Antioxidant and tyrosinase inhibitory activity of Rosa roxburghii fruit and identification of main bioactive phytochemicals by UPLC‐Triple‐TOF/MS

The content of bioactive phytochemicals, antioxidant activity and tyrosinase inhibitory activity of the hydroalcoholic extracts of Rosa roxburghii were determined. Yellow fruits of cultivated R. roxburghii showed the highest phenolic content (154.81 mg gallic acid g^?1), and the green fruits of wild R. roxburghii showed higher content of flavonoid and triterpenoid. Rosa roxburghii fruits from different cultivars and maturity stages all demonstrated as good antioxidant agents and tyrosinase inhibitors, with IC50 value about twice of the positive standard in the DPPH assay and triple of the standard in the tyrosinase inhibitory activity assay. Nineteen compounds, mainly ellagic acids and its derivatives, flavonoids and their glycosides were identified by UPLC‐Triple‐TOF/MS analysis. As the first study of bioactive phytochemicals of R. roxburghii by UPLC‐MS, the present research may provide valuable information for fulfilling the potential of R. roxburghii in the functional food area.     

Quantitative UPLC‐MS/MS analysis of chlorogenic acid derivatives in antioxidant fractionates from dandelion (Taraxacum officinale) root

While qualitative studies have identified chlorogenic acids in antioxidant extracts, particularly ethyl acetate‐derived extracts, of Taraxacum officinale, quantitative analysis of these phenolic compounds remains largely unreported for this species. In this study, bioactivity‐guided fractionation of an antioxidant crude ethyl acetate extract (DPPH = 295.481 ± 0.955 mg TE g^?1 extract) from T. officinale root resulted in a number of reverse‐phase fractions that demonstrated high antioxidant activity (DPPH = 1058.733–1312.136 mg TE g^?1 extract), stronger than that of the synthetic antioxidant Trolox^®. UPLC‐MS/MS screening of these fractions for the presence of selected mono‐ and di‐caffeoylquinic acids revealed large quantities of 1,5‐dicaffeoylquinic acid present in several fractions (853.052–907.324 μg mg^?1), respectively. Due to the antioxidant potency and high levels of 1,5‐dicaffeoylquinic acid observed in these fractions, it was concluded that specifically this chlorogenic acid derivative is a major contributor to the antioxidant efficacy of dandelion root.     

Optimisation of ultrasound extraction for flavonoids from semen astragali complanati and its identification by HPLC‐DAD‐MS/MS

The optimisation of ultrasound extraction of semen astragali complanati flavonoids was studied by measuring characteristic absorbance at 266 nm as the response and using response surface methodology (four‐variable, three‐level Box–Behnken design, BBD) in this article. The optimal conditions were obtained as 52 °C, 34 min, 26:1 (mL:g) and 100 mesh (0.120–0.150 mm) for extraction temperature, extraction time, solvent‐to‐sample ratio as well as particle size, respectively. Under these conditions, validation experiments were carried out and the experimental value of A₂₆₆ was 0.9907 ± 0.032 (n = 3), which corresponded to an experimental extraction yield of 7.08%. Compounds in the extracts obtained with the optimum extraction conditions were identified by high‐performance liquid chromatography coupled with diode array and mass spectrometry detectors (HPLC–DAD–MS). Among the 14 compounds that were tentatively identified in the extracts according to their ultraviolet‐visible spectroscopy, mass spectrometry and related literature reports, four were reported for the first time.     

Comparison of ginsenosides in radix and rhizome of wild Panax species using LC‐ELSD and LC‐Q‐TOF‐MS

High‐performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) and quadrupole time‐of‐flight mass spectrometry (Q‐TOF‐MS) were used for qualitative and quantitative analysis of wild Panax species, especially wild P. vietnamensis, which is an important medicinal plant. We determined the types and concentrations of ginsenosides in radix and rhizome of wild P. vietnamensis. Identification of ginsenosides was achieved using Q‐TOF‐MS; concentrations were determined by ELSD. The most abundant ginsenosides in wild Vietnamese ginseng were of the ocotillol type, accounting for more than 50% of the total. Compared to the rhizome, the radix had 31% higher ginsenoside content due to variation in protopanaxatriol‐type ginsenoside contents. We also found an unusual difference in the chromatograms of the two parts of wild P. vietnamensis. This difference did not appear in other wild species such as P. ginseng and P. quinquefolius. Our study provides an opportunity for further in‐depth study of the distinctive characteristics of P. vietnamensis.     

Evaluation of physico‐chemical properties,trace metal content and antioxidant activity of Indian honeys

In this study, effect of plant sources viz. Gossypium hirsutum, Coriander sativum, Murraya koenigii and Dalbergia sisso on twelve physico‐chemical properties, phenolic content, flavonoids content as well as on trace mineral (Fe, Cu, Ni, Mn, Cd and Pb) contents of honey were investigated and compared. All the physico‐chemical values were in the range of approved limits of European Commission Regulation and the source of honey had a significant (P < 0.05) effect on physico‐chemical properties, phenol content, flavonoid content and trace mineral content. The results of positive correlations between physico‐chemical properties (colour and antioxidant properties) and compositional components (phenols and flavonoids content) established that antioxidant properties were dependent on source of honey rather than on colour of honey. Pattern recognition methods such as principal component analysis and linear discriminate analysis were performed to classify honey on the basis of physico‐chemical properties, phenolic content, flavonoids content and trace metal content. The variables proline and lead exhibited higher discrimination power.     

Isolation and identification of two major acylated anthocyanins from purple sweet potato (Ipomoea batatas L. cultivar Eshu No. 8) by UPLC‐QTOF‐MS/MS and NMR

In recent years, researches on the isolation and preparation of monomeric anthocyanins have intensified because of the requirements of quantitative and structure–bioactivity relationship analyses. However, simple and effective methods about the scale of monomeric anthocyanins from the natural purple sweet potato powder are rarely reported. In this study, high molecular weight acylated monomeric anthocyanins were isolated from purple sweet potato (Ipomoea batatas L. cultivar Eshu No. 8) via the combination of column chromatography and semi‐preparative HPLC technology and identified mainly by ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight tandem mass spectrometry/mass spectrometry (UPLC‐QTOF‐MS/MS) and ¹H and ¹³C nuclear magnetic resonance (NMR). Two major acylated anthocyanins were unambiguously determined as peonidin 3‐O‐(6‐O‐(E)‐caffeoyl‐(2‐O‐(6‐O‐p‐hydroxybenzoyl)‐β‐D‐glucopyranosyl)‐β‐D‐glucopyranoside)‐5‐O‐(β‐D‐glucopyranoside) and peonidin 3‐O‐(6‐O‐(E)‐caffeoyl‐(2‐O‐(6‐O‐(E)‐feruloyl)‐β‐D‐ glucopyranosyl)‐β‐D‐glucopyranoside)‐5‐O‐(β‐D‐glucopyranoside). The results of this study may help promote the purification of high molecular weight acylated anthocyanins from purple sweet potato as well as from other plant materials in nature.     

Phenolic composition,antioxidant and pancreatic lipase inhibitory activities of Chinese sumac (Rhus chinensis Mill.) fruits extracted by different solvents and interaction between myricetin‐3‐O‐rhamnoside and quercetin‐3‐O‐rhamnoside

This work was designed to investigate the phenolic composition, antioxidant and pancreatic lipase inhibitory activities of Rhus chinensis Mill. fruits extracted by different solvents, and to illustrate which major phenolic compounds were responsible for lipase inhibition and to evaluate their interactions. Results showed that R. chinensis Mill. fruits were rich in phenolics, which included 13 types identified and quantified by UHPLC‐ESI‐HRMS/MS. Among the identified phenolics, myricetin‐3‐O‐rhamnoside and quercetin‐3‐O‐rhamnoside were the most dominant detected in all extracts. Extracts with 80% methanol, 80% ethanol and 80% acetone exhibited strong antioxidant and pancreatic lipase inhibitory activities in vitro, and these activities were positively correlated with phenolic contents. Myricetin‐3‐O‐rhamnoside and quercetin‐3‐O‐ rhamnoside demonstrated good lipase inhibitory activities in a dose‐dependent manner and synergistically inhibited lipase. This work may provide insights into the potential uses of R. chinensis Mill. fruits in food and nutraceutical industries.     

Isolation,purification and characterisation of angiotensin I‐converting enzyme–inhibitory peptides derived from catfish (Clarias batrachus) muscle protein thermolysin hydrolysates

The angiotensin I‐converting enzyme (ACE)‐inhibitory activities of catfish (Clarias batrachus) muscle protein hydrolysates were investigated. Thermolytic digests of C. batrachus sarcoplasmic and myofibrillar proteins exhibited inhibitory activity towards ACE and were purified with the aim of ultrafiltration, gel filtration and reversed‐phase high‐performance liquid chromatography (RP‐HPLC). The amino acid sequences of hydrolysates with the highest ACE‐inhibitory activities were determined using electrospray quadrupole time‐of‐flight tandem mass spectrometry (ESI‐TOFQ MS/MS). The sequences of GPPP (IC₅₀ = 0.86 μm ) and IEKPP (IC₅₀ = 1.2 μm ) corresponding to the fragments 986–989 and 441–445 of myosin‐I heavy chain were identified for the sarcoplasmic and myofibrillar protein hydrolysates, respectively. Peptide GPPP exhibited a mixed‐type inhibition whereas peptide IEKPP could only bind to the active sites of ACE. The results demonstrate that hydrolysates of C. batrachus muscle proteins obtained by thermolysin may contain bioactive peptides.     

Development of a green two‐dimensional HPLC‐DAD/ESI‐MS method for the determination of anthocyanins from Prunus cerasifera var. atropurpurea leaf and improvement of their stability in energy drinks

This study aimed to develop a green two‐dimensional HPLC‐DAD/ESI‐MS method for analysing anthocyanins from Prunus cerasifera var. atropurpurea leaf and improve their stability in energy drinks by the addition of phenolic acids. Ethanol and tartaric acid solutions were used as mobile phases for one‐dimensional HPLC‐DAD for quantitative analysis of anthocyanins, and the primary anthocyanins were identified as cyanidin‐3‐O‐galactoside, cyanidin‐3‐O‐glucoside and cyanidin‐3‐O‐rutinoside using two‐dimensional HPLC‐MS. Method validation showed that the developed method was accurate, stable and reliable for the analysis of P. cerasifera anthocyanins. The effects of gallic, ferulic and caffeic acid on the stability of cyanidin‐3‐O‐galactoside, cyanidin‐3‐O‐glucoside, cyanidin‐3‐O‐rutinoside and total anthocyanins from P. cerasifera leaf in energy drinks were evaluated, and the degradation of P. cerasifera anthocyanins ideally followed a first‐order model (R² > 0.98). Gallic acid showed stronger protective effects on P. cerasifera anthocyanins in energy drinks, and adding/increasing ferulic and caffeic acids accelerated the degradation reactions.     

Development of fermented Hericium erinaceus juice with high content of L‐glutamine and L‐glutamic acid

Fermented plant beverages (FPB) with a high content of desirable principle components are served as functional foods from several years. Hericium erinaceus is famous for its antimicrobial, antioxidant, antihypertensive and antidiabetic nature. Accordingly, the current study was aimed to produce fermented H. erinaceus juice with a high content of L‐glutamine (Gln) and L‐glutamic acid (GA) through lactic acid bacteria (LAB) isolated from fermented Thai foods. LAB isolates were screened and identified the potent protease‐producing bacteria Enterococcus faecalis (G414/1) that facilitate the production of Gln and GA through protein hydrolysis. Box–Behnken design (BBD) and response surface methodology (RSM) were adapted for the optimisation of conditions for the increased production of Gln and GA during fermentation of H. erinaceus. We succeeded with an optimum concentration of cofactor (CaCl₂), pH and temperature for improved protease activity and subsequent Gln and GA production. The ability of isolated E. faecalis strain to produce Gln and GA was demonstrated in this study. Further, upstream processes like strain improvement and media optimisation will direct the way to produce enriched H. erinaceus based FPB.     

Determination of purine alkaloids and catechins in different parts of Camellia assamica var. kucha by HPLC‐DAD/ESI‐MS/MS

BACKGROUND: Kucha (Camellia assamica var. kucha) is a novel wild tea resource grown in China and a tea plant containing a sizable amount of theacrine (1,3,7,9‐tetramethyluric acid). High‐performance liquid chromatography (HPLC) analysis of purine alkaloids and catechins in young leaves of Kucha has been reported previously. However, the compositions of purine alkaloids and catechins in other parts of the plant remain unknown, and more information about the chemical constituents of Kucha is also necessary for further research and development of this new tea resource. RESULTS: Using HPLC with diode array detection coupled with electrospray ionisation tandem mass spectrometry (HPLC‐DAD/ESI‐MS/MS), three purine alkaloids, seven catechins and four non‐catechin phenolic compounds were identified or tentatively identified in Kucha. Purine alkaloids and catechins in leaves at different developmental stages, flowers, stems, pericarps and seeds of the plant were also quantified for the first time by the HPLC method, which was fully validated. Recoveries of the quantified compounds ranged from 96.67 to 104.33%. CONCLUSION: The results showed that the total contents of purine alkaloids and catechins were highest in young leaves of Kucha. Theacrine was detected in all parts of the plant and found to be most abundant in pericarps. Copyright © 2009 Society of Chemical Industry     

Lipase‐catalysed acidolysis of mango kernel fat with capric acid to obtain medium‐ and long‐chain triacylglycerols

Mango kernel fat (MKF) was blended with capric acid (1:5 mole ratio) and subjected to acidolysis using 1,3 specific lipase Lipozyme IM (Mucor miehei) for different time intervals (30 min to 24 h). The capric acid content increased gradually up to 43.5 mol% with corresponding decrease in stearic acid content (45.7–17.4 mol%). DSC crystallisation thermograms showed a new exothermic peak at lower temperature, and HPLC profile showed new peaks both indicating the formation of new lower melting triglycerides. A decrease in higher melting triglycerides and gradual increase in new triglycerides was observed. Two prominent newly formed triglycerides were characterised by ESI/MS studies and identified as 2‐oleo‐dicaprin (10, 18′, 10) and stearo‐oleo‐caprin (18, 18′, 10). Solid fat content decreased at all temperatures and samples interesterified for 5 h remained liquid at ambient conditions. The modified MKF can increase the food application from MKF in addition to contributing to health benefits of medium‐ and long‐chain triglycerides.     

Effect of plant polyphenols and ascorbic acid on lipid oxidation,residual nitrite and N‐nitrosamines formation in dry‐cured sausage

The effects of green tea,grape seed polyphenols and ascorbic acid on pH, water activity (a_w), microbiological counts, TBARS, residual nitrite and N‐nitrosamines were determined in dry‐cured sausages during the ripening period. Results showed that TBARS increased gradually during ripening (P < 0.05), but were significantly reduced with plant polyphenols and ascorbic acid (P < 0.05). Green tea polyphenol (GTP) was most effective (P < 0.05) in reducing TBARS. Plant polyphenols and ascorbic acid significantly decreased residual nitrite, ascorbic acid being most effective (P < 0.05). The amount of N‐nitrosamines increased during ripening, but was significantly reduced with plant polyphenols and ascorbic acid (P < 0.05). Plant polyphenols had no significant effects on moisture content, a_w, pH or microbiological counts in dry‐cured sausage during ripening (P > 0.05). It was concluded that plant polyphenols and ascorbic acid were effective in maintaining the quality and safety of dry‐cured sausages.     

Changes during storage of dried Moringa oleifera leaves prepared by heat pump‐assisted dehumidified air drying

Moringa oleifera leaves contain phytochemicals that are retained during heat pump‐assisted dehumidified air drying. Changes in phytochemicals, antioxidant capacity and colour were evaluated at 15–35 °C, during storage of dried leaves in polypropylene (PP) or high barrier (PET/Al/PE) packaging for up to 6 months. The a_w of samples in PP increased from 0.373 to 0.669. Decreases in total phenolics were greatest at 35 °C in PP (48%) and least at 15 °C in PET/Al/PE (19%). There were few significant changes in DPPH inhibition after 2 months storage. There was little change in kaempferol and some increase in quercetin. During storage, samples became less green, suggesting breakdown in chlorophyll had occurred. The degradation of flavonoids followed first‐order kinetics. The half‐life for total flavonoids ranged from 2.13 to 1.47 months for samples stored in PP and from 2.59 to 1.83 months for samples stored in PET/Al/PE.     

Efficacy of Acorus calamus L. essential oil as a safe plant‐based antioxidant,Aflatoxin B1 suppressor and broad spectrum antimicrobial against food‐infesting fungi

The study explores the efficacy of Acorus calamus L. essential oil (EO) as a safe plant‐based broad spectrum antifungal, antiaflatoxin, antioxidant food additive. The oil completely inhibited the growth and toxin production of the toxigenic strain of Aspergillus flavus at 0.4 and 0.25 μL mL^?1, respectively. EO exhibited pronounced antifungal activity against sixteen food‐infesting fungal species at 0.5 μL mL^?1. The EO showed strong antioxidant efficacy (IC₅₀ 1.06 μL mL^?1) and nonphytotoxic nature on germination of chickpea seeds. The EO was found nonmammalian toxic showing high LD₅₀ (4877.4 μL kg^?1) for mice (oral, acute). The chemical profile of EO was determined through GC and GC–MS analysis. The findings strengthen the possibility of A. calamus EO as a plant‐based food additive in view of its favourable safety profile, antioxidant and antiaflatoxigenic efficacy and broad spectrum antimicrobial activity against food‐infesting fungi.     

Anti‐inflammatory properties of high pressure‐assisted extracts of Grifola frondosa in lipopolysaccharide‐activated RAW 264.7 macrophages

The aim of this study was to determine the in vitro anti‐inflammatory properties of the shake extract (SE) and the high pressure‐assisted extract (PE) of the mycelia of Grifola frondosa in a lipopolysaccharide‐stimulated RAW 264.7 macrophage model. The content of total polysaccharides and β‐glucans of PE at 600 MPa (PE‐600) was 41.2 and 6.2 mg g^?1 dry weight, respectively, which were significantly higher than SE extracts. The results showed that treatment with 500 μg mL^?1 of PE by 600 MPa (PE‐600) did not reduce RAW 264.7 cell viability but did significantly inhibit the production of LPS‐induced NO, PGE₂ and intracellular ROS. The PE‐600 inhibited the activation of NF‐kB and then reduced the production of LPS‐induced TNF‐α, IL‐6 and IL‐1β in a dose‐dependent manner. Thus, the PE could be used as an alternative extraction method for improving the extraction efficacy of G. frondosa and serve as an alternative source of anti‐inflammatory agents.     

γ‐Glu‐Met synthesised using a bacterial glutaminase as a potential inhibitor of dipeptidyl peptidase IV

This study describes γ‐glutamyl dipeptides as competitive inhibitors of dipeptidyl peptidase‐IV (DPP‐IV), and the feasible synthesis of γ‐Glu‐Met through transpeptidation catalysed by a commercial glutaminase of Bacillus amyloliquefaciens. γ‐Glu‐Met, γ‐Glu‐Leu, γ‐Glu‐Phe, γ‐Glu‐Trp or γ‐Glu‐Tyr exhibited a competitive inhibitory effect on DPP‐IV. The yield of γ‐Glu‐Met was 26.16% under optimised conditions: 200 mm Gln, 20 mm Met, 0.1 U mL^?1 enzyme, pH 9.0, 37 °C and reaction time 3 h. For the first time, the side products containing characteristic sequences, that is poly‐γ‐glutamyl short chains with a terminal Met residue (γ‐Glu‐γ‐Glu‐Met and γ‐Glu‐γ‐Glu‐γ‐Glu‐Met) were identified. The superiority of the commercial glutaminase in the synthesis of DPP‐IV‐inhibitory peptides can enable the application of this novel process for manufacturing γ‐glutamyl‐peptides as potential functional ingredients in the type 2 diabetic diet.     

Presence of two forms of methylated (–)‐epigallocatechin‐3‐gallate in green tea

Crude catechins extract from Chinese green tea were fractionated using Sephadex LH‐20 column chromatography. The fraction containing (–)‐epigallocatechin‐3‐gallate (EGCG) was then subjected to a semipreparative high‐performance liquid chromatography (HPLC). Using a mobile phase of water : dimethyl formamide : methanol : acetic acid (157 : 49 : 2 : 1 v/v/v/v( the mixture of two methylated catechins was separated and isolated. According to mass spectrometry (MS) and nuclear magnetic resonance (¹H‐NMR) date, these compounds were identified as (–)‐epigallocatechin‐3‐(3‐O‐methylgallate) and (–)‐epigallocatechin‐3‐(4‐O‐methylgallate).     

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.     

3‐Hydroxypyridinone‐l‐phenylalanine conjugates with antimicrobial and tyrosinase inhibitory activities as potential shrimp preservatives

To explore the potential of novel tyrosinase inhibitors, 3‐hydroxypyridinone‐l ‐phenylalanine conjugates, as shrimp preservatives, compounds 1 and 2 were evaluated for the antimicrobial activity, and compound 2 was investigated for the shrimp preservative efficacy. It was found that they both possess a stronger antibacterial effect than kojic acid against two Gram‐positive bacteria and three Gram‐negative bacteria. The minimum inhibitory concentrations (MICs) of compound 2 against Escherichia coli, Staphylococcous aureus, Salmonella gallinarum, Vibrio parahaemolyticus and Bacillus subtilis were determined as 18.5, 37, 148, 37 and 295 μg mL^?1, respectively, whereas MICs of kojic acid against the same 5 bacterial strains were determined to be 355, 178, 1420, 1420 and 355 μg mL^?1, respectively. It has also been demonstrated that treatment with compound 2 improves the sensory properties, retards the growth of spoilage bacteria, decreases the total volatile basic nitrogen (TVB‐N) and increases the pH of Penaeus vannamei Boone, thereby extending the shelf life to 10 days. In contrast, the shelf life of shrimp treated with kojic acid and the control group was 7 and 6 days, respectively. Clearly, 3‐hydroxypyridinone‐l ‐phenylalanine conjugates could find application as shrimp preservatives by inhibiting melanosis and by preventing the growth of bacteria during the storage.