New type of chitosan/2-hydroxypropyl-ß-cyclodextrin composite membrane for gallic acid encapsulation and controlled release.

A new type of chitosan/2-hydroxypropyl-ß-cyclodextrin composite membrane have been developed for the encapsulation and controlled release of gallic acid. The morphology of the composite membrane was investigated by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), whereas swelling gallic acid and release properties were investigated by UV-visible spectroscopy. The release behavior with pH changes was also explored. The composite membrane based on chitosan/2-hydroxypropyl-ß-cyclodextrin with gallic acid included showed improved antioxidant capacities compared to plain chitosan membrane. The information obtained in this study will facilitate the design and preparation of composite membrane based on chitosan and could open a wide range of applications, particularly its use as an antioxidant in food, food packaging, biomedical (biodegradable soft porous scaffolds for enhance the surrounding tissue regeneration), pharmaceutical and cosmetics industries.

A quasi non-destructive approach for amber geological provenance assessment based on head space solid-phase microextraction gas chromatography-mass spectrometry.

Head space (HS) solid-phase micro-extraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile fraction of ambers of different geological origin. In particular, Romanian (romanite) and Baltic (succinite) amber samples were studied. Both types of amber have nearly similar bulk chemical compositions and could probably reflect only some differences of paleobiological and/or diagenetic origin. The present study shows that amber head space fingerprint, obtained by SPME/GC-MS, can provide a simple and quasi non-destructive method capable of romanite/succinite differentiation. Among the numerous compounds present in the head space, a number of few informative variables could be selected that were able to differentiate the ambers as demonstrated by Principal Component and Cluster Analysis.

Identification of a dicer homologue gene (DCL2) in Nicotiana tabacum.

Eukaryotes possess a mechanism that generates small interfering RNA (siRNA) and microRNA (miRNA) and use these to regulate gene expression at the transcriptional or post-transcriptional level. These small RNAs (21-24nt) are processed from long double-stranded RNA precursors by type III RNase enzymes, referred to as DICER or DICER-LIKE proteins (DCLs). In Arabidopsis, there are four DCL genes and their role in small RNA biogenesis and silencing has been the subject of intense study. DCL2 is less well studied than the other DCL proteins although it is known to play a role in formation of natural antisense siRNA and may be involved in transitive silencing of transgene transcripts. This study provides basic genomic information on DCL2 in the Nicotiana tabacum (NtDCL2) gene family and its probable roles in plant growth and development.

Highly sensitive detection and discrimination of LR and YR microcystins based on protein phosphatases and an artificial neural network.

The inhibition characteristics of three different protein phosphatases by three microcystin (MC) variants--LR, YR, and RR--were studied. The corresponding K (I) for each enzyme-MC couple was calculated. The toxicity of MC varies in the following order: MC-LR > MC-YR > MC-RR. The sensitivity of the enzymes increased in the following order: mutant PP2A < mutant PP1 < natural PP2A. The best limit of detection obtained was 21.2 pM MC-LR using the most sensible enzyme. Methanol, ethanol, and acetonitrile up to 2 % (v/v) may be used in inhibition measurements. An artificial neural network (ANN) was used to discriminate two MC variants--LR and YR--using the differences in inhibition percentages measured with mutant PP1 and natural PP2A. The ANN is able to analyze mixtures with concentrations ranging from 8 to 98 pM MC-LR and 31 to 373 pM MC-YR.

Biosensor for enantioselective analysis of S-cilazapril, S-trandolapril, and S-pentopril.

The purpose of this research was to construct an amperometric biosensor on L-amino acid oxidase (L-AAOD) supported on a carbon paste for the enantioselective analysis of S-cilazapril (I), S-trandolapril (II), and S-pentopril (III). A chemically modified carbon paste was constructed with L-AAOD. The proposed amperometric biosensor proved reliable for the purity of I, II, and III. The linear working ranges obtained for drug assay were 0.001-100 mumol/l (I), 0.02-10 mumol/l (II), 0.08-50 mumol/l (III) over the pH ranges 7.0-7.4 (I), 6.8-7.4 (II), and 7.0-7.4 (III). The low limits of detection obtained were 5 pmol/l (I), 15 mumol/l (II), and 5 mumol/l (III), respectively. The selectivity of the biosensors was checked by both mixed and separate solution methods. Polyvinylpyrolidone and D-proline did not interfere with the assay of the studied drugs, whereas L-proline presented a potent interfering species. The relative standard deviation values (< 0.2%) make the biosensors suitable for direct amperometric assay of these angiotensin-converting enzyme (ACE) inhibitors. The proposed amperometric biosensor that was based on L-AAOD proved reliable in the analysis of the above-mentioned ACE inhibitors and can be used for the quality control of these drugs.

Biosensor for the enantioselective analysis of S-perindopril.

Because S-perindopril enantiomer is the eutomer which is responsible for the angiotensin-converting enzyme inhibition activity, it is necessary to develop a reliable method for its assay from its distomer, the R-enantiomer. For this purpose, an amperometric biosensor was developed based on L-amino acid oxidase. The working range of the described biosensor was 20pmol/L-10 micromol/L on the 7.0-7.4 pH range, with a detection limit of 2pmol/L. The low enantioselectivity for R-perindopril, as compared with S-enantiomer, was demonstrated by both mixed solutions and separate solutions methods (amperometric selectivity coefficient is 1.0 x 10(-4)). The biosensor was also selective towards D-proline and polyvinylpyrrolidone. The amperometric biosensor can be used for enantioselective analysis of S-perindopril in raw material, with an RSD < 1%. The life time (t95%) of the biosensor is three weeks.

Biosensors for the enantioselective analysis of S-enalapril and S-ramipril.

S-Enalapril, and S-ramipril are angiotensin-converting enzyme (ACE) inhibitors which are used for treatment of hypertension. Due to the fact that only the S enantiomer possesses the ACE inhibiting activity, it is necessary to develop an enantioselective analytical method for its discrimination from the less active R-enantiomer. An amperometric biosensor, based on L-amino acid oxidase, was developed and proved reliable for the analysis of the S-enantiomer of these ACE inhibitors. The working range of the biosensor for S-enalapril assay (A) is 0.4-120 mumol/L, and for S-ramipril assay (B) is 0.2-100 mumol/L, with a limit of detection of 163 nmol/L (A) and 107 nmol/L (B), respectively. It is of interest to mention that the biosensors demonstrated enantioselectivity versus D-proline (1.4 x 10(-3) mol/L(A), 5.3 x 10(-3) mol/L(B) and also the selectivity versus the polyvinylpyrolidone (3.0 x 10(-3) mol/L(A), 3.2 x 10(-3) mol/L(B), respectively. The working pH ranges are: 6.8-7.4 (A), and 6.2-7.0 (B), respectively. The RSD < 1% assured by using the amperometric biosensors for S enantiomers assay in raw materials, in tablet formulations, and their suitability for the analysis of these drug enantiomers.