High-performance Liquid Chromatography-electrospray Ionization-mass Spectrometry Research Articles

Condensed tannins from the leave of Dimocarpus longan Lour. exhibit anti-tyrosinase, anti-melanogenesis, anti-browning, anti-α-glucosidase, and anti-glycation activities

Dimocarpus longan Lour. is a valuable industrial crop for its broad applications in food, traditional Chinese medicine, and other fields. In this paper, condensed tannins were isolated from the leave of D. longan Lour., and their structure, anti-tyrosinase, anti-melanogenesis, anti-browning, anti-α-glucosidase, and anti-glycation properties were methodically clarified. The joint application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), electrospray ionization time-of-flight mass spectrometer (ESI+ TOF MS), and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) confirmed that the longan leave condensed tannins (LLCTs) were polymers of procyanidins (majority) and prodelphinidins. The polymers powerfully inhibit tyrosinase (TY) with a competitive mechanism. These compounds altered the microenvironment of the binding site through hydrophobic interaction and hydrogen bond, and caused conformational modification of the enzyme by changing the polypeptide framework and secondary structure, leading to a decrease in TY activity. Cell assays further suggested that LLCTs exhibited a strong inhibition against intracellular TY activity and melanin production, and caused apoptosis in B16F10 cells. Anti-browning studies demonstrated that LLCTs suppress the browning of fresh-cut apples. Furthermore, the LLCTs exhibited an impressive inhibition on both α-glucosidase and nonenzymatic glycation. Therefore, this study confirms the potential of LLCTs as new inhibitors of tyrosinase, melanogenesis, browning, α-glucosidase, and nonenzymatic glycation, which provided a theoretical basis for the potential utilization of these polymers in the cosmetics, pharmaceutical, and food industries.

Brown sugar polyphenols as natural inhibitors of α‐amylase and α‐glucosidase enzymes

SummaryThis study investigated the compositional profile and inhibitory effect of brown sugar polyphenols (BSPs) on porcine pancreatic α‐amylase (PPA) and Baker's yeast α‐glucosidase (BYG) activities. The HPLC‐ESI‐MS (high‐performance liquid chromatography‐electrospray ionisation‐mass spectrometry) analysis showed that BSPs comprised of four hydroxybenzoic acids including protocatechuic, p‐hydroxybenzoic, vanillic and syringic acids (PA, PHBA, VA and SA, respectively) and three hydroxycinnamic acids including chlorogenic, p‐coumaric and ferulic acids (CHA, PCA and FA, respectively), where CHA (29.24%) and SA (31.31%) were the main BSPs. The enzyme inhibition analysis expressed as IC50 values (except PA and VA) showed that CHA, PCA and FA exhibited higher PPA and BYG inhibitory activities than PHBA and SA, following the order of CHA > PCA > FA > PHBA > SA. Moreover, the BSPs showed better inhibitory activities against BYG than PPA. The inhibition mechanism analysis through inhibitory kinetics, fluorescence quenching, differential scanning calorimetry and molecular docking demonstrated that the BSPs inhibited the enzymes by binding with them mainly via hydrogen bonds. The results suggested that BSPs could be natural inhibitors of PPA and BYG.

Characterization of Phenolic Compounds of Olea europaea L. and Ceratonia siliqua L. Leaf Extracts by HPLC-ESI-MS

Background: Olive (Olea europaea L.) and carob (Ceratonia siliqua L.), which contain considerable amounts of phenolic compounds, are the most important nutritional and therapeutic plants in the Mediterranean basin. Objectives: The goal of this work is to revalue carob and olive leaves as key sources of polyphenols, hence increasing the value of waste goods. Methods: In this study, aqueous acetone or ethanol (80% v/v) extracts of olive (O. europaea L. cultivar aimel) and carob (C. siliqua L.) leaves from Algeria were evaluated for phenolic content, and the extracts were characterized by reverse-phase high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS). Discussion and Results: The total phenolic content of olive and carob leaf extracts ranged from 5.6 to 23 mg GAE/g. The use of HPLC-ESI-MS to investigate phenolics revealed that the extracts included a variety of phenolic compounds, including 23 compounds in olive leaf extracts and 17 compounds in carob leaf extracts. In olive and carob, the major phenolic components are oleuropein and myricetin rhamnoside, respectively. Conclusion: According to our findings, olea europaea and Ceratonia siliqua appear to be rich suppliers of natural chemicals. These plants have a lot of potential in terms of medications and functional foods.

Speciation of inorganic arsenic with mixed mode HPLC-ESI-MS and Arsenite Oxidation

It has been challenging to analyze inorganic arsenic (iAs) with anion exchange HPLC-Electrospray Ionization-Mass spectrometry (HPLC-ESI-MS), because arsenite (As(III)) is difficult to retain on column and the salts in mobile phase causes ionization suppression of iAs. To address these issues, a method has been developed involving the determination of arsenate (As(V)) with mixed mode HPLC-ESI-MS and the conversion of As(III) to As(V) for total iAs. As(V) was separated from other chemicals on Newcrom B, a bi-modal HPLC column involving anion exchange and reverse phase interaction. The elution employed a two-dimensional gradient, including a formic acid gradient to elute As(V) and a concurrent alcohol gradient to elute organic anions used in sample preparations. As(V) was detected by Selected Ion Recording (SIR) in negative mode at m/z = 141 with a QDa (single quad) detector. As(III) was quantitatively converted to As(V) by mCPBA oxidation and measured for total iAs. By replacing salt with formic acid in elution, the ionization efficiency for As(V) was greatly enhanced in ESI interface. The limit of detection (LOD) for As(V) and As(III) were 0.0263 μM (1.97 ppb) and 0.0398 μM (2.99 ppb), respectively. The linear range was 0.05–1 μM.The method has been used to characterize iAs speciation change in the solution and precipitation in a simulated iron-rich groundwater caused by air exposure.

Phytochemical Screening, Antioxidant Potential, and LC-ESI-MS Profiling of Ephedra alata and Ephedra altissima Seeds Naturally Growing in Tunisia.

Most Ephedra species are adapted to arid and desert conditions and are widely used in folk medicine to treat several disorders. The design of the current study was to determine the functional properties of seeds of two Ephedra species (E. alata and E. altissima) naturally growing in Tunisian arid zones by evaluating their mineral contents and bioactive compounds. The flame atomic absorption spectrometry revealed that seeds contained remarkable amounts of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn), and iron (Fe). The colorimetric investigation revealed high total polyphenol, flavonoid, and condensed tannin contents. Furthermore, by utilizing high-performance liquid chromatography-electrospray ionization-mass spectrometry method (HPLC-ESI/MS), a total of 11 phenolics were identified and quantified including 7 flavonoid compounds and 4 phenolic acids that were mostly predominated by gallic acid and quercetrin. Results so far have been very encouraging and proved that Ephedra seeds are a valuable source of natural bioactive compounds and minerals which could potentially be used for industrial and pharmaceutical purposes.

Structure analysis and tyrosinase, melanogenesis, α-glucosidase, and nonenzymatic glycation inhibitory activities of polymeric proanthocyanidins from the pulp of Crataegus pinnatifida Bge.

Crataegus pinnatifida Bge. is a worthwhile industrial crop for its extensive application in Chinese herbal pharmaceuticals, food, and other industries. In this study, proanthocyanidins were extracted from the pulp of Crataegus pinnatifida Bge., and the structure, antityrosinase, antimelanogenesis, anti-α-glucosidase, and anti-glycation activities of these compounds were systematically elucidated. The combined utilization of high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS), matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), and nuclear magnetic resonance (NMR) demonstrated that the proanthocyanidins were B-type procyanidin polymers consisting of epicatechin . These polymers were efficient, reversible, and competitive inhibitors of both tyrosinase and α-glucosidase with IC 50 values of 0.10 ± 0.01 mg/mL (for monophenolase), 0.16 ± 0.02 mg/mL (for diphenolase), and 0.50 ± 0.02 µg/mL, respectively. Moreover, the process of nonenzymatic glycation was also delayed by proanthocyanidins. Further cell assays suggested that these polymers strongly inhibited intracellular tyrosinase activity and melanogenesis and induced apoptosis in mouse melanoma cells. The results of circular dichroism (CD), molecular docking , and molecular dynamics (MD) consistently revealed that the inhibition of procyanidins on the two enzymes was primarily driven by hydrogen bonding and hydrophobic interactions, and the binding of epicatechin caused structural stretching and conformational modification of tyrosinase. Consequently, this study confirms novel tyrosinase, melanogenesis, α-glucosidase, and nonenzymatic glycation inhibitors, which might offer scientific evidence for potential applications in the cosmetics and pharmaceutical industries. • Proanthocyanidins can be produced industrially for a yield of 11.08%. • Various biological activities of proanthocyanidins enabled their wide applications. • Hydrogen bond and hydrophobic interaction loosened tyrosinase secondary structures. • Proanthocyanidins can reduce melanogenesis by down-regulating tyrosinase proteins.

Simultaneous Determination of Glibenclamide and Silymarin Released from Chitosan Microparticles by HPLC-ESI-MS Technique: Method Development and Validation.

The study aim was to develop and validate a high-performance liquid chromatography–electrospray ionization mass spectrometry (HPLC-ESI-MS) method to simultaneously determine glibenclamide (Gli) and silymarin (Sil) released from chitosan (CS) microparticles in aqueous solutions. The CS microparticles were synthesized using an ionic gelation method, and their morphology, swelling degree, encapsulation efficiency and active substance release were investigated. Gli and Sil were loaded in different concentrations, and their identification and quantification were performed using the HPLC-ESI-MS method, which was further validated. The drugs’ characteristic m/z was found in the higher intensity of retention time (Rt) (Gli, 8.909 min; Sil A, 5.41 min; and Sil B, 5.66 min). The method selectivity and precision are very good, and the blank solution proved no interference. The linearity of the answer function is very good for Sil A (R2 = 1), Sil B (R2 = 0.9998) and Gli (R2 = 0.9991). For Gli, we obtained a limit of detection (LOD) = 0.038 mg/mL and limit of quantification (LOQ) = 1.275 mg/mL; for Sil A, a LOD = 0.285 mg/mL and LOQ = 0.95 mg/mL; and for Sil B, a LOD = 0.045 mg/mL and LOQ = 0.15 mg/mL. A high-resolution HPLC-ESI-MS method was developed and validated, which allowed the simultaneous determination of Gli and Sil loaded in CS microparticles, in a concentration range of 0.025–1 mg/mL.

Horseradish Peroxidase–mediated Polymerization of Natural Phenol and Pyrrole for Coloration and Functionalization of Silk Fabrics

ABSTRACT In this study, we successfully polymerized natural phenol (gallic acid, ferulic acid) and pyrrole (Py) monomers by oxidative polymerization of horseradish peroxidase (HRP). Then, we successfully colored silk fabrics using these chemicals. We analyzed the polymerization mechanism of polyphenol and polypyrrole complexes in detail using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS). In addition, we investigated the electrochemical activity, thermal properties and anti-UV activity of the colored silk fabrics. We found that the oxidative polymerization of phenol and Py on silk fibers under mild reaction conditions using HRP produced technically conductive silk fabrics that combine the superior chemical and physical properties of silk fabrics with superior levels of electrochemical activity and thermal stability. Upon analyzing the color depth of the fabrics, we found that silk fabrics treated with Py have a darker color than silk fabrics treated in the absence of Py. Additionally, the fabrics had slightly different levels of color fastness, but all were within the acceptable range. This technique expands the range of applications of natural phenols for textile dyeing and functionalization as well as providing new prospects for the enzymatically environmentally friendly production of natural functional fabric.

Maceration and liquid-liquid extractions of phenolic compounds and antioxidants from Algerian olive oil mill wastewater.

Olive oil mill wastewater (OMW) is a major waste stream generated in olive oil industry. It is highly polluted due to phenolic compounds. The present study focused on the physicochemical properties of OMW as well as the quantitative and qualitative effects of two extraction methods of phenolic compounds which were liquid-liquid and maceration methods. Spectrophotometry and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) were adopted to quantify the phytochemical contents and the phenolic compounds. The extract obtained by the maceration method showed the highest yields of total polyphenol, flavonoid, and tannin contents. The LC-MS results revealed the presence of 16 phenolic compounds in the macerated, and only 12 phenolic compounds were found in the extract of the second method. Quinic acid was identified as the most abundant compound. Moreover, the macerated extracts possessed the highest antioxidant potential as evidenced by their strong ferric reducing antioxidant power (FRAP) and their 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging activities. The phytochemical contents, as well as the antioxidant potentials of OMW after extraction using maceration, were significantly greater than using liquid-liquid method. Therefore, maceration seemed to be the most effective method for extracting phenolic compounds from OMW. The OMW constitute a rich source of natural phenolic compounds that could be used as a potential source of natural antioxidants.

Horseradish peroxidase‐mediated polyethylene glycol‐templated polymerisation of gallic acid and pyrrole to improve the functionalisation and dyeing properties of silk fabrics

AbstractSilk fabrics treated with gallic acid/pyrrole (PGA/PPy) complexes polymerised using horseradish peroxidase have higher electrochemical activity than silk fabrics dyed with gallic acid alone. However, the degree of polymerisation decreases. As a result, the ultraviolet (UV) protection and fastness of the silk fabric were lowered. To solve this problem, we studied the degree of polymerisation of the complex and the functionality of dyed silk fabrics by applying a polyethylene glycol (PEG) template to the enzymatic polymerisation of PGA/PPy. The polymerisation mechanism of the complexes was analysed in detail using UV‐visible spectroscopy, Fourier‐transform infrared (FTIR) spectroscopy, and high‐performance liquid chromatography electrospray ionisation mass spectrometry (HPLC‐ESI‐MS). Consequently, the PGA/PPy/PEG complex has a higher degree of polymerisation than the PGA/PPy prepared without PEG, indicating that the PEG template can promote the polymerisation of PGA and PPy. As a result, we found that the presence of the PEG template improved the thermal stability and UV protection function of the dyed silk fabric, but did not impair the electrochemical activity of silk fabric. As a result of analysing the colour depth, it exhibited a higher K/S value compared to the dyed silk fabric in the absence of PEG. Additionally, its colour fastness was improved.

Phenolic Profile and Fingerprint Analysis of Akebia quinata Leaves Extract with Endothelial Protective Activity.

In contrast to the stem and fruit of Akebia quinata, A. quinata leaves as a source rich in phenolic compounds with potentially beneficial pharmacological activities have been largely overlooked. To develop and use A. quinata leaves as a resource, we evaluated its potential as a cardiovascular-protective agent. Herein, we investigated the effects and potential mechanisms of A. quinata leaves extract on lipopolysaccharide (LPS)-induced inflammatory responses in human umbilical vein endothelial cells. We found that A. quinata leaves extract pretreatment of 10 μg/mL significantly attenuated LPS-induced protein expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1. Furthermore, this extract also suppressed LPS-induced phosphorylation of nuclear factor-κB p65. In order to elucidate the chemical profiles of the samples, the HPLC fingerprint was established, and prominent peaks were identified via HPLC–electrospray ionization–mass spectrometry. Multivariate statistical analyses, including hierarchical cluster analysis, principal component analysis, and partial least-squares discriminant analysis, were performed to evaluate the clustering of the samples. It was found that isochlorogenic acid C was a key marker for the classification of A. quinata leaves from the Gongju and Muju city in Korea. Collectively, this study not only suggested the potential of A. quinata leaves as a novel therapeutic candidate for inflammatory cardiovascular disease but also developed a quality control method for A. quinata leaves, which could help to expand the application of A. quinata.

Is selenium beneficial or detrimental to earthworm? Growth and metabolism responses of Eisenia Fetida to Na2SeO3 exposure

Se unevenly distributed in soils due to variations of geology and anthropogenic input, which results in different effects on earthworms. The effects of Se were characterized by analyzing the growth and metabolism responses of earthworms after exposure to three different concentrations of Na2SeO3. The results showed that except the possible growth promotion at 5 mg/kg, low and middle-level exposure to Na2SeO3 (0.3–10 mg/kg) did not significantly affect the growth of earthworms. While a significant inhibition effect on growth was observed in the high-level exposure group (30–70 mg/kg). There was an inflection point for Se performing promotion to inhibition effects on earthworm growth. To investigate the metabolic response of earthworms, a novel HPLC-ESI-MS (High Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry) method was used to determine sensitive biomarkers. Selenium exposure significantly altered the metabolism of seven essential amino acids, namely tyrosine, leucine, phenylalanine, valine, alanine, glycine, and lysine, and two selenoamino acids, namely selenomethionine and methylselenocysteine. The overall metabolism level of earthworms was not affected at low exposure concentrations, but was affected at medium and high exposure concentrations. The metabolic pathways that integrated the selenocompound metabolism and the tricarboxylic acid cycle from the perspective of energy supply and demand were affected by Na2SeO3 exposure. The derived reactive oxygen species at high exposure concentrations were probably the reason for the growth inhibition effect of Se on earthworms. This study provides biochemical insights into the effects of Na2SeO3 on earthworms and suggests that an Se concentration of about 2.3 mg/kg is appropriate for soil organism health.

Secondary metabolic profiles and anticancer actions from fruit extracts of immature pomegranates.

Immature fruits from Punica granatum L. thinning are a neglected side product of pomegranate production with cumbersome disposal costs for farmers. To explore value potential of immature fruits from pomegranate ‘Wonderful’ cultivars, the compositional landscapes and antitumorigenic activities of pomegranate extracts from two different stages of maturation were assessed. Cancer cell proliferation and cytotoxicity was quantified in human lung H1299 and colon HCT116 adenocarcinomas by crystal violet staining, MTS assay and caspase-3 activity. High performance liquid chromatography—diode array detector (HPLC/DAD) and high performance liquid chromatography—electrospray ionization—mass spectrometry (HPLC/ESI-MS) analyses indicate that immature fruits are rich sources of gallotannins and ellagitannins, with the highest amounts contained in immature fruit peels. Biological investigations reveal a robust anticancer activity by those immature P. granatum fruit extracts, which reflected induction of tumor cytotoxicity and cell death mechanisms. Together, present observations suggest P. granatum byproducts from the thinning process may provide unexplored values for virtuous circular economy.

Spectral Characteristics Related to Chemical Substructures and Structures Indicative of Organic Precursors from Fulvic Acids in Sediments by NMR and HPLC-ESI-MS.

The aim of this work was to determine Fulvic Acids (FAs) in sediments to better know their composition at the molecular level and to propose substructures and structures of organic precursors. The sediment samples were obtained from a priority area for the conservation of ecosystems and biodiversity in Mexico. FAs were extracted and purified using modifications to the International Humic Substances Society method. The characterization was carried out by 1D and 2D nuclear magnetic resonance (NMR) and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) in positive (ESI+) and negative (ESI−) modes. Twelve substructures were proposed by the COSY and HSQC experiments, correlating with compounds likely belonging to lignin derivatives obtained from soils as previously reported. The analysis of spectra obtained by HPLC-ESI-MS indicated likely presence of compounds chemically similar to that of the substructures elucidated by NMR. FAs studied are mainly constituted by carboxylic acids, hydroxyl, esters, vinyls, aliphatics, substituted aromatic rings, and amines, presenting structures related to organic precursors, such as lignin derivatives and polysaccharides.

Separation, kinetics of purification of syringin by macroporous resin from Syringa oblata Lindl. leaves and the evaluation of bioactivities

PurposeThis paper aims to explore the adsorption kinetics of syringin from Syringa oblata Lindl. leaves on macroporous resin and develop an efficient, simple and recyclable technology for the separation and purification of syringin.Design/methodology/approachStatic adsorption and desorption properties of six resins were tested to select a suitable resin for the purification of syringin. Langmuir and Freundlich isotherm models were used to estimate the adsorption behavior of syringin on AB-8 resin. Breakthrough point and eluent volume were determined by dynamic adsorption and desorption tests. High-performance liquid chromatography-electrospray ionization-mass spectrometry was applied to identify the syringin in the purified product [syringin product (SP)]. Antioxidant and antibacterial activities of SP in vitro were evaluated by free radical scavenging ability and biofilm formation inhibitory tests.FindingsAB-8 exhibited the most suitable adsorption and desorption capacity. Adsorption isotherm parameters indicated favorable adsorption between AB-8 and syringin. The optimal results were as follows: for adsorption, the sample concentration was 1.85 mg/mL, the sample volume was 3.5 bed volume (BV), the flow rate was 0.5 mL/min; for desorption, the ethanol concentration was 70%, the elution volume was 2.5 BV, the elution velocity was 1.0 mL/min. SP with 80.28% syringin displayed the potent antioxidant activities and inhibitory effects on biofilm formation of Streptococcus suis.Originality/valueTo the best of authors’ knowledge, there are no reports on purifying syringin from Syringa oblata Lindl. leaves using macroporous resins. This paper may also provide a theoretical reference for the purification of other phenylpropanoid glucosides.

Simultaneous extraction of polysaccharides and polyphenols from blackcurrant fruits: Comparison between response surface methodology and artificial neural networks

A procedure for simultaneous extraction of polysaccharides and polyphenols from blackcurrant fruits by microwave-assisted aqueous two-phase system (MA-ATPS) was studied. Ethanol/(NH4)2SO4 was determined as the most suitable ATPS including 18.99 % (NH4)2SO4 and 31.65 % of absolute ethanol. Apart from response surface methodology (RSM), artificial neural network linked genetic algorithms and grey relational analysis (ANN-GA-GRA) was also employed to optimize the extraction process of polysaccharides and polyphenols from blackcurrant fruits. GA was used to give assistance to the parameters optimization of ANN model and GRA was subsequently utilized to optimize the variables. ANN model displayed relatively higher coefficient of determination (R2, 0.9805) and lower absolute average deviation (AAD, 0.6648) than those of RSM (R2 = 0.9783, AAD = 0.8505), indicating ANN possessed more excellent prediction and estimation capabilities. Under the optimum conditions (liquid-to-material ratio, extraction time, extraction temperature and microwave power predicted by RSM were 60.01 mL/g, 9.96 min, 59.57 °C, and 592.98 W, while predicted by ANN were 56.10 mL/g, 9.78 min, 60.92 °C, and 640.78 W), the yields of polysaccharides, anthocyanins, polyphenols, and DPPH radical scavenging activities of two phases given by ANN (46.75 %, 6.75 mg/g, 53.51 mg/g, 95.17 %, and 97.05 %) were higher than those deriving from RSM (43.48 %, 6.62 mg/g, 52.48 mg/g, 93.72 %, and 96.65 %). In addition, gas chromatography (GC) analysis confirmed that the polysaccharides in bottom phase were composed of six monosaccharides, and thirteen phenolic compounds were determined in the extract of top phase by high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). Therefore, microwave-assisted ethanol/(NH4)2SO4 extraction may be a promising technique to simultaneously prepare multiple active compounds from blackcurrant, and ANN-GA-GRA was an effective mathematical model to predict and optimize this extraction process.

Improving sesquiterpenoids production of Sarcandra glabra callus culture

Sarcandra glabra, a traditional Chinese medicine and herbal tea, has benefits from treating inflammation and fractures to curing cancer. The anti-inflammatory properties of sesquiterpenoids (chloranthalactone A, CTA; atractylenolide II, AT-II) have made S. glabra to a great potential for research and development. Here this study developed S. glabra callus culture to circumvent particular needs of the plant growing seasons and Hardiness zone, with the goal being able to produce sesquiterpenoids in vitro. The half strength Murashige and Skoog (1/2MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D, 2.0 mg/L) and 6-benzylaminopurine (6-BA, 1.0 mg/L) was effective for callus induction. The 1/2MS medium supplemented with 2,4-D (2.0 mg/L) and 6-BA (0.5 mg/L) was superior for callus proliferation. The callus was friable, yellowish and rapidly grown without tissue differentiation. Moreover, high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis indicated that the contents of CTA and AT-Ⅱ in multiple subculture S. glabra callus were 3.72 ± 0.51 mg/g and 0.50 ± 0.12 mg/g in fresh weight (FW), respectively. Using abiotic stresses and elicitors, production of CTA (by ultraviolet-B radiation for 48 h) and AT-II (by methyl jasmonate, 100 μmol/L) was enhanced by 2.3-fold. In conclusion, this work not only established the S. glabra callus culture for in vitro production of CTA and AT-II, but also provided the foundation for further development and utilization of S. glabra.

Analysis of Polygonum Aviculare and Polygonum Maritimum for Minerals by Flame Atomic Absorption Spectrometry (FAAS), Polyphenolics by High-Performance Liquid Chromatography-Electrospray Ionization – Mass Spectrometry (HPLC-ESI-MS), and Antioxidant Properties by Spectrophotometry

Polygonum aviculare and Polygonum maritimum, commonly known as knotgrass and sea knotgrass, have been widely used for several purposes. Leaves, stems, and roots of these species were evaluated for mineral composition, phytochemical contents, and antioxidant properties. The minerals were characterized by flame atomic absorption spectrometry (FAAS). The polyphenolics were investigated colorimetrically and by high-performance liquid chromatography-electrospray ionization – mass spectrometry (HPLC-ESI-MS). The antioxidant potential was evaluated by total antioxidant capacity (TAC), DPPH-radical scavenging activity, and reducing power (RPA). The mineral contents differed remarkably between and within species. For P. maritimum, the leaves showed the highest sodium, potassium, calcium, and magnesium contents while the roots accumulated the highest iron. The stems of P. aviculare contained higher Na, K, Ca and Fe compared to roots and leaves. P. maritimum extracts contained higher phytochemical contents compared to P. aviculare. The stems and leaves of P. maritimum were the richest in polyphenols and flavonoids while the roots possessed the highest condensed tannins. For P. aviculare, the stems contained the highest phenolics. HPLC-ESI-MS determined 20 phenolics including quinic acid, gallic acid, protocatechuic acid, (+)-catechin, quercetin-3-O-galactoside, and cirsiliol. P. maritimum extracts contained more antioxidants than P. aviculare. The results suggest that the selected species may be important sources of bioactive molecules.

HPLC–electrospray ionization–mass spectrometry optimization by high‐performance design of experiments for astrocyte glutamine measurement

AbstractThe amino acid glutamine (Gln) is a likely source of energy in the brain during neuroglucopenia. Effects of glucose deficiency on astrocyte Gln homeostasis remain unclear, as analytical tools of requisite sensitivity for quantification of intracellular levels of this molecule are not currently available. Here, a primary hypothalamic astrocyte culture model was used in conjunction with design of experiments (DOE)‐refined high‐performance liquid chromatography–electrospray ionization–mass spectrometry (LC–ESI–MS) methodology to investigate the hypothesis that glucoprivation alters astrocyte Gln content in a sex‐specific manner. Critical mass spectrometric parameters for Gln derivative chromatographic response were identified by comparing the performance of central composite design, Box–Behnken design, and Optimal Design (OD)‐A, ‐D, ‐I, ‐Distance, and ‐Modified Distance DOE models. The outcomes showed that the OD‐A‐generated response was superior relative to other design outcomes. Forecasted surface plot critical mass spectrometric parameters were maximized by OD‐A, OD‐Distance, and OD‐Modified Distance designs. OD‐A produced a high‐performance method that yielded experimental run and forecasted surface plot maximal responses. Optimized mass spectrometric analysis of male versus female astrocyte Gln content provides novel evidence that glucoprivation significantly depletes this amino acid in female, but not in male, and that this sex‐specific response may involve differential sensitivity to estrogen receptor signaling. This technological advance will facilitate efforts to ascertain how distinctive physiological and pathophysiological stimuli impact astrocyte Gln metabolism in each sex.

Anti-tyrosinase and antioxidant activity of proanthocyanidins from Cinnamomum camphora

ABSTRACT In this study, total phenols (TP) and proanthocyanidins (PAs) in the leaves and branches of Cinnamomum camphora were investigated, and isolated PAs were determined using reversed-phase high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS). The anti-tyrosinase and antioxidant activities were also evaluated. Furthermore, scanning study and dihydroxyphenylalanine (L-DOPA) oxidation were performed to further analyze the inhibition mechanism of PAs on tyrosinase catalytic activity. PAs had strong inhibitory effects on tyrosinase monophenolase activity, with effectively prolonged the delay time and decreased the steady-state of monophenolase activity. For diphenolase activity, PAs both showed reversible and mixed inhibition. Moreover, the PAs showed strong antioxidant activities in scavenging 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 1,2ʹ-azino-bis(3-ethylbenzthiazoline-6-sulphonicacid) (ABTS) and the ferric reducing antioxidant power (FRAP) assays. The PAs in leaves showed stronger anti-tyrosinase and antioxidant capacity, suggesting that C. camphora may be a good resource for tyrosinase inhibitors and antioxidants. This study could provide a scientific basis for the resource utilization of C. camphora and the development of new natural tyrosinase inhibitors and antioxidants in medical, cosmetic, food, and agricultural industries.