Molecular imprinted polymer for β-carotene for application in palm oil mill effluent treatment

Palm oil mill effluent (POME) is one of the most significant pollutant in the form of wastewater. It could have negative effects on the environment include the emission of biogas and water pollution which comes from discharging the brownish tick POME to the water bodies if not properly managed. Discharge of dark brownish colored of POME directly into water bodies may affect the aquatic life as it will reduce sunlight penetration and suppress the photosynthetic activity. A molecularly imprinted polymer (MIP) for removal of β-carotene from POME has been aimed to develope in this study. The preparation of β-carotene imprinted and non-imprinted polymer (NIP) involves polymerization of β-carotene (or without it) with β-cyclodextrin (β-CD), 9-vinylcarbazole (9VC), tolylene diisocyanate (TDI) and N,N-dimethylformamide (DMF) as the monomer, co-monomer, cross-linker and solvent (porogen), respectively. Analysis from FTIR showed that MIP and NIP have similar characteristic peak with different peaks intensity, indicating the similarity in the backbone structure of polymerization. TGA result displayed high thermal stability with final decomposition at 320 °C for MIP-β-CD-9VC as compared to NIP-β-CD-9VC. The pH study shows that sorption of β-carotene increased with decreasing the pH of POME and the maximum sorption capacities achieved at pH 2 were 10 μg/g and 7 μg/g for MIP-β-CD-9VC and NIP-β-CD-9VC, respectively. The maximum sorption achieved by using 500 mg of MIP as the sorption of β-carotene increased with increasing the dosage of MIP. Kinetic model evaluation has been applied on this prepared materials. The sorption equilibrium data was well described by Freundlich model. The results indicated that the sorption of β-carotene on MIP follows a pseudo–second–order kinetic.     

Acetyl- and O-alkyl- derivatives of β-mangostin from Garcinia mangostana and their anti-inflammatory activities

Pure β-mangostin (1) was isolated from the stem bark of Garcinia mangostana L. One monoacetate (2) and five O-alkylated β-mangostin derivatives (3–7) were synthesised from β-mangostin. The structures of these compounds were elucidated and determined using spectroscopic techniques such as 1D NMR and MS. The cytotoxicities and anti-inflammatory activities of these five compounds against RAW cell 264.7 were tested. The structural-activity relationship studies indicated that β-mangostin showed a significant activity against the LPS-induced RAW cell 264.7, while the acetyl- as well as the O-alkyl- β-mangostin derivatives did not give good activity. Naturally occurring β-mangostin demonstrated comparatively better anti-inflammatory activity than its synthetic counterparts.     

Isolation and structural modifications of ananixanthone from Calophyllum teysmannii and their cytotoxic activities

Two naturally occurring xanthones, ananixanthone (1) and β-mangostin (2), were isolated using column chromatographic method from the n-hexane and methanol extracts of Calophyllum teysmannii, respectively. The major constituent, ananixanthone (1), was subjected to structural modifications via acetylation, methylation and benzylation yielding four new xanthone derivatives, ananixanthone monoacetate (3), ananixanthone diacetate (4), 5-methoxyananixanthone (5) and 5-O-benzylananixanthone (6). Compound 1 together with its four new derivatives were subjected to MTT assay against three cancer cell lines; SNU-1, K562 and LS174T. The results indicated that the parent compound has greater cytotoxicity capabilities against SNU-1 and K562 cell lines with IC₅₀ values of 8.97 ± 0.11 and 2.96 ± 0.06 μg/mL, respectively. Compound 5 on the other hand exhibited better cytotoxicity against LS174T cell line with an IC₅₀ value of 5.76 ± 1.07 μg/mL.     

Non-linear and non-constant variance calibration curves in analysis of volatile organic compounds for testing of water by the purge-and-trap method coupled with gas chromatography/mass spectrometry

Currently used operating conditions for analysing volatile organic compounds (VOCs) by purge-and-trap gas chromatography/mass spectrometry (GC/MS) produced non-linear calibration curves with non-uniform variance. Second-order polynomial models therefore had to be used in weighted regression analysis of measurements of replicates spiked at various concentrations. A transparent procedure based on a reported method of very low computational complexity allowed calculation of the parameters of second-order models, confidence bands of regression lines, prediction bands, and confidence intervals of discriminated analyte concentrations. Tolerance intervals were introduced for this last purpose. Critical, detection and quantification levels drawn from the calibration curves were compared with those calculated by the EPA method.     

A comparison between the use of a redox mediator in solution and of surface modified electrodes in the electrocatalytic oxidation of nicotinamide adenine dinucleotide

Cyclic voltammetry was successfully applied to study the oxidation of nicotinamide adenine dinucleotide (NADH) both in homogeneous and heterogeneous phase. The first case was realized with a solution containing p-methylamino-phenolsulphate (MAP) as redox mediator and the diaphorase (DI) from Clostridium kluveri as enzyme while the second one by using both a glassy carbon (GC) and a carbon nanotube paste (CNTP) electrode modified with electrodeposited films derived from 3,4-dihydroxybenzaldehyde (3,4-DHB). Such systems were successively coupled with glucose dehydrogenase (GDH) reaction to realize the redox chain present in glucose biosensors. A critical comparison of the two systems was also reported.     

Electrocatalytic oxidation of NADH at single-wall carbon-nanotube-paste electrodes: kinetic considerations for use of a redox mediator in solution and dissolved in the paste

Cyclic voltammetry has been successfully used to study the oxidation of nicotinamide adenine dinucleotide (NADH) at single-wall carbon-nanotube-paste (CNTP) electrodes modified with p-methylaminophenolsulfate (p-MAP) and 3,4-dihydroxybenzaldehyde (3,4-DHB). Diffusion-like behaviour was observed for p-MAP-modified electrodes, and a diffusion coefficient of 2.4×10^–6 cm² s^–1 was calculated for p-MAP in the paste. The behaviour of 3,4-DHB-modified CNTP electrodes was typical of that of surface-confined mediators. p-MAP electrocatalytic activity was first checked in solution, and a rate constant of 9.2 mol^–1 L s^–1 was obtained for the reaction between NADH and the mediator. The p-MAP-modified electrode did not have significant electrocatalytic activity for electro-oxidation of NADH, probably because of the formation of a complex between NADH and the confined mediator. In contrast, the 3,4-DHB-modified electrode had very good NADH electrocatalytic activity, with a heterogeneous rate constant of approximately 20×10² mol^–1 L s^–1.     

Conjugate Addition of Hydroxylamines to 4-Substituted Butenolides

Abstract

4-Substituted-butenolides treated with free hydroxylamine at pH=5 undergo conjugate addition - rearrangement to afford isoxazolidin-5-ones. This is in contrast to N-substituted hydroxylamines which under the same conditions produce Michael adducts only. In the presence of base, butenolides undergo racemization via flat tautomeric forms.     

Qualitative and Quantitative LC Profile of Embelin and Rapanone in Selected Lysimachia Species

Qualitative and quantitative determination of the pharmacologically active benzoquinones, embelin and rapanone, in different organs of eight Lysimachia species has been conducted by reversed-phase high-performance liquid chromatography. An analytical Hypersil BDS C-18 column and a mobile phase of water containing 0.1% v/v H₃PO₄ and acetonitrile (10:90) at a flow rate of 1.0 mL min⁻¹ were used. UV detection was at 286 nm. The recovery of the method was 81.5% for embelin and 80.5% for rapanone. Good linearity (r > 0.999) was obtained for both compounds. The leaves of L. ephemerum had the highest amount of rapanone (1.69%) while the roots of L. punctata had the highest amount of embelin (1.28%).     

Effectiveness of isotopically labelled and non‐isotopically labelled internal standards in the gas chromatography/mass spectrometry analysis of sulfur compounds in wines: use of a statistically based matrix comprehensive approach

The effectiveness of isotopically and non‐isotopically labelled internal standards in reducing matrix‐induced effects is evaluated. The question is addressed in the quantitative analysis by gas chromatography/mass spectrometry (GC/MS) of dimethyl sulphide, chosen as a typical example of volatile sulphur compounds, in wine matrices. When matrix/run effects are not cancelled out the use of a variance component model (VCM) to handle the linear calibrations obtained by regression technique is successful. The method implies the estimation of an overall calibration straight line, which properly takes into account the uncertainty due to different matrices, the calibration run and the measurement error, making the use of an isotopically labelled internal standard not necessary. The obtained results show that the benefits of lowering times and costs for routine analyses compensate for the small increase in uncertainty in the concentration values obtained in the regression analysis and the slight increase in the detection limit. Copyright © 2009 John Wiley & Sons, Ltd.