Methanol Eluate Research Articles

Band profiles of reacting acido-basic compounds with water–methanol eluents at different [formula omitted] and ionic strengths in reversed-phase liquid chromatography

Overloaded band profiles of aniline (25 μ L injection of a 30.5 mM solution) eluted with a methanol-aqueous buffer solution (30/70, v/v) were recorded at the exit of a 150 mm × 4.6 mm column packed with 3.5 μ m XBridge-C 18porous particles. The pH W S of the mobile phase was adjusted with phosphate ( pH W S ∼ 2.7 and pH W S ∼ 7.5 ) or acetate buffers ( pH W S ∼ 5.3 ) of different concentrations (11, 56, and 278 mM). The elution times and profiles of the bands observed at low ionic strength were succesfully accounted for using the extended Debye–Hückel theory to estimate the activity coefficients of the ions in the bulk phase and a simple non-competitive Langmuir adsorption model, the adsorption of pure aniline or pure anilinium onto XBridge-C 18 being described by a Langmuir isotherm. The band profiles were calculated using this adsorption model and the equilibrium-dispersive model of chromatography. The calculated and the experimental band profiles are in excellent agreement at all buffer pH and ionic strength. This demonstrates that the elution times and the band profiles are controlled by the chromatographic dilution process and by the reaction of aniline with the buffer solution.

In vitro vasorelaxation mechanisms of bioactive compounds extracted from Hibiscus sabdariffa on rat thoracic aorta

BackgroundIn this study, we suggested characterizing the vasodilator effects and the phytochemical characteristics of a plant with food usage also used in traditional treatment of arterial high blood pressure in Senegal.MethodsVascular effects of crude extract of dried and powdered calyces of Hibiscus sabdariffa were evaluated on isolated thoracic aorta of male Wistar rats on organ chambers. The crude extract was also enriched by liquid-liquid extraction. The various cyclohexane, dichloromethane, ethyl acetate, butanol extracts obtained as well as the residual marc were subjected to Sephadex LH-20 column chromatography. The different methanolic eluate fractions were then analyzed by Thin Layer (TLC) and High Performance Liquid Chromatography (HPLC) and their vascular effects also evaluated.ResultsThe H. Sabdariffa crude extract induced mainly endothelium-dependent relaxant effects. The endothelium-dependent relaxations result from NOS activation and those who not dependent to endothelium from activation of smooth muscle potassium channels. The phytochemical analysis revealed the presence of phenolic acids in the ethyl acetate extract and anthocyans in the butanolic extract. The biological efficiency of the various studied extracts, in term of vasorelaxant capacity, showed that: Butanol extract > Crude extract > Residual marc > Ethyl acetate extract. These results suggest that the strong activity of the butanolic extract is essentially due to the presence of anthocyans found in its fractions 43-67.ConclusionThese results demonstrate the vasodilator potential of hibiscus sabdariffa and contribute to his valuation as therapeutic alternative.

Application of SPE‐HPLC‐DAD and SPE‐TLC‐DAD to the determination of pesticides in real water samples

Planar chromatography with diode array scanning (TLC-DAD) and high-performance chromatography with diode array detection (HPLC-DAD) were used to screen water samples for pesticides. Pesticides were enriched from lake water samples by SPE on C18/SDB-1, C18, C18 Polar Plus and cyanopropyl (CN) cartridges. The recovery rates were high for all extraction materials except for all pesticides on CN cartridges, for which the values were lower. SPE was used not only for preconcentration of analytes but also for their fractionation. The analytes were eluted first with methanol and then with dichloromethane. Methanol eluates were analysed by HPLC-DAD, the dichloromethane eluates with TLC-DAD. The method was validated for precision, repeatability and accuracy. The calibration plots were linear between 0.1 and 50.0 microg/mL for all pesticides, the correlation coefficients, r, were between 0.9992 and 1.000 as determined by HPLC-DAD. In the TLC experiments, the best fit for the calibration lines was found when the calibration data were analysed using a second-degree polynomial regression. Calibration plots lay between 0.1 and 17 microg/spot for all pesticides, the correlation coefficients, r, were between 0.9974 and 0.9997 determined by TLC-DAD. The LOD was between 0.04 and 0.65 microg/spot (TLC-DAD) and between 0.02 and 3.68 microg/mL (HPLC-DAD).

Determination of Pesticides in Water Samples from the Wieprz-Krzna Canal in the czysko-Wodawskie Lake District of Southeastern Poland by Thin-Layer Chromatography with Diode Array Scanning and High-Performance Column Liquid Chromatography with Diode Array Detection

High-performance thin-layer chromatography with diode array scanning (TLC-DAD) and high-performance column liquid chromatography with a diode array detector (HPLC-DAD) were used to screen water samples for pesticides. Atrazine, clofentezine, chlorfenvinphos, hexaflumuron, terbuthylazine, lenacyl, neburon, bitertanol, and metamitron were enriched from canal water samples by solid-phase extraction (SPE) on octadecyl silane (C18)/styrene-divinylbenzene-1, C18, C18 Polar Plus, and cyanopropyl (CN) cartridges. Recovery rates were high for all extraction materials except CN, for which values for all pesticides were lower. SPE was used for both preconcentration and fractionation of the analytes. Analytes were eluted by means of methanol and dichloromethane. Methanol eluates were analyzed by HPLC-DAD and dichloromethane eluates by TLC-DAD. The method was validated for precision, repeatability, and accuracy. Calibration graphs were linear between 0.1 and 50.0 microg/mL for all pesticides, and correlation coefficient (r) values were between 0.9994 and 1.000 as determined by HPLC-DAD. Calibration graphs were linear between 0.1 and 1.5 microg/spot for all pesticides, and r values were between 0.9899 and 0.9987 as determined by TLC-DAD. The limit of detection was between 0.04 and 0.23 microg/spot for TLC-DAD and 0.02 and 0.45 microg/mL for HPLC-DAD.

Use development of functional materials in the leaves of Perilla frutescens (L.) Britton var. acuta Kudo (red perilla) with Japanese dietary pickled plum (Umeboshi)

Six phenolic compounds and one steroid were isolated from the leaves of Perilla frutescens Britton var. acuta (red perilla) with Japanese dietary pickled plum (Ume). Their structures were determined based on UV, MS, 1H-NMR and 13C-NMR spectroscopic data as β-sitosterol (1), shisonin (2), kaempferol 3-O-rutinoside (3), rosmarinic acid (4), rosmarinic acid methyl ester (5), 4-glucopyranosylcinnamic acid (6), and caffeic acid methyl ester (7). In the bioassay, remarkable superoxide scavenging activity was found in the 1-butanol extract, and 20% methanol-water eluate, 50% methanol-water eluate and methanol eluate of an Amberlite XAD-2. In addition, remarkable inhibitory effect was found in rosmarinic acid and rosmarinic acid methyl ester which are those isolation compounds.

SINTESIS SENYAWA ETILENDIAMIN KALANON MELALUI REAKSI ADISI GUGUS ETILENDIAMIN TERHADAP IKATAN RANGKAP C7-8 DAN UJI AKTIVITAS ANTILEUKEMIA TERHADAP SEL LEUKEMIA L1210

Calanone is a natural compound which could be isolated from tree bark of Calophyllum biflorum Hend and WS ( 0,37 % w/w, crude extract) which have been potency as antileucemia drug (IC50= 59,4 ug/mL). Based on the research, the compound can be used as an anti leukemia drug if it value of IC50 < 10 ug/mL. So the aim of this research are in order to get higher calanone activity by modified of double bond carbon-carbon and to obtained several compounds as well which has a higher activity than calanone of its original compound. Several compounds, several compound can be obtained by modified of doble bond carbon-carbon by ethylendiamine group and antileukemia test of the new compound calanone derivatives towards L1210 leukemia cell. The result of the analysis, using thin layer chromatography with eluent methanol:dichlorometane ( 1:6) , give Rf at 0.51 and initial melting point at range 149oC – 151oC. Infra red spectrophotometry and mass spectrometry were used to identify the synthesized product. The result showed that the mass spectra of ethylendiamine calanone give molecular ion at 449 (M+- H2O, NH3) and ions fragmen at m/e 449; m/e 434; m/e 393; m/e 105, m/e 77. Infra red spectra of its compound showed new peaks at 1620 cm -1 and 1063 cm -1. The activity value toward leukemia cell was IC50= 46,28 µg/mL and its value higther than calanone origin.

High-throughput determination of fudosteine in human plasma by liquid chromatography–tandem mass spectrometry, following protein precipitation in the 96-well plate format

A 96-well protein precipitation, liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and fully validated for the determination of fudosteine in human plasma. After protein precipitation of the plasma samples (50 μL) by the methanol (150 μL) containing the internal standard (IS), erdosteine, the 96-well plate was vortexed for 5 min and centrifuged for 15 min. The 100 μL supernatant and 100 μL mobile phase were added to another plate and mixed and then the mixture was directly injected into the LC–MS/MS system in the negative ionization mode. The separation was performed on a XB-CN column for 3.0 min per sample using an eluent of methanol–water (60:40, v/v) containing 0.005% formic acid. Multiple reaction monitoring (MRM) using the precursor-product ion transitions m/ z 178 → 91 and m/ z 284 → 91 was performed to quantify fudosteine and erdosteine, respectively. The method was sensitive with a lower limit of quantification (LLOQ) of 0.02 μg mL −1, with good linearity ( r > 0.999) over the linear range of 0.02–10 μg mL −1. The within- and between-run precision was less than 5.5% and accuracy ranged from 94.2 to 106.7% for quality control (QC) samples at three concentrations of 0.05, 1 and 8 μg mL −1. The method was employed in the clinical pharmacokinetic study of fudosteine formulation product after oral administration to healthy volunteers.

Validation of a HPLC method for flavonoid biomarkers in skullcap (Scutellaria) and its use to illustrate wide variability in the quality of commercial tinctures.

To compare the flavonoid biomarker content (baicalin, baicalein and wogonin) of eleven commercial tinctures derived from Scutellaria lateriflora aerial parts (n=7) and Scutellaria baicalensis root (n=4). S. lateriflora tinctures are used in by western herbal practitioners to treat anxiety whereas S. baicalensis tinctures are used to treat inflammatory disease. Baicalin and baicalein were purchased from Aldrich Chemical Co. and Wogonin was purchased from ChromaDex. The internal standard (4-hydroxybenzoic acid) was obtained from Acros Organics. The column used was a Luna C18, 5 m (150 x 4.6 mm, Phenomenex) maintained at ambient room temperature. A HP1050 HPLC system was used, comprising a gradient pump with degasser, a variable wavelength UV detector set to 270 nm, and an autosampler. Gradient elution was performed using 0.1% formic acid (eluent A) and methanol (eluent B). The gradient elution initial conditions were 45% B with linear gradient to 60% from 2 to 10 min, followed by linear gradient to 70% B at 30 min, and then linear gradient to 99% B at 31 min, this proportion being maintained for 1 min. The mobile phase was then returned to initial conditions at 33 min and maintained until the end of the run at 35 min. The flow rate was 1 mL/min. The assay was validated for sensitivity, accuracy and reproducibility. The concentration range of biomarkers (baicalin, baicalein and wogonin) in commercial tinctures is reported for S. lateriflora (baicalin: 0-12.66 mg/mL; baicalein: 0-0.63 mg/mL; wogonin: 0-0.16 mg/mL) and for S. baicalensis (baicalin: 0.12-10.61 mg/mL; baicalein: 0.52-5.88 mg/mL; wogonin: 0.08-1.61 mg/mL). The wide variability in biomarker concentrations between commercial tinctures has important implications for the manufacturers of commercial tinctures, for herbal practitioners in the choice of tinctures and not least for pharmacology and clinical researchers.

Insect Antifeedant Sesquiterpene Acetals from the Liverwort Lepidolaena clavigera. 2. Structures, Artifacts, and Activity

Clavigerin A ( 1) was isolated from the New Zealand liverwort Lepidolaena clavigera and shown to be a polyoxygenated bergamotane sesquiterpene with an unusual ring system. L. clavigera shows infraspecific variation, since 1 was the only clavigerin detected in a North Island collection, whereas the previously reported clavigerins B ( 2) and C ( 3) were found in South Island collections with no sign of 1. Three new clavigerins, 4- 6, were identified, but these are artifacts formed by alcoholysis of the acetoxy acetal group of the clavigerins 2 and 3, with either the extraction solvent ethanol or the RP column eluent methanol. The insect antifeedant and cytotoxic activities of these compounds are reported, and it is proposed that they act as hidden 1,4-dicarbonyl compounds.

High-performance liquid chromatography with fluorescence detection for quantitation of tryptophan and tyrosine in a shrimp waste protein concentrate

A new, simple, and reproducible isocratic high-performance liquid chromatography (HPLC) method has been developed for the determination of free and total tyrosine and tryptophan in a protein concentrate. To determine total amino acids, the method involves alkaline hydrolysis of the proteins with sodium hydroxide at 120 °C for 4 h in the absence of air. Best results were achieved with a SS Exil ODS column 5 μm (25 cm × 0.46 cm i.d.), with an eluent of methanol: 40 mM sodium acetate buffer (adjusted to pH 4.5 with acetic acid; 20:80, v/v), a flow rate of 0.80 mL/min at 26 °C, and with programmable fluorescence detection. Under optimum conditions excellent linearity was obtained, and the overall recovery was 90.5, and 95.9% for total tryptophan and tyrosine, respectively. The precision results showed that the relative standard deviation of the repeatability and reproducibility were ≤4.78 and ≤4.65, respectively. This method was used to quantify the cited analytes in the protein concentrate obtained during the lactic acid fermentation of shrimp waste.

Simultaneous Determination of Veterinary Drugs in Livestock Foods and Seafoods Using Liquid Chromatography/Tandem Mass Spectrometry

A simultaneous determination of veterinary drugs in livestock food and seafood using liquid chromatography with tandem mass spectrometry (LC/MS/MS) was developed. Veterinary drugs were extracted with 95% acetonitrile. The solution was passed through a Florisil column, and the solvent was replaced with phosphate buffer. The extract was charged on a Sep-Pak Plus C(18) mini-column and divided into 40% methanol eluate fraction and 70% acetonitrile eluate fraction. Test solutions were analyzed by LC/MS/MS with gradient elution. By using this method, 37 kinds of veterinary drugs were obtained with over 60% recovery, and quantitation was possible in cattle muscle, egg and fish. This method was inapplicable to 28 kinds of veterinary drugs. Although quantitation was not achieved, 42 other kinds of veterinary drugs can be screened. Since the limit of quantitation for this method is less than the provisional limit in general, it is useful as a screening method in residual analysis of veterinary drugs.

Comparison of rosmarinic acid content in commercial tinctures produced from fresh and dried lemon balm (Melissa officinalis)

To measure the rosmarinic acid content of eight commercial tinctures derived from fresh (n= 5) and dried (n=3) Melissa officinalis herb. Rosmarinic acid and the internal standard (esculin) were purchased from Aldrich Chemical Co. The column used was a Luna C18, 5 um (150 x 4.6 mm I.D., Phenomenex) maintained at ambient room temperature. The HPLC system consisted of a Shimadzu SCL-6B controller, Shimadzu LC-6A pumps, Shimadzu SPD-6A UV single wavelength spectrophotometric detector set to 320 nm and Shimadzu SIL-6B autosampler. Gradient elution of the samples and standard were performed using ammonium formate (0.02 M; pH 6.25 at 27 oC; eluent A) and methanol (eluent B). The gradient elution initial conditions were 2% of eluent B with linear gradient to 60% at 30 min, followed by linear gradient to 90% of eluent B at 31 min, this proportion being maintained for 4 min. The column was then returned to the initial condition at 36 min and maintained until the end of the run at 43 min. The flow rate was 1 mL/min. The assay was validated for sensitivity, accuracy and reproducibility. The content of rosmarinic acid in commercial tinctures was significantly higher in the tinctures made from dried plant material (2.96 - 22.18 mg/mL) compared to fresh plant tinctures (</= 0.92 mg/mL). These results have implications both for the manufacturers of commercial tinctures and also for herbal practitioners in the choice of tinctures for treating Herpes simplex infection.

Validation of an HPLC Method for the Determination of Valdecoxib and its Degradation Product: a Mixture of α- and β-n-Lactosyl Sulfonamide Anomers

An HPLC method has been developed for the separation of valdecoxib and a degradation product consisting of α and β-N-lactosyl sulfonamide, i.e. α and β anomers (SC-77852). Best results were achieved with a Chromolith Performance RP-18e column (100 mm × 4.6 mm), macropore size 2 μm, mesopore size 13 nm, with an eluent of methanol:water containing a 1% solution of TEA (36:64 v/v), pH 7.4 (adjusted with 85% orthophosphoric acid), at 22 °C. Detection was at 220 nm. The method was validated for its selectivity, linearity, precision (repeatability) and robustness. Quantitation and detection limits were determined for both valdecoxib and SC-77852. Method robustness was further evaluated by performing 23 full factorial design experiments. The final step, optimisation of the variables, was performed using response surface design. The validated method was used for assay of valdecoxib and SC-77852 in Bextra® film-coated tablets.

Clenbuterol Determination in Calf Hair by UPLC-MS-MS: Case Report of a Fraudulent Use for Cattle Growth

A method for clenbuterol determination in hair has been developed. Hair specimens collected from two calves were decontaminated using hot water followed by methylene chloride. Hair was cut into small pieces, and 100 mg was incubated in 1 mL 0.1M hydrochloric acid overnight at 45 degrees C in the presence of 1 ng acebutolol used as internal standard. After neutralization with 1 mL 0.1M NaOH, 2 mL of bicarbonate buffer (pH 8.6) were added and the preparation was then purified using solid-phase extraction with an Isolute C18 column. Methanolic eluent was evaporated to dryness and the residue was reconstituted with 50 microL methanol. A 5-microL portion was injected onto an ACQUITY UPLC BEH C18 column (2.1 x 50 mm, 1.7 microm) and separation was achieved using a gradient of acetonitrile and formate buffer delivered at a flow rate of 0.6 mL/min. Detection was done on a Waters Micromass Quattro Micro API triple-quadrupole mass spectrometer. Ionization was achieved using electrospray in positive mode. Clenbuterol was identified by two transitions (m/z 277.1 > 203.2 and m/z 277.1 > 132.1). Quantitation was performed with the most intensive transition (m/z 277.1 > 203.2) versus the internal standard monitored using the transition (m/z 337.3 > 116.1). When compared with gas chromatography methods that are generally used for the determination of beta-adrenergics, the major advantages of this method were the sensitivity, a shorter run time, and the absence of a derivatization step. The analysis of two hair samples from calves suspected of drug administration showed low clenbuterol concentrations at 3.6 and 4.8 pg/mg.

1,1-Diphenyl-2-picrylhydrazyl Radical Scavenging Activity and Tyrosinase Inhibitory Effects of Constituents of Sugarcane Molasses

In the course of our work into the use of cane by-products, we have studied the isolation and structural determination of bioactive compounds in sugarcane molasses. In this study, three stereo isomers of syringyl glycerol 3'-O-beta-D-glucopyranoside, three stereo isomers of guaiacyl glycerol 3'-O-beta-D-glucopyranoside, a syringyl glycerol 2'-O-beta-D-glucopyranoside, tachioside and a 2,3-dihydro-3,5-dihydroxy-6-methyl-4-(H)-pyran-4-one (DDMP) were isolated from the 25% methanol eluate by Amberlite XAD-2 column chromatography of sugarcane molasses. The structures of these compounds were determined on the basis of spectroscopic evidence. These isolated compounds were examined for their scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical species, and for their inhibitory activity against mushroom tyrosinase. All of the isolated compounds showed DPPH radical scavenging activity, while DDMP and tachioside showed mushroom tyrosinase inhibitory activity.

Flow-through solid-phase reflectometric method for simultaneous multiresidue determination of nitrophenol derivatives

In this paper, a flow-through optosensor based on diffuse reflectance spectroscopy and multivariate regression modelling is proposed for simultaneous multiresidue determination of trace level concentrations of nitro-substituted phenols. The optrode integrates on-line anion-exchange sorptive preconcentration and matrix removal with direct detection of sorbed species onto the sensing layer and chemometric deconvolution of overlapped spectra. After recording of the reflectometric spectrum, fast chemosensor regeneration is accomplished with an acidic methanolic eluent followed by a metered volume of alkaline solution. The full automation of the analytical procedure is ensured by flow-programming as executed via a software-controlled multisyringe pump and a set of multiposition and solenoid valves. Under the optimized chemical and physical variables, the 3 σ blank detection limits for 2-, and 4-nitrophenol and 2,4-dinitrophenol were 0.69, 0.42 and 0.37 μg L −1, respectively, for a sample loading volume of 4.0 mL with enrichment factors of 73, 74 and 81, respectively , and repeatability better than 3.0%. The analytical applicability of the optosensing system was asserted by the satisfactory results attained in its application to monitoring of nitrophenol derivatives in spiked environmental waters including highly saline matrices via the standard additions method.

Trichoderma brevicompactum Complex: Rich Source of Novel and Recurrent Plant-Protective Polypeptide Antibiotics (Peptaibiotics)

Three strains of Trichoderma brevicompactum and another four that are closely related to that species (Trichoderma cf. brevicompactum) were analyzed for the formation of polypeptide antibiotics (peptaibiotics) by LC/ESI-MS(n). These isolates were selected because of an antagonistic potential against Eutypa dieback and Esca disease of grapevine and have not yet been investigated for the production of peptide antibiotics. Fully grown cultures on potato dextrose agar were extracted with CH2Cl2/MeOH, and this extract was subjected to SPE using C18 cartridges. The methanolic eluates were analyzed by LC/ESI-MS(n). All strains were found to produce membrane-active alamethicins F30. In addition to that, novel peptaibiotics were detected, namely, 14 12-residue trichocryptins B, 12 11-residue trichocryptins A, 19 11-residue trichobrevins A and B, 6 10-residue trichoferins, and 17 8-residue trichocompactins. These compounds may partially be responsible for the plant-protective action of the producers. Chemotaxonomic considerations also indicated the necessity to introduce another new species that is closely related to T. brevicompactum.

Peptaibiomics: Screening for Polypeptide Antibiotics (Peptaibiotics) from Plant-ProtectiveTrichoderma Species

Eight strains of Trichoderma species (T. strigosum, T. erinaceus, T. pubescens, T. stromaticum, and T. spirale as well as T. cf. strigosum, T. cf. pubescens) were selected because of their antagonistic potential against Eutypa dieback and Esca which are fungal diseases of grapevine trunks. These isolates were screened for the production of a group of polypeptide antibiotics named peptaibiotics, including its subgroups peptaibols and lipopeptaibols. Fully-grown fungal cultures on potato-dextrose agar were extracted with CH(2)Cl(2)/MeOH, and these extracts were subjected to SPE using C(18) cartridges. The methanolic eluates were analyzed by on-line LC/ESI-MS(n) coupling--a method which is referred to as 'peptaibiomics'. New seven-, ten-, and eleven-residue lipopeptaibols, with N-terminal alkanoyl, and C-terminal leucinol or isoleucinol residues were found and named lipostrigocins and lipopubescins. Furthermore, new 18-residue peptaibols named trichostromaticins and 19-residue peptaibols named trichostrigocins were discovered. One peptaibiotic carrying a free C-terminal valine (or isovaline) named trichocompactin XII was also sequenced. These results corroborate the hypothesis that peptaibiotics might contribute to the plant-protective action of their fungal producers. The data also point out that comparison of peptaibiotic sequences is of limited relevance in order to establish chemotaxonomic relationships among species of the genus Trichoderma.

Solid‐phase sediment toxicity identification evaluation in an agricultural stream

The lower Santa Maria River watershed provides important aquatic habitat on the central California coast and is influenced heavily by agricultural runoff. As part of a recently completed water quality assessment, we conducted a series of water column and sediment toxicity tests throughout this watershed. Sediment from Orcutt Creek, a tributary that drains agricultural land, consistently was toxic to the amphipod Hyalella azteca, which is a resident genus in this river. Toxicity identification evaluations (TIEs) were conducted to determine cause(s) of toxicity. We observed no toxicity in sediment interstitial water even though concentrations of chlorpyrifos exceeded published aqueous toxicity thresholds for H. azteca. In contrast to interstitial water, bulk sediment was toxic to H. azteca. In bulk-phase sediment TIEs, the addition of 20% (by volume) coconut charcoal increased survival by 41%, implicating organic chemical(s). Addition of 5% (by volume) of the carbonaceous resin Ambersorb 563 increased survival by 88%, again suggesting toxicity due to organic chemicals. Toxicity was confirmed by isolating Ambersorb from the sediment, eluting the resin with methanol, and observing significant toxicity in control water spiked with the methanol eluate. A carboxylesterase enzyme that hydrolyzes synthetic pyrethroids was added to overlying water, and this significantly reduced toxicity to amphipods. Although the pesticides chlorpyrifos, DDT, permethrin, esfenvalerate, and fenvalerate were detected in this sediment, and their concentrations were below published toxicity thresholds for H. azteca, additivity or synergism may have occurred. The weight-of-evidence suggests toxicity of this sediment was caused by an organic contaminant, most likely a synthetic pyrethroid.

Structure–Function Relation of Efomycines, a Family of Small-Molecule Inhibitors of Selectin Functions

Selectin-mediated leukocyte adhesion to endothelia, the crucial first step initiating the pathogenic cascade of inflammation, is an attractive target for specific therapies. The small-molecule macrolide, efomycine M, inhibits selectin-mediated leukocyte adhesion in vitro and in vivo, and effectively alleviates inflammatory disorders in vivo. To define the molecular basis of the therapeutically relevant antiadhesive properties of efomycines, several new species of this family were purified and/or synthesized. Efomycines E and G were isolated from Steptomyces BS1261. Efomycine O was synthesized by Lewis acid-catalyzed acetalization and efomycine M was generated by base-catalyzed deglycosylation. Efomycine S resulted from ester cleavage of the macrolide ring system, and efomycine T represents the peracetylated form of efomycine M. When the functional activity of efomycines on adhesion of leukocytes to vascular endothelium was studied, some remarkable differences between the compounds became apparent, inasmuch as efomycines E, G, M, and O significantly inhibited adhesion of both human and porcine leukocytes to the vascular endothelium, whereas efomycines S and T did not show any biological activity. A novel docking engine (ProPose), generating an improved, fully configurable protein-ligand interaction model, demonstrated that biological activities of efomycines can be predicted in silico, thus highlighting the utility of such combinatorial approaches.