Effect of steam treatment on soluble phenolic content and antioxidant activity of the Chaga mushroom (Inonotus obliquus)

The effect of steam treatment on free phenolic acids in Chaga mushrooms (Inonotus obliquus) was investigated. Untreated and steam-treated (120 °C, 3 h) samples of I. obliquus were extracted with organic solvents and free phenolic acid-containing fractions were isolated. Free phenolic acids were determined by LC/PDA (liquid chromatography/photodiode array), ESI LC/MS (electrospray ionisation liquid chromatography/mass spectrometry), and GC/MS (gas chromatography/mass spectrometry). After the steam treatment, the soluble phenolic content determined by modified Folin–Ciocalteu method was increased and antioxidant activity was enhanced, as confirmed by a DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity assay. The amounts of vanillic acid, protocatechuic acid, syringic acid, and 2,5-dihydroxyterephthalic acid were increased significantly as the result of the steam treatment, suggesting that the liberation of low molecular weight free phenolics was enhanced by the steaming process. Consequently, the radical scavenging activity was also significantly enhanced by free phenolics produced using this method.     

Changes in phenolic profile and antioxidant activity during production of diced tomatoes

Tomatoes and tomato-based products are rich in antioxidants such as carotenoids, vitamin C and polyphenols. The industrial processing of diced tomatoes involves heat treatments in which these antioxidant compounds may be potentially affected. In this study, we evaluate the effect of each separate step in the dice-making process. Three technological processes were investigated: Hot, Cold and Cold treated with calcium salt (CaCl₂). Four stages were monitored in each process: (1) fresh tomatoes; (2) peeled tomatoes; (3) diced tomatoes; and (4) final product after sauce addition. The main tool for minimising or counteracting the eventual processing damage was the strategy of ‘reconstitution’, achieved by adding a sauce rich in seeds and peels with high levels of antioxidants and phenolics to the diced tomatoes. Different analyses were carried out in order to evaluate the effect of each processing step. First, total polyphenols (TP) were evaluated using Folin–Ciocalteau (F–C) assay and antioxidant activity using ABTS⁺ and DPPH assays. Flavonols, flavanones, hydroxycinnamic and phenolic acids were then quantified using liquid chromatography/electrospray ionisation tandem mass spectrometry (HPLC–ESI–MS/MS). The combination of principal component analysis (PCA) and analysis of variance (ANOVA) revealed that each processing step induces alterations in the antioxidant and phenolic profile, and in particular sauce addition and calcium treatment significantly affected the levels of antioxidants and phenolics during the dice-making process.     

Determination of phenolic and other polar compounds in flaxseed oil using liquid chromatography coupled with time-of-flight mass spectrometry

A new method based on high-performance liquid chromatography coupled with electrospray ionisation time-of-flight-mass spectrometry (HPLC–ESI–TOF (MS)) has been used to analyse phenolic compounds in flaxseed oil. Some phenolic compounds such as secoisolariciresnol, ferulic acid and its methyl ester, coumaric acid methyl ester, diphyllin, pinoresinol, matairesinol, p-hydroxybenzoic acid, vanillin and vanillic acid have been detected from flaxseed oil. The quantification of these compounds in three varieties of flaxseed oils was carried out using their commercial standards. The efficiency, rapidity and high resolution of HPLC coupled to the sensitivity, selectivity, mass accuracy and true isotopic pattern from TOF (MS) have revealed an enormous separation potential allowing the determination of a broad series of phenolic and other polar compounds present in flaxseed oil for the first time.     

Determination of Polyphenols in Commercial Extra Virgin Olive Oils from Different Origins (Mediterranean and South American Countries) by Liquid Chromatography–Electrospray Time-of-Flight Mass Spectrometry

The phenolic profiles of extra virgin olive oil samples from different origins and varieties have been studied and compared. The determination of 13 target polyphenols (gallic acid, hydroxytyrosol, tyrosol, vanillic acid, caffeic acid, syringic acid, gibberellic acid, p-coumaric acid, ferulic acid, oleuropein, resveratrol, luteolin, and apigenin) was carried out by liquid chromatography using a column (C₁₈, 4.6?×?100 mm) with small particle size (1.8 μm) and mass spectrometric detection using electrospray time-of-flight mass spectrometry (LC–TOFMS). Prior to LC–MS analysis, a solid-phase extraction procedure using SPE-Diol cartridges was used to isolate the polyphenol fraction. The full-scan mass spectra acquisition by TOF analyzers offered the possibility of searching for a large number of compounds by means of accurate mass information of the molecules and allowed the detection of other phenolic compounds not included in the initial target list, namely ligstroside aglycon, oleuropein aglycon, and elenolic acid. The proposed method was successfully applied to the analysis of 78 samples of extra virgin olive oil collected from ten different countries: Argentina (5), Chile (6), France (1), Greece (1), Italy (1), Morocco (4), Peru (32), Portugal (1), Spain (26), and Syria (1). No qualitative differences in the composition of the phenolic fraction were found between samples of different origins. Only quantitative differences were observed for some phenolic compounds. Therefore, further studies are still needed to exploit the possibility of using phenolic profile as a marker for olive oil geographical origin.     

Separation and characterization of phenolic compounds in argan fruit pulp using liquid chromatography–negative electrospray ionization tandem mass spectroscopy

Liquid chromatography (LC) coupled to negative electrospray ionization (ESI) tandem mass spectrometry (MS/MS) was used for the sensitive identification of phenolic compounds in argan fruit pulp. Sixteen compounds were identified, mainly flavonoid glycosides and flavonoid aglycons.     

Development and validation of a LC-ESI-MS/MS method for the determination of phenolic compounds in honeydew honeys with the diluted-and-shoot approach

A simple, reproducible and sensitive method has been optimized and validated for simultaneous determination of 32 phenolic compounds in bracatinga (Mimosa scabrella Benth.) with the diluted-and-shoot approach, without the need of any additional clean-up steps. It has been based on high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry and electrospray ionization (HPLC-ESI-MS/MS). The chromatography conditions were optimized, and due to the selectivity provided by MRM monitoring, LC separation required only 9 min. The developed method was validated on the basis of Eurachem and European Commission Decision 2002/657/EC guidelines. Mean recoveries ranged from 70.4 to 110%. Intra-day and inter-day precision with RSD (relative standard deviations) from 0.14 to 18.9% and 0.34 to 20.0%, respectively were achieved. Limits of detection (LOD) and quantification (LOQ) ranged from 0.03 to 3.20 μg L^− 1 and 0.20–12.8 μg L^− 1. Finally, the method was applied to samples and 20 phenolic compounds were quantified in all the samples analyzed, representing a contribution to the characterization and quantification of phenolic compounds from bracatinga (M. scabrella Bentham) honeydew honey.     

Phenolic acid analysis and antioxidant activity assessment of oil palm (E. guineensis) fruit extracts

Phenolic compounds in oil palm fruit (E. guineensis) were extracted in soluble free (SFP), insoluble-bound (ISBP) and esterified (EFP) forms. The total phenolic content (TPC) of the oil palm fruit extracts was determined using the Folin–Ciocalteu method and found to range from 5.03 to 9.04 g/L per g of dried weight (DW). The antioxidant activities of oil palm phenolic extracts were analysed using free radical scavenging assays and results showed that oil palm phenolic extracts contained antioxidant activities in the order of ISBP > EFP > SFP. Eight different phenolic acids were identified and quantified using a simple reversed-phase high performance liquid chromatography (HPLC) with a diode array detector (DAD) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Ferulic, p-hydroxybenzoic and p-coumaric acid were the dominant phenolic acids found in oil palm fruit extracts and ranged from 55 to 376 μg/g of DW.     

Phenolic and aroma compositions of pitomba fruit (Talisia esculenta Radlk.) assessed by LC–MS/MS and HS-SPME/GC–MS

Pitomba (Talisia esculenta Radlk.) is a Brazilian exotic fruit consumed specially in the Amazonian region. Because of its large consumption and also due to the lack of knowledge regarding its chemical composition, pitomba fruit was studied in relation to its phenolic and aroma constitution. Using liquid chromatography tandem mass spectrometry (LC–MS/MS), 13 phenolic compounds (catechins, flavonoids and organic acids) were tentatively identified by comparison with standards and by fragmentation patterns. A validated method was applied to quantify common phenolic compounds of the pitomba pulp, for which quinic acid was the main compound (507.8 ± 7.4 μg g^− 1 DWP). Gas chromatography mass spectrometry (GC–MS) was employed along with headspace solid-phase microextraction (HS-SPME) to assess the aroma composition of pitomba fruit. A total of 27 volatile organic compounds (VOCs) were tentatively identified for pitomba fruit, for which 2-phenethyl acetate (17.89%) and isopentyl acetate (13.43%) esters were the main VOCs, contributing to the characteristic aroma of pitomba. The antioxidant capacity of the extract of pitomba fruit was evaluated by ABTS, DPPH and ORAC assays. We observed that pitomba has a moderate antioxidant activity.     

Ultrasound‐assisted extraction of polyphenols from potato peels: profiling and kinetic modelling

Ultrasound‐assisted extraction (UAE) at 33 and 42 kHz has been investigated in the extraction of polyphenols from peels of two potato varieties, cream‐skinned Lady Claire (LC) and pink‐skinned Lady Rosetta (LR), commonly used in snack food production. Extraction efficacy between the UAE‐untreated (control) and the UAE‐treated extracts was assessed on the total phenolic content and antioxidant capacities (DPPH and FRAP). Application of UAE showed significantly higher recovery of phenolic compounds compared to solid–liquid extraction process alone. Lower ultrasonic frequency (33 kHz) was more effective in recovering polyphenols compared to 42 kHz ultrasonic treatment. The liquid chromatography‐tandem mass spectrometry revealed that chlorogenic acid and caffeic acid were the most prevalent phenolics in LR peels, whereas caffeic acid was dominant in LC peels. Peleg's equation showed a good correlation (R² > 0.92) between the experimental values and the predicted values on the kinetics of UAE of phenolic compounds.     

Characterization of a new anthocyanin in black raspberries (Rubus occidentalis) by liquid chromatography electrospray ionization tandem mass spectrometry

Anthocyanin composition of black raspberry (Rubus occidentalis) was studied using high-performance liquid chromatography coupled to photodiode array (PDA) detection and electrospray ionization mass spectrometry (LC-ESI/MS) and tandem mass spectrometry (MS/MS). Pelargonidin 3-rutinoside was isolated and identified in black raspberries using HPLC, UV–Vis spectroscopy, MS, and NMR spectroscopy. No pelargonidin derivative had been previously found in Rubus occidentalis. In addition, the presence and identities of four previously reported anthocyanins (cyanidin 3-glucoside, cyanidin 3-sambubioside, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside) were confirmed by HPLC/MS and MS/MS analyses.     

Characterization of phenolics of Sarcandra glabra by non-targeted high-performance liquid chromatography fingerprinting and following targeted electrospray ionisation tandem mass spectrometry/time-of-flight mass spectrometry analyses

In this study, we successfully characterised the phenolic profiles of Sarcandra glabra (Thunb.) Nakai by high-performance liquid chromatography (HPLC) fingerprinting analyses and mass spectrometry (MS) identification. We first established a specific and valid HPLC approach for fingerprint analysis of S. glabra based on HPLC–UV detection. Using several chemometric methods such as similarity evaluation and principal components analysis, we determined herb-markers peaks from many HPLC peaks. The structures of these herb-markers were further identified targetedly by electrospray ionisation tandem mass spectrometry (ESI-MS/MS)/time-of-flight mass spectrometry (TOF-MS) analyses. As results, four phenolics, including chlorogenic acid, caffeic acid, 4-O-glucopyranosyl rosmarinic acid and rosmarinic acid, were characterised as major herb-markers for the stems of S. glabra, while another three phenolics, including kaempferol-3-O-β-d-glucuronic acid, chlorogenic acid and rosmarinic acid, were characteristic components for the leaves. The compounds may be very useful for further phenolome analysis.     

Antioxidant properties of garden strawberry leaf extract and its effect on fish oil oxidation

The present study characterises garden strawberry leaf extract and reports its effect on shelf life and quality characteristics of fish oil. Radical scavenging capacity of the extract in DPPH^? and ABTS^?+ assays was equivalent to 1207 and 1579 μmol g^?1 of trolox equivalents, respectively, total phenolic content was 257 mg g^?1 of gallic acid equivalents. Phenolic and volatile constituents were analysed by liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS). The extract was added to fish oil and its oxidation was followed during 42 days: peroxide, p‐anisidine values and hexanal concentration were lower in the samples with extract, particularly at the end of storage. The effect of extract on fatty acid composition was not significant, however the changes in the percentages of some individual acids were observed. Fish oil containing 5% of extract had lower levels of lipid oxidation in comparison to other samples. The results indicate that strawberry leaves could be a potential source of natural antioxidants.     

An improved mass spectrometric method for identification and quantification of phenolic compounds in apple fruits

Thirty-nine phenolic compounds were analysed using ultra high performance liquid chromatography (UHPLC) coupled with diode array and accurate mass spectrometry detection using electrospray ionisation (DAD/ESI-am-MS). Instrumental parameters such as scan speed, resolution, and mass accuracy were optimised to establish accurate mass measurements. The method was fully validated in terms of model deviation (r² > 0.9990), range (typically 10–3500 ng g⁻¹), intra/inter-day precision (<6% and <8%, respectively) and accuracy (typically 100 ± 10%). The mass accuracy of each selected phenolic compound was below 1.5 ppm. The results confirmed that the UHPLC-DAD/ESI-am-MS method developed here was convenient and reliable for the determination of phenolic compounds in apple extracts.     

Polyphenolic compounds characterization and reactive nitrogen species scavenging capacity of Oenothera paradoxa defatted seed extracts

Biological investigations have revealed high scavenging capacity of Oenothera paradoxa defatted seed extract on reactive nitrogen species such as NO and ONOO⁻. The characteristics of the polyphenols present in the extracts were checked using high performance liquid chromatography coupled with electrospray negative ionization ion trap mass spectrometry. Extracts contained five groups of compound: phenolic acids (gallic acid, ethyl gallate, ellagic acid and ferulic acid pentoside), flavanols (catechin, catechin gallate) and oligomeric procyanidins, flavonols (quercetin-3-O-glucoside, quercetin-3-O-glucuronide, quercetin-3-O-pentoside and quercetin), and gallotannins (tetragalloyl glucose, pentagalloyl glucose and hexagalloyl glucose). Penta-O-galloyl-β-d-glucose were present in the extracts in concentrations from 9.44 to 16.75 mg/g, which demonstrated a significant NO and ONOO⁻ scavenging activity with IC₅₀ 0.20 and 0.06 μM, respectively, may be considered as an O. paradoxa extract quality marker.     

Analytical evaluation of phenolic compounds and minerals of Opuntia robusta J.C. Wendl. and Opuntia ficus-barbarica A. Berger

In this study, 19 phenolic compounds were detected using high-throughput instrument ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC–ESI–MS/MS) in Opuntia ficus-barbarica A. Berger and Opuntia robusta J.C. Wendl. fruits. The five macro- and five micro-minerals determined in both species were analyzed using inductively coupled plasma–mass spectrometer. The phenolic compounds, mineral content, and the antioxidant capacity of the fruits of O. robusta and O. ficus-barbarica were analyzed. All phenolic compounds and minerals varied significantly between the two species. The total of phenolic compounds content was calculated as 69.237 and 66.385 mg kg^?1, respectively, in O. ficus-barbarica and O. robusta. Ferulic acid was the highest quantities, 31.620 and 26.931 mg kg^?1 in O. robusta and O. ficus-barbarica, in all phenolic contents, respectively. The macroelements calcium and potassium were the most abundant in both Opuntia species. The antioxidant activity of O. ficus-barbarica and O. robusta fruit samples was measured in the extracts of hexane, ethyl acetate, methanol, and water. The DPPH assay of Opuntia samples displayed a good radical scavenging inhibition, similar to butylated hydroxyanisole and butylated hydroxytoluene standards, as half maximal inhibitory concentration IC₅₀ = 69.32 and 67.57 μg mL^?1 in ethyl acetate extracts of O. ficus-barbarica and O. robusta fruits, respectively. This work presents a suitable method for the extraction, detection, and quantification of phenolic compounds by UPLC–ESI–MS/MS. MS/MS determination for multiclass determination was validated in Opuntia samples obtaining good results.

Abbreviations: ABTS, 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid; AChE, acetylcholinesterase; BChE, butyrylcholinesterase; BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene; DPPH, 2,2-diphenyl-1-picrylhydrazyl; DTNB, (5,50-Dithio-bis(2-nitrobenzoic)acid; ICP/MS, inductively coupled plasma/mass spectrometer; LoD, yhe limit of detection; MRM, multiple reaction monitoring; QEs, quercetin equivalents; PEs, pyrocatechol equivalents; R², correlation coefficients; r, Pearson’s correlation coefficient; SD, standard deviation; TIC, total ion chromatogram; UPLC–ESI–MS/MS, ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry     

Analysis of phenolic compounds in cork from Quercus suber L. by HPLC–DAD/ESI–MS

The aim of the present work was to identify the extractable phenolic compounds present in cork from Quercus suber L. The structures of thirty three compounds were tentatively identified by liquid chromatography coupled to electrospray ionisation mass spectrometry (HPLC–DAD/ESI–MS). The majority of those compounds were gallic acid derivatives, in the form of either galloyl esters of glucose (gallotannins), combinations of galloyl and hexahydroxydiphenoyl esters of glucose (ellagitannins), dehydrated tergallic-C-glucosides or ellagic acid derivatives. Others were found to correspond to low molecular weight phenolic compounds, like acids and aldehydes. Mongolicain, a flavanoellagitannin in which hydrolysable tannin and flavan-3-ol moieties are connected through a carbon–carbon linkage, was also detected in cork from Q. suber L. The results illustrate the rich array of phenolic compounds present in cork.     

Phytochemical profile of Rosmarinus officinalis and Salvia officinalis extracts and correlation to their antioxidant and anti-proliferative activity

The goal of this study was to monitor the anti-proliferative activity of Rosmarinus officinalis and Salvia officinalis extracts against cancer cells and to correlate this activity with their phytochemical profiles using liquid chromatography/diode array detection/electrospray ion trap tandem mass spectrometry (LC/DAD/ESI-MSⁿ). For the quantitative estimation of triterpenic acids in the crude extracts an NMR based methodology was used and compared with the HPLC measurements, both applied for the first time, for the case of betulinic acid. Both extracts exerted cytotoxic activity through dose-dependent impairment of viability and mitochondrial activity of rat insulinoma m5F (RINm5F) cells. Decrease of RINm5F viability was mediated by nitric oxide (NO)-induced apoptosis. Importantly, these extracts potentiated NO and TNF-α release from macrophages therefore enhancing their cytocidal action. The rosemary extract developed more pronounced antioxidant, cytotoxic and immunomodifying activities, probably due to the presence of betulinic acid and a higher concentration of carnosic acid in its phytochemical profile.     

Isolation and structure elucidation of phenolic compounds in Chinese olive (<Emphasis Type="Italic">Canarium album</Emphasis> L.) fruit

Chinese olive (Canarium album L.), one native and well-known tropical fruit tree in the southeast of China, contain a large amount of phenolics and possess great pharmacological activities. In this study, phenolics were extracted from Chinese olive fruit using 80% (v/v) aqueous acetone, and seven phenolic compounds were isolated and purified by Polyamide column and Toyopearl HW-40 column chromatography from crude extracts. Their structures were elucidated by high performance liquid chromatography coupled to diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS), and where possible by ¹H NMR and ¹³C NMR spectrometry. Except gallic acid and hyperin, five phenolic compounds including methyl gallate, ethyl gallate, corilagin, kaempferol-3-glucoside and amentoflavone were first identified in Chinese olive.     

Identification of in vitro and in vivo metabolites of isoimperatorin using liquid chromatography/mass spectrometry

The objective of the present study was to develop a practical strategy for the identification of metabolites following the in vivo metabolism and in vitro microbial biotransformation of isoimperatorin using liquid chromatography hybrid triple quadrupole-linear ion trap mass spectrometry (LC/QTRAP–MS) and liquid chromatography time of flight mass spectrometry (LC/TOF–MS). As a result, 19 metabolites were characterised in rat urine, plasma, bile and faeces after the oral administration of isoimperatorin and 13 products were identified in the sample from the transformation. Four metabolites were prepared by in vitro microbial biotransformation, and one was confirmed to be a novel compound. The side chain of isoimperatorin was found to be the primary metabolic site that underwent oxidation metabolism both in vivo and in vitro, and the metabolism of isoimperatorin in vivo and in vitro has good correlation. This is the first study of the metabolism of isoimperatorin in vivo.     

Phenolic compound characterisation and antiproliferative activity of “Annurca” apple,a southern Italian cultivar

In Annurca apples, a southern Italian variety, polyphenols were studied. The phenolic composition of Annurca apple peel was determined by HPLC coupled with electrospray negative ionisation multistage ion trap mass spectrometry (HPLC/ESI–ITMSⁿ). In addition, the antiproliferative and pro-apoptotic activities of peel extracts enriched in polyphenols and prepared from Annurca (APE), Red Delicious (RDPE) and Golden Delicious (GPE) varieties were evaluated on an HL-60 cell line. APE exhibited the highest total phenol content among the three apple cultivars tested, as determined by Folin–Ciocalteau’s procedure and HPLC–UV analysis. APE also showed higher amounts of chlorogenic acid, procyanidins, flavonols, dihydrochalcones and cyanidin-3-O-galactoside than GPE or RDPE. All three apple extracts were able to significantly decrease cell viability, from 50% to 80%, with APE appearing the most effective, while GPE was the least cytotoxic among the three samples. Similarly, APE and RDPE induced a significant increase of caspase-3 activity, whose activation represents a hallmark of apoptosis.