Ultra-performance Liquid Chromatography-electrospray Tandem Mass Research Articles

High-Performance Liquid Chromatographic Quantification of the Plant Hormone Abscisic Acid at ppb Levels in Plant Samples after a Single Immunoaffinity Column Cleanup.

High-performance liquid chromatography with ultraviolet detection (HPLC-UV) is a common analysis technique due to its high versatility and simple operation. In the present study, HPLC-UV detection was integrated with immunoaffinity cleanup (IAC) of the sample extracts. The matrix effect was greatly reduced, and the limit of detection was as low as 1 ng/g of free abscisic acid (ABA) in fresh plant tissues. A monoclonal antibody 3F1 (mAb 3F1) was developed to specifically recognize free ABA but not ABA analogues. The mAb 3F1-immobilized immunoaffinity column exhibited a capacity of 850 ng/mL and an elution efficiency of 88.8-105% for standards. The extraction recoveries of the column for ABA ranged from 80.4 to 108.9%. ABA content was detected in various plant samples with IAC-HPLC-UV. The results were verified with ultraperformance liquid chromatography-electrospray tandem mass spectrometry. IAC-HPLC-UV can be a sensitive and cost-efficient method for plant hormone analysis.

Nutrition and flavor analysis of Spirulina through co-fermentation with Lactobacillus acidophilus and Kluyveromyces marxianus and its effect on attenuating metabolic associated fatty liver disease

Spirulina is widely known as the “Super Nutritious Food of the Future” due to its exceptional nutritional properties. In this article, we investigated the effects of fermentation using a combination of Lactobacillus acidophilus KDB-03 and Kluyveromyces marxianus GDMCC 2.119 on Spirulina. Fermentation significantly increased the total flavonoid and phenol levels in Spirulina, and enhanced the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity and ferric-reducing antioxidant power. Untargeted ultra-performance liquid chromatography-electrospray tandem mass spectrometry-based metabolomics and gas chromatography-ion mobility spectrometry analysis revealed alterations in the metabolites and flavor components of fermented Spirulina (FS). Furthermore, a mice experiment demonstrated that FS could effectively alleviate metabolism-associated fatty liver disease (MAFLD) by regulating liver metabolism, intestinal flora, and facilitating communication between the liver and gut. These findings suggest that fermentation could be a innovative approach to enhance the diversity of Spirulina products, and potentially be used as a strategy for the prevention and treatment of MAFLD.

Influence of industrial blanching, cutting, and freezing treatments on in vitro gastrointestinal digestion stability of orange (Citrus sinensis L.) and lemon (Citrus limon L.) peel polyphenols.

Citrus peels, which are often discarded as waste in the food-processing industry, are rich sources of polyphenols. The aim of the current study was to investigate the influence of an industrial freezing process along with blanching and cutting pretreatments on the in vitro gastrointestinal digestion stability of orange (Citrus sinensis L.) and lemon (Citrus limon L.) peel polyphenols. The major polyphenols were identified and quantified with ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI-MS/MS) and high performance liquid chromatography-photodiode array detector (HPLC-PDA), respectively. The results revealed that hesperidin and chlorogenic acid were the predominant flavonoid and phenolic acids in orange peels whereas, for lemon peels, eriocitrin and caffeic acid were the dominant flavonoid and phenolic acids, respectively. Blanching pretreatment enhanced the levels of major flavonoids in orange and lemon peels (by 39-82% and 54-146%, respectively) (P < 0.05) after in vitro gastrointestinal digestion. On the other hand, the application of cutting treatment after blanching significantly reduced the levels of flavonoids (23-62%) (P < 0.05); however, there was no statistically significant difference between the phenolic acid levels of cut and uncut citrus peels. Overall, the bioaccessibility of individual flavonoids and phenolic acids from frozen orange peels was generally slightly lower than that of untreated peels (9-34% and 9-49%, respectively). Nevertheless, frozen lemon peels contained higher bioaccessible flavonoids and phenolic acids in comparison with untreated peels (40-172% and 32-98%, respectively). These results suggest that industrial freezing steps could largely preserve the bioaccessibility of polyphenols in orange and lemon peels. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Optimization of pressurized ethanol extraction for efficient recovery of hyperoside and other valuable polar antioxidant-rich extracts from Betula pendula Roth leaves

Silver birch (Betula pendula Roth) leaves, known for their long-standing uses in traditional medicine, are bioactive compound-rich by-products of the birch logging industry, abundantly available throughout the northern hemisphere. Considering the current demands for the sustainable valorization of various plant materials and their processing by-products, this study aimed to optimize pressurized ethanol extraction (PLE-EtOH) parameters in order to produce hyperoside and other valuable polar antioxidant-rich extracts from silver birch leaves. A central composite design along with response surface methodology (CCD-RSM) was used to optimize the temperature and time of PLE-EtOH for yield, total phenolic (TPC) and flavonoid (TFC) content, Trolox equivalent antioxidant capacity (TEAC) measured in oxygen radical absorbance capacity (ORAC), cupric ion reducing antioxidant capacity (CUPRAC), and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays, and hyperoside content measured by ultraperformance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI/MS2) analysis. The optimal PLE-EtOH conditions were 86 °C and 39 min, which produced an extract with 32.2% yield, high TPC (97.3 mg gallic acid equivalents/g), TFC (37.3 mg quercetin equivalents/g) and proanthocyanidin (301.2 mg catechin hydrate equivalents/g) content, also strong in vitro antioxidant capacity in ORAC, CUPRAC and ABTS assays (999.3, 297.0 and 392.3 mg Trolox equivalents/g, respectively). Hyperoside (54.1 mg/g), betuloside (18.3 mg/g) and chlorogenic acid (11.5 mg/g) were the prime phenolic compounds in the PLE-EtOH extract. Additionally, a high sun protection factor (37.4 at 1 mg/mL) was determined by in vitro method for this extract. Such products from B. pendula leaves have potential cosmetical, nutraceutical, and pharmaceutical applications.

Functional Characterization of AP2/ERF Transcription Factors during Flower Development and Anthocyanin Biosynthesis Related Candidate Genes in Lycoris.

The APETALA2/ethylene-responsive transcription factor (AP2/ERF) family has been extensively investigated because of its significant involvement in plant development, growth, fruit ripening, metabolism, and plant stress responses. To date, there has been little investigation into how the AP2/ERF genes influence flower formation and anthocyanin biosynthesis in Lycoris. Herein, 80 putative LrAP2/ERF transcription factors (TFs) with complete open reading frames (ORFs) were retrieved from the Lycoris transcriptome sequence data, which could be divided into five subfamilies dependent on their complete protein sequences. Furthermore, our findings demonstrated that genes belonging to the same subfamily had structural similarities and conserved motifs. LrAP2/ERF genes were analyzed for playing an important role in plant growth, water deprivation, and flower formation by means of gene ontology (GO) enrichment analysis. The expression pattern of the LrAP2/ERF genes differed across tissues and might be important for Lycoris growth and flower development. In response to methyl jasmonate (MeJA) exposure and drought stress, the expression of each LrAP2/ERF gene varied across tissues and time. Moreover, a total of 20 anthocyanin components were characterized using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) analysis, and pelargonidin-3-O-glucoside-5-O-arabinoside was identified as the major anthocyanin aglycone responsible for the coloration of the red petals in Lycoris. In addition, we mapped the relationships between genes and metabolites and found that LrAP2/ERF16 is strongly linked to pelargonidin accumulation in Lycoris petals. These findings provide the basic conceptual groundwork for future research into the molecular underpinnings and regulation mechanisms of AP2/ERF TFs in anthocyanin accumulation and Lycoris floral development.

Simultaneous Determination of Five Iridoids of Picrorhiza scrophulariiflora in Rat Plasma Using UHPLC-ESI-MS/MS.

In this study, we developed an ultra-performance liquid chromatography-electrospray tandem quadrupole mass spectrometry (UHPLC-ESI-MS/MS) method to simultaneously determine Picroside-I, Picroside-II, Picroside-III, minecoside, and sweroside in rat plasma. The chromatographic column was an ACQUITY UHPLC® BEH Amide Column (2.1 × 100 mm, 1.7 µm; Waters, MA, USA), column temperature 40 °C. The mobile phase was 0.1% formic acid aqueous solution-0.1% formic acid acetonitrile solution. The flow rate was 0.4 mL/min. Multiple reaction monitoring (MRM) and negative ion modes were adopted. The results showed that the calibration curves of five compounds in plasma showed good linearity (r > 0.9911) over the studied dose range. The lower limits of quantification (LLOQ) for Picroside-I, Picroside-II, Picroside-III, minecoside, and sweroside were 6.876, 5.193, 5.040, 1.260, and 4.527 ng/mL, respectively. The intra-day and inter-day precision were <15%. The matrix effects ranged from 95.77 to 101.9%. The Tmax were 1.1 ± 0.2, 1.1 ± 0.1, 0.8 ± 0.1, 1.0 ± 0.2, and 2.1 ± 0.1 h. This study will be useful in understanding the behavior of drugs in the body and the body's effect on drugs. It also offers theoretical underpinnings and highlights the importance of clinical applications and creating novel drugs.

Assessment of lipid composition and eicosapentaenoic acid/docosahexaenoic acid bioavailability in fish oil obtained through different enrichment methods.

In this study, we analyzed the eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) lipid composition of fish oil obtained through enzymatic treatment, fractional distillation and silica gel column purification, and further assessed EPA/DHA bioavailability. Lipid subclass composition information was obtained through ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS), and bioavailability tests were performed using the Caco-2 cell monolayer model. Results showed that enzymatic treatment improved the incorporation of EPA/DHA as diacylglycerol (DG) while silica gel column chromatography enriched the content of EPA/DHA as phosphatidylglycerol (PG) (12.58%) and phosphatidylethanolamine (PE) (4.99%). Furthermore, increasing the purity of EPA/DHA could improve its bioavailability and after 24 incubation, binding forms of triglyceride (TG) was superior to ethyl ester (EE) (p < 0.05) at the same purity level. Those findings are helpful to provide research basis for exploring the bioactivity of fish oil.

Characterization of the WRKY Gene Family Related to Anthocyanin Biosynthesis and the Regulation Mechanism under Drought Stress and Methyl Jasmonate Treatment in Lycoris radiata.

Lycoris radiata, belonging to the Amaryllidaceae family, is a well-known Chinese traditional medicinal plant and susceptible to many stresses. WRKY proteins are one of the largest families of transcription factors (TFs) in plants and play significant functions in regulating physiological metabolisms and abiotic stress responses. The WRKY TF family has been identified and investigated in many medicinal plants, but its members and functions are not identified in L. radiata. In this study, a total of 31 L. radiata WRKY (LrWRKY) genes were identified based on the transcriptome-sequencing data. Next, the LrWRKYs were divided into three major clades (Group I-III) based on the WRKY domains. A motif analysis showed the members within same group shared a similar motif component, indicating a conservational function. Furthermore, subcellular localization analysis exhibited that most LrWRKYs were localized in the nucleus. The expression pattern of the LrWRKY genes differed across tissues and might be important for Lycoris growth and flower development. There were large differences among the LrWRKYs based on the transcriptional levels under drought stress and MeJA treatments. Moreover, a total of 18 anthocyanin components were characterized using an ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) analysis and pelargonidin-3-O-glucoside-5-O-arabinoside as well as cyanidin-3-O-sambubioside were identified as the major anthocyanin aglycones responsible for the coloration of the red petals in L. radiata. We further established a gene-to-metabolite correlation network and identified LrWRKY3 and LrWRKY27 significant association with the accumulation of pelargonidin-3-O-glucoside-5-O-arabinoside in the Lycoris red petals. These results provide an important theoretical basis for further exploring the molecular basis and regulatory mechanism of WRKY TFs in anthocyanin biosynthesis and in response to drought stress and MeJA treatment.

Transcription and Metabolism Pathways of Anthocyanin in Purple Shamrock (Oxalis triangularis A.St.-Hil.).

Anthocyanins are water-soluble pigments that can impart various colors to plants. Purple shamrock (Oxalis triangularis) possesses unique ornamental value due to its purple leaves. In this study, three anthocyanins, including malvidin 3-O-(4-O-(6-O-malonyl-glucopyranoside)-rhamnopyranosyl)-5-O-(6-O-malonyl-glucopyranoside), delphinidin-3-O-rutinoside and malvidin-3,5-di-O-glucoside, were characterized with ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) in purple shamrock. To investigate the molecular mechanism of anthocyanin biosynthesis in green shamrock (Oxalis corymbosa) and purple shamrock, RNA-seq and qRT-PCR were performed, and the results showed that most of the anthocyanin biosynthetic and regulatory genes were up-regulated in purple shamrock. Then, dark treatment and low temperature treatment experiments in purple shamrock showed that both light and low temperature can induce the biosynthesis of anthocyanins.

Enhanced Bioavailability and Pharmacokinetics of a Natural Self-Emulsifying Reversible Hybrid-Hydrogel System of Quercetin: A Randomized Double-Blinded Comparative Crossover Study.

Despite the vast array of health beneficial pharmacological effects, the bioavailability of the dietary flavonoid quercetin was found to be poor due to insolubility, incompatibility, and rapid biotransformation. Herein, we investigated the solubility, morphology, particle size, stability, in vitro release, and human pharmacokinetics of a hybrid-hydrogel formulation of quercetin (FQ-35) using fenugreek galactomannans as the hydrogel scaffold. Physicochemical characterization revealed that the crystalline quercetin was well encapsulated in the hydrogel matrix to form translucent microgel particles of FQ-35 with enhanced solubility (96-fold). The mean particle size was found to be 183.6 ± 42.7 nm with a zeta potential of 35.1 ± 3.8 mV. Pharmacokinetic investigation on healthy volunteers (N = 16) employing tandem mass spectrometric (ultra-performance liquid chromatography-electrospray tandem mass spectrometry) measurements of the concentration of free (unconjugated) and conjugated quercetin metabolites revealed an 18.6-fold improvement in free (unconjugated) quercetin bioavailability and 62-fold improvement in total quercetin (sum of free and conjugated) bioavailability, compared to the unformulated quercetin extracted from Sophora japonica. In summary, the natural self-emulsifying reversible hybrid-hydrogel delivery system was found to offer significant solubility, stability, and bioavailability of quercetin upon single-dose oral administration.

Lipidomic analysis and triglyceride profiles of fish oil: Preparation through silica gel column and enzymatic treatment

A comprehensive study of lipidomic coupled with triglyceride profiles onto four fish oils was performed through ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). Overall, 1010 lipids belonging to 6 categories and 38 lipid classes were identified. Triglycerides (TGs) were the dominant component in four fish oils (40 %–99 % of total lipids), and glycerophospholipids (GPs) and sphingolipids (SLs) were another two major lipid categories in the fish oil (TG50) which prepared through silica gel column. These results revealed that enzymatic treatment has slight effect on lipid distribution but silica gel column could change the lipids composition. TGs composition of four fish oils were separated completely, and the most TG molecule in TG50 is TG(18:3_14:0_18:0), possessed 13.03 ± 5.07 % relative content, these results implied that silica gel column could protect the nature structure of TGs from destroying which may also limited to further improve eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) purity, but enzymic method was not restricted by this.

Ozone treatment promotes physicochemical properties and antioxidant capacity of fresh-cut red pitaya based on phenolic metabolism.

Pitaya is an important fresh-cut product in the global fruit market. The health benefits of fresh-cut red pitaya fruit are attributed to its unique phenolic content and other antioxidants, but the fruit is highly susceptible to spoilage which causes a decline in nutritional quality. In this study, we monitored changes in quality and phenolic compounds of pitaya fruit treated with gaseous ozone during storage at 8 ± 2°C for 4 days. Compared with the control group, ozone treatment was an effective strategy for preserving quality by controlling the growth of microorganisms, preventing weight loss and softening, and improving the content of soluble solids and titratable acids. The results showed that ozone induced the accumulation of phenolic compounds while maintaining the quality. The content of phenolic compounds in fresh-cut pitaya was positively correlated with antioxidant activity. Ultra-performance liquid chromatography-electrospray tandem mass spectrometry was used to fingerprint the phenolic metabolites and metabolomic analysis identified 26 phenolic compounds. The majority of these were phenylpropanoids, and the key metabolic pathways were phenylpropane metabolism and flavonoid synthesis. This study illustrated the mechanism by which of ozone prolongs the shelf life of fresh-cut pitaya fruit and validated ozone as a valuable phenolic inducer and regulator of antioxidant activity, positively influencing the potential health benefits of fresh-cut products.

Quantification of six types of cytokinins: Integration of an ultra-performance liquid chromatographic-electrospray tandem mass spectrometric method with antibody based immunoaffinity columns equally recognizing cytokinins in free base and nucleoside forms

Cytokinins (CTKs) exist in various types in plants. The accurate quantification of free base and nucleoside types of cytokinins are helpful for better understanding their physiological role. In the present study, antibodies against trans-zeatin riboside (tZR) and N6-isopentenyladenine riboside (iPR) antibodies with equal recognition to free base and nucleoside cytokinins were developed. The cross-reactivity of tZR mAb 3G101G7 with tZR, trans-zeatin (tZ), dihydrozeatin riboside (DHZR), dihydrozeatin (DHZ), iPR, and N6-isopentenyladenine (iP) was 100.0%, 95.7%, 19.1%, 18.0%, 1.1%, and 0.7%, and that of iPR mAb 5C82F1 with above-mentioned 6 types of cytokinins was 1.5%, 1.4%, 5.7%, 3.1%, 100.0% and 92.6%, respectively. The obtained antibodies were used to prepare two immunoaffinity columns (IAC). The elution efficiencies of tZR 3G101G7-IAC for tZ and tZR, DHZ and DHZR and of iPR 5C82F1-IAC for iP and iPR were almost no difference with the same loading amount on their corresponding IACs. Subsequently, six types of cytokinins in mepiquat chloride (MC)-treated cotton (Gossypium hirsutum L.) roots were determined by IACs combined with ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI-MS/MS). The contents of tZR, iPR and DHZR were increased by 9.3∼38.5%, 6.6∼23.5%, and 30.1∼110.0%, respectively, whereas those of tZ and iP were reduced by 5.3∼20.0% and 27.7∼32.1%, respectively. The decreased tZ and iP levels led to the ratio of auxin-to-active cytokinins increase to promote lateral root initiation in MC-treated cotton seeding. Integration of the IACs equally recognizing cytokinins in their free base and nucleoside forms with UPLC-ESI-MS/MS can accurately quantify different cytokinins in plant tissues.

Effect of fermentation stages on glucosinolate profiles in kimchi: Quantification of 14 intact glucosinolates using ultra-performance liquid chromatography-tandem mass spectrometry.

We developed and validated an ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry-based analytical method to determine intact glucosinolates in kimchi and evaluate the effects of fermentation stages on glucosinolate profiles. The developed method yielded reliable data in the kimchi matrix in terms of selectivity, matrix effect (88%-105%), linearity (coefficients of determination ≥0.9991), sensitivity (limits of quantification ≤35nmol/L), accuracy (82%-101%), and precision (≤8%). The kimchi samples contained progoitrin, sinigrin, glucoraphanin, glucoraphenin, glucoalyssin, gluconapin, glucobrassicanapin, glucobrassicin, glucoberteroin, gluconasturtiin, 4-methoxyglucobrassicin, and neoglucobrassicin, of which 4-methoxyglucobrassicin, glucobrassicanapin, and gluconapin were the major compounds. Total glucosinolate content was decreased by 31%-97% and 91-100% in the moderate-fermented and over-fermented samples, respectively, compared with that in the non-fermented samples, revealing sudden glucosinolate degradation between the moderate- and over-fermentation stages. In summary, we report an efficient analytical method to estimate kimchi glucosinolate profiles, which could be a foundation for future studies.

Determination and Occurrence of Mineralocorticoids in Taihu Lake of China

We developed a sensitive method for monitoring six natural (aldosterone) and synthetic mineralocorticoids (canrenone, spironolactone, 7β-spironolactone, 7α-thio spironolactone, and 7α-thiomethyl spironolactone) in sediment and water using ultra-performance liquid chromatography–electrospray tandem mass spectrometry, and then 30 water and 30 sediment samples were analyzed to reveal their occurrence and distributions in Taihu Lake. All target six mineralocorticoids were detected in sediment and water samples with the detection frequencies as high as 96–100%. The median concentrations of mineralocorticoids ranged from 0.04 ng/L (7α-thiomethyl spironolactone) to 14 ng/L (aldosterone) in water and 0.01 ng/g (7β-spironolactone and canrenone) to 1.44 ng/g (aldosterone) in sediment in dry weight. Natural aldosterone was the predominant mineralocorticoid detected in both water and sediment samples, indicating the mineralocorticoid pollution in Taihu Lake was mainly derived from human and/or animal excrement rather than pharmaceutical industry and usage. Two metabolites 7β-spironolactone and 7α-thio spironolactone were first found in this study. Low ratios of metabolites to spironolactone were observed in sediment (0.05–0.75) in contrast to water (0.12–2.26), indicating that spironolactone was prone to degradation in water phase compared to sediment environment.

Volatile organic compound and endogenous phytohormone characteristics during callus browning in Aquilaria sinensis

Callus browning, a common feature in plant cell cultures, has hardly been explored in Aquilaria sinensis. Here, the volatile organic compounds (VOCs) were characterized during the browning of A. sinensis cells using Gas Chromatography-Mass Spectrometry (GC–MS), and total sesquiterpene accumulation was significantly induced and peaked during A. sinensis callus browning, after 60 days of callus growth. Additionally, 14 types of sesquiterpenes were detected in the browning A. sinensis callus, with greater sesquiterpene diversity than in the ones treated with methyl jasmonate and salicylic acid (SA) in a previous study. To further evaluate the mechanism of regulation of agarwood sesquiterpenes during cell browning in A. sinensis, changes on phytohormone concentrations were explored using ultra-performance liquid chromatography-electrospray tandem mass spectrometry system (UPLC-ESI-MS/MS). Both endogenous jasmonic acid and SA, key plant defense hormones, increased during A. sinensis callus browning. 1-aminocyclopropanecarboxylic acid, an ethylene (ET) precursor, decreased significantly after A. sinensis callus browning. Conversely, two primary growth hormones, auxin and cytokinin, exhibited opposite trends, suggesting that they also play roles in agarwood sesquiterpene accumulation. Our results potentially offer novel insights that could facilitate the production valuable phytochemical compounds such as agarwood sesquiterpenes, using plant cell cultures treated with appropriate phytohormone combinations.

In vitro Acetylcholinesterase inhibitory activity of polyphenolic compounds identified from Matricaria recutita

Acetylcholinesterase (AChE) is a key enzyme enhancing the cognitive disorder, leading to Alzheimer’s disease, and AChE inhibition is a crucial therapeutic mechanism against it. Matricaria recutita (MR) is widely used as a herbal medicine due to its phytotherapeutic properties. For this reason, MR flower was evaluated to identify polyphenolic compounds (PC), and then each PC is examined for AChE inhibitory activity. The ultra-performance liquid chromatography-electrospray tandem mass spectrometry UPLC-ESI-MS/MS was used to detect PC, and molecular docking was performed to insight potential inhibitory activity of PC against AChE. A series of 13 PC compounds were identified in the fractions of MR plant. Docking studies revealed that the inhibitory free energy and the position of the docked compounds in the active site are favored for the active compounds complex formed between AChE and the identified PC compounds. The accurate analysis of the docking result demonstrates that Kaempferol-3-O-rutinoside (KR) and Luteolin-8-C-glucoside (orientin) (LG) are the most significant inhibitory compounds against AChE. It can be concluded that MR is a significant source of PC compounds, and KR and LG are the most promising compounds that have high-affinity binding to AChE, based on docking outcome. Further experiments are recommended to explore in vivo enzyme compound interaction and toxicity models to establish the maximum suggested dose.

Profiling of Widely Targeted Metabolomics for the Identification of Secondary Metabolites in Heartwood and Sapwood of the Red-Heart Chinese Fir (Cunninghamia Lanceolata)

The chemical composition of secondary metabolites is important for the quality control of wood products. In this study, the widely targeted metabolomics approach was used to analyze the metabolic profiles of heartwood and sapwood in the red-heart Chinese fir (Cunninghamia lanceolata), with an ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry system. A total of 224 secondary metabolites were detected in the heartwood and sapwood, and of these, flavonoids and phenolic acids accounted for 36% and 26% of the components, respectively. The main pathways appeared to be differentially activated, including those for the biosynthesis of phenylpropanoids and flavonoids. Moreover, we observed highly significant accumulation of naringenin chalcone, dihydrokaempferol, pinocembrin, hesperetin, and other important secondary metabolites in the flavonoid biosynthesis pathway. Our results provide insight into the flavonoid pathway associated with wood color formation in Chinese fir that will be useful for further breeding programs.

Pharmacokinetic studies of a novel tubulin inhibitor SK1326 in rat plasma by UPLC-MS/MS.

A sensitive method for quantitation of SK1326 in rat plasma has been established using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI/MS/MS). SK1326 and the internal standard (tramadol) in plasma sample were extracted using acetonitrile. A centrifuged upper layer was then evaporated and reconstituted with a mobile phase of 0.5% formic acid-acetonitrile (35:65, v/v). The reconstituted samples were injected into a C18 reversed-phase column. Using MS/MS in the multiple reaction monitoring mode, SK1326 and tramadol were detected without severe interference from the rat plasma matrix. SK1326 produced a protonated precursor ion ([M + H]+ ) at m/z 432.3 and a corresponding product ion at m/z 114.4. The internal standard produced a protonated precursor ion ([M + H]+ ) at m/z 264.4 and a corresponding product ion at m/z 58.1. Detection of SK1326 in rat plasma by the UPLC-ESI/MS/MS method was accurate and precise with a quantitation limit of 1.0 ng/mL. The validation, reproducibility, stability and recovery of the method were evaluated. The method has been successfully applied to pharmacokinetic studies of SK1326 in rat plasma. The pharmacokinetic parameters of SK1326 were evaluated after intravenous (at a dose of 10 mg/kg) and oral (at a dose of 20 mg/kg) administration of SK1326 in rats. After oral administration (20 mg/kg) of SK1326, the F (fraction absorbed) value was ~77.1%.

Effect of Mobile Phase pH on the Electrospray Ionization Efficiency and Qualitative Analysis of Pharmaceuticals in ESI+LC-MS/MS.

The effect of mobile phase pH on positive ionization process and retention time of nine pharmaceuticals on ultra-performance liquid chromatography-electrospray-tandem mass spectrometry (LC-MS/MS) was discussed. The effective use of high and low mobile phase pH in LC-MS/MS qualitative analyses method was also evaluated by comparing the instrument detection limit, quantification limit, precision, linearity and signal to noise (S/N) under low and high mobile phase pH. In this work, six mobile phase pH that ranged between pH2 and pH10 were used to evaluate the effect of the mobile phase pH changes on the ionization process in electrospray ionization. Results revealed that high mobile phase pH ionized more pharmaceuticals molecules and gave a higher signal than low mobile phase pH in positive ionization mode. The results proved that ammonium ion was better as a proton donor in high pH mobile phase than the hydronium ion in acidic mobile phase. The results revealed that the qualitative LC-MS/MS analyses method by using high mobile phase pH has better performance for most analytes in terms of sensitivity, precision, linearity and S/N than the low mobile phase pH.