Hydroxyl Benzoic Acid Research Articles

Phytochemical-mediated regulation of aflatoxigenic fungi contamination in a shifting climate and environment.

Mycotoxin contamination poses a significant problem in developing countries, particularly in northern Pakistan's fluctuating climate. This study aimed to assess aflatoxin contamination in medicinal and condiment plants in Upper Dir (dry-temperate) and Upper Swat (moist-temperate) districts. Plant samples were collected and screened for mycotoxins (Aflatoxin-B1 and Aflatoxin-B-2). Results showed high levels of AFB-1 (11,505.42 ± 188.82) as compared to AFB-2 (846 ± 241.56). The maximum contamination of AFB-1 in Coriandrum sativum (1154.5 ± 13.43ng to 3328 ± 9.9ng) followed by F. vulgare (883 ± 9.89ng to 2483 ± 8.4ng), T. ammi (815 ± 11.31ng to 2316 ± 7.1ng), and C. longa (935.5 ± 2.12ng to 2009 ± 4.2ng) while the minimum was reported in C. cyminum (671 ± 9.91ng to 1995 ± 5.7ng). Antifungal tests indicated potential resistance in certain plant species (C. cyminum) while A. flavus as the most toxins contributing species due to high resistance below 80% (54.2 ± 0.55 to 79.5 ± 2.02). HPLC analysis revealed hydroxyl benzoic acid (5136 amu) as the dominant average phytochemical followed by phloroglucinol (4144.31 amu) with individual contribution of 8542.08 amu and 12,181.5 amu from C. cyaminum. The comparison of average phytochemicals revealed the maximum concentration in C. cyminum (2885.95) followed by C. longa (1892.73). The findings revealed a statistically significant and robust negative correlation (y = - 2.7239 × + 5141.9; r = - 0.8136; p < 0.05) between average mycotoxins and phytochemical concentrations. Temperature positively correlated with aflatoxin levels (p < 0.01), while humidity had a weaker correlation. Elevation showed a negative correlation (p < 0.05), while geographical factors (latitude and longitude) had mixed correlations (p < 0.05). Specific regions exhibited increasing aflatoxin trends due to climatic and geographic factors.

Characterization and biological activity of some anti-diabetic plants: Medicago sativa Gongronema latifolium and Pterocarpus santalinoides

Plants are believed to be an essential source of new chemical substances with potential therapeutic effect. The aim of this study is to test for the GCMS analysis and FT-IR analysis of the extract of Medicago sativa , Gongronema latifolium and Pterocarpus santalinoides. FTIR spectroscopy of all selected extracts confirms the presence of alkanes, alkynes, carboxylic acids, aldehydes and nitriles functional groups while the major bioactive compounds detected in the extracts were protchaechenic acid, hydroxyl benzoic acid , b-Phenyl caffate and kaempherol.

Evaluation of diflunisal a difluoro-derivative of salicylic acid as an inhibitor of human serum albumin using molecular docking tools

Aim: To evaluate the binding interaction of diflunisal at active site of Human Serum Albumin (HSA), an important enzyme responsible for osteoarthritis disease. Methodology: The gas phase molecule was optimized with B3LYP/6-311G** basis set, while a single point energy calculation was carried out for the molecule lifted from the active site. Bader’s theory of atoms in molecules (AIM) was used to determine the electron density and Laplacian of electron density. The protein was assigned with polar hydrogens and Kollman charges. Iterated local search procedure was performed during docking, during this, both protein and ligand were considered as rigid. Among the ten poses, lowest binding energy pose was considered for further ligand protein interaction analysis and QTAIM studies. Results: A close observation of the results shows that diflunisal has interactions in the binding sites IIA and IIIA of HSA as reported earlier. Two strong classical H-bonding interactions, three hydrophobic contacts with the amino acids VAL456, ALA194 andARG197, two close fluorine interactions, and two Pi-Sigma interactions have been observed. Apart from the H-bond interactions, the stability of HAS-Diflunisal complex was further empathized by five hyrdrophobic interactions framed between hydroxyl benzoic acid ring with ALA194, GLN459 and ARG197amino acid residue and difluorobenzene ring with ALA194 and VAL456. Interpretation: The results of drug-likeness study showed that diflunisal is highly reactive and less toxic.

Sarcococca saligna extract attenuates formaldehyde-induced arthritis in Wistar rats via modulation of pro-inflammatory and inflammatory biomarkers.

Sarcococca saligna plant is commonly used as traditional therapy for arthritis especially in Asian countries. The current study is designed to explore the anti-arthritic potential of S. saligna aqueous methanolic extract (SSME). Preliminary proximate study and HPLC analysis were performed to investigate the phytochemical characterization and quality control. The safety of the SSME was evaluated by performing an acute oral toxicity study (OECD guidelines 425). The anti-arthritic potential of SSME was explored by in vivo formaldehyde-induced arthritis model. The antiarthritic effect of the SSME was determined through paw diameter, arthritic index, body weight, biochemical and haematological parameters. Radiographic and histopathological studies were also carried out to evaluate the results. qRT-PCR was performed to determine the upregulation and downregulation of anti- and pro-inflammatory cytokines in rats while ELISA was done to determine the concentration of HSP-70, IL-6 and TNF-α in the serum. Results of acute oral toxicity showed no abnormality and mortality. There was no noticeable change in haematological and biochemical parameters. Histopathological examination exhibited the normal structure of vital organs. So, SSME might be safe at a 2000mg/kg dose, proposing that LD50 was higher than 2000mg/kg body weight. Gallic acid, catechin, hydroxyl benzoic acid, sinapic acid, caffeic acid, ferulic acid and p-cumaric acid were identified by HPLC. The outcomes of in vivo formaldehyde-induced arthritic model showed that SSME significantly reduced paw inflammation and arthritic index and improved haematological and biochemical parameters. Moreover, the SSME influentially down-regulated the gene expression of IL-1β, IL-6, COX-2, PGE2, TNF-α and NF-κB, and up-regulated the expression of IL-4, and IL-10. The results of the undertaken study suggest that S. saligna have strong anti-arthritic activity supporting its conventional application as the remedy of rheumatoid arthritis.

Role of hydroxyl benzoic acid foliar spray on amelioration of lead tolerance on Triticum aestivum L.

Heavy metal pollution of water and soil has become a global issue, which extensively effect the major cereal crops and human health in the world. Current study aimed to conduct the role of exogenously applied Hydroxyl Benzoic Acid (HBA) foliar spray on agronomic and physicochemical parameters of two varieties of Triticum aestivum L. i.e. Jhanbaz and Galaxy 2013 under the lead (heavy metal) stress. Leaves of the above plants were treated (after 7, 14, 21 days) with distilled water (control), 2ppm Pb2+ (T1), 2ppm Pb2+ +HBA (T2),4 ppm Pb2+ (T3), and 2ppm Pb2+ +HBA (T4) and response of plants was observed at first, second and third week of the germination. Results of the lead (Pb2+) treatment of 4ppm and 2ppm showed high adverse effect on physiochemical and growth performance. Whereas HBA foliar spray revealed better performance by improving seedling vigorous index, agronomic parameters and percent field capacity under application of lead at 4ppm and 2ppm. This indicated that the toxic effects generated by heavy metal stress were relatively overcome by the application of HBA. However, results exhibited the better growth and physicochemical performance were recorded in Jhanbaz as compared to Galaxy 2013 and recommended variety under induced lead stress (lead). Keywords: Growth performance; Heavy metal; HBA; Lead; Triticum aestivum L. http://dx.doi.org/10.19045/bspab.2021.100088

Enhancement effect of Hydroxyl Benzoic Acid (HBA) foliar application on growth performance of Triticum aestivum L. (Wheat) under induced chromium toxicity

Heavy metals are toxic to plants even at low concentration, resulting in growth and total biomass reduction. Present research was intended to assess the effect of induced chromium toxicity on growth and performance of wheat varieties (Ta-Habib and Sahar) extensively growing in Peshawar region, Khyber Pakhtunkhwa surrounded by industrial area, adding 2-4 ppm Cr+3 in the form of effluents to irrigation water. The study also focused on the enhancement effect of Hydroxyl benzoic acid (HBA) foliar spray under chromium toxicity wheat plant. Highest amplitude of agronomic characteristics, germination percentage and vigor index was observed in Ta-Habib indicated tolerant variety as compared to variety Sahar which has been proved by the hyper accumulation of Cr+3 in the mentioned variety. It was reported that treatments T1 (2ppm Cr+3) and T3 (4ppm Cr+3) showed adverse effects which were mitigated by the foliar application of Hydroxyl benzoic acid (HBA). Keywords: Chromium toxicity; Foliar application; Hydroxyl benzoic acid; Wheat http://dx.doi.org/10.19045/bspab.2020.90269

Characteristics and performance of rutile/anatase/brookite TiO2 and TiO2–Ti2O3(H2O)2(C2O4)·H2O multiphase mixed crystal for the catalytic degradation of emerging contaminants

The as-synthesized rutile/anatase TiO2 and rutile/anatase/brookite TiO2–Ti2O3(H2O)2(C2O4)·H2O, particularly rutile/anatase TiO2, showed excellent catalytic oxidation of organic contaminants (MO and HBA).

Theoretical study of some structures of titanium(IV) complexes derived from 2-, 3- and 4-hydroxyl-benzoic acids

Complexes of fluoride titanium(IV) using hydroxyl benzoic acids as ligands are known for their great interest for care of the teeth, of the oral cavity or of dentures. Their activity is closely linked to the stability of their geometry. In this paper, we studied the structures of Ti(IV) complexes derived from hydroxyl-2-benzoic acid, hydroxyl-3-benzoic and hydroxyl-4-benzoic acids by molecular modelling. Calculations by molecular mechanics, Extended Huckel Theory (EHT) calculations have enabled access to the values of steric energy, bond lengths and bond angles, torsion angles, charges, coordinates of the atoms and the total energy values. The data obtained using molecular modelling are in the same range of those obtained in literature. Both data showed an octahedral structure around the metal ion of Ti(IV) complex with a small distortion. KEY WORDS : Hydroxy benzoic acids, Ti(IV) complexes, Molecular modelling, Steric Energy, Stability Bull. Chem. Soc. Ethiop. 2018 , 32(3), 571-577. DOI: https://dx.doi.org/10.4314/bcse.v32i3.15

Front-face fluorescence spectroscopy in combination with parallel factor analysis for profiling of clonal and vineyard site differences in commercially produced Pinot Noir grape juices and wines

The applicability of using front-face fluorescence spectroscopy to compare profiles of commercially produced New Zealand Pinot Noir grape juice and wine samples from closely related vineyard sites and different grapevine clones was assessed by monitoring eleven batches of grape juices (different sites and clones) during the commercial winemaking process (pre-fermentation, pre-barrelling, barrelled wines). Deconvolution of the recorded fluorescence excitation-emission matrices was carried out using parallel factor analysis (PARAFAC) and the scores plots thereof showed sample groupings on the basis of clone and indicated chemical differences based on vineyard site, winemaking and barrel properties. The four components revealed by the PARAFAC models had their excitation/emission maxima at 278/360 nm, 260/390 nm, 278/315 nm and 320/415 nm, respectively and were tentatively assigned to multiple fluorophore contributions of tryptophan and hydroxyl benzoic acid derivatives (vineyard site discrimination), caffeic acid (clone discrimination), catechin and tyrosol related fluorophores (winemaking based discrimination). The applied methods after further validation have potential to be used as a rapid way to screen grape juices and wines and to provide winemakers with information on the potential quality of their wine.

Multisubstrate specific flavin containing monooxygenase from Chlorella pyrenoidosa with potential application for phenolic wastewater remediation and biosensor application

ABSTRACTMicrobial degradation of phenolic pollutants in industrial wastewater is dependent on enzymatic pathway comprising a cascade of phenol metabolizing enzymes. Phenol hydroxylase is the first enzyme of the pathway catalysing the initial attack on phenol in green algae Chlorella pyrenoidosa. The present work reports cost-effective production of partially purified microalgal phenol hydroylase by single-step purification and characterization of its kinetic properties with the view of application for enzyme-based remediation of phenolic wastewater or in phenolic biosensor. The enzyme with a molecular weight of 25 kDa shows all characteristics of phenol hydroxylases, that is, hydroxylation of phenol to catechol (confirmed by HPLC), substrate-dependent NADPH oxidation, absorption spectrum typical of flavoproteins and peptide mass fingerprint corresponding to flavoprotein hydroxylase. The enzyme utilizes phenol with apparent Michealis constant (Km) of 1.71 µM, maximal velocity (Vmax) of 0.4 µM/min with optimal activity at pH 7 and 35°C. Fe2+chelators (Phenanthroline and sodium arsenate), heavy metals, denaturants and oxidizing agents showed inhibitory effect on phenol hydroxylation activity of the enzyme. The enzyme has broad substrate specificity against isomeric diphenols, isomeric methylphenols, halogen-substituted phenols, amino-substituted phenols, nitrophenols, hydroxybenzaldehyde and hydroxylbenzoic acid. The enzyme shows remarkable storage stability at room temperature and at 4°C. The multisubstrate specificity coupled to remarkable storage stability of the microalgal phenol hydroxylase opens up avenues for its application in remediation of a wide range of phenolics released in industrial wastewater or phenolic biosensor application.

Anti-oxidant and anti-microbial properties of some ethno-therapeutically important medicinal plants of Indian Himalayan Region.

Therapeutic potential of medicinal plants as a source of noble natural anti-oxidants and anti-microbial agents has been well recognised all across the globe. In this study, phenolic compounds, in vitro anti-oxidant activity and anti-microbial properties have been investigated in five Himalayan medicinal plants, (e.g., Acorus calamus, Habenaria intermedia, Hedychium spicatum, Roscoea procera and Valeriana jatamansi) in different solvent systems. R. procera exhibited significantly (p < 0.05) higher phenolics; while H. spicatum was rich in flavonoids and V. jatamansi in anti-oxidant activity. Also, R. procera and H. spicatum were found rich in gallic acid; V. jatamansi in catechin, hydroxylbenzoic acid and caffeic acid and H. intermedia in hydroxyl benzoic acid. Solvent systems showed species specific response for extraction of total flavonoids and anti-oxidant activity. All the extracts were found effective against different bacterial and fungal strains in a dose dependent manner and maximum antimicrobial activity was found in R. procera as compared to other species. All the plant extracts showed greater activity against bacterial strains as compared to fungal strains. The results of this study suggest that extract of these species can be used as natural anti-oxidant to reduce free radical mediated disorders and as natural alternative for food preservation.

Efficient Catalytic Ozonation over Reduced Graphene Oxide for p-Hydroxylbenzoic Acid (PHBA) Destruction: Active Site and Mechanism.

Nanocarbons have been demonstrated as promising environmentally benign catalysts for advanced oxidation processes (AOPs) upgrading metal-based materials. In this study, reduced graphene oxide (rGO) with a low level of structural defects was synthesized via a scalable method for catalytic ozonation of p-hydroxylbenzoic acid (PHBA). Metal-free rGO materials were found to exhibit a superior activity in activating ozone for catalytic oxidation of organic phenolics. The electron-rich carbonyl groups were identified as the active sites for the catalytic reaction. Electron spin resonance (ESR) and radical competition tests revealed that superoxide radical ((•)O2(-)) and singlet oxygen ((1)O2) were the reactive oxygen species (ROS) for PHBA degradation. The intermediates and the degradation pathways were illustrated from mass spectroscopy. It was interesting to observe that addition of NaCl could enhance both ozonation and catalytic ozonation efficiencies and make ·O2(-) as the dominant ROS. Stability of the catalysts was also evaluated by the successive tests. Loss of specific surface area and changes in the surface chemistry were suggested to be responsible for catalyst deactivation.

Compositional Analysis and Antioxidant Activity of Volatile Components of Two &lt;i&gt;Salvia&lt;/i&gt; spp

Purpose: To identify and compare the composition of volatile components of two Salvia species, and also their free radical scavenging activity. Method: The essential oil of two Salvia species was analyzed using gas chromatography-mass spectroscopy (GC-MS) techniques while their phenolic contents were analyzed by high performance liquid chromatography (HPLC). The in vitro antioxidant activity of the essential oils was evaluated by 1, 1-diphenyl-2 picryl hydrazyl (DPPH) radical scavenging technique. Results: Seven derivatives were identified for S. verticillata and four derivatives for S. suffruticosa . For both species, the main compounds were 1, 8-cineole ( S. suffruticosa : 31.21 % and S. verticillata : 38.26 %) and camphor ( S. suffruticosa : 27.11 % and S. verticillata : 22.98 %). The content of the phenolic compounds was: ascorbic acid ( S. suffruticosa : 23.98 % and S. verticillata : 33.53 %), p- hydroxyl benzoic acid ( S. suffruticosa 11.50 % and S. verticillata 3.83 %), vanilic acid ( S. suffruticosa 5.86% and S. verticillata : 6.55 %), syringic acid ( S. suffruticosa 6.29 %), ferulic acid ( S. suffruticosa : 6.35 % and S. verticillata 6.04 %) and sinapic acid ( S. suffruticosa 6.26 % and S. verticillata 4.93%). DPPH radical scavenging ability was 0.548 % for S. suffruticosa for S. suffruticosa and 0.558 % for S. verticillata . Conclusion: The results of this study demonstrated that these two species are rich in 1, 8-cineole, camphor and phenolic compounds. There is no significant difference between the radical scavenging activities of the two essential oils. Keywords: S. verticillata , S. suffruticosa , essential oil, antioxidant activity, GC-MS, HPLC activity

The organoleptic and microbial quality of some herbal medicinal products marketed in Freetown, Sierra Leone.

Background: The WHO has advocated for the integration of herbal medicinal products into the primary health care system of developing countries. Safety, however, is a concern to the drug regulatory bodies. This study was carried out to determine the organoleptic properties and the microbial quality of herbal products available to consumers in the Freetown metropolis of Sierra Leone.Materials and Methods: Twenty herbal preparations purchased within the Freetown metropolis were assessed for taste, colour, odour, and pH. The microbial load and the presence of pathogens were determined. The residual antibacterial activity of two of the preparations that showed no microbial contamination was determined using the cup plate method. The ability of a combination of methyl- and propyl-parabens to prevent growth in some of the herbal products was studied.Results: It was found that 80% of the samples contained mean bacterial and fungal counts ranging from 1.47 x 108 to 9.375 x 108cfu/ml and 3.45x108 to 1.6x109cfu/ml, respectively. The bacterial contaminants were predominantly Gram-positive organisms of the genera Bacillus and Staphylococcus. Escherichia coli, Salmonella spp. and Shigella spp. were among the isolated pathogens. Aspergillus spp., Trichoderma harzianum, Candida albicans and Cryptococcus neoformans were the predominant fungal contaminants. Two of the herbal samples from which no contaminants were recovered inhibited test organisms while the tested preservative system consisting of a mixture of methyl- and propyl-para hydroxyl benzoic acid in the ratio 2:1 and a use concentration of 0.2%w/v completely inhibited growth in tested samples.Conclusion: The findings of the study suggest that many of the herbal medicinal preparations marketed in Freetown are likely to be contaminated with potentially pathogenic microorganisms. The microbial quality of these herbal products may however be improved by the incorporation of appropriate preservatives.Key words: Herbal products, Sierra Leone, organoleptic properties, microbial quality, preservatives

Chemical characterisation of bioactive compounds in Medicago sativa growing in the desert of Oman

Medicago sativa Linn growing in Omani desert were chemically characterised using flame photometry, inductively coupled plasma, gas chromatography–mass spectrometry and high performance liquid chromatographic (HPLC) analysis. HPLC analyses were performed to determine the phenolics and flavonoids present in M. sativa. The major compounds detected in M. sativa leaves were protchaechenic acid (3.22%), hydroxyl benzoic acid (1.05%), β-Phenyl caffate (0.97%) and kaempherol (0.89%). Pterostilbene, a cholesterol-lowering compound, was detected in M. sativa.

Synthesis, structural characterization and Hirshfeld analysis studies of three novel co-crystals of trans-4-[(2-amino-3,5-dibrobenzyl) amino] cyclohexanol with hydroxyl benzoic acids

Combination of active pharmaceutical ingredients, trans-4-[(2-amino-3,5-dibrobenzyl) amino] cyclohexanol (AMB) and some organic acids, e.g., p-hydroxybenzoic acid (PHBA), m-hydroxybenzoic acid (MHBA), and 3,4-dihydroxy benzoic acid (DHBA), yield three novel co-crystals characterized by X-ray single-crystal, Fluorescence spectroscopy and thermal analysis (DSC and TGA), which included co-crystal 1 with 2:2: 1 stoichiometry of AMB, PHBA and H2O, co-crystal 2 with 1:1 stoichiometry of AMB and MHBA, and co-crystal 3 with 1:1:1 stoichiometry of AMB, DHBA and CH3OH. Constituents of the co-crystalline phase were also investigated in terms of Hirshfeld surfaces. In the crystal lattice, a three-dimensional hydrogen-bonded network is observed, including formation of a two-dimensional molecular scaffolding motif. Hirshfeld surfaces and fingerprint plots of three co-crystals show that structures are stabilized by H⋯H, N–H⋯O, H⋯Br and C⋯H intermolecular interactions. Besides, the studies of the solubility showed that this co-crystal strategy could promote the solubility of AMB and follow the order: co-crystal 1<co-crystal 2<co-crystal 3.

Synthesis of Poly(β-cyclodextrin-maleic anhydride) Conjugated Magnetic Nanoparticles via RAFT Polymerization for Adsorption of Organic Compound

In this paper, novel magnetic nanoparticles by initiating maleic anhydride-β-cyclodextrin (MAHCD) polymerization onto the surface of Fe3O4 nanoparticles were prepared. Firstly, MNPs were modified by silane couple agent, and then the modified MNPs reacted with 3-benzylsulfanyl thiocarbonyl sulfanyl propionic acid chloride to obtain RAFT chain transfer modified Fe3O4 nanoparticles. Then, maleic anhydride-β-cyclodextrin (MAHCD) was prepared by the reaction of maleic anhydride with β-cyclodextrin. Finally, MNP@P(MAHCD-co-MMA) nanoparticles were prepared using MAHCD and methyl methacrylate (MMA) as monomers and modified Fe3O4 nanoparticles as chain transfer agent by RAFT in the presence of initiator AIBN. The structure and size of the MNP@P(MAHCD-co-MMA) nanoparticles were confirmed by FTIR, TGA, XRD and TEM. The results showed that the MNP@P(MAHCD-co-MMA) nanoparticles about 200 nm were successfully prepared. Moreover, the MNP@P(MAHCD-co-MMA) nanoparticles showed well adsorption property using hydroxylbenzoic acid as the guest compound. Therefore, the MNP@P(MAHCD-co-MMA) nanoparticles have the capability to adsorb suitable guest compounds, and could be used for water treatment.

Study of Abl1 tyrosine kinase inhibitors by liquid chromatography–electrospray ionization-mass spectrometry

A method to study Abl1tyrosine kinase inhibitors (TKIs) by liquid chromatography–electrospray ionization-mass spectrometry (LC–ESI-MS) was developed and validated. Chromatographic separation was achieved on a Symmetry® C-18 column using a gradient. The detection was performed by selected ion monitoring (SIM) mode via positive ESI interface. The limit of quantification (LOQ) was 40.8nM for p-Abltide [product, KKGEAIpYAAPFA-NH2] and 26.7nM for Abltide (substrate, KKGEAIYAAPFA-NH2). The residual plot of linearity calibration curve indicated a good fit with a linear model. Intra- and inter-day precision was less than 10% and accuracy was from −6.93% to +0.15%. Matrix effect was not significant in this method. The validated method was applied to an Abl1 TKIs study. Imatinib mesylate (IM) and dasatinib were used to evaluate this method and the IC50 values were 202.1nM and 925.1pM, respectively. Two natural products (−)- epigallocatechingallate (EGCG) and caffeic acid were tested with this model. The IC50 value of EGCG was found at 64.03nM and caffeic acid showed fluctuant inhibitory activity from 26% to 55% in the concentration range from 1nM to 1mM. The IC50 value of a dimethylpyrrole hydroxylbenzoic acid derivative (MPB) was 1.915μM.

EVALUATION OF COMMONLY USED PRESERVATIVES IN VARIOUS ANALGESIC SUSPENSIONS THROUGH HPLC AND MICROBIAL ASSAY

Stability of pharmaceutical products is the ultimate objective of the pharmaceutical sector. Preservatives are the essential and effective part of all types of Syrup and suspension formulations. A fast reversed-phase high performance liquid chromatography method is developed for the determination of sodium benzoate (SB) and alkyl esters of Para hydroxyl benzoic acid such as ethyl paraben (EP), methyl paraben (MP), and propyl paraben (PP) in marketed analgesic suspensions collected from different sources. Complete separation of all the analytes was achieved on an Hypercil C18 (256 mm × 6.4 mm; 5 µm) column using acetonitrile and acetate buffer (pH 5) in the ratio of (35:65, v/v) as the mobile phase pumped at a flow rate of 1.5 mL/min in isocratic mode. Under the optimized experiment conditions, separation of the analytes was achieved in less the 10 min. Efficacy of the preservatives is determined in the prepared suspensions using the identified strains of bacteria, that is, Escherichia coli ATCC (8739), Pseudomonas aeruginosa ATCC (9027), and Staphylococcus aureus ATCC (6538) for a period of 28 d.

Hydrogen Radical Removal Causes Complex Overlapping Isotope Patterns of Aromatic Carboxylic Acids in Negative-ion Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

We studied the ionization process of aromatic carboxylic acids, including ones with or without hydroxy groups in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), because many natural products, metabolites, and drags contain those structural units. In the actual experimental data, benzoic acid was ionized as only deprotonated molecule [M-H](-). In contrast, both of negative molecular ion M(-) and deprotonated molecule [M-H](-) were generated from 2-naphthoic acid and 2-anthracenecarboxylic acid, and the ratio of negative molecular ion to deprotonated molecule M(-)/[M-H](-) was increased in 2-anthracenecarboxylic acid. In addition, the ratio of 2-anthracenecarboxylic acid was much higher than those of 1- and 9-anthracenecarboxylic acids among the three isomers. Therefore, 2-substitution induced the generation of the negative molecular ion M(-), which can made us prediction of the substituted positions from their overlapping peak isotope patterns. 2,5-Dihydroxybenzoic acid (2,5-DHBA) showed two deprotonated molecules, [M-H](-) and [M-H*-H](-), which was generated from a neutral hydrogen radical (H*) removal from a phenolic hydroxy group. The deprotonated molecule [M-H*-H](-) of 2,5-DHBA was the most abundant among six DHBAs and three hydroxybenzoic acids (hBAs). This observation raises the possibility that such a property of 2,5-DHBA could be a clue to explain its highest efficiency as a MALDI matrix. The order of the hydrogen radical removal from the phenolic hydroxy groups was the 3-<4-≪5-positions in the DHBAs, and the 3-<4-positions in hBAs. We can distinguish among six DHBA isomers and three hBA isomers from their spectral pattern around the deprotonated molecules [M-H*-H](-) and [M-H](-). The intra-molecular hydrogen bonding between 1-carboxy and 2-hydroxy groups was an important factor in hydrogen radical removal in the hydroxylbenzoic acids and dihydroxybenzoic acids.