One-Pot Preparation of (NH)-Phenanthridinones and Amide-Functionalized [7]Helicene-like Molecules from Biaryl Dicar-boxylic Acids

A one-pot transformation of biaryl dicarboxylic acids to (NH)-phenanthridinone derivatives based on a Curtius rearrangement and subsequent basic hydrolysis was developed. This method is also applicable for the preparation of optically active amide-functionalized [7]helicene-like molecules. Furthermore, aza[5]helicene derivatives with a phosphate moiety were isolated as a product of the Curtius rearrangement step in the case of substrates that bear chalcogen atoms. The stereostructures of these products, revealed by X-ray diffraction analysis, suggested that chalcogen-bonding and pnictogen-bonding interactions might contribute to their stabilization. The configurational stability of the helicene-like molecules and their chiroptical properties were further investigated.

Properties and Degradation Performances of Biodegradable Poly(lactic acid)/Poly(3-hydroxybutyrate) Blends and Keratin Composites

From environmental aspects, the recovery of keratin waste is one of the important needs and therefore also one of the current topics of many research groups. Here, the keratin hydrolysate after basic hydrolysis was used as a filler in plasticized polylactic acid/poly(3-hydroxybutyrate) blend under loading in the range of 1–20 wt%. The composites were characterized by infrared spectroscopy, and the effect of keratin on changes in molar masses of matrices during processing was investigated using gel permeation chromatography (GPC). Thermal properties of the composites were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of keratin loading on the mechanical properties of composite was investigated by tensile test and dynamic mechanical thermal analysis. Hydrolytic degradation of matrices and composites was investigated by the determination of extractable product amounts, GPC, DSC and NMR. Finally, microbial growth and degradation were investigated. It was found that incorporation of keratin in plasticized PLA/PHB blend provides material with good thermal and mechanical properties and improved degradation under common environmental conditions, indicating its possible application in agriculture and/or packaging.

Four New Chromones from the Endophytic Fungus Phomopsis asparagi DHS-48 Isolated from the Chinese Mangrove Plant Rhizophora mangle

Four new chromones, phomochromenones D–G (1–4), along with four known analogues, diaporchromone A (5), diaporchromanone C (6), diaporchromanone D (7), and phomochromenone C (8), were isolated from the culture of Phomopsis asparagi DHS-48 from Chinese mangrove Rhizophora mangle. Their structures were elucidated on the basis of comprehensive spectroscopic analysis. The absolute configurations of 1 and 4 were assigned on the basis of experimental and calculated electronic circular dichroism (ECD) data, and those of enantiomers 2 and 3 were determined by a modified Mosher’s method and basic hydrolysis. To the best of our knowledge, phomochromenones D–F (1–4) possessing a 3-substituted-chroman-4-one skeleton are rarely found in natural sources. Diaporchromone A (5) showed moderate to weak immunosuppressive activity against T and/or B lymphocyte cells with IC50 of 34 μM and 117 μM.

Stability Indicating Method Development, Validation and Forced Degradation Study for Vilazodone Hydrochloride API

The current study describes the short, stability indicative HPLC method development and successive validation of Assay and Related Substances methods for Vilazodone Hydrochloride API. This study also covers Vilazodone process impurities viz. Impurity A and Impurity B. The chromatographic conditions for Related Substances and Assay are similar except sample concentration. The proposed method utilizes C18 column (15 cm X 4.6 mm, 5 µ, make ZORBAX SB) and mobile phase having Methanol and 0.05 M KH2PO4 (55: 45 v/v). The separation between all three analytes was achieved in less than five minutes. The analytical validation of these method was carried out successfully as per ICH and other international guidelines. The API was subject to various stress conditions like temperature, humidity, acidic and basic hydrolysis, oxidative degradation. The exposed samples analysed for impurities and assay. The mass balance for each condition was found more than 98%.

Two-step continuous-flow synthesis of α-terpineol

α-Terpineol is a monoterpene naturally present in essential oils, of high value on the market as it is a compound widely used as a flavoring, aromatic substance in the cosmetics and food industry. This study aims to produce α-terpineol by two different synthetic strategies, using both batch and continuous flow systems, focusing on the optimization of the process, improving the reaction conversion and selectivity. The first strategy adopted was a one-stage hydration reaction of α-pinene by an aqueous solution of chloroacetic acid (molar ratio 1:1 between pinene and the acid) in continuous flow conditions. This reaction was carried out at 80 ºC with a residence time of 15 min, obtaining good values of conversion (72 %) and selectivity (76 %), and productivity of 0.67 Kg.day-1. The second strategy accomplished was a two-step cascade reaction with limonene as starting material, where the first step is a chemo specific double bond addition using trifluoroacetic acid, and the second step is the basic hydrolysis of the ester promoted by a solution of sodium hydroxide (2.25 M) in methanol (1:1). This reaction was adapted to a continuous flow condition, where all steps happen in a residence time of 40 min, at 25 ºC, with no quenching between steps required, giving a conversion of 97 % and selectivity of 81 %, with productivity of 0.12 Kg.day-1.

Residual Aluminium in Water Intended for Human Consumption

Aluminium is one of the environmental factors that may have an impact on Alzheimer’s and Parkinson’s disease. Some epidemiological studies show a relationship between the concentration of aluminium in drinking water and the incidence of Alzheimer’s disease. The article presents and discusses the results of research on the effect of the type and dose of non-prehydrolyzed aluminium coagulants on the concentration of residual aluminium in water intended for human consumption. Aluminium sulphate (VI) and sodium aluminate were tested as coagulants. Analysis of the obtained test results showed that lower concentrations of residual aluminium were found after coagulation with aluminium sulphate (VI), which is hydrolyzed acidally, lowering the pH of the water in the range of 7.47 to 7.12 providing good conditions for the formation of Al(OH)3. A less useful coagulant due to the concentration of residual aluminium was sodium aluminate, which undergoes basic hydrolysis creating conditions for the transition of Al(OH)3 into soluble Al(OH)4−.

STABILITY INDICATING RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF PIOGLITAZONE, AMLODIPINE, ATORVASTATIN AND CLOPIDOGREL

A new simple, rapid, isocratic and stability indicating reverse phase high performance liquid chromatography (HPLC) method has been developed for simultaneous estimation of pioglitazone (P), amlodipine (AM), atorvastatin (AT) and clopidogrel (CP). Isocratic separation was achieved on Millennium M Sil C18 (125 mm ´4.6 mm) column, with mobile phase comprising of methanol: 0.02 M KH2PO4 (55:45 V/V), pH adjusted 4.0 with 0.01% ortho phosphoric acid. The flow rate was maintained 1mL/min and analytes were screened with U.V. detector. The method was validated according to ICH guidelines with respect to linearity, accuracy, precision and specificity. The drugs were exposed to various stress conditions like acidic and basic hydrolysis, oxidation, exposure to UV light and temperature (dry heat) and the stressed sample were analysed by the proposed method. No co-eluting, interfering peaks from excipients, impurities were observed during stress condition and all the degraded peaks are well resolved from parent peaks.

Existing problems and ways of their solution in the analysis of amino acid composition

For obtain accurate aminoacids analysis results for peptide samples it is need to pay attention for method of analysis and method of sample preparation. Now some samplpreparation methods are known: acid and basic hydrolysis. In this article the comparison of two methods of aminoacids analysis were observed: pre-column or post-column derivatization. Analysis of lysine in lysine sulphate was studied, results were compared with control samples. For pre-column derivatization o-phthalic anhydride was used, and for post-column derivatization ninhydrin reagent was used. In experimental part advantages of post-column derivatization was shown and more accurate results were obtained. Chromatographic separation, derivatization and detection were carried out on aminoacids analisators Hitachi (Japan) и Sykam (Germany). Samplepreparation methods were observed on valine and threonine analysis using postcolumn derivatization with ninhydrin reagent. The effect of pH adjustment after acid hydrolysis was studied. Basic solution addition best results in comparison with sample evaporation and reconstitution were shown. For final sample analysis optimal methods of analysis and samplepreparation were chosen. Results were compared with results of European Accredited Laboratory.