Molecular Peak Research Articles

Dielectric barrier discharge (DBD) plasma induced flavonoid degradation kinetics and mechanism in water

In this work, we evaluated the degradation mechanism of standard flavonoids when treated with dielectric barrier discharge (DBD) plasma in water. Five different standard flavonoids were chosen for analysis, including apigenin, myricetin, kaempferol, rutin, and quercetin. All flavonoids were treated for 5 min, and the samples were collected at different time intervals. The degradation kinetics of DBD plasma-treated samples were analyzed using HPLC, which follows first-order reaction kinetics. Various degradation peaks were observed in the HPLC chromatogram that started appearing within 10 s of DBD plasma treatment and increased until 60 s–90 s, subsequently degraded completely within 5 min of plasma treatment. LC-MS analysis was performed for the quercetin fragments obtained at 7.54 min. Based on the obtained major molecular ion peak at m/z 152.98 And 196.96; a quercetin degradation mechanism is suggested. The effect of two different feed gases (clean dry air and N2) on flavonoid degradation was also evaluated.

Development of bioconjugated nano-molecules against targeted microbial pathogens for enhanced bactericidal activity

The study reports development of bio-conjugated nano-molecules (BCM's) for enhanced antibacterial activity against targeted pathogens of global concern. The conjugation was achieved with biomolecular interaction of silver clusters with 3-Dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) which was purified and characterized with TLC which displayed prominent band at Rf 0.5 and HPLC analysis displayed chromatographic peak eluting at (tR) 6–8 min. The LC-MS analysis displayed single major peak at tR = 4.610 corresponding to molecular ion peak at m/z = 227.19. The developed BCM molecule was determined with UV–Visible spectroscopy which displayed the absorbance peaks of conjugated molecules with shoulder peak observed and morphological characteristics were well defined with TEM analysis which showed cluster formation. The size ranged from 20 to 80 nm in size with majority of the BCM displaying spherical in size. The process of bio-conjugation was further studied with FTIR analysis which corresponded with different vibrational stretches owing to the presence of amide, carbonyl alkynes, nitriles and carboxylic acid groups. The presence of functional moieties was also studied using 1H and 13C NMR spectra. The crystalline characteristics was confirmed with XRD analysis which displayed Bragg's intensities along with additional peaks occurring at 2 theta angle corresponds to (111), (200), (220), (311) face centric cube of silver planes. The antibacterial activity of BCM's was profound against all the test pathogen which was validated and compared with standard antibiotics. Among the test pathogens, highest activity was conferred against Staphylococcus epidermidis (MTCC 435) with 29 mm. The minimal inhibition concentration of BCM's was in the range of 0.97–3.12 μg/ml. The results of MIC were in accordance with well diffusion assay indicating the Gram + ve test pathogen Staphylococcus epidermidis to be the most sensitive. In addition, the broth dilution assay resulted in decrease in the optical density measured at 600 nm against the increase in the concentration of BCM's. The outcome of the present investigation revealed the role of bio-conjugation chemistry to increase fold activity against pathogens which can act as alternative tool to combat drug resistant menace across the globe.

A novel plasmid-encoded mcr-4.3 gene in a colistin-resistant Acinetobacter baumannii clinical strain.

To identify the molecular mechanism of colistin resistance in an MDR Acinetobacter baumannii clinical strain isolated in 2008 from a meningitis case in Brazil. Long- and short-read WGS was used to identify colistin resistance genes in A. baumannii strain 597A with a colistin MIC of 64 mg/L. MS was used to analyse lipid A content. mcr was cloned into pET-26b (+) and transformed into Escherichia coli BL21(λDE3)pLysS for analysis. A novel plasmid (pAb-MCR4.3) harbouring mcr-4.3 within a Tn3-like transposon was identified. The A. baumannii 597A lipid A MS spectra showed a main molecular ion peak at m/z=2034, which indicated the addition of phosphoethanolamine to the lipid A structure. E. coli BL21 transformed with pET-26b-mcr-4.3 gained colistin resistance with a colistin MIC of 8 mg/L. Colistin resistance in A. baumannii 597A was correlated with the presence of a novel plasmid-encoded mcr-4.3 gene.

Synthesis and Characterization of Some Bromochalcones Derivatives

Chalcones are considered to be precursors of flavonoids and have variety of biological activities. Three of bromochalcones derivatives were synthesized by a green chemistry approach using grinding technique and their structure also confirmed. Synthesis of bromochalcone, 4′-bromo-4-methoxychalcone, 4′-bromo-3, 4-dimethoxychalcone, 4′-bromo-3, 4, 5-trimethoxychalcone were carried out using starting material of 4-bromoacetophenone through Claisen-Schmidt base catalyzed condensation. The structures of the synthesized compounds were confirmed by gas chromatography–mass spectrometry (GC-MS). The mass spectra of the compounds were showed corresponding molecular ion peak which was correlated with their molecular weight of that respected compound (4′-bromo-4-methoxychalcone = 317, 4′-bromo-3, 4-dimethoxychalcone = 347, 4′-bromo-3, 4, 5-trimethoxychalcone = 377).

Heteronuclear and homonuclear Ni(II) complexes constructed based on 8-hydroxyquinoline-2-carbaldehyde oxime: Structure and its behavior in solution

The organic ligand (E)-8-hydroxyquinoline-2-carbaldehyde oxime (H2L) was used to react with Ni(CH3COO)2·4H2O and NaN(CN)2 at 100 °C to obtain the complex [Ni3Na(HL)3(L)2]n·4nCH3CN (1). Interestingly, the five ligands in the structure chelate three Ni ions, and the uncoordinated O on the ligand captures one Na+. However, the above scheme remains the same, and after adding isonicotinic acid (ina), it obtained the complex [Ni4(HL)4(L)2]2·2CH3CN (2), which eight Ni2+ ions are coordinated by twelve ligands. The component distribution of the complexes in different solutions was measured by electrospray-ionization mass spectrometry (ESI-MS). It was found that the complexes exhibited different component distribution in different solutions. Not only the existence of low-nuclear molecular ion peaks could be monitored, but even higher-nuclear components could also be detected, and the alkali metal ions could be effectively identified. It was indicating that the compounds would assemble differently in different solutions. Surprisingly, homonuclear clusters 2 was providing a basis for further directing the directed synthesis of higher nuclear clusters.

Synthesis of Antioxidant Peptide SCAP1 (Leu-Ala-Asn-Ala-Lys)

SCAP1 is a pentapeptide isolated from the hydrolysate of oyster (Saccostrea cucullata), which has antioxidant and anticancer properties. This study aims to find a novel strategy to obtain antioxidant peptide SCAP1 (Leu-Ala-Asn-Ala-Lys) through chemical synthesis. This study reports the first synthesis of SCAP1 through the solid phase peptide synthesis (SPPS) method with Fmoc strategy on 2-chlorotrityl chloride resin. A HATU-HOAt coupling reagent was employed in all amide bond formations and 95% TFA in water was employed to release the desired peptide from the solid support. The crude peptide was purified using successive preparative-RP-MPLC and RP-HPLC to obtain the pure peptide. The synthesized peptide was confirmed by mass spectrometry, showing a correct molecular ion peak at m/z 516.3143 (M+H)+, referring to the desired SCAP1. 1H-NMR spectra of the peptide revealed protons signals consistent to the structure of SCAP1. During the synthesis, the coupling between Ala and Asn(Trt) was not straightforward, which led to a low yield of the final product. The use of Trt-based Asn was not a suitable option, as it could cause aggregation during the synthesis, eventually leading to a poor yield of the final product. SCAP1 was obtained as a white solid with a percent yield of 8.28%.

Comparative gas chromatographic/mass spectrometric characterization of di- and trialkyl phosphites.

Homologous series of alkyl esters of phosphorus-containing acids, namely, dialkyl phosphonates (synonym: dialkyl phosphites) and trialkyl phosphites, were characterized by electron ionization (EI) mass spectra and gas chromatographic retention indices (GC RI) on semi-standard non-polar stationary phases. It is confirmed that GC/MS characterization of any sets of homologues should not be restricted to independent registration of these analytical parameters. Their joint processing in the form of so-called homologous increments of GC RIs means, firstly, a novel way of evaluating the chromatographic polarity of analytes and, secondly, a new algorithm for the prediction of their molecular weights if no peaks of molecular ions are registered in the mass spectra. A standard GC/MS technique, including determination of GC RIs on semi-standard nonpolar stationary phases in temperature-programmed regime and electron ionization (EI) mass spectra was used. A total of 31 dialkyl phosphonate homologues and 37 trialkyl phosphite homologues were characterized by EI mass spectra and GC RIs for the first time. Joint processing of these analytical parameters allows the calculation of so-called homologous increments of GC RIs, which are useful parameters for evaluating the chromatographic polarity of analytes and predicting their molecular weights. GC/MS characterization of any sets of homologues should not be restricted to independent registration of the mass spectra and chromatographic retention parameters. Their joint processing in the form of so-called homologous increments of GC retention indices means, firstly, a novel way of evaluating the chromatographic polarity of analytes and, secondly, a new algorithm for predicting their molecular weights.

Cu61(StBu)26S6Cl6H14]+: A Core–Shell Superatom Nanocluster with a Quasi-J36 Cu19 Core and an “18-Crown-6” Metal-Sulfide-like Stabilizing Belt

Although core–shell copper metal nanoclusters are important emerging materials for practical applications and fundamental scientific research, their synthesis lags behind that of gold and silver nanoclusters–challenged by copper’s much lower half-cell reduction potential, M(I)/M(0). To overcome this synthetic hurdle, we introduce a simple reaction strategy, involving the mild reducing agent borane tert-butylamine complex, to produce a core–shell superatom copper nanocluster, [Cu61(StBu)26S6Cl6H14]+ (−StBu; tert-butyl thiolate), which is the largest Cu(0)-containing structurally-solved core–shell copper cluster to-date. The nanocluster exhibits a quasi-elongated triangular gyrobicupola (quasi-J36, J36 = Johnson solid) Cu19 core and a shell held together by a novel “18-crown-6” metal-sulfide-like belt. Because of its stability, this cluster displays a single molecular ion peak in mass spectrometry measurements without any cluster fragmentation signals—a first observation of its kind for copper nanoclusters that paves the way for researchers to study nanocluster composition, charge, stability, and reaction mechanisms with atomic precision that only mass spectrometry could afford.

Co(II),Cu(II),Ni(II),Fe(II)and Cr(III) Complexes of N,O-Type Schiff base ligand derived from 4,4,-methylenedianiline Synthesis, Characterization and antibacterial studies

Complexes of Co(II),Cu(II),Ni(II),Fe(II)and Cr(III) were prepared from reaction between (E)-2-(((4-(4-aminobenzyl)phenyl)imino)methyl)phenol and hydrated metal ions such as CoCl2.6H2o,NiCl2.6H2O.FeCl2.6H2O and CrCl3.H2O characterization by analytical and spectra chemical methods .the metal:ligand stoichiometric ratio is 1:1 n the all complexes.it was determined that bidentate behavior of the ligand is accomplished via the phenolic oxygen and the azomethine nitrogen atom .the presence of water revealed by thermogram and supported by the presence of relevant bonds in their IR Spectra. These new complexes showed areasonable amount antibacterial activity.a ligand was synthesized by reaction (4,4'-Methylenedianiline and Salicylaldehyde. The newly synthesized compounds were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Nuclear Magnetic Resonance Spectroscopy (1H NMR), elemental analyses (C, H, N), mass spectral, conductivity measurement, magnetic sensitivity measurement and atomic Absorption. The mass spectrum of the ligandexhibits a molecular ion peak [M]+.at 302 m/z.

Stepwise construction and destruction of nickel thiolate Ni3 cluster revealed by mass spectrometry and crystallography

Trinuclear nickel thiolate cluster [Ni3(μ3-S)(L)3]NO3 (HL = (1-methyl-1H-benzo[d]imidazol-2-yl)methanethiol) (1) has been synthesized from Ni(NO3)2·6H2O and HL at solvothermal condition at 80 °C using methanol as solvent. It has been characterized by X-ray single crystal diffraction, elemental analysis, electrospray ionization mass spectrometry (ESI-MS), and thermogravimetric analysis. The stability of the cluster in methanol is reflected by the fact that the molecular ion peak of [Ni3(μ3-S)(mbms)3]+ is dominant in ESI-MS. Furthermore, the release of H2S from 1 was observed at elevated in source energy condition and in tandem mass spectrometry. The H2S fragment was also detected during the destruction of 1 by thermogravimetric analysis combined with mass spectrometry (TG-MS). Key fragments [NiLS]+ and [Ni2L2]+ were percepted in solution by ESI-MS during the reaction, which have also been detected at elevated in source energy condition. A plausible stepwise assembly process including [NiL]+ to the mixture of [NiLS]+ and [Ni2L2]+ which then combined to give the product [Ni3L3S]+ was proposed.

Direct mapping of hydrangea blue-complex in sepal tissues of Hydrangea macrophylla

The original sepal color of Hydrangea macrophylla is blue, although it is well known that sepal color easily changes from blue through purple to red. All the colors are due to a unique anthocyanin, 3-O-glucosyldelphinidin, and both aluminum ion (Al3+) and copigments, 5-O-caffeoyl and/or 5-O-p-coumaroylquinic acid are essential for blue coloration. A mixture of 3-O-glucosyldelphinidin, 5-O-acylquinic acid, and Al3+ in a buffer solution at pH 4 produces a stable blue solution with visible absorption and circular dichroism spectra identical to those of the sepals, then, we named this blue pigment as ‘hydrangea blue-complex’. The hydrangea blue-complex consists of 3-O-glucosyldelphinidin, Al3+, and 5-O-acylquinic acid in a ratio 1:1:1 as determined by the electrospray ionization time-of-flight mass spectrometry and nuclear magnetic resonance spectra. To map the distribution of hydrangea blue-complex in sepal tissues, we carried out cryo-time-of-flight secondary ion mass spectrometry analysis. The spectrum of the reproduced hydrangea blue-complex with negative mode-detection gave a molecular ion at m/z = 841, which was consistent with the results of ESI-TOF MS. The same molecular ion peak at m/z = 841 was detected in freeze-fixed blue sepal-tissue. In sepal tissues, the blue cells were located in the second layer and the mass spectrometry imaging of the ion attributable to hydrangea blue-complex overlapped with the same area of the blue cells. In colorless epidermal cells, atomic ion of Al3+ was hardly detected and potassium adduct ion of 5-O-caffeoyl and/or 3-O-acylquinic acid were found. This is the first report about the distribution of aluminum, potassium, hydrangea blue-complex, and copigment in sepal tissues and the first evidence that aluminum and hydrangea blue-complex exist in blue sepal cells and are involved in blue coloration.

Screening of Metabolic Markers of Qi‐Yin deficiency in Chronic Heart Failure Mice by Untargeted Metabolomics Method

Qi‐Yin deficiency is the main syndrome of chronic heart failure that one of the major heart disease that threatening human health. Clarifying the time‐history of Qi‐Yin deficiency in chronic heart failure disease, and further exploring the metabolic markers of Qi‐Yin deficiency can help to explain the pathological mechanism and Precise treatment of Qi‐Yin deficiency in chronic heart failure. This study adopted chronic heart failure model induced by coronary artery ligation in mice. We investigated the changes in the appearance of clinical indications corresponding to symptoms of Qi‐Yin deficiency at different time points, which aimed to clear the time‐history of Qi‐Yin deficiency appeared in chronic heart failure model mice. Positive (Yiqifumai) and negative (Danhong) control group were set up to assistant define the time‐history of Qi‐Yin deficiency. We found that Chronic heart failure mice appeared significant weight loss, decreased food intake, spontaneous activity , accelerated heart rate, and increased T wave amplitude in the first 2–3 weeks after modeling. What's more, Yiqifumai had better effects than Danhong in the improvement of Qi‐Yin deficiency in the first 2–3 weeks, which assistant proved that this period was Qi‐Yin deficiency. The coagulation function test results also suggest that it may turn into blood stasis syndrome around 4–5 weeks. In addition, LC‐MS/MS technology was used to determine the endogenous metabolites in serum and urine of mice on the positive ion mode. The data of accurate molecular weight and fragment ion peak were checked on HMDB database, and the identification methods of PCA and OPLS‐DA were used to analyze the multivariable data. Metabolites of the chronic heart failure model mice during the period of Qi‐Yin deficiency and non Qi‐Yin deficiency were compared to explore specific metabolite groups significant related to Qi‐Yin deficiency. The untargeted metabolomic workflow is showed in Figure 1. The results of metabolomic analysis of serum and urine of model mice showed that metabolites were well‐differentiated between the two groups at 2–3 weeks and 4–5 weeks. 29 significant difference metabolites in serum and 19 significant difference metabolites in urine were identified in this study. Hence, these results demonstrated that ischemia‐induced chronic heart failure may be mainly manifested as Qi‐Yin deficiency syndrome in the first 2–3 weeks, followed by conversion to blood stasis syndrome. Metabolites of chronic heart failure mice also changed as the syndrome transformed.Support or Funding InformationNational Natural Science Foundation of China (NO. 81774150)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Peculiarities of Mass Spectra of Substituted Pyrroloquinolines

The results of the mass spectrometric studies of a series of substituted isomeric pyrrolo[2,3-g], [3,2-f], [3,2-g], and [2,3-f]quinolines are presented and analyzed. Angular pyrroloquinolines with bulk peri substituents are less stable under electron ionization conditions than the corresponding linear isomers. The differences in the magnitude of the ratio of the intensity of a molecular ion peak to the total ionic current expressed as a percentage (WM) depend on the steric requirements of peri-located groups in angular systems. The data obtained make it possible to identify the structure of the resulting isomeric tricyclic heterosystems. A mechanism for the mass spectral decomposition of methyl-, phenyl-, methoxy-, hydroxyl-, and ethoxycarbonyl-substituted pyrroloquinolines is proposed.

Synthesis and Physico Chemical Studies of Some Cobalt (II) Complexes with Bromide and Biologically Active Ligands

Eleven cobalt (11) complexes of type [Co(L)6]Br2 (where L=imidazole, pyridine, peperidine, piperazine, indole, benzimidazole, benzotriazole, triazole, quinoline, iso-qunoline, carbazole) have been synthesized and are well characterized by elemental analysis, IR. UV. Mass Spectra and magnetic measurement. All these complexes are soluble in ethanol and the conductance measurement shows that all these complexes are of 1: 2 type electrolyte. The IR spectra indicate the coordination between the central cobalt atom and nitrogen atom of the ligands. In the mass spectra molecular ion peak of these complexes appear at appropriate place. The thermo gravimetric analysis shows the strong bond between the central cobalt atom and bromine atom of the complexes. In the complexes the ligands are loosely attached to the central cobalt atom as these are removed first on heating. Finally considering all the spectral analysis conductance values, thermo gravimetric analysis, conductance values octahedral structure are proposes for these complexes

GC-MS and LC-MS Identification of the Phenolic Compounds Present in the ethyl Acetate Fraction Obtained from Senna tora, L. Roxb. seeds

The aim of this work is to characterize the active constituents present in the ethyl acetate fraction of Senna tora, L. Roxb. seeds. Due to the fact that the main biological activity of S. tora, L seeds is attributed to its phenolic compounds which are mainly isolated from Ethyl acetate fraction, to avoid repetition of work and to save time, it was deemed necessary to confirm the identity of these phenolic compounds. This was done by GC-MS and LC-MS analysis of the ethyl acetate fraction where the structures of the isolated compounds were established on the basis of molecular ion peak and their fragmentation pattern. They were identified as Chrysophanol, Chrysarobin, 10-hydroxy-5-methoxy-2-methyl-1, 4-anthracenedione, Rubrofusarin, Parietin, Griseoxanthone-B, Isotorachrysone, and Cumbiasin B.

Bananas decrease acetaminophen potency in in vitro assays.

Edible portions of bananas contain high levels of polyphenol oxidase, which catalyzes reactions in the melanin formation pathway. Tyrosine, a physiological substrate of polyphenol oxidase, has an analogous structure to acetaminophen. We investigated whether banana extract causes structural changes in acetaminophen and a decrease in its potency. Acetaminophen concentration in banana extract was measured under different conditions to characterize incompatibility. Reaction products in solution were identified using liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS). Acetaminophen potency decreased with time in the presence of banana extract. The reaction proceeded most efficiently in temperatures 30–37°C and neutral to weakly acidic conditions. Molecular ion peaks derived from the oxidized catechol moiety of acetaminophen were identified in LC/ESI/MS spectra. Our findings suggest that incorporation or simultaneous administration of acetaminophen medication and banana juice may result in decreased efficacy of the clinically important drug. This interaction is likely due to the oxidation of acetaminophen by polyphenol oxidase activity in banana pulp. Therefore, we investigated and characterized a novel interaction between bananas and acetaminophen. To establish a safe and effective antipyretic analgesic regimen using acetaminophen, future studies of this interaction are expected to be performed in humans.

Study to Probe Subsistence of Host-Guest Inclusion Complexes of \u03b1 and \u03b2-Cyclodextrins with Biologically Potent Drugs for Safety Regulatory Dischargement

Host-guest interaction of two significant drugs, phenylephrine hydrochloride and synephrine with α and β-cyclodextrins were studied systematically. Initially two simple but reliable physicochemical techniques namely conductance and surface tension were employed to find out saturation concentration for the inclusion and its stoichiometry. The obtained 1:1 stoichiometry was further confirmed by two spectrometric methods, UV-Vis study and spectrofluorimetry. Significant shifts in IR stretching frequency also support the inclusion process. Relative stabilities of the inclusion complexes were established by the association constants obtained from UV-Vis spectroscopic measurements, program based mathematical calculation of conductivity data. Calculations of the thermodynamic parameters dictates thermodynamic feasibility of the inclusion process. Spectrofluorometric measurement scaffolds the UV-Vis spectroscopic measurement validating stability of the ICs once again. Mass spectroscopic measurement gives the molecular ion peaks corresponding to the inclusion complex of 1:1 molar ratio of host and guest molecules. The mechanism of inclusion was drawn by 1H-NMR and 2D ROESY spectroscopic analysis. Surface texture of the inclusion complexes was studied by SEM. Finally, the cytotoxic activities of the inclusion complexes were analyzed and found, Cell viability also balances for non-toxic behavior of the ICs. Moreover, all the studies reveal the formation of inclusion complexes of two ephedra free, alternatively emerging drugs (after their banned product having ephedra) SNP, PEH with α and β-CD which enriches the drug delivery system with their regulatory release without any chemical modification.

Ultrafast Deep-Ultraviolet Laser Ionization Mass Spectrometry Applicable To Identify Phenylenediamine Isomers

The application of low-fragmentation mass spectrometry to identify chemicals has been recognized to be of particular importance in chemistry, biomedicine, and materials science. Utilizing a customized all-solid-state picosecond-pulsed deep-ultraviolet (DUV) laser, here we present new advances into photoionization mass spectrometry. The DUV laser ionization mass spectrometry (DUV-LIMS) results in very clean spectra pertaining to minimized structure relaxation and fragmentation under the ultrafast ionization process. Typical DUV-LIMS applications are illustrated not only for small organic molecules but also for long-chain unsaturated hydrocarbons and clusters of benzene. The unique advantages of DUV-LIMS enable us to detect and analyze confusing organic compound mixtures, indicating promising applications. DUV-LIMS is also found to be applicable in the identification of phenylenediamine isomers. An in-depth analysis of reaction dynamics is provided showing how hydrogen-atom-transfer (HAT) initiates the distinguishable photodissociation of phenylenediamines under near-resonant excitation. In particular, ortho-phenylenediamine (OPD) finds a remarkable dehydrogenation product with comparable intensity to the molecular ion peak, which is associated with the quantum tunnelling tautomers, providing new subjects for studying intramolecular noncovalent interactions.

Isolation and purification of antibacterial compound from Streptomyces levis collected from soil sample of north India.

During the screening programme for microbial cultures producing antimicrobial agents, an active microbial strain of Streptomyces was isolated from the agricultural soil of Narnaul, Haryana India. Physiological, biochemical characteristics and 16S ribosomal RNA sequence homology studies revealed that it was similar to Streptomyces levis (sequence similarity 100%). The microbial strain was submitted to Genomebio Technologies Pvt. Ltd., Pune, Maharashtra, India under Accession No. EU124569. The isolated strain was found to produce extracellular active compound showing strong antimicrobial activity against Klebsiella pneumoniae MTCC 109, Pseudomonas aeruginosa MTCC 741 and Staphylococcus aureus MTCC 96. The antibacterial compound was successfully isolated and purified. Structure elucidation of antibacterial metabolite with EI-MS/ HRMS showed molecular ion peak at m/z 686 [M+H]+. Whereas, elemental analysis of the said compound showed C = 61.31, H = 8.61, N = 2.04 and O = 28.02, and indicated a molecular formula of C35H59NO12. The presence of ‘chromone’ nucleus in the compound’s chemical structure was confirmed by using 1HNMR studies. The present study reports the purification of potential antibacterial compound from Streptomyces levis isolated from the unexplored soil of north India and warrants for further characterization of this potential compound for optimum utilization for antimicrobial purposes.

Direct Observation of Hydrangea Blue-Complex Composed of 3-O-Glucosyldelphinidin, Al3+ and 5-O-Acylquinic Acid by ESI-Mass Spectrometry.

The blue sepal color of hydrangea is due to a metal complex anthocyanin composed of 3-O-glucosyldelphinidin (1) and an aluminum ion with the co-pigments 5-O-caffeoylquinic acid (2) and/or 5-O-p-coumaroylquinic acid (3). The three components, namely anthocyanin, Al3+ and 5-O-acylquinic acids, are essential for blue color development, but the complex is unstable and only exists in an aqueous solution. Furthermore, the complex did not give analyzable NMR spectra or crystals. Therefore, many trials to determine the detailed chemical structure of the hydrangea-blue complex have not been successful to date. Instead, via experiments mixing 1, Al3+ and 2 or 3 in a buffered solution at pH 4.0, we obtained the same blue solution derived from the sepals. However, the ratio was not stoichiometric but fluctuated. To determine the composition of the complex, we tried direct observation of the molecular ion of the complex using electrospray-ionization mass spectrometry. In a very low-concentration buffer solution (2.0 mM) at pH 4.0, we reproduced the hydrangea-blue color by mixing 1, 2 and Al3+ in ratios of 1:1:1, 1:2:1 and 1:3:1. All solution gave the same molecular ion peak at m/z = 843, indicating that the blue solution has a ratio of 1:1:1 for the complex. By using 3, the observed mass number was m/z = 827 and the ratio of 1, 3 and Al3+ was also 1:1:1. A mixture of 1, 3-O-caffeoylquinic acid (4) and Al3+ did not give any blue color but instead was purple, and the intensity of the molecular ion peak at m/z = 843 was very low. These results strongly indicate that the hydrangea blue-complex is composed of a ratio of 1:1:1 for 1, Al3+ and 2 or 3.