caracterizados quanto à sua constituição em açúcares. Algumas fracções ricas em polissacarídeos pécticos foram seleccionadas para uma análise estrutural mais detalhada, nomeadamente o sobrenadante do resíduo celulósico da pêra fresca (SnCR). Estes polissacarídeos pécticos foram hidrolisados com uma endo- poligalacturonase (PG), uma hidrolase específica para os resíduos de ácido poligalacturónico em ligação w-(1 4). Os oligossacarídeos obtidos foram separados por tamanho utilizando uma cromatografia de exclusão molecular. As fracções de menor peso molecular foram analisadas por espectrometria de massa com ionização por electrospray (ESI-MS e ESI-MS/MS). Para comparação das características estruturais dos polissacarídeos das peras com a de outros frutos, estudou-se ainda uma pectina comercial proveniente de citrinos

Compostos fenólicos das peras de S. Bartolomeu.

Pyrus communis L. var. S.Bartolomeu é uma pêra usada para produzir a pêra passa de Viseu, um produto tradicional português produzido por secagem ao sol. O produto final é um fruto pequeno, de cor castanha-avermelhada, com propriedades elásticas. As propriedades organolépticas que influenciam a qualidade do produto final são a cor, o sabor e a textura, tendo os compostos fenólicos uma função importante nestes atributos. As procianidinas são os principais compostos fenólicos da pêra de S. Bartolomeu. Com o processamento a Pêra Passa de Viseu, o conteúdo em compostos fenólicos diminui 64%, verificando-se que as procianidinas aumentam o seu grau de polimerização, com diminuição da sua extractabilidade. Com o objectivo de desenvolver uma metodologia capaz de substituir a secagem solar tradicional, foram processadas peras utilizando uma estufa solar estufa de convecção forçada e, em alternativa, um túnel de ar quente, a 40 ºC, sem exposição solar. Estas peras assim processadas foram comparadas com as obtidas pelo método tradicional e com as peras não processadas. Os compostos fenólicos de cada uma das amostras foram extraídos com soluções de metanol e de acetona/água (6:4, v:v) e a sua identificação e caracterização foi feita por espectrometria de massa (ESI-MS e ESI-MS/MS). A extractabilidade das procianidinas com grau de polimerização entre 2 e 6 (DP2-DP6) é muito afectada pelo processo de secagem e varia com o processo utilizado. Os polímeros das amostras não processadas e processadas em túnel foram extraídos em maior quantidade pelo metanol do que os das amostras que foram sujeitas à exposição solar, tendo estes compostos sido extraídos em maior quantidade com a solução de acetona/água. Para além das procianidinas, o composto fenólico mais abundante nos extractos foi o ácido clorogénico. Foram também identificados, principalmente nos extractos das amostras expostas à luz solar, isorhamnetina-3-Hex, canferol-3-Hex e quercetina-3-Hex

Study of the viability of using lipase-hydrolyzed commercial vegetable oils to produce microbially conjugated linolenic acid-enriched milk

This work studied the viability of using vegetable oils as precursor substrates to develop a dairy product enriched in microbial conjugated linoleic (CLA) and conjugated linolenic (CLNA) acids. Hydrolysis of hempseed, flaxseed (FSO) and soybean (SBO) oils was tested with Candida rugosa (CRL), Pseudomonas fluorescens, or Pancreatic porcine lipases. FSO and SBO, previously hydrolyzed with CRL, were further selected for cow’s milk CLA/CLNA-enrichment with Bifidobacterium breve DSM 20091. Thereafter, higher substrate concentrations with hydrolyzed FSO were tested. For all tested oils, CRL revealed the best degrees of hydrolysis (>90%). Highest microbial CLA/CLNA yield in milk was achieved with hydrolyzed FSO, which led to the appearance of mainly CLNA isomers (0.34 mg/g). At higher substrate concentrations, maximum yield was 0.88 mg/g CLNA. Therefore, it was possible to enrich milk with microbial CLNA using vegetable oil, but not with CLA, nor develop a functional product that can deliver a reliable effective dose.info:eu-repo/semantics/publishedVersio

Lipidomic signatures reveal seasonal shifts on the relative abundance of high-valued lipids from the brown algae Fucus vesiculosus

Fucus vesiculosus is an edible brown macroalga, with health benefits associated with its consumption and also a source of bioactive molecules. It is acknowledged that the biochemical composition of macroalgae changes when exposed to different environmental conditions occurring on different habitats, such as the water temperature, and light intensity. In the present study, the polar lipidome of Fucus vesiculosus was characterized for the first time using modern high-resolution HILIC-MS, and MS/MS approaches, to evaluate the phenotypic variability in two seasons of the year, e.g., winter and spring. A total of 187 molecular species were identified over eighteen classes of glycolipids, phospholipids and betaine lipids. Principal component analysis (PCA) multivariate statistical analysis and cluster analysis of polar lipid classes, polar lipid species and total fatty acids (FA) datasets, showed clustering according to the seasonal groups. While the lipid profile of Fucus vesiculosus harvested in the winter and spring yielded the same molecular species, the relative abundance of these species was significantly different. In the winter, changes were mainly due to the increased relative abundance of some molecular species of glycolipids and phospholipids, bearing octadeca(poly)enoic (18:3, 18:4) and eicosa(poly)enoic (20:4, 20:5) FA and betaine lipids species with short saturated FA (14:0) and polyunsaturated FA (PUFA). Importantly, glycolipids with n-3 PUFA and sulfolipids, have been reported to have important biological activities and therapeutic value. Overall, Fucus vesiculosus is a promising source of bioactive compounds that can be used as functional food or ingredients for human nutrition, feed, pharma, and cosmetic formulations. In this study, samples harvested in the winter season maximized yields of these bioactive components, when compared with samples harvested in the spring.publishe

Mitochondrial Fatty Acid β-Oxidation Disorders: From Disease to Lipidomic Studies—A Critical Review

ReviewThis article belongs to the Special Issue Lipid Metabolism in Pathology and Health.Fatty acid oxidation disorders (FAODs) are inborn errors of metabolism (IEMs) caused by defects in the fatty acid (FA) mitochondrial β-oxidation. The most common FAODs are characterized by the accumulation of medium-chain FAs and long-chain (3-hydroxy) FAs (and their carnitine derivatives), respectively. These deregulations are associated with lipotoxicity which affects several organs and potentially leads to life-threatening complications and comorbidities. Changes in the lipidome have been associated with several diseases, including some IEMs. In FAODs, the alteration of acylcarnitines (CARs) and FA profiles have been reported in patients and animal models, but changes in polar and neutral lipid profile are still scarcely studied. In this review, we present the main findings on FA and CAR profile changes associated with FAOD pathogenesis, their correlation with oxidative damage, and the consequent disturbance of mitochondrial homeostasis. Moreover, alterations in polar and neutral lipid classes and lipid species identified so far and their possible role in FAODs are discussed. We highlight the need of mass-spectrometry-based lipidomic studies to understand (epi)lipidome remodelling in FAODs, thus allowing to elucidate the pathophysiology and the identification of possible biomarkers for disease prognosis and an evaluation of therapeutic efficacy.This research was funded by FCT/MEC (PIDDAC) for their financial support to LAQVREQUIMTE (UIDB/50006/2020), CESAM (UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020), and the RNEM-Portuguese Mass Spectrometry Network (LISBOA-01-0145-FEDER-402-022125), financed by FCT/MCTES through national funds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. Ana Moreira thanks the research contract under the research unit LAQV-REQUIMTE. Inês M. S. Guerra (2021.04754.BD) and Helena B. Ferreira (2020.04611.BD) are grateful to FCT for the PhD grants. Tânia Melo thanks the Junior Researcher contract in the scope of the Individual Call to Scientific Employment Stimulus 2020 (CEECIND/01578/2020). The authors are thankful to the COST Action EpiLipidNET, CA19105-Pan-European Network in Lipidomics, and EpiLipidomics.info:eu-repo/semantics/publishedVersio

Site-specific lipidomic signatures of sea lettuce (Ulva spp., Chlorophyta) hold the potential to trace their geographic origin

The wild harvest and aquaculture of Ulva spp. has deserved growing attention in Europe. However, the impact of geographical origin on the biochemical composition of different species and/or strains is yet to be described in detail. Hence, the present study aimed to detect the variability of the lipidome of different species and/or strains of Ulva originating from different geographic locations. We hypothesized that lipidomic signatures can be used to trace the geographic origin post-harvesting of these valuable green seaweeds. Ulva spp. was sampled from eight distinct ecosystems along the Atlantic Iberian coast and Ulva rigida was sourced from an aquaculture farm operating a land-based integrated production site. Results showed significant differences in the lipidomic profile displayed by Ulva spp. originating from different locations, namely, due to different levels of polyunsaturated betaine lipids and galactolipids; saturated betaine lipids and sulfolipids; and some phospholipid species. Overall, a set of 25 site-specific molecular lipid species provide a unique lipidomic signature for authentication and geographic origin certification of Ulva species. Present findings highlight the potential of lipidome plasticity as a proxy to fight fraudulent practices, but also to ensure quality control and prospect biomass for target bioactive compounds.publishe

Lipidomic signature of the green macroalgae Ulva rigida farmed in a sustainable integrated multi-trophic aquaculture

Ulva species, green macroalgae, are widely distributed across the globe, being one of the most heavily traded edible seaweeds. Nonetheless, although this genus has been largely used in scientific studies, its lipidome remains rather unexplored. The present study sheds light over the lipid profile of Ulva rigida produced in a land-based integrated multi-trophic aquaculture (IMTA) system using liquid chromatography coupled to high-resolution mass spectrometry for molecular lipid species identification. The lipidome of U. rigida revealed the presence of distinct beneficial n-3 fatty acids for human health, namely alpha-linoleic acid (ALA) and docosapentaenoic acid (DPA). A total of 87 molecular species of glycolipids, 58 molecular species of betaine lipids, and 57 molecular species of phospholipids were identified in the lipidome of U. rigida including some species bearing PUFA and with described bioactive properties. Overall, the present study contributes to the valorization and quality validation of sustainably farmed U. rigida.publishe

Short-communication: study of fatty acid metabolites in microbial conjugated fatty acids-enrichment of milk and discovery of additional undescribed conjugated linolenic acid isomers

Microbially enriched food in conjugated linoleic (CLA) and conjugated linolenic (CLNA) acids is intensively studied nowadays. The conversion of linoleic (LA) and α-linolenic acids (α-LNA) into these compounds may involve different fatty acid (FA) intermediates. This research aimed to investigate potential FA byproducts in milk during microbial CLA/CLNA-enrichment using Bifidobacterium breve DSM 20091. Milk fermented with pure α-LNA showed a decrease in free myristic acid, while pure LA led to an increase in free stearic acid. No additional FA compounds were found alongside CLA/CLNA isomers. The strain produced several CLA isomers from LA, but only when administered alone. Nonetheless, when α-LNA was assayed, additional CLNA isomers, never reported before for bifidobacteria, were observed. In conclusion, except for stearic acid in the presence of LA, no side-FA metabolites were released during milk microbial CLA/CLNA-enrichment. Results suggest either CLA/CLNA production occurs in one single-step or intermediates biotransformation is very fast.N/

Perspectives on the development of CLA/CLNA-enriched milk through in situ microbial production

Over the past decade several food-derived lipids with potential bioactive properties to be used in the development of innovative functional foods have been identified. These include conjugated linoleic (CLA) and conjugated linolenic (CLNA) acids with well described anti- inflammatory, anti-obesity and anticarcinogenic properties. Limited availability in their natural sources (e.g. ruminants’ milk and meat or vegetable oils) has driven studies on in situ microbial production in dairy products to improve CLA/CLNA daily intake. Several probiotic strains have been reported to produce CLA/CLNA isomers using linoleic (LA) and alpha-linolenic (α-LNA) acids as precursor substrates, respectively. This research work aimed to evaluate the viability of developing a CLA/CLNA-enriched milk through in situ microbial production at a laboratory scale. A combination of genetic screening, substrate tolerance and production assays, identified three CLA/CLNA-producing candidates from a pool of 85 probiotic bacteria. Since Bifidobacterium breve DSM 20091 stood out from the others with CLA/CLNA production yields around 0.3 mg/mL, it was selected to proceed with milk CLA/CLNA-enrichment. Seeking to explore industrial viability, edible vegetable oils were applied as substrate sources instead, namely soybean (SBO; rich in LA) and flaxseed (FSO; rich in α-LNA) oils, which had been previously hydrolyzed with Candida rugosa lipase. Microbial CLA/CLNA-enrichment of pasteurized bovine milk was tested with each hydrolyzed oil, individually or in combination, to provide 0.5 mg/mL of LA and/or α-LNA. Viable cell numbers of B. breve achieved 9 log cycles upon 24 h fermentation. Highest CLA/CLNA-enrichment was achieved using FSO alone (~0.4 mg/g), where CLNA isomers were those mainly produced. Surprisingly, only traces of CLA were found, either with SBO alone or in combination. Milk enrichment was further assayed with FSO alone to concentrations up to 10 mg/mL α-LNA, where at 2 mg/mL the maximum yield of ~1 mg/g CLA+CLNA was obtained. In conclusion, the development of a CLA/CLNA-enriched bovine milk through in situ microbial production remains challenging, given the limited number of strains able to produce CLA/CLNA at considerable levels, and because it is difficult to develop a dairy product simultaneously enriched in CLA and CLNA. An in situ strategy has its limitations; nevertheless, this study demonstrates that B. breve DSM 20091 has potential for the development of CLNA-enriched dairy products.info:eu-repo/semantics/publishedVersio