Ionization Tandem Mass Spectrometry Research Articles

Mercaptans in malodorants break disulfide bridges in human serum albumin and form adducts suitable as biomarkers of exposure in vitro.

Malodorants comprise notoriously smelling mercaptans and might be applied for crowd control. Because exposure to malodorants may lead to irritation of the respiratory system, choking, and coma, bioanalytical verification of poisoning might be required in a medical and forensic context. We herein present the detection and identification of novel biomarkers of exposure to ethyl mercaptan, n-butyl mercaptan, tert-butyl mercaptan, and iso-amyl mercaptan. These alkyl thiol compounds were found to form disulfide adducts in human serum albumin (HSA) in plasma in vitro with the only non-disulfide-bridged Cys34 residue and with other residues being part of the disulfide-bridged pattern in HSA. After proteinase K-catalyzed proteolysis, adducts of all mercaptans were detected simultaneously as the tripeptide Cys34*ProPhe and the dipeptides Cys369*Tyr, ValCys316*, and Cysx*Ala (x denominates either Positions 91, 200, 253, 361, and/or 448) by a sensitive micro-liquid chromatography-electrospray ionization tandem mass spectrometry (μLC-ESI MS/MS) method working in the scheduled multiple reaction monitoring (sMRM) mode. Time- and concentration-dependent adduct formations while exposure and proteolysis were investigated and the suitability of adducts as biomarkers of exposure was elaborated. Adducts at Cys34 showed the lowest limits of identification (LOIs, 6nM to 1.2μM mercaptan in plasma) and superior stability in plasma at 37°C. Therefore, Cys34*ProPhe appears as the most promising target to prove exposure to mercaptans at least in vitro.

Metabolism of quercitrin in the colon and its beneficial regulatory effects on gut microbiota.

Quercitrin is a dietary flavonoid widely found in plants with various physiological activities. However, whether quercitrin alters gut microbiota in vivo is not well understood. The aim of this study was to investigate metabolism of quercitrin in the colon and its regulation on gut microbiota in mice. Herein, 22 flavonoids related to quercitrin metabolism were identified based on ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Gas chromatography and 16S rDNA gene sequencing were used to investigate short-chain fatty acid (SCFA) content and diversity of composition of gut microbiota, respectively. The results showed that quercitrin significantly alters the beta-diversity of the gut microbiota, probiotics such as Akkermansia and Lactococcus were significantly increased, and the production of propanoate, isovalerate and hexanoate of the quercitrin group were enhanced significantly. The Spearman's association analysis provided evidence that Gardnerella and Akkermansia have obvious correlations with most of quercitrin metabolites and SCFAs. Quercitrin and its metabolites in the colon altered the structure of the mice gut microbiota and increased the content of SCFAs. Our experiments provide valuable insights into quercitrin research and application. © 2024 Society of Chemical Industry.

Peptide Analysis of Protein Extracts from Caulerpa Lentillifera by Nano LC-ESI-Ms/Ms and Their Potential as Precursor of Biologically Active Peptides – In Silico Approach

Peptidomics research is gradually positioning in food science fields due to an increasing interest in peptides released from food proteins with health benefits and nutraceutical properties. Referable to the complexity of these compounds, their study requires advanced analytical techniques such as tandem mass spectrometry. Seaweed naturally has high nutritional value and many health-promoting effects. Hence, this work aimed to characterize the peptide and to virtual screening for their potential as a precursor of biologically active peptides. The total soluble protein was extracted from Caulerpa lentillifera using the phenol ammonium acetate precipitation method. In solution, digestion was carried out using trypsin on 500 µg of protein. Peptide sequencing was accomplished using nano liquid chromatography-electrospray ionization tandem mass spectrometry (nLC-ESI-MS/MS), and Peaks Studio 7 was used for the analysis of MS/MS data and de novo peptide sequencing using an average local confidence above 90%. The results showed that 76 peptides mapped to selected proteins and 145 were de novo peptide sequences. In silico approaches of both peptide sequences resulted in 15 types of biological activity characteristics of peptides from among 44 categories as listed in the BIOPEP-UWM database, and motifs with the ACE inhibitory activity occur most frequently. These findings are relevant to the search for bio-functional ingredients as constituents of functional foods or provide added value to nutraceutical foods. Significantly, the methodology described here might apply to discovering the potential in any organism with incomplete genome data.

Identification of a Chimera Mass Spectrum of Isomeric Lipid A Species Using Negative Ion Tandem Mass Spectrometry.

The toxic nature of bacterial endotoxins is affected by the structural details of lipid A, including the variety and position of acyl chains and phosphate group(s) on its diglucosamine backbone. Negative-ion mode tandem mass spectrometry is a primary method for the structure elucidation of lipid A, used independently or in combination with separation techniques. However, it is challenging to accurately characterize constitutional isomers of lipid A extracts by direct mass spectrometry, as the elemental composition and molecular mass of these molecules are identical. Thus, their simultaneous fragmentation leads to a composite, so-called chimera mass spectrum. The present study focuses on the phosphopositional isomers of the classical monophosphorylated, hexaacylated Escherichia coli-type lipid A. Collision-induced dissociation (CID) was performed in an HPLC-ESI-QTOF system. Energy-resolved mass spectrometry (ERMS) was applied to uncover the distinct fragmentation profiles of the phosphorylation isomers. A fragmentation strategy applying multi-levels of collision energy has been proposed and applied to reveal sample complexity, whether it contains only a 4'-phosphorylated species or a mixture of 1- and 4'-phosphorylated variants. This comparative fragmentation study of isomeric lipid A species demonstrates the high potential of ERMS-derived information for the successful discrimination of co-ionized phosphorylation isomers of hexaacylated lipid A.

Production and biological activity of β-1,3-xylo-oligosaccharides using xylanase from Caulerpa lentillifera

In this study, β-1,3-xylanase (Xyl3088) was designed and prepared by constructing the expression vector plasmid and expressing and purifying the fusion protein. β-1,3-xylo-oligosaccharides were obtained through the specific enzymatic degradation of β-1, 3-xylan from Caulerpa lentillifera. The enzymolysis conditions were established and optimized as follows: Tris-HCl solution 0.05 mol/L, temperature of 37 °C, enzyme amount of 250 μL, and enzymolysis time of 24 h. The oligosaccharides' compositions and structural characterization were identified by thin-layer chromatography (TLC), ion chromatography (IC) and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS). The IC50 values for scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethyl-benzothiazoline-p-sulfonic acid (ABTS+), and superoxide anion radical (•O2−) were 13.108, 1.258, and 65.926 mg/mL for β-1,3-xylo-oligosaccharides, respectively, and 27.588, 373.048, and 269.12 mg/mL for β-1,4-xylo-oligosaccharides, respectively. Compared with β-1,4-xylo-oligosaccharides, β-1,3-xylo-oligosaccharides had substantial antioxidant activity and their antioxidant effects were concentration dependent. β-1,3-xylo-oligosaccharides also possessed a stronger anti-inflammatory effect on RAW 264.7 cells stimulated by lipopolysaccharide (LPS) than β-1,4-xylo-oligosaccharides. At a working concentration of 100 μg/mL, β-1,3-xylo-oligosaccharides inhibited the release of NO and affected the expression of IL-1β, TNF-α, and other proteins secreted by cells, effectively promoting the release of pro-inflammatory mediators by immune cells in response to external stimuli and achieving anti-inflammatory effects. Therefore, β-1,3-xylo-oligosaccharides are valuable products in food and pharmaceutical industries.

Identification of polyphenol composition in grape (Vitis vinifera cv. Bidaneh Sefid) stem using green extraction methods and LC-MS/MS analysis.

The utilization of grape stems, a by-product of the grape processing industry, as a source of valuable bioactive compounds, particularly polyphenols, has gained attention in recent years. This study aimed to investigate different eco-friendly extraction methods for obtaining polyphenols from grape (Vitis vinifera cv. Bidaneh Sefid) stems, focusing on green solvents and innovative techniques. Four extraction methods were tested, involving the use of water and polyethylene glycol (PEG) as green solvents, along with maceration, microwave, ultrasound, and reduced-pressure techniques. High-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) was used to characterize and quantify the bioactive compounds in the extracts. A total of 29 polyphenols, including phenolic acids, flavonoids, proanthocyanidins, and stilbenes, were detected. Among the four extraction methods tested, methods 1 (water + microwave + ultrasound + atmospheric pressure) and 2 (water + microwave + ultrasound + reduced pressure) were found to be the most effective. Our study demonstrated that using water and PEG as green solvents, combined with techniques like microwave, ultrasound, and reduced pressure, effectively extracted both hydrophobic and hydrophilic compounds from the grape stems. These findings suggest that further exploration of these methods could lead to the development of value-added products from grape stems, emphasizing the significance of green extraction techniques for the recovery of polyphenols from winemaking by-products.

Characterization of the covalent binding of cyanidin-3-glucoside to bovine serum albumin and its inhibition mechanism for advanced nonenzymatic glycosylation reactions.

Nonenzymatic glycosylation of proteins can generate advanced glycosylation end products, which are closely associated with the pathogenesis of certain chronic physiological diseases and aging. In this study, we characterized the covalent binding of cyanidin-3-glucoside (C3G) to bovine serum albumin (BSA) and investigated the mechanism by which this covalent binding inhibits the nonenzymatic glycosylation of BSA. The results indicated that the covalent interaction between C3G and BSA stabilized the protein's secondary structure. Through liquid chromatography-electrospray ionization tandem mass spectrometry analysis, we identified the covalent binding sites of C3G on BSA as lysine, arginine, asparagine, glutamine, and cysteine residues. This covalent interaction significantly suppressed the nonenzymatic glycosylation of BSA, consequently reducing the formation of nonenzymatic glycosylation products. C3G competitively binds to nonenzymatic glycosylation sites (e.g., lysine and arginine) on BSA, thereby impeding the glycosylation process and preventing the misfolding and structural alterations of BSA induced by fructose. Furthermore, the covalent attachment of C3G to BSA preserves the secondary structure of BSA and hinders subsequent nonenzymatic glycosylation events.

Widely Targeted Metabolomic Analysis Reveals the Improvement in Panax notoginseng Triterpenoids Triggered by Arbuscular Mycorrhizal Fungi via UPLC-ESI-MS/MS.

Panax notoginseng is a highly valued perennial medicinal herb in China and is widely used in clinical treatments. The main purpose of this study was to elucidate the changes in the composition of P. notoginseng saponins (PNSs), which are the main bioactive substances, triggered by arbuscular mycorrhizal fungi (AMF) via ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). A total of 202 putative terpenoid metabolites were detected, of which 150 triterpene glycosides were identified, accounting for 74.26% of the total. Correlation analysis, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) of the metabolites revealed that the samples treated with AMF (group Ce) could be clearly separated from the CK samples. In total, 49 differential terpene metabolites were identified between the Ce and CK groups, of which 38 and 11 metabolites were upregulated and downregulated, respectively, and most of the upregulated differentially abundant metabolites were mainly triterpene glycosides. The relative abundances of the two major notoginsenosides (MNs), ginsenosides Rd and Re, and 13 rare notoginsenosides (RNs), significantly increased. The differential saponins, especially RNs, were more easily clustered into one branch and had a high positive correlation. It could be concluded that the biosynthesis and accumulation of some RNs share the same pathways as those triggered by AMF. This study provides a new way to obtain more notoginsenoside resources, particularly RNs, and sheds new light on the scientization and rationalization of the use of AMF agents in the ecological planting of medicinal plants.

Determination of 16 ultraviolet–absorbing compounds in marine invertebrates by using LC-USI-MS/MS coupled with QuEChERS

In this study, we examined multiple endocrine-disrupting ultraviolet-absorbing compounds (UVACs) in marine invertebrates used in personal care products and packaging. Modified QuEChERS and liquid chromatography UniSpray ionization tandem mass spectrometry were used to identify 16 UVACs in marine invertebrates. Matrix-matched calibration curves revealed high linearity (r ≥ 0.9929), with limits of detection and quantification of 0.006–1.000 and 0.020–3.000 ng/g w.w., respectively. In oysters, intraday and interday analyses revealed acceptable accuracy (93%–120%) and precision (≤18%), except for benzophenone (BP) and ethylhexyl 4-(dimethylamino) benzoate. Analysis of 100 marine invertebrate samples revealed detection frequencies of 100%, 98%, 89%, 64%, and 100% for BP, 4-hydroxybenzophenone, 4-methylbenzophenone, 4-methylbenzylidene camphor, and benzophenone-3 (BP-3), respectively. BP and BP-3 were detected at concentrations of 4.40–27.39 and < 0.020–0.560 ng/g w.w., respectively, indicating their widespread presence. Overall, our proposed method successfully detected UVACs in marine invertebrates, raising concerns regarding their potential environmental and health effects.

Omega-3 Long-Chain Polyunsaturated Fatty Acids in Nonseafood and Estimated Intake in the USA: Quantitative Analysis by Covalent Adduct Chemical Ionization Mass Spectrometry.

Omega-3 long-chain polyunsaturated fatty acids (LCPUFA) play critical roles in human development and health. Their intake is often effectively estimated solely based on seafood consumption, though the high intake of terrestrial animal-based foods with minor amounts of LCPUFA may be significant. Covalent adduct chemical ionization (CACI) tandem mass spectrometry is one approach for de novo structural and quantitative analysis of minor unsaturated fatty acids (FA), for which standards are unavailable. Here, CACI-MS and MS/MS are used to identify and quantify minor omega-3 LCPUFA of terrestrial animal foods based on the application of measured response factors (RFs) to various FA. American mean intakes of pork, beef, chicken, and eggs contribute 20, 27, 45, and 71 mg/day of docosahexaenoic acid (DHA), respectively. The estimated intake of omega-3 DHA, eicosapentaenoic acid, and docosapentaenoic acid from nonseafood sources is significant, at 164, 103, and 330 mg/day, greater than most existing estimates of omega-3 LCPUFA intake.

Simultaneous Detection Method of 11 Respiratory Drug Substances Including Theobromine, Oxymetazoline, etc. in Adulterated Dietary Supplements Using Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry and Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry Analysis.

Recently, the demand for respiratory disease-related products has surged due to the influence of coronavirus disease 2019, prompting warnings about illegal dietary supplements containing unauthorized substances. Additionally, adulterated dietary supplements are continuously detected in open markets, posing significant public health safety problem. In this study, we developed and validated an analytical method for 11 respiratory drug substances using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) and proposed optimal conditions for LC-quadrupole time-of-flight MS (LC-QTOF-MS) to determine the fragmentation patterns of each substance. This method underwent thorough validation considering specificity, linearity, limits of detection and quantification, accuracy, precision, matrix effect, stability, etc. All results met international guidelines. These validated methods were applied to 52 dietary supplements advertised for treating respiratory diseases and enhancing respiratory function, among which one sample was found to contain 313.7mg/g of theobromine. This determination was made by comparing the product ion ratios with the standards and subsequent quantification. To re-confirm the detected substances, their fragmentation patterns were compared with those of the standards using LC-QTOF-MS. In conclusion, the mass-based information, coupled with the LC-ESI-MS/MS method development, can be successfully applied to rapidly identify 11 respiratory drug substances in illegal dietary supplements used for respiratory disease treatment. The developed simultaneous detection method contributes to public health and safety improvements.

UPLC-ESI-MS\MS Phytochemicals Profiling of n-Butanol Fraction of Xanthium strumarium Fruit Extract

The work aimed to explore the phytochemicals of various fractions of Xanthium strumarium fruit extract since this plant is found to be toxic for both humans and animals in Iraq. The extracts underwent phytochemical screening, which indicated the occurrence of flavonoids, alkaloids, phenols, coumarin, saponin, tannins, and terpenoids. After extraction, fractionation was done using hexane, chloroform, and N-butanol respectively, for identifying the phytochemicals found in each fraction, UPLC-electrospray ionization–tandem mass spectroscopy was used which revealed the presence of 6 sterol and terpenes compound in hexane fraction, Nine compounds were detected in the chloroform fraction, among which 2-acetyl-atractyligenin and Artemisinin were the primary components. Additionally, this particular plant has been found to contain these compounds for the first time. Furthermore, Pungiolide C, dihydroartemisinin, and atractylenolide II were also detected for the first time in this plant. For the n-Butanol fraction, eight diterpene glycosides were recognized, with Atractyloside and Carboxyatractyloside and their desulphated derivatives as the major compounds responsible for the plant's toxicity. The butanol fraction also showed the presence of eight phenolic compounds, among which caffeoylquinic acid derivatives and flavonoid Syringetin were the major compounds in this fraction.

Volatile organic compounds and mortality from ischemic heart disease: A case-cohort study

BackgroundVolatile organic compounds (VOCs) are major components of air pollution and tobacco smoke, two known risk factors for cardiovascular diseases. VOCs are ubiquitous in the environment and originate from a wide range of sources, including the burning of biomass, fossil fuels, and consumer products. Direct evidence for associations between specific VOCs and ischemic heart disease (IHD) mortality in the general population is scarce. MethodsIn a case-cohort study (stratified by age groups, sex, residence, and tobacco smoking), nested within the population-based Golestan cohort study (n = 50,045, 40–75 years, 58% women, enrollment: 2004–2008) in northeastern Iran, we measured urinary concentrations of 20 smoking-related VOC biomarkers using ultra high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. We calculated hazard ratio (HR) and 95% confidence interval (CI) for their associations with IHD mortality during follow-up to 2018, using Cox regression models adjusted for age, ethnicity, education, marital status, body mass index, physical activity, wealth, and urinary cotinine. ResultsThere were 575 non-cases from random subcohort and 601 participants who died from IHD, mean (standard deviation) age, 58.2 (9.3) years, with a median of 8.4 years follow-up. Significant associations [3rd vs. 1st tertile, HR (95% CI), P for trend] were observed between biomarkers of acrylamide [1.68(1.05,2.69), 0.025], acrylonitrile [2.06(1.14,3.72), 0.058], acrolein [1.98(1.30,3.01), 0.003 and 2.44(1.43,4.18), 0.002], styrene/ethylbenzene [1.83(1.19,2.84), 0.007 and 1.44(1.01,2.07), 0.046], dimethylformamide/methylisocyanate [2.15(1.33,3.50), 0.001], and 1,3butadiene [2.35(1.52,3.63),<0.001] and IHD mortality. These associations were independent of tobacco smoking, and they were only present in the non-smoking subgroup. ConclusionOur findings provide direct evidence for associations between exposure to several VOCs with widespread household and commercial use and IHD mortality many years after these exposures. These results highlight the importance of VOC exposure in the general population as a risk factor for cardiovascular diseases and underline the importance of bio-monitoring non-tobacco VOC exposure.

Effect of saponins in Panax notoginseng (Burkill) F. H. Chen on the steroid hormone levels in the chronic unpredictable mild stress model of depression in rats

Recent research has indicated that Panax notoginseng saponins (PNS) extracted from the radix of Panax notoginseng (Burkill) F. H. Chen exert antidepressant effects. This study aimed to assess the antidepressive effects of ginsenoside Rg1 and PNS in a depression model induced by chronic unpredictable mild stress (CUMS). Over a period of three weeks, rats were administered ginsenoside Rg1 at a dose of 30 mg/kg and PNS at dosages ranging from 100 to 200 mg/kg body weight per day. To assess how ginsenoside Rg1 and PNS influence depression-like behaviours in rats, various assessments were conducted, including coat state evaluation, forced swim test, and elevated plus maze test. The levels of cortisol and testosterone in serum samples were analysed using the liquid chromatography-electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS) method. LC-ESI-MS/MS method provides precise and accurate results. The lower limit of quantification values for cortisol and testosterone were determined as 100 and 2 pg/mL, respectively. Our data demonstrated that both ginsenoside Rg1 and PNS significantly reversed depression-like behaviour in rats by improving coat condition, reducing immobility time in the forced swim test, and increasing time spent in the open arms of the elevated plus maze test. Furthermore, ginsenoside Rg1 and PNS exhibited a regulatory effect on cortisol and testosterone levels in plasma. These findings suggest that ginsenoside Rg1 and PNS may be potential antidepressants in clinical treatment.

Simultaneous determination of semi-essential nutrients taurine, l-carnitine and choline in infant formulas and adult/pediatric nutritional formulas by hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry.

The nutritional intake of formula-fed newborns is often limited to a single source, so it must be supplemented with essential nutrients for the growth and proper development of infants. Taurine, l-carnitine, and choline are considered conditionally essential nutrients especially in newborns and infants. In this work, a simple routine hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry (HILIC-ESI-MS/MS) method was developed and validated for the simultaneous determination of these semi-essential nutrients in infant and adult/pediatric milk formulas. The extraction recoveries were between 90% and 114%. Precision of the method offered relative standard deviation below 5% and 7% for intra-day and inter-day precision, respectively. The proposed method was successfully applied to quantification of taurine, l-carnitine, and choline in milk formula. The contents found were in good agreement with those provided on the product label for almost all samples. In view of these results, it can be concluded that the developed method can be a useful approach for the simultaneous determination of taurine, l-carnitine and choline in powdered milk samples, so it can be useful in the routine quality control of this kind of samples. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Phytochemical characterization of callus cultures from the endangered plant Crocus scepusiensis (Rehm. & Woł.) Borbás ex Kulcz.

Crocus scepusiensis (Rehm. & Woł.) Borbás ex Kulcz., a critically endangered herbaceous plant which serves as a valuable source of bioactive compounds found across Europe and Asia. The aim of this study was to produce a calli from two different plant parts (leaf and shoot tip) for the critically endangered C. scepusiensis through tissue culture techniques, characterize the resulting calli through chemical profiling, with a focus on identifying key phytoconstituents, and lay the groundwork for future research on the biological activities of these calli extracts. Leaf disc and micro shoot tip explants were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of 6-benzylaminopurine (BA) and α-naphthaleneacetic acid (NAA) to induce organogenic calli. The resulting calli exhibited distinct biochemical profiles. Moreover, a phytochemical analysis was conducted to compare the metabolite composition of callus 1 (derived from leaf discs) and callus 2 (derived from shoot tips). Callus 1 displayed a higher total phenolic content (30.3558 ± 1.3564 mg (GAE)/g) compared to callus 2 (29.1543 ± 0.9754 mg (GAE)/g). Similarly, callus 1 exhibited a greater total flavonoid content (26.0089 ± 1.8029 mg (RE)/g) than callus 2 (18.4464 ± 1.4797 mg (RE)/g). Liquid chromatography-photodiode array-electrospray ionization-tandem mass spectrometry (LC-PDA-ESI-MS/MS) analysis revealed the presence of 26 and 25 constituents in callus 1 and 2, respectively. Fourteen and thirteen of these identified compounds have been previously reported in other Crocus species, with 22 constituents common to both calli. Twelve constituents were reported here in Crocus for the first time as far as we know.

Improvement of Alginate Extraction from Brown Seaweed (Laminaria digitata L.) and Valorization of Its Remaining Ethanolic Fraction.

This study aimed to improve the conventional procedure of alginate isolation from the brown seaweed (Laminaria digitata L.) biomass and investigate the possibility of further valorization of the ethanolic fraction representing the byproduct after the degreasing and depigmentation of biomass. The acid treatment of biomass supported by ultrasound was modeled and optimized regarding the alginate yield using a response surface methodology based on the Box-Behnken design. A treatment time of 30 min, a liquid-to-solid ratio of 30 mL/g, and a treatment temperature of 47 °C were proposed as optimal conditions under which the alginate yield related to the mass of dry biomass was 30.9%. The use of ultrasonic radiation significantly reduced the time required for the acid treatment of biomass by about 4 to 24 times compared to other available conventional procedures. The isolated alginate had an M/G ratio of 1.08, which indicates a greater presence of M-blocks in its structure and the possibility of forming a soft and elastic hydrogel with its use. The chemical composition of the ethanolic fraction including total antioxidant content (293 mg gallic acid equivalent/g dry weight), total flavonoid content (14.9 mg rutin equivalent/g dry weight), contents of macroelements (the highest content of sodium, 106.59 mg/g dry weight), and microelement content (the highest content of boron, 198.84 mg/g dry weight) was determined, and the identification of bioactive compounds was carried out. The results of ultra high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis confirmed the presence of 48 compounds, of which 41 compounds were identified as sugar alcohol, phenolic compounds, and lipids. According to the 2,2-diphenyl-1-picrylhydrazyl assay, the radical scavenging activity of the ethanolic fraction (the half-maximal inhibitory concentration of 42.84 ± 0.81 μg/mL) indicated its strong activity, which was almost the same as in the case of the positive control, synthetic antioxidant butylhydroxytoluene (the half-maximal inhibitory concentration of 36.61 ± 0.79 μg/mL). Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis, and Bacillus cereus) were more sensitive to the ethanolic fraction compared to Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Shigella sonnei). The obtained results indicated the possibility of the further use of the ethanolic fraction as a fertilizer for plant growth in different species and antifouling agents, applicable in aquaculture.

Impact of radish seeds (Semen Raphani) on the absorption and transportation of ginsenosides in the Caco-2 cell model: a UPLC-ESI-MS analysis

This study examined the impact of Semen raphani on the absorption of ginsenosides from Panax ginseng C.A. Meyer (ginseng) using a Caco-2 cell model and Ultra-High-Performance Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry (UPLC-ESI-MS). Six primary ginsenosides (Rg1, Re, Rb1, Rb2, Rc, Rd) were quantified. Results showed that Semen Raphani increased the efflux rate of ginsenosides, particularly at higher concentrations, suggesting it inhibits their absorption. The research elucidates the intestinal absorption process of ginsenosides and the antagonistic mechanism of Semen Raphani against ginseng.

Photostability evaluation of manidipine tablets and structural determination of its photoproducts.

Manidipine (MP) is a dihydropyridine drug, which is treated for the reduction of high blood pressure. The aim of this study is to clarify the photochemical behavior of MP in the case of ultraviolet light (UV) irradiation for MP tablets (Calslot® tablets). The tablets and its altered forms (powders and suspensions) were UV-irradiated using a black light, and residual amounts of active pharmaceutical ingredients (APIs) were monitored by high-performance liquid chromatography (HPLC). Due to the photoproducts of MP were detected in HPLC chromatograms, the elucidation of their chemical structures was carried out utilizing electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). As a result, APIs in Calslot® tablets were almost completely photodegraded in the case that Calslot® tablets were suspended in an aqueous media along with the generation of some MP photoproducts. LC-ESI-MS/MS analysis clarified the chemical structures of three MP photoproducts, indicating that they were a pyridine analogue, benzophenone and a hydrolysate. Benzophenone was a main MP photoproduct. It was possible that MP might be firstly oxidized to form its pyridine analogue, followed by the oxidation of a dimethyl methylene moiety. This moiety seemed to be eliminated as a benzophenone, and the cleavage of an ester bond of the residual moiety resulted in the generation of a hydrolysate. Finally, toxicological potencies of MP and its photoproducts were predicted in silico toxicity evaluation, suggesting some of biological effects of the photoproducts might be altered compared with MP.

Electrospray ionization tandem mass spectrometry of 4-aryl-3,4-dihydrocoumarins.

We have investigated the gas-phase fragmentation reactions of 11 synthetic 4-aryl-3,4-dihydrocoumarins by electrospray ionization tandem mass spectrometry (ESI-MS/MS) on a quadrupole-time-of flight (Q-TOF) hybrid mass spectrometer. We have also estimated thermochemical data for the protonated coumarins (precursor ion A) and product ion structures by computational chemistry at a B3LYP level of theory to establish the ion structures and to rationalize the fragmentation pathways. The most abundant ions in the product ion spectra of coumarins 1-11 resulted from C8H8O2, CO2, C4H4O3, C8H10O3, C8H8O2, and CH3OH eliminations through retro-Diels-Alder (RDA) reactions, remote hydrogen rearrangements (β-eliminations), and β-lactone ring contraction. Although the investigated coumarins shared most of the fragmentation pathways, formation of a benzylic product ion and its corresponding tropylium ion was diagnostic of the substituents at ring C. The thermochemical data revealed that the nature and position of the substituents at ring C played a key role in the formation of this product ion and determined its relative intensity in the product ion spectrum. The results of this study contribute to knowledge of the gas-phase ion chemistry of this important class of organic compounds.