Determination of minor carbohydrates in carrot (Daucus carota L.) by GC–MS

Minor carbohydrates present in carrot (Daucus carota L.) have been studied by GC–MS analysis of their trimethylsilyl derivatives because of their remarkable role in a variety of biological functions. Scyllo-inositol and sedoheptulose (d-altro-2-heptulose), identified for the first time in this paper were present in all the carrots analysed in concentrations ranging 1.5–5.8 and 1.4–24.6 mg g⁻¹ dried weight, respectively. Other minor carbohydrates detected in carrot were myo- inositol (2.2–9.8 mg g⁻¹) and mannitol (traces-1.3 mg g⁻¹). Whereas small amounts (close to 2 mg g⁻¹) of scyllo-inositol were experimentally determined in other vegetables from the Apiaceae family (parsley, coriander and fennel), sedoheptulose was only detected at trace levels.     

HPLC–MS analyses and bioactivities of novel chemicals in Devil’s club (Oplopanax horridus (Sm.) Miq.)

Devil’s club (Oplopanax horridus (Sm.) Miq.) has traditionally been used as a folk medicine by native North Americans for the treatment of various chronic diseases. A methanolic extract and its sub-fractions by liquid–liquid re-extraction, i.e., chloroform (CHCl₃), ethyl acetate (EtOAc), n-butanol (BuOH), and water fractions, were analysed by their anti-cancer activity with in vitro cell proliferative bioassays, and their antioxidant capacities in terms of the determination of total phenolic content (TPC), ORAC value, and DPPH free radical scavenging activity. The whole extract of the dried root contained high TPC and possessed strong ORAC and DPPH radical scavenging activities. In addition, the extract exhibited a strong anti-proliferative ability against HT-29 cancer cells, e.g., with an inhibitive rate of 56.5% with a 0.2-mg/mL extract. Further investigation by HPLC–UV–MS identified significant bioactive phenolic compounds in the chloroform fraction, including gallic acid, caffeic acid, 4-O-feruloylquinic acid, 5-O-feruloylquinic acid, ferulic acid, methyl feruloylquinate, methyl ferulate, and quercetin. These results suggested that the associated bioactivity of the plant might result from the contribution of phenolic compounds.     

Optimization of microwave-assisted extraction of anthocyanins from purple corn (Zea mays L.) cob and identification with HPLC–MS

A Box–Behnken design was used to obtain the optimal conditions of microwave-assisted extraction (MAE). The effects of operating conditions, such as extraction time, solid–liquid ratio, and microwave irradiation power, on the extraction yield of anthocyanins were studied through a response surface methodology (RSM). The highest total anthocyainin content (TAC) from purple corn cob (185.1 mg/100 g) was obtained at an extraction time of 19 min, a solid–liquid ratio of 1:20, and a microwave irradiation power of 555 W. Six major kinds of anthocyanins were detected and identified as cyanidin-3-glucoside, pelargonidin-3-glucoside, peonidin-3-glucoside, and their respective malonated counterparts. In comparison with the conventional solvent extraction, MAE was highly efficient and rapid in extracting anthocyanins from Chinese purple corn cob.Industrial relevanceIn the last decades, the interest in anthocyanin pigments has increased because of their possible utilization as natural food colorants and especially as antioxidant and anti-inflammatory agents. Purple corn cob was the byproduct during the corn processing. Purple corn cob is dark purple to almost black color due to its high content of anthocyanins, which makes this byproduct a good source of anthocyanins.     

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.     

Purification and identification of ACE inhibitory peptides from Haruan (Channa striatus) myofibrillar protein hydrolysate using HPLC–ESI-TOF MS/MS

Haruan myofibrillar protein was hydrolysed with proteinase K and thermolysin to isolate Angiotensin converting enzyme (ACE) inhibitory peptides. The thermolysin hydrolysate of myofibrillar protein with the highest ACE inhibition activity (IC₅₀ = 0.033 mg/ml) was fractionated by ultrafiltration and size exclusion chromatography to three fractions. Fraction F2 with higher ACE inhibitory activity was separated into five fractions (A–E) using reversed-phased high performance liquid chromatography (RP-HPLC). Fraction C showed 81% inhibition activity and was subjected to HPLC coupled to electrospray ionisation-time-of-flight mass spectrometry (ESI-TOF MS/MS). Two peptide sequences for the most abundant fragments were identified as VPAAPPK (IC₅₀ = 0.45 μM) at 791.155 m/z and NGTWFEPP (IC₅₀ = 0.63 μM) at 1085.841 m/z. The presence of two proline residues at the C-terminal sequence is responsible for the high ACE inhibitory activity of these peptides. The results suggest that Haruan meat protein hydrolysate is a potent ACE inhibitor and may be used to decrease blood pressure.     

HPLC–PDA–ESI–MS/MS profiling and chemopreventive potential of Eucalyptus gomphocephala DC

An HPLC–PDA–ESI/MS/MS method was developed to identify the phytoconstituents of the EtOAc fraction of Eucalyptus gomphocephala DC. The antioxidant effect of the EtOAc fraction together with its sub-fractions was determined in vitro. The cytotoxicity was evaluated on different cell lines. The EtOAc fraction exhibited strong antioxidant activity, reduced the viability of all cell lines and was more active on MCF-7 and HepG-2 cell lines. Subsequently, the cytotoxicity of the sub-fractions and the isolated compounds were tested on MCF-7, HepG-2. The EtOAc fraction possessed potential antitumour promoting properties. It inhibited the stimulated NO (20%), 5-LOX (48.0%) and COX-2 (49.7%) respectively (at concentration of 20 μg/ml). This study suggests that this fraction is a source of different antioxidant and cytotoxic compounds with potential chemopreventive properties that might prevent different stages of the carcinogenesis process.     

Quantitative analysis of triterpenoids in different parts of Ilex hainanensis, Ilex stewardii and Ilex pubescens using HPLC–ELSD and HPLC–MS and antibacterial activity

An HPLC–ELSD method was first developed for the quantitative analysis of principle triterpenoids in Ilex hainanensis, Ilex stewardii and Ilex pubescens. The established method, with excellent precision, repeatability and recovery, was successfully applied to determine four triterpenoids in 24 samples from different species and medicinal parts of Ilex, and the changing trend was discussed. HPLC–ESI–MSⁿ was used for the identification of constituents in samples. The proposed method was simple, effective and suitable for investigations of these plants. Furthermore, the ethanol extracts from leaves of Ilex species, as well as their main components, were assessed for their antibacterial activities. The results indicated that the extracts of I. hainanensis, I. stewardii and I. pubescens could inhibit the growth of the tested oral pathogens, Streptococcus mutans and Actinomyces viscosu. Particularly, ilexgenin A was the most effective with MIC values of 7.8 and ?3.9 μg/ml, respectively.     

HPLC–MS identification and quantification of flavonol glycosides in 28 wild and cultivated berry species

Berries and red fruits are rich dietary sources of polyphenols with reported health benefits. More than 50 different flavonols (glycosides of quercetin, myricetin, kaempferol, isorhamnetin, syringetin and laricitrin) have been detected and quantified with HPLC–MSⁿ in fruits of blueberry, bilberry, cranberry, lingonberry, eastern shadbush, Japanese wineberry, black mulberry, chokeberry, red, black and white currants, jostaberry, red and white gooseberry, hardy kiwifruit, goji berry, rowan, dog rose, Chinese and midland hawthorn, wild and cultivated species of blackberry, raspberry, strawberry and elderberry. The phenolic constituents and contents varied considerably among the analyzed berry species. Elderberry contained the highest amount of total flavonols (450–568 mg kg⁻¹ FW), followed by berry species, containing more than 200 mg kg⁻¹ FW of total: chokeberry (267 mg kg⁻¹), eastern shadbush (261 mg kg⁻¹), wild grown blackberry (260 mg kg⁻¹), rowanberry (232 mg kg⁻¹), american cranberry (213 mg kg⁻¹) and blackcurrants (204 mg kg⁻¹). Strawberry (10.5 mg kg⁻¹) and white currants (4.5 mg kg⁻¹) contained the lowest amount of total flavonols. Quercetins represent the highest percentage (46–100%) among flavonols in most analyzed berries. In wild strawberry and gooseberry the prevailing flavonols belong to the group of isorhamnetins (50–62%) and kaempferols, which represent the major part of flavonols in currants (49–66%). Myricetin glycosides could only be detected in chokeberry, rowanberry and species from the Grossulariaceae, and Adoxaceae family and Vaccinium genus. Wild strawberry and blackberry contained from 3- to 5-fold higher total flavonols than the cultivated one.     

Flavonol glucosides in Allium species: A comparative study by means of HPLC–DAD–ESI-MS–MS

Cultivars and consumption typologies of some Allium species can significantly vary from a chemical point of view and even small differences can be important for their characterization and differentiation. Bulbs of three varieties and four consumption typologies of onion (Allium cepa L.) and two varieties of shallot (Allium ascalonicum Hort.) were subjected to HPLC–DAD–ESI-MS–MS analysis. Seven flavonol glucosides were identified in all the samples, two of which, quercetin 3,4′-diglucoside and quercetin 4′-glucoside, represent about the 90% of the overall contents. Cultivars and consumption typologies of the Allium species under study show significant differences in flavonol contents, from the very low quantity of antioxidant compounds in white onion, about 7 mg/kg against 600–700 mg/kg that were found in red and gold varieties, to the enormous content of flavonols that are present in onions of prompt consumption, where quercetin 4′-glucoside exceeds 1 g/kg and quercetin 3-glucoside is present in a ratio higher then 10:1 with respect to its value in the other onion typologies. Shallots are very rich in the two major flavonols.     

Rapid screening and identification of antioxidants in aqueous extracts of Houttuynia cordata using LC–ESI–MS coupled with DPPH assay

Houttuynia cordata Thunb. has been used traditionally as immune stimulant and anticancer agent. An aqueous extract of H. cordata tea showed high radical scavenging activity determined by off-line DPPH assays. Then, it was screened for its antioxidant components via an on-line DPPH radical scavenging technique coupled with a liquid chromatography–electrospray ionization mass spectrometer (LC–ESI–MS). Based on their mass spectra and fragmentation patterns; the antioxidant compounds were identified as quinic acid derivative, caffeic acid derivatives, procyanidin B, neo-chlorogenic acid, catechin, chlorogenic acid, crypto-chlorogenic acid and quercetin hexoside. LC–MS/MS in multiple reactions monitoring (MRM) mode was used to quantify these antioxidant compounds. Chlorogenic acid was found to be a major component in H. cordata tea.     

A validated GC–MS method for the detection of tropane alkaloids in buckwheat (Fagopyron esculentum L.) fruits,flours and commercial foods

A novel analytical method was developed and validated for the rapid and simultaneous detection of toxic tropane alkaloids (scopolamine, atropine) in commercial buckwheat (Fagopyron esculentum Moench.) samples and related food products, using gas-chromatography–mass-spectrometry in single-ion mode. A suitable and tailored protocol for extraction, sample clean-up and derivatization was set up in order to maximise recoveries and detection limits. The limits of detection for atropine and scopolamine were found to be 0.3 and 1 μg/kg, respectively, while limits of quantitation were obtained at 1 and 6 μg/kg, respectively, corresponding approximately to less than one Datura stramonium seed per million of buckweed fruits, a ratio accepted by the European law on animal nutrition. The established method is considered suitable for the routine determination of traces of tropane alkaloids in flour or other buckwheat products for food and feed purpose and was applied to a variety of commercial samples and buckwheat-derived food products (pasta, porridge, crackers, and flakes). The protocol may be enforceable to other potential food and feed contaminants from the Datura genus (D. innoxia, D. ferox).     

Determination of flavonoid level variation in onion (Allium cepa L.) infected by Fusarium oxysporum using liquid chromatography–tandem mass spectrometry

In order to evaluate the flavonoid level variation in an onion (Allium cepa L.) infected by Fusarium oxysporum, the bulbs of a healthy onion and of an infected one were analysed for flavonoids via high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC–MS/MS). Among eleven flavonoids characterised, isorhamnetin 4′-O-galactoside (8) was identified in an onion for the first time. When the healthy bulb was inoculated with the fungus, the two quercetin derivatives (4 and 7) and the two isorhamnetin derivatives (5 and 9) underwent concentration changes typical for the defense materials against pathogens. The yellow granules that were accumulated on the abaxial epidermal cell layers after 8 days of inoculation were confirmed as quercetin (10) and isorhamnetin (11). It was deduced that they were produced from flavonoids 4, 5, 7 and 9 by hydrolysis enzyme of the fungus.     

Analysis of proanthocyanidins in almond blanch water by HPLC–ESI–QqQ–MS/MS and MALDI–TOF/TOF MS

Almond seeds contain low molecular weight phenolics and larger polyphenols of the proanthocyanidin (PA) family that may provide health benefits associated with antioxidant and other physiological effects. In the process of blanching, the seed coating is removed by hot water treatment and the resulting effluent (almond blanch water, ABW) is already a diluted extract with potential applications. By using a combination of mass spectrometry techniques, HPLC–ESI–QqQ–MS/MS and MALDI–TOF/TOF MS, we report here for the first time the PA composition of ABW up to decamers. Freeze-dried ABW contains about 322 μg/g of oligomeric (2–4 units) PA relatively quantified as procyanidin B1 dimer equivalents. We show that the PA present in ABW include monogalloylated and probably polygalloylated species apart from the procyanidins, prodelphinidins and propelargonidins previously reported in the seeds. ABW is a byproduct from almond processing that can be considered a source of oligomeric PA with potential applications as a dietary and functional ingredient.     

Selenium speciation analysis of Misgurnus anguillicaudatus selenoprotein by HPLC–ICP–MS and HPLC–ESI–MS/MS

Analytical methods for selenium (Se) speciation were developed using high-performance liquid chromatography (HPLC) coupled to either inductively coupled plasma mass spectrometry (ICP?CMS) or electrospray ionization tandem mass spectrometry (ESI?CMS/MS). Separations of selenomethionine (Se-Met) and selenocysteine (Se-(Cys)₂) with favorable peak shape and resolution were obtained by both HPLC-ICP-MS and HPLC?CESI?CMS/MS. Both methods achieved low limits of detection, high sensitivity and favorable stability. With HPLC?CESI?CMS/MS, signal suppression was observed when complex matrix was co-eluted, but excellent structural characterization was still achieved. Thus, HPLC-ICP-MS is better for the detection of Se species, and HPLC?CESI?CMS/MS is essential for molecular identification and confirmation. A water-soluble selenoprotein from purified M. anguillicaudatus muscle tissue was analyzed by the two complementary systems (HPLC-ICP-MS and HPLC?CESI?CMS/MS) with high sensitivity and accuracy. The results demonstrated that Se-Met was the predominant selenoamino acid in the purified selenoprotein from M. anguillicaudatus muscle tissue, and the concentration of Se-Met in the selenoprotein was 6.280?mg/kg (dry mass). In addition, in HPLC-ICP-MS, an unknown Se-containing compound with similar polarity to Se-(Cys)₂ was discovered. Using complementary data from HPLC?CESI?CMS/MS, it was determined that this unknown Se-containing compound was not Se(Cys)_2.     

Characterisation of flavonoids in Orostachys japonicus A. Berger using HPLC–MS/MS: Contribution to the overall antioxidant effect

Orostachys japonicus cultivated in the Republic of Korea was analysed for flavonoid content via HPLC coupled to MS/MS. Amongst 16 compounds that were characterised, eight flavonoids and one alkaloid were characterised for the first time: two procyanidin dimer gallate isomers (1 and 2), epigallochatechin-3-gallate (3), two procyanidin dimer digallate isomers (4 and 9), quercetin 3-O-rhamnosyl-7-O-glucoside (6), myricetin 3-O-glucoside (10), kaempferol (16) and N¹,N⁵,N¹⁰-tri-p-(E,E,E)-coumaroylspermidine (15). The identified compounds were quantified by HPLC–UV/DAD. The antioxidant activity of the O. japonicus flavonoids was determined via 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS^•+) and nitric oxide radical (NO^•) scavenging assays.     

LC/ESI–MS/MS method for the identification and quantification of spinosad residues in olive oils

This paper reports the use of liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) method for the identification and quantification of residues of the natural insect control agent Spinosad in olive oils. The method determines the active ingredients Spinosyns A and D and two minor metabolites Spinosyns B and K without laborious sample treatment. All four analytes are determined simultaneously in a single injection using positive electrospray ionisation LC–MS with multiple reaction monitoring (MRM). For the quantitative analysis of samples an external calibration curve was built. The calibration curves for each analyte were linear in the concentration range 20–500 ng/mL with a correlation coefficient ranging between 0.995 and 0.999. Results from spike and recovery experiments at levels of 100 and 200 ng/mL gave mean recoveries ranging from 87–116% with satisfactory precision (relative standard deviation (RSD) from 1–8%). The excellent selectivity and sensitivity allows quantification and identification of low levels of Spinosad in olive oils (limits of quantification (LOQs) 0.004–0.073).     

Fast LC–MS analysis of gallotannins from mango (Mangifera indica L.) kernels and effects of methanolysis on their antibacterial activity and iron binding capacity

Mango (Mangifera indica L.) kernels were successively extracted with hexane and methanol and the effects of extraction on the profile of gallotannins as well as on their antimicrobial activity and iron-binding capacity were determined. A new method based on fast liquid chromatography with diode array and mass spectrometric detection was developed which allowed the separation of gallotannins in less than 7 min. Gallotannins remained stable during Soxhlet extraction with hexane. Methanolysis led to the degradation of highly galloylated tannins to yield penta-O-galloylglucose and methyl gallate. The antimicrobial activity of the extracts was not affected by the compositional change, whereas the iron binding capacity increased with increasing amounts of methyl gallate. The less complex profile of antimicrobial compounds obtained after methanolysis compared to the crude extract will facilitate the standardization of extracts and their application in target products.     

Application of an HPLC–MS/MS method for mycotoxin analysis in commercial baby foods

This article describes the validation of an analytical method for the detection of 21 mycotoxins in baby food. The analytical method is based on the simultaneous extraction of selected mycotoxins by matrix solid-phase dispersion (MSPD) followed by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) using a hybrid triple quadrupole-linear ion trap mass spectrometer (QTRAP®). Information Dependent Acquisition (IDA), an extra confirmation tool for samples that contain the selected mycotoxins, was used. The matrix effects were evaluated, and the corrections for the matrix effects were performed using two calibration approaches: external matrix-matched calibration and internal standard calibration. Matrix-matched calibration was ultimately used for accurate quantification, and the recoveries obtained were generally higher than 70%. The analytical method was applied to the analysis of 35 samples of commercial baby foods. No sample exceeded the maximum limit (ML) fixed by the European Union for these mycotoxins in baby food. However, this survey highlighted the occurrence of mycotoxins in cereal-based infant foods.