Preparation of quercetin glucuronides and characterization by HPLC–DAD–ESI/MS

Quercetin is the main flavonol in the human diet, and the most commonly used in studies of biological activity. The major circulating forms of quercetin found in the human plasma after consumption of food containing distinct quercetin glycosides are glucuronides and sulfates. In this work quercetin glucuronides have been obtained from green beans (quercetin 3-glucuronide) and by enzymic synthesis (quercetin 4′-glucuronide) using a modification of the method described by Plumb et al. (Methods in polyphenol analysis, The Royal Society of Chemistry, Cambridge, pp 187, 2003) so as to improve the original low yields of that methodology. The method finally optimised got yields of 19% in the preparation of quercetin 4′-glucuronide, which allows its further isolation for their use in biological assays. In addition, quercetin 3′-glucuronide, 3-glucuronide and a diglucuronide were synthesised with lower yields. The compounds prepared have been employed to perform assays in order to obtain data for their identification by HPLC coupled to photodiode array detection and tandem mass spectrometry. It was observed that the analysis by HPLC–ESI/MS/MS could allow the identification of different quercetin glucuronides based on the presence of some minor key MS² fragments.     

Flavonoid content and antioxidant capacity of spinach genotypes determined by high‐performance liquid chromatography/mass spectrometry

BACKGROUND: Flavonoids in different spinach genotypes were separated, identified, and quantified by a high‐performance liquid chromatographic method with photodiode array and mass spectrometric detection. The antioxidant capacities of the genotypes were also measured using two antioxidant assays–oxygen radical absorbance capacity (ORAC_FL) and photochemiluminescence (PCL)–which measure the response to the peroxyl and superoxide anion radicals, respectively. RESULTS: Eighteen flavonoids representing glucuronides and acylated di‐ and triglycosides of methylated and methylene dioxide derivatives of 6‐oxygenated flavonols were identified (patuletin, spinacetin, spinatoside, jaceidin). The total flavonoids ranged from 1805 to 3703 mg kg^?1, indicating 2.0‐fold variation among genotypes. The ORAC_FL and PCL values ranged from 48.7 to 84.4 mmol kg^?1 and from 9.0 to 14.0 mmol kg^?1, respectively, representing as much as 1.7‐fold variation among genotypes. CONCLUSION: The ORAC_FL and PCL values were highly correlated with total flavonoid content (r_xy = 0.96). Copyright © 2008 Society of Chemical Industry     

Use of thiolysis hyphenated to RP-HPLC-ESI(-)-MS/MS for the analysis of flavanoids in fresh lager beers

Proanthocyanidins are well known for their involvement in haze and colour development during beer ageing. New methodologies are needed, however, to understand what happens to them in the bottled beer. For the first time in the brewing field, thiolysis was hyphenated to RP-HPLC-ESI(-)-MS/MS to investigate these flavanoids. Thirty minutes at 40 °C followed by 10 h at room temperature emerged as the best conditions for complete depolymerisation. NP-HPLC-ESI(-)-MS/MS was used to quantify and isolate fractions from monomers to trimers in a Sephadex LH20 acetone/water (70/30, v/v) beer extract. Unsurprisingly, a lower dimer/monomer ratio was evidenced in PVPP-treated beers than in silica gel-filtered beers. Most beer dimers are procyanidins B3 (two catechin units) whilst most trimers are prodelphinidins (catechin in terminal units and gallocatechins or catechins in extension units). Gallocatechin appeared to come mainly from malt. Despite the absence of chromatographic peaks corresponding to oligomers above trimers, an apparent degree of polymerisation close to six was calculated in the total LH20 extract. Still higher mean degrees of polymerisation (mDPs) were calculated for malt and hop, indicating selective extraction or depolymerisation from raw materials to beer. The main part of beer polyphenols is composed of complex undefined structures not degraded by toluene-α-thiol.     

火龙果色素的基本性质及结构鉴定

采用液质联用(HPLC/MS)的方法,将色素的不同组分分离,并对分离组分进行结构鉴定.结果表明:火龙果果肉、果皮色素同为甜菜苷类色素,从果肉中分离出4种甜菜苷色素为betanin,2 descarboxy betanin,phyllocactin,2 descarboxy phyllocactin;果皮中分离出2种甜菜苷色素为be tanin,phyllocactin.火龙果中甜菜苷红色素的质量分数分别为676.9mg/kg(以鲜果肉计),97.7mg/kg(以鲜果皮计).     

Flavonoid glycosides and antioxidant capacity of various blackberry,blueberry and red grape genotypes determined by high‐performance liquid chromatography/mass spectrometry

Anthocyanin and flavonol glycosides of various blackberry, blueberry and red wine grape genotypes were identified and measured by a high‐performance liquid chromatographic (HPLC) separation method with photodiode array (PDA) and mass spectrometric (MS) detection. With this method, two distinct elution regions of anthocyanins and flavonols were obtained with near baseline separation of most compounds. Blackberry, blueberry and red wine grape genotypes varied markedly in total anthocyanins and total flavonols as well as oxygen radical absorbance capacity (ORAC). The respective ranges of total anthocyanin (TA) and total flavonol (TF) contents of tested samples were: blackberries, 1143.9–2415.4 and 102.0–160.2 mg kg^?1; blueberries, 1435.2–8227.3 and 172.5–327.5 mg kg^?1; and red wine grapes, 380.9–7904.7 and 21.0–322.2 mg kg^?1. Antioxidant activities and contents of total anthocyanins and total flavonols in blackberries, blueberries and red wine grapes were highly correlated, with linear relationships between ORAC and TA (r_xy = 0.94) and TF (r_xy = 0.90) for grapes, TA (r_xy = 0.95) for blueberries and TA (r_xy = 0.74) for blackberries. Copyright © 2004 Society of Chemical Industry     

Determination of 1-phenylazo-2-naphthol (Sudan I) in chilli powder and in chilli-containing food products by GPC clean-up and HPLC with LC/MS confirmation

A simple and rapid method is reported for the routine determination 1-phenylazo-2-naphthol (Sudan I) in chilli powder and in chilli-containing food products. The method involved Soxtec extraction from the products followed by high-pressure gel permeation chromatographic clean-up collecting the appropriate fraction. Analysis of this fraction was by HPLC with UV/VIS detection. The limit of detection was 7 μg kg^-1 and the limit of quantification was 13 μg kg^-1. The identity of Sudan I in food products was established by electrospray LC/MS with MS/MS confirmation. From a small survey of 30 retail samples, 11 samples of crushed chilli, Italian pasta, chilli-snack and vegetable sauce contained levels of Sudan I ranging from 24 to 5591 μg kg^-1.     

Determination of antioxidant activity and phenolic compounds of Muntingia calabura Linn. peel by HPLC‐DAD and UPLC‐ESI‐MS/MS

Antioxidant activity in Muntingia calabura Linn. peel was evaluated by DPPH radical, ORAC, ABTS cation radical, FRAP assays and total phenolic contents by different extraction conditions. In addition, a method for determination of phenolic compounds in calabura peel samples harvested in Brazil using methanol:water and magnetic stirring as the extraction method, HPLC‐DAD and UPLC‐ESI‐MS/MS analysis were developed. Calabura peel showed antioxidant activity for all extraction conditions and assays evaluated, the most polar solvents being more effective. The developed HPLC‐DAD method allowed the accurate determination of phenolic compounds, with recoveries in the range of 72–107% and precision values ≤4%, with exception for chlorogenic acid. Gallic acid was determined at the highest concentration levels, followed by myricetin, ferulic acid and vanillic acid. However, all the five proposed phenolic compounds were identified in calabura peel samples by UPLC‐ESI‐MS/MS. Thus, calabura peel, an uncommon edible fruit part, can be appointed as a rich source of phenolic compounds.     

Polyphenols content and antioxidant capacity of eggplant pulp

The influence of organic and conventional farming practices on the phenolic content in eggplant samples belonging to two cultivars, Blackbell (American eggplant) and Millionaire (Japanese eggplant) grown under similar environmental conditions was evaluated. Phytochemical investigation of the eggplant extracts showed that N-caffeoylputrescine, 5-caffeoylquinic acid, and 3-acetyl-5-caffeoylquinic acid made up the bulk of total eggplant phenolics. In addition, this is the first report on identification of trace quantities of three additional flavonols, namely, quercetin-3-glucoside, quercetin-3-rhamnoside, and myricetin-3-galactoside in freeze-dried eggplant pulp. The phenolic content of the conventionally grown Blackbell variety was marginally higher or equal to those grown organically. However, the phenolic content of the Millionaire organic variety was much greater than the conventionally grown samples. Eggplant extract inhibition of cupric-ion mediated oxidation of low-density lipoproteins was highly correlated with the content of 5-caffeolquinic acid (R² = 0.9124), the most abundant phenolic acid identified.     

Development of the Rhodiola rosea Fuqu and Rhodiola rosea soy sauce,and the determination of their functional properties

A mixed starter, composed of high‐quality Rhodiola rosea Fuqu, was developed. Compared with normal Fuqu, Rhodiola rosea Fuqu demonstrated higher spore numbers, spore germination rates, protease activity, liquefying amylase activity and total acid and amino acid nitrogen. Specifically, the spore number was 1.36 times that of regular Fuqu. Protease activity, liquefying amylase activity, total acid and amino acid nitrogen were 0.475 g/100 mL, 104.16 U/g dry Qu, 35.67 mmol/L and 26.08 g/100 mL, respectively. These values were 21.48, 7.41, 6.07 and 67.82% higher than the regular Fuqu. The Rhodiola rosea soy sauce indices were also better than those for the control. The DPPH scavenging abilities of R. rosea soy sauce, control soy sauce, market soy sauce 1 and market soy sauce 2 were 74.25, 44.01, 34.73 and 11.38%, respectively. The total phenolic content in these four samples was 387.38, 309.23, 212.85 and 202.60 mg GAE/g, respectively. As observed with the DPPH and total phenolic assay, the R. rosea soy sauce showed the highest antioxidant capacity. A simple, rapid, and sensitive determination method of salidroside in R. rosea Fuqu and R. rosea soy sauce using HPLC‐ESI‐MS/MS was developed and validated with multiple reaction monitoring in the negative mode.     

Quantitative bioactive compounds assessment and their relative contribution to the antioxidant capacity of commercial orange juices

Dietary recommendations for healthy eating include the consumption of fruit juices whose health effects are ascribed, in part, to carotenoids, phenolic compounds and vitamin C. These bioactive compounds have been implicated in the reduction of degenerative human diseases, mainly due to their antioxidant potential. Orange juice is characterized by substantial accumulation (apart from ascorbic acid) of flavonoids and carotenoids. Commercial orange juice is the main human dietary source of antioxidant compounds in developed countries. The qualitative and quantitative determination of carotenoid, flavonoid and vitamin C content of Spanish commercial orange juices was achieved by high‐performance liquid chromatography. The health‐related properties of bioactive compounds contained in orange juice are based on their antioxidant activity. The antioxidant capacity of these juices was assessed by 2,2‐diphenyl‐1‐picrylhydrazyl stable radical scavenging and was compared with a freshly squeezed orange juice. In addition, the relative contribution of the different bioactive compounds to the antioxidant activity of orange juices was calculated. Total vitamin C was found to be the major contributor to the antioxidant potential of the orange juices studied, followed by flavonoid and carotenoid compounds. Ascorbic acid, total vitamin C and β‐cryptoxanthin content correlated positively with the free‐radical scavenging parameters. No significant differences, in terms of antioxidant capacity, were found between commercial traditional pasteurized orange juices and freshly squeezed orange juice. Copyright © 2003 Society of Chemical Industry     

Identification of Low Molecular Weight Peptides in Chinese Rice Wine (Huang Jiu) by UPLC‐ESI‐MS/MS

The aim of this work was to increase the general knowledge of peptide identification and to examine the low molecular weight peptides in Chinese rice wine (Huang Jiu) as there are very few publications in the literature on this topic. Chinese rice wine (Huang Jiu) has a high content of peptides and more than 500 peptides have been tentatively identified by ultra‐performance liquid chromatography‐quadrupole time‐of‐flight tandem mass spectrometry (UPLC‐ESI‐MS/MS), including 43 potential bio‐active peptides and 3 sensory‐active peptides, based on published references to date. These peptides have been tentatively identified according to the MS/MS spectra which produced sufficient information of product ions (complementary y ions and b ions). Results from this work indicated that it is feasible to produce rice wine with rich bioactive peptides and that there is potential to examine for rice wine authenticity and traceability based on the origin of the peptides.     

Flavonol content in the water extract of the mulberry (Morus alba L.) leaf and their antioxidant capacities

Abstract: The biological activities of the mulberry (Morus alba L.) leaf have been attributed to its flavonoid content. The water extract of the mulberry leaf (WEML) was prepared by autoclaving at 121 °C for 15 min, and the flavonol content of the WEML was determined by HPLC The WEML contained 4 flavonols in the following order: quercetin‐3‐β‐D‐glucose (QT‐G) > quercetin‐3‐O‐glucose‐6″‐acetate (QT‐GA) > rutin (RT) > quercetin (QT). In the oxygen radical absorbance capacity (ORAC) assay, QT had the highest peroxyl radical‐scavenging capacity and a similar hydroxyl radical‐scavenging capacity as its glycosides (QT‐G, QT‐GA, and RT). QT exhibited a stronger cellular antioxidant capacity (CAC) against 2,2′‐Azobis(2‐amidinopropane) dihydrochloride (AAPH)‐ and Cu²⁺‐induced oxidative stress in HepG2 cells compared to its glycosides, indicating that the intracellular antioxidant capacity of QT and its glycosides may depend upon both the permeability across the cell membrane and the peroxyl or hydroxyl radical‐scavenging capacity. Practical Application: The information presented might be used for developing mulberry leaf‐based functional foods.     

The antioxidant and antimicrobial properties of the methanolic extract from Cocos nucifera mesocarp

The antioxidant activity of the methanolic extract prepared from different stages of Cocos nucifera L. mesocarp was demonstrated, by DPPH, FRAP and deoxyribose assays, and suggests the potential of the mesocarp extract to be used for therapeutic purposes. Antimicrobial activity of the crude mesocarp extract was tested against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 441, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa MTCC 7925. The extract exhibits a potent anti-staphylococcal activity. Probable compounds responsible for the bioactivity were identified by means of HPLC and UV/ESI–MS spectroscopic analyses. Their structures were deduced as 5-O-caffeoylquinic acid (chlorogenic acid), dicaffeoylquinic acid and three tentative isomers of caffeoylshikimic acid.     

Proanthocyanidin content,antioxidant capacity and scavenger activity of Portuguese sparkling wines (Bairrada Appellation of Origin)

BACKGROUND: The main object of the present study was to investigate the different proanthocyanidin fraction (monomeric, oligomeric and polymeric fraction) contents, antioxidant capacity and scavenger activity of the most important and representative commercial sparkling wines available in Bairrada Portuguese Appellation of Origin. RESULTS: The white commercial sparkling wines tested had much less total phenolic, proanthocyanidin content, antioxidant capacity and scavenger activity than the sparkling red wines. For all white and red sparkling wines the polymeric fraction of proanthocyanidins was the most abundant fraction quantified. The antioxidant capacity was positively correlated with the different proanthocyanidin fractions studied. However, in general, higher correlations between total polyphenols, different proanthocyanidin fractions and antioxidant capacity were found only for red sparkling wines. CONCLUSION: The results confirm that Portuguese sparkling wines from Bairrada Appellation of Origin are good sources of antioxidants when compared with other wines elaborated from other grapes varieties and from other regions. At same time, good linear correlations between the levels of each different proanthocyanidin fractions and total polyphenols with antioxidant capacity were found for the commercial sparkling wines analysed. Copyright © 2010 Society of Chemical Industry     

Determination of carotenoids in Dunaliella salina cultivated in Taiwan and antioxidant capacity of the algal carotenoid extract

A simple HPLC method with good separation efficiency was developed to determine all-trans and cis forms of carotenoids in Dunaliella salina cultivated in Taiwan. The analysis used a C30 column (250 × 4.6 mm, 5 μm) and an isocratic solvent system (flow rate = 1 mL/min) mixing methanol–acetonitrile–water (84/14/2, v/v/v) and methylene chloride, (75/25, v/v). Carotenoids were detected at 450 nm. Moreover, the antioxidant capacities of the algal carotenoid extract were also evaluated with Trolox equivalent antioxidant capacity (TEAC) assay, reducing power and 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging assay. Results showed that 7 carotenoids in the algal extract could be separated simultaneously within 30 min and the total amount of them was 290.77 mg/g algae. The contents of all-trans-β-carotene and 9- or 9′-cis-β-carotene, the major carotenoids in the algae, were 138.25 and 124.65 mg/g algae, respectively. The contents of all-trans-lutein, all-trans-zeaxanthin, 13- or 13′-cis-β-carotene, all-trans-α-carotene and 9- or 9′-cis-α-carotene were 6.55, 11.27, 4.95, 2.69, and 2.41 mg/g algae, respectively. The algal carotenoid extract had significantly higher antioxidant activity than all-trans forms of α-carotene, β-carotene, lutein and zeaxanthin in all antioxidant assays. The cis forms of carotenoids, especially 9- or 9′-cis-β-carotene, might play crucial roles for the antioxidant capacities of the algal extract.     

HPLC-PDA-ESI/MS鉴定芥蓝中脱硫芥子油苷

利用液相色谱-二极管阵列-电喷雾质谱联用(HPLC-PDA-ESI/MS)对芥蓝中脱硫芥子油苷进行鉴定,通过分析各种脱硫芥子油苷在正、负离子两种模式下的质谱特点和PDA图谱特点,由正、离子两种模式下的脱硫芥子油苷离子碎片信息可以推断出芥蓝中含有11种脱硫芥子油苷,其中7种为脂肪族芥子油苷、4种为吲哚族芥子油苷。进一步对PDA图谱分析发现,因结构差异,脂肪族脱硫芥子油苷在220～230nm波长范围内只有一个大的吸收峰,而吲哚族脱硫芥子油苷在220～230nm波长范围内有两个吸收峰。     

超高效液相色谱-串联质谱法测定食品包装材料中全氟辛酸及其盐类物质

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)结合加速溶剂萃取测定食品包装材料中全氟辛酸及其盐类物质(PFOA)的方法.采用甲醇作为溶剂,加速溶剂提取法提取食品包装材料中的PFOA,提取液经0.2 μm有机滤膜过滤后,以甲醇、水为流动相,梯度洗脱,经UPLC分离后用多级反应监测(MRM)方式测定.用两个子离子的...     

5种海棠叶茶抗氧化成分组成及品质差异性分析

以5种海棠叶制成的茶为材料,利用高效液相色谱法（HPLC）,DPPH·,ABTS+·清除力测定以及总还原力测定等方法对其抗氧化成分及能力进行差异性分析,并按照《GB/T23776-2009茶叶感官评审方法》对海棠叶茶进行感官评价。结果表明:五种海棠叶茶总酚含量变化范围为（69.32±2.16）^89.54±1.14mg/g,雪球海棠最高,钻石海棠最低。5种海棠叶茶检测出酚类物质有没食子酸、原花青素B2、根皮苷、绿原酸、芦丁、栎素、矢车菊素半乳糖苷,其中根皮苷含量最高。抗氧化实验结果表明,王族海棠,湖北海棠,雪球海棠在DPPH·,ABTS+·清除能力,以及总还原力上均明显高于草莓果冻与钻石海棠。茶叶感官评价结果显示,与传统湖北海棠叶茶比较,王族海棠、雪球海棠叶茶色泽均匀,香气浓耐闻,口感醇香,具有茶涩味,整体品质佳。结果表明,王族海棠、雪球海棠叶茶抗氧化能力强,茶叶品质佳,开发成新型茶叶潜力大。