Bacitracin production by a new strain ofBacillus subtilis

A new strain ofBacillus subtilis C 126 was isolated from sugar cane fermentation and produced an antibiotic that inhibited the growth ofMicrococcus flavus. The production of the antibiotic in culture medium followed to extraction withn-butanol, thin layer chromatography, and microbiological tests indicated that a polypeptide antibiotic was produced. The fraction obtained by Sephadex G-25 column and analyzed by HPLC indicated that bacitracin complex was produced.     

Electrospray ionization mass spectrometry fingerprinting of perfumes: Rapid classification and counterfeit detection

A fast procedure to classify perfumes and identify counterfeit samples is described. Dilution of a few microL of the sample in a 1:1 methanol/water solution is followed by detection of its major polar components via direct infusion electrospray ionization mass spectrometry (ESI-MS) in the positive ion mode. As proof-of-principle cases, three famous brands of perfumes were used. The ESI+-MS fingerprints of authentic samples were very characteristic, showing distinctive sets of polar markers for each sample. Principal component analysis (PCA) placed samples of the three perfume brands in well-defined groups. Counterfeit samples were also clearly detected owing to contrasting ESI-MS fingerprints, with PCA placing these samples far away from the authentic samples.     

Development and validation of a rapid and sensitive LC-ESI-MS/MS method for ondansetron quantification in human plasma and its application in comparative bioavailability study

The validation of a high throughput and specific method using a high‐performance liquid chromatography coupled to electrospray (ES+) ionization tandem triple quadrupole mass spectrometric (LC‐ESI‐MS/MS) method for ondansetron quantification in human plasma is described. Human plasma samples were extracted by liquid–liquid extraction (LLE) using methyl tert‐butyl ether and analyzed by LC‐ESI‐MS/MS. The limit of quantification was 0.2 ng/mL and the method was linear in the range 0.2–60 ng/mL. The intra‐assay precisions ranged from 1.6 to 7.7%, while inter‐assay precisions ranged from 2.1 to 5.1%. The intra‐assay accuracies ranged from 97.5 to 108.2%, and the inter‐assay accuracies ranged from 97.3 to 107.0%. The analytical method was applied to evaluate the relative bioavailability of two pharmaceutical formulations containing 8 mg of ondansetron each in 25 healthy volunteers using a randomized, two‐period crossover design. The geometric mean and respective 90% confidence interval (CI) of ondansetron test/reference percent ratios were 90.15% (81.74–99.44%) for C_max and 93.11% (83.01–104.43%) for AUC_0–t. Based on the 90% confidence interval of the individual ratios (test formulation/reference formulation) for C_max and AUC_0‐inf, it was concluded that the test formulation is bioequivalent to the reference one with respect to the rate and extent of absorption of ondansetron. Copyright © 2010 John Wiley & Sons, Ltd.     

Combining mesoporous silica–magnetite and thermally-sensitive polymers for applications in hyperthermia

In this work, the synthesis strategy of a multifunctional system of [SBA-16/P(N-iPAAm)/Fe₃O₄] hybrids of interest for magneto-hyperthermia was explored. Magnetite nanoparticles coated by mesoporous silica were prepared by an alternative chemical route using neutral surfactant and without the application of any functionalization method. Monomer adsorption followed by in situ polymerization initiated by a radical was used to incorporate the hydrogel into the pore channels of the silica nanocomposite. Structural and magnetic characterization of the obtained materials was carried out by using thermal analysis, X-ray diffraction, N₂ adsorption desorption isotherms, ⁵⁷Fe Mössbauer spectroscopy, vibrating sample magnetometry and transmission electron microscopy. Measurements of alternating current magnetic-field-induced heating behaviour under different applied magnetic fields showed that the [SBA-16/P(N-iPAAm)/Fe₃O₄] hybrid here synthesized is suitable as a hyperthermia agent for biological applications.     

Determination of furanic aldehydes in sugarcane bagasse by high‐performance liquid chromatography with pulsed amperometric detection using a modified electrode with nickel nanoparticles

A glassy carbon electrode chemically modified with nickel nanoparticles coupled with reversed‐phase chromatography with pulsed amperometric detection was used for the quantitative analysis of furanic aldehydes in a real sample of sugarcane bagasse hydrolysate. Chromatographic separation was carried out in isocratic conditions (acetonitrile/water, 1:9) with a flow rate of 1.0 mL/min, a detection potential of – 50 mV vs. Pd, and the process was completed within 4 min. The analytical curves presented limits of detection of 4.0 × 10^?7 mol/L and 4.3 × 10^?7 mol/L, limits of quantification of 1.3 × 10^?6 and 1.4 × 10^?6 mol/L, amperometric sensitivities of 2.2 × 10⁶ nA mol/L and 2.7 × 10⁶ nA mol/L for furfural and 5‐hydroxymethylfurfural, respectively. The values obtained in this sample by the standard addition method were 1.54 ± 0.02 g/kg for 5‐hydroxymethylfurfural and 11.5 ± 0.2 g/kg for furfural. The results demonstrate that this new proposed method can be used for the quick detection of furanic aldehydes without the interference of other electroactive species, besides having other remarkable merits that include excellent peak resolution, analytical repeatability, sensitivity, and accuracy.     

Production and application of amylases of Rhizopus oryzae and Rhizopus microsporus var. oligosporus from industrial waste in acquisition of glucose

Amylases from Rhizopus oryzae and Rhizopus microsporus var. oligosporus were obtained using agro-industrial wastes as substrates in submerged batch cultures. The enzymatic complex was partially characterised for use in the production of glucose syrup. Type II wheat flour proved better than cassava bagasse as sole carbon source for amylase production. The optimum fermentation condition for both microorganisms was 96 hours at 30°C and the amylase thus produced was used for starch hydrolysis. The product of the enzymatic hydrolysis indicated that the enzyme obtained was glucoamylase, only glucose as final product was attained for both microorganisms. R. oligosporus was of greater interest than R. oryzae for amylase production, taking into account enzyme activity, cultivation time, thermal stability and pH range. Glucose syrup was produced using concentrated enzyme and 100 g L^?1 starch in a 4 hours reaction at 50°C. The bioprocess studied can contribute to fungus glucoamylase production and application.     

Structural, optoelectronic, infrared and Raman spectra of orthorhombic SrSnO3 from DFT calculations

Orthorhombic SrSnO₃ was investigated using density functional theory (DFT) considering both the local density and generalized gradient approximations, LDA and GGA, respectively. The electronic band structure, density of states, complex dielectric function, optical absorption, and the infrared and Raman spectra were computed. Calculated lattice parameters are close to the experimental measurements, and an indirect band gap (2.27 eV) was obtained within the GGA (LDA) level of calculation. Effective masses for holes and electrons were estimated, being very anisotropic in comparison with similar results for orthorhombic CaSnO₃. The complex dielectric function and the optical absorption of SrSnO₃ were shown to be sensitive to the plane of polarization of the incident light. The infrared spectrum between 100 and 600 cm⁻¹ was obtained, with its main peaks being assigned, and a nice agreement between experimental and theoretical peaks of the Raman spectrum of orthorhombic SrSnO₃ was achieved.     

Enantiomers separation by simulated moving bed chromatography. Non-instantaneous equilibrium at the solid-fluid interface

The simulated moving bed (SMB) technology, first conceived for large bulk-scale separations in the petrochemical industry, has found increasingly new applications in the pharmaceutical industry. Among these, the separation of fine chemicals has been the subject of considerable study and research. This work presents the modeling, simulation and design of the operation of a SMB plant in order to separate a binary chiral mixture. The usual assumption of instantaneous equilibrium at the solid-fluid interface is questioned and a first-order kinetics of adsorption is taken into account. The cases of linear, Langmuir and modified Langmuir equilibria are studied. The equivalent true moving bed (TMB) model was used assuming axial dispersion for the fluid flow and plug flow for the solid-phase flow. Intraparticle diffusion was described by a linear driving force (LDF) approximation. Simulation results indicate that, under certain conditions, equilibrium is not actually reached at the adsorbent surface. This leads to different unit performances, in terms of product purities and recoveries, as compared to those predicted assuming instantaneous equilibrium. Moreover, SMB units may be improperly designed by the usual methods (flow-rate ratio separation regions) if non-equilibrium effects are overlooked.     

Synthesis of the [(η6-p-cymene)Ru(dppb)Cl]PF6 complex and catalytic activity in the transfer hydrogenation of ketones

Catalysis under mild conditions is of great importance to various chemistry areas, particularly for the development of novel active compounds and for natural products modifications, among others. In this study, the synthesis, characterization, and evaluation of the catalytic activity of a new ruthenium(II) compound, [(η⁶-p-cymene)Ru(dppb)Cl]PF₆ (A) where dppb=1,4-bis(diphenylphosphine)butane, is presented. Catalytic activity of the new Ru(II) compound was tested on hydrogen transfer reaction in various substrates, acetophenone, benzophenone, cyclohexanone, and methyl-ethyl-ketone. Potassium hydroxide was used as base, whereas isopropanol served as both solvent and hydrogen source. Samples comprising substrate: base: catalyst at a 200?:?20?:?1 ratio were poured into 5 mm tubes and monitored in situ at 40, 50, and 60 °C in a 600 MHz NMR spectrometer. The complex was active in the transfer hydrogenation of ketones, achieving conversions superior to 90% within 4 h at 60 °C, which suggests under mild conditions. Therefore, in situ monitoring the reactions through ¹H NMR was a valuable technique to establish the possible catalytic mechanism of Ru(II) precatalyst.     

Cytotoxicity of a Lipid-Rich Extract from Native Mexican Avocado Seed (Persea americana var. drymifolia) on Canine Osteosarcoma D-17 Cells and Synergistic Activity with Cytostatic Drugs

Osteosarcoma is the most common malignant bone tumor in both children and dogs. It is an aggressive and metastatic cancer with a poor prognosis for long-term survival. The search for new anti-cancer drugs with fewer side effects has become an essential goal for cancer chemotherapy; in this sense, the bioactive compounds from avocado have proved their efficacy as cytotoxic molecules. The objective of this study was to determine the cytotoxic and antiproliferative effect of a lipid-rich extract (LEAS) from Mexican native avocado seed (Persea americana var. drymifolia) on canine osteosarcoma D-17 cell line. Also, the combined activity with cytostatic drugs was evaluated. LEAS was cytotoxic to D-17 cells in a concentration-dependent manner with an IC₅₀ = 15.5 µg/mL. Besides, LEAS induced caspase-dependent cell apoptosis by the extrinsic and intrinsic pathways. Moreover, LEAS induced a significant loss of mitochondrial membrane potential and increased superoxide anion production and mitochondrial ROS. Also, LEAS induced the arrest of the cell cycle in the G0/G1 phase. Finally, LEAS improved the cytotoxic activity of cisplatin, carboplatin, and in less extension, doxorubicin against the canine osteosarcoma cell line through a synergistic effect. In conclusion, avocado could be a potential source of bioactive molecules in the searching treatments for osteosarcoma.