Improved efficiency and stability of secnidazole – An ideal delivery system

Secnidazole (α,2-Dimethyl-5-nitro-1H-imidazole-1-ethanol) is a highly effective drug against a variety of G⁺/G⁻ bacteria but with significant side effects because it is being used in very high concentration. In this study, gold nanoparticles (GNP_S) were selected as a vehicle to deliver secnidazole drug at the specific site with more accuracy which made the drug highly effective at substantially low concentrations. The as-synthesized GNPs were capped with Human Serum Albumin (HSA) and subsequently bioconjugated with secnidazole because HSA provides the stability and improves the solubility of the bioconjugated drug, secnidazole. The quantification of covalently bioconjugated secnidazole with HSA encapsulated on enzymatically synthesized GNPs was done with RP-HPLC having SPD-20 A UV/VIS detector by using the C-18 column. The bioconjugation of GNPs with secnidazole was confirmed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The bioconjugated GNPs were characterized by UV–VIS spectroscopy, TEM, Scanning Electron Microscopy (SEM) and DLS. Zeta potential confirmed the stability and uniform distribution of particles in the emulsion of GNPs. The separation of bioconjugated GNPs, unused GNPs and unused drug was done by gel filtration chromatography. The minimal inhibitory concentration of secnidazole-conjugated gold nanoparticles (Au-HSA-Snd) against Klebsiella pneumonia (NCIM No. 2957) and Bacillus cereus (NCIM No. 2156) got improved by 12.2 times and 14.11 times, respectively, in comparison to pure secnidazole. Precisely, the MIC of Au-HSA-Snd against K. pneumonia (NCIM No. 2957) and B. cereus (NCIM No. 2156) were found to be 0.35 and 0.43 μg/ml, respectively whereas MIC of the pure secnidazole drug against the same bacteria were found to be 4.3 and 6.07 μg/ml, respectively.     

Electron-capture gas chromatographic assays of 5-nitroimidazole class of antimicrobials in blood

Sensitive and selective electron-capture gas chromatographic methods for the determination of N-1-substituted 5-nitroimidazole class of antiprotozoals from blood are described. Metronidazole, secnidazole and ornidazole having a hydroxyl function in the N-1 substitution, were converted to their respective trimethylsilyl derivatives before chromatography on an OV-11 column. Tinidazole and satranidazole, devoid of the hydroxy group but containing a sulphur atom in the molecule, were chromatographed as such on the same stationary phase. Blood levels as low as 50 ng/ml for all the 5-nitroimidazoles have been measured with good precision. The methods can be readily utilized for pharmacokinetic studies.     

Quantitation and interaction of glycosaminoglycans with Alcian blue in dimethyl sulfoxide solutions.

An improved method is described for the quantitation of glycosaminoglycans separatedon cellulose acetate, stained with Alcian blue, and dissolved in a dimethyl sulfoxide solution. Standard curves are shown for all eight glycosaminoglycans. It is shown that absorption at the Alcian blue orthochromatic E_max is depressed under conditions which favor formation of dye-glycosaminoglycan complexes. The interaction between Alcian blue and the eight glycosaminoglycans was studied in dimethyl sulfoxide solutions of varying composition. It was shown that the extent of complex formation depends both on the glycosaminoglycan and the composition of the dimethyl sulfoxide solution. A dimethyl sulfoxide solution which contains 0.094 m H₂SO₄ is described which maximizes dye-glycosaminoglycan dissociation and thus the absorbance. Also, an improved staining method is described which improves dye uptake by the glycosaminoglycans and consequently increases the sensitivity of glycosaminoglycan quantitation.     

Sensitive fluorimetric determination of gentamicin sulfate in biological matrices using solid-phase extraction, pre-column derivatization with 9-fluorenylmethyl chloroformate and reversed-phase high-performance liquid chromatography

A high-performance liquid chromatographic method is described for the determination of gentamicin in bacterial culture medium or plasma with increased sensitivity and improved separation of the C₁ component. Gentamicin was extracted from the biological matrix with high efficiency using carboxypropyl (CBA)-bonded silica. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C₁₈ reversed-phase chromatography allowed the fluorimetric detection of gentamicins C₁, C_1a and C₂. A fourth component, considered to be gentamicin C_2a, was partially resolved from the C₂ peak. Optimal conditions for the extraction and derivatization of gentamicin are described. The detection limit was below 50 μg/l, the assay was linear to 5 mg/1 and showed good reproducibility. It is concluded that pre-column derivatization with FMOC-Cl substantially improves the analysis of gentamicin compared with present methods based on reaction with o-phthaldialdehyde.     

Control of pH and inorganic carbon in batch cultures of cyanobacteria

Summary Synechococcus leopoliensis was grown in batch cultures gassed with air or CO₂ in air to test for effects of gassing on pH drift and growth. A method is described whereby pH and inorganic carbon are held constant during rapid growth.     

Fluorescence polarization assay of plasmin, plasminogen, and plasminogen activator

A chromatographic method involving medium-pressure liquid chromatography on alumina impregnated with silver nitrate is described for the separation of a series of closely related C₂₇ sterol precursors of cholesterol differing only in the number and location of olefinic double bonds. The features of the described system are compared with those of previously described thin-layer, gas-liquid, gravity column, and high-pressure liquid chromatographic methods.     

Disintegration of aggregates and coccospheres in sediment trap samples

A method for non-destructive disaggregation of coccoliths contained in fecal pellets, marine snow and on coccospheres is described. It consists of repeated chemical oxidation of organic material with (NaClO and H₂O₂) combined with brief periods of ultrasonification.     

Neuraminidase ofCorynebacterium diphtheriae: Isolation,purification and some characteristics

A method is described for neuraminidase isolation from a nontoxicogenic C₇ strain ofCorynebacterium diphtheriae by means of a precipitation from cultivation liquid using ZnCl₂ and a subsequent fractionation on a P-60 biogel column. The method yields a neuraminidase preparation homogeneous with respect to antigenity and exhibiting also homogeneity during studies with free electrophoresis.     

Synthesis, spectroscopic characterization and radiosensitizing properties of acetato-bridged copper(II) complexes with 5-nitroimidazole drugs

Three novel acetato-bridged dinuclear copper(II) complexes with 5-nitroimidazoles (CuAcNtrim) and the known copper-acetato-metronidazole have been prepared by an environment-friendly route and spectroscopically characterized. The CuAcNtrim compounds of formula [Cu₂(μ-O₂CCH₃)₄Ntrim₂], where Ntrim = metronidazole (1), secnidazole (2), tinidazole (3) or nimorazole (4), exhibit dimeric copper-acetato paddle-wheel structures with Ntrim axial ligands coordinated to copper(II) ions through the N₃ atoms of the imidazole rings. EPR data indicate antiferromagnetic behavior for this novel series of copper complexes. The constant coupling has been found to decrease along with the increasing of basicity of the Ntrim axial ligand. The CuAcNtrim complexes and the correspondent Ntrim parent drugs have shown radiosensitizer properties for Hep2 (human larynx cancer) cell line in vitro. The best enhancement of radiosensitizer activity upon coordination of the Ntrim drug to copper(II) has been found for the nimorazole compound which has the strongest Cu-Ntrim bond and exhibits the highest lipophilicity within the series of CuAcNtrim complexes.     

Calculation of s20,w values using ultracentrifuge sedimentation data from linear sucrose gradients,an improved,simplified method

A mathematical method is described for calculating the sedimentation coefficient (s_{20, w}) with ultracentrifuge data from linear sucrose gradients. Gradient density and viscosity functions are precisely described by regression equations, which permit continuous evalution (by integration) of the effects of gradient geometry on particle sedimentation. The results agree with previously used and more complex methods.     

High-performance liquid chromatographic analysis for the determination of miconazole in human plasma using solid-phase extraction

A high-performance liquid chromatographic method for the determination of miconazole in human plasma is described. A solid-phase extraction was performed on an octadecyl (C₁₈) cartridge. Miconazole was eluted with methanol, separated on a reversed-phase column and was measured by ultraviolet detection at 230 nm. The absolute extraction recovery from plasma samples was 85%. The limit of detection was established as 5 ng/ml. The coefficient of variation of the determination of plasma levels by this method over the standard curve concentration range was less than 10%, except with the concentration of 10 ng/ml. The plasma levels of miconazole in twelve healthy volunteers given a 250-mg oral dose of two tablet forms were determined by this method.     

Identification ofEscherichia coli heat-labile enterotoxin by means of a ganglioside immunosorbent assay (GM1-ELISA) procedure

A sensitive, quantitative method for determination ofEscherichia coli heat-labile enterotoxin (LT) is presented. The assay is based on the specific binding of LT to polystyrene-adsorbed G_M1 ganglioside and subsequent enzyme immunological demonstration of the bound toxin. Enterotoxin titers determined with this G_M1 enzyme-linked immunosorbent assay (ELISA) method agreed closely with those obtained with the adrenal cell bioassay. The G_M1-ELISA procedure was capable of demonstrating LT in allE. coli overnight cultures that gave positive adrenal cell results. The simplicity and high reproducibility of the described method should make it well suited for routine laboratory diagnosis of LT enterotoxigenicE. coli strains.     

Carbon dioxide evolution as a measure of attack of wood by fungi and its application to testing wood preservatives and sap stain preventives

A method of assessing fungal attack on wood, using a conductivity respirometer to measure the CO₂ evolution of the attacking fungus, is described and its application to the testing of wood preservatives and sapstain preventives is explored. Tests made by this method established in 9–13 days that the minimum fungitoxic concentration of Timbor (disodium octaborate decahydrate) was between 0·05 and 0·1%—a value agreeing with that given by the standard wood-block test lasting 12 weeks. The use of the CO₂-measurement method for fungitoxicity determinations on a copper-chrome-arsenate wood preservative and on the sapstain preventive, Santobrite (a sodium pentachlorophenate preparation), gave unsatisfactory results.     

Studies on the O-phenanthroline method for determining iron in plant materials

Summary A method of determining Fe from plant materials using O-phenanthroline is described.The absorbance of the Fe(C₁₂H₈N₂) ₃ ⁺⁺ complex from pure iron solutions or from extracts of different plant materials did not vary over a pH range of 2 to 5. Maximum absorbance was obtained after a period of 2 hours of color development and was constant for at least 24 hours. The standard curves prepared by a procedure described elsewhere⁶ were quite similar to the ones obtained by the method described in this paper.A comparison of 3 methods of extracting Fe from the ash indicated that HCl + H₂O₂ gave higher results than either of the other methods. The Fe content obtained by this procedure was very similar to the values obtained by AAS.A high percentage of the Fe added to plant tissues and peats was recovered when extracted by HCl + H₂O₂ and that the reproducibility was good. This is recommended as a simple and satisfactory procedure for accurate determination of Fe.Contribution No. 162. Research Branch, Research Station, P.O. Box 1210, Charlottetown, P.E.I.     

The use of HClO4 in the determination of reductant soluble iron phosphate in soil

Summary An improved method for the determination of reductant soluble iron-phosphate in the Chang and Jackson's inorganic phosphate fractionation procedure is described.The Use of HClO₄ eliminates the use of H₂0₂ which is usually highly contaminated with phosphorus.A highly significant correlation was established between the HClO₄ method and that of Peterson and Corey of using 0.25 M KmnO₄.     

High-performance liquid chromatographic analysis of nitrite and nitrate in human plasma as S-nitroso-N-acetylcysteine with ultraviolet absorbance detection

A rapid HPLC method with UV absorbance detection at 333 nm for the measurement of nitrite and nitrate in ultrafiltrate samples of human plasma is described. The method is based on hydrochloric acid-catalyzed conversion of nitrite by N-acetyl-l-cysteine to S-nitroso-N-acetyl-l-cysteine and isocratic elution using 10 mM NaH₂PO₄ in acetonitrile–water, pH 2.0 (15:85, v/v). The limit of detection of the method is 50 nM nitrite. The method was validated by gas chromatography–mass spectrometry.     

Simultaneous determination of seven nitroimidazole residues in meat by using HPLC-UV detection with solid-phase extraction

A method was developed for the determination of the seven nitroimidazoles including metronidazole (MNZ), ronidazole (RNZ), dimetridazole (DMZ), tinidazole (TNZ), ornidazole (ONZ), secnidazole (SNZ) and the common metabolite of RNZ and hydroxydimetridazole (DMOHZ) in poultry and pork muscles by high-performance liquid chromatography (HPLC) with ultraviolet detection (UV). After extraction with ethyl acetate and evaporation, the nitroimidazoles were redissolved in ethyl acetate and purified using strong cation exchange (SCX) solid-phase extraction (SPE) column. The HPLC separation was carried through on a C(18) bonded silica column with a deionized water-methanol-acetonitrile mobile phase using a gradient elution procedure. The limit of detection of all the seven nitroimidazoles was 0.2 microg/kg. The recoveries of the seven nitroimidazoles for chicken, pork and bacon samples spiked with 1-20 microg/kg were in the range of 71.4-99.5%. The linearity is satisfactory with a correlation coefficient of >0.998 at concentrations ranging from 0.7 to 60 microg/kg. The relative standard deviations of 10 measurements for spiked chicken, pork and bacon samples at the concentration of 1 and 20 microg/kg were in the range of 6.2-13.9% and 4.0-8.7%, respectively. The intra-day precision (n=5) for nitroimidazoles residues in chicken spiked at 20 microg/kg is 6.9%, and the inter-day precision for 5 days (n=25) is 11%. The method is capable of identifying nitroimidazole residues at > or =0.7 microg/kg levels and was applied in the determination of nitroimidazole residues in meat sample.     

A convenient quantitative synthesis of methylglyoxal for glyoxalase I assays

A simple, convenient, and quantitative method for the preparation of methylglyoxal (pyruvaldehyde) solutions is described. The method involved acid hydrolysis (5% H₂SO₄) of pyruvaldehyde dimethyl acetal at 100°C for 25 min. The hydrolysis method is quite reproducible and does not require standardization of the methylglyoxal solutions. The preparations of methylglyoxal by the procedure described have been used in the study of glyoxalase I activity.     

A new method for hybrid seed production based on cytoplasmic male sterility combined with a lethal gene and a female sterile pollenizer in Capsicum annuum L.

Summary A new improved method for hybrid seed production was successfully tested. This method is based on using a cytoplasmic male sterile line possessing a lethal gene with action that can be easily inhibited and a female sterile pollenizer. The lethal gene ensures 100% purity of the F₁ crop. The female sterile pollenizer provides a permanent abundant flowering with excess of pollen grains that leads to increased hybrid seed production without additional labour expenses. The described scheme is applicable for other crops as well.     

Assay of HA-966 in rat plasma by capillary gas—liquid chromatography with nitrogen-selective detection

A gas—liquid chromatographic method for the determination of the γ-aminobutyric acid-like drug 1-hydroxy-3-aminopyrrolidone-2 (HA-966) in plasma is described. HA-966 was converted into its diacetyl derivative Ac₂HA-966 with acetic anhydride. This compound could be suitably eluted from a capillary OV-17 support-coated open tubular column. A sensitive detection method was achieved by making use of nitrogen—phosphorus-selective flame ionization.