LC determination of glimepiride and its related impurities

Five impurities in glimepiride drug substance were detected and quantified using a simple isocratic reverse phase HPLC method. For the identification and characterization purpose these impurities were isolated from a crude reaction mixture of glimepiride using a normal phase HPLC system. Based on the spectroscopic data like NMR, FTIR, UV and MS these impurities were characterized and used as impurity standards for determining the relative response factor during the validation of the proposed isocratic reverse phase HPLC method. The chromatographic separation was achieved on a Phenomenex Luna C8 (2) 100 Å, 5 μm, 250 mm × 4.6 mm using a mobile phase consisting of phosphate buffer (pH 7.0)–acetonitrile–tetrahydrofuran (73:18:09, v/v/v) with UV detection at 228 nm and a flow rate of 1 ml/min. The column temperature was maintained at 35 °C through out the analysis. The method has been validated as per international guidelines on method validation and can be used for the routine quality control analysis of glimepiride as active pharmaceutical ingredient (API).     

Preparation and characterization of an acellular bovine pericardium intended for manufacture of valve bioprostheses

Major problems with biological heart valves post-implantation are associated with progressive structural deterioration and calcification attributed to glutaraldehyde processing, dead cells, and cell fragments present in the native tissue. In spite of these problems, glutaraldehyde still is the reagent of choice. The results with acellular matrix xenograft usually prepared by detergent treatment in association with enzymes are rather conflicting because while preserving mechanical properties, tissue morphology and collagen structure are process dependent. This work describes a chemical approach for the preparation of an acellular bovine pericardium matrix intended for the manufacture of heart valve bioprostheses. Cell removal was performed by an alkaline extraction in the presence of calcium salts for periods ranging from 6 to 48 h. The results showed that cell removal was achieved after 12 h, with swelling and negative charge increasing with processing time. Nevertheless, collagen fibril structure, ability to form fibrils, and stability to collagenase were progressive after 24-h processing. There was no denaturation of the collagen matrix. A process is described for the preparation of acellular bovine pericardium matrices with preserved fibril structure and morphology for the manufacture of cardiac valve bioprostheses and may be used in other applications for tissue reconstruction.     

Evaluation of supercritical fluid technology as preparative technique of benzocaine-cyclodextrin complexes--comparison with conventional methods

The objective of this study was to investigate the effect of the preparation method on the physico-chemical properties of complexes prepared between beta-cyclodextrin (beta-Cyd) and benzocaine (BZC). In particular, the effectiveness of a new technique based on supercritical carbon dioxide (SC CO(2)) for preparing solid drug-cyclodextrin complexes was investigated and compared to other more conventional methods such as kneading (KN), co-evaporation (COE), co-grinding (GR) and sealed-heating (S.H.). Effects of temperature, pressure and exposure time on the properties of complexes prepared by SC CO(2) technology were also studied. The different systems were characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffractometry (PXRD) and dissolution test according to the dispersed amount method. The co-grinding (GR) method resulted in amorphous products while other methods led to crystalline or partially amorphous products depending on both the method and its experimental conditions. SC CO(2) method revealed to be an effective technique for preparing solid systems between beta-cyclodextrin and benzocaine, avoiding the use of organic solvents (and problems of their complete removal) and allowing an easy scale-up of the process. As for the influence of the experimental conditions in promoting the solid-state drug-carrier interaction when using the SC CO(2) method, temperature seemed to play the major role, whereas pressure and exposure times had more limited effects. Dissolution tests confirmed a limited but favourable effect in increasing the exposure time, while indicated a possible interaction effect between temperature and pressure in influencing the dissolution performance of the final product. The best product obtained by the SC CO(2) method showed dissolution properties similar to those of the co-ground product and only slightly lower than the system obtained by sealed-heating, which was the most effective technique.     

Characterization and quantitative determination of impurities in piperaquine phosphate by HPLC and LC/MS/MS

Four impurities in piperaquine phosphate bulk drug substance were detected by a newly developed gradient reverse phase high performance liquid chromatographic (HPLC) method. These impurities were identified by LC/MS/MS. The structures of impurities were confirmed by spectroscopic studies (NMR and IR) conducted using synthesized authentic compounds. The synthesized reference samples of the impurity compounds were used for the quantitative HPLC determination. The system suitability of HPLC analysis established the validity of the separation. The method was validated according to ICH guidelines with respect to specificity, precision, accuracy and linearity. Forced degradation studies were also performed for piperaquine phosphate bulk drug samples to demonstrate the stability indicating power of the newly developed HPLC method.     

Structural identification and characterization of potential impurities of pantoprazole sodium

Six impurities in pantoprazole sodium bulk drug substance were detected by a simple high performance liquid chromatographic method (HPLC) whose area percentage ranged from approximately 0.05 to 0.34%. Liquid chromatography-mass spectrometry (LC-MS) was performed to identify the molecular weight of the impurities. A thorough study was undertaken to characterize these impurities. These impurities were synthesized, subsequently characterized and were co-injected with the sample containing impurities and found the retention time match of the spiked impurities. Based on their spectral data (IR, NMR and MS), these impurities were characterized as; 5-(difluoromethoxy)-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]thio]-1H-benzimidazole (Impurity-I); 5-(difluoromethoxy)-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]sulfonyl]-1H-benzimidazole (Impurity-II); 5-(difluoromethoxy)-2-[[(3,4-dimethoxy-1-oxide-2-pyridinyl)methyl]sulfonyl]-1H-benzimidazole (Impurity-III); 5-(difluoromethoxy)-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]thio]-1-((3,4-dimethoxy-2-pyridinyl)methyl)-1H-benzimidazole (Impurity-IV); 5-(difluoromethoxy)-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1-((3,4-dimethoxy-2-pyridinyl)methyl)-1H-benzimidazole (Impurity-V); 5-(difluoromethoxy)-2-[[(3,4-dimethoxy-1-oxide-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole (Impurity-VI). The formation of these impurities was proposed. The structure of the Impurity-II was unambiguously confirmed by single crystal X-ray diffraction (XRD) studies.     

东方巴贝斯虫核糖体蛋白L26全长cDNA克隆及蛋白特性分析

目的克隆东方巴贝斯虫核糖体蛋白L26（RPL26）全长cDNA序列,对编码的蛋白特性进行分析,并探讨它们在研究系统发育中的应用。方法采用经EST测序获得的东方巴贝斯虫RPL26的5′特异性引物及文库载体3′通用引物对东方巴贝斯虫cDNA文库进行扩增,测序获得东方巴贝斯虫RPL26全长cDNA序列。用BLASTX程序搜索相似性序列及保守结构域,所获序列在GenBank中登记,并用Neighbor-Joining（N-J）法构建基于L26氨基酸序列的系统发育树。结果东方巴贝斯虫RPL26全长cDNA序列（GenBank登录号为FJ492804）长度为716 bp,开放阅读框为414 bp,编码137个氨基酸;同源性分析结果表明东方巴贝斯虫RPL26序列较保守,与牛巴贝斯虫（Babesia bovis）、小泰勒虫（Theileria par-va）等亲缘关系较近,在系统发育树中的遗传距离也较近。结论首次获得东方巴贝斯虫RPL26基因,其可能作为分子指标应用于研究生物系统发育。     

树舌多糖的分离纯化、理化性质及抗炎镇痛活性研究

目的：分离纯化树舌多糖,获得均一多糖,并对其理化性质进行研究。对树舌多糖抗炎镇痛活性进行研究。方法：分离纯化采用DEAE离子交换色谱法和葡聚糖凝胶色谱法;纯度鉴定及分子量测定采用高效液相色谱法,示差折光检测器;单糖组成采用气相色谱质谱联用法测定。抗炎实验采用小鼠二甲苯性耳廓水肿法及大鼠角叉菜胶足肿胀法,镇痛实验采用小鼠醋酸扭体法。结果：获得三种均一多糖（GapsⅠ、GapsⅡ、GapsⅢ）,峰位分子量分别为6221、5535、3518D。红外光谱证实GapsⅢ结构中有β构型异头碳,核磁共振氢谱和碳谱均证实GapsⅢ结构中有α、β构型异头碳。树舌多糖明显减轻二甲苯所致的小鼠耳廓肿胀和角叉菜致大鼠足肿胀,并减少小鼠扭体次数。结论：三种多糖分子量分布及单糖组成均不同,均主要由葡萄糖组成。     

Simultaneous characterization and quantitation of 11 coumarins in Radix Angelicae Dahuricae by high performance liquid chromatography with electrospray tandem mass spectrometry

A high performance liquid chromatography with electrospray tandem mass spectrometry (HPLC–ESI-MS/MS) method has been developed to characterize and quantify 11 coumarin compounds in Radix Angelicae Dahuricae simultaneously. By using this HPLC–ESI-MS/MS method, all 11 coumarins were separated and determined within 10 min. These coumarins were detected by ESI⁺ ionization method and quantified by multiple reaction monitor (MRM). The linear regressions were acquired with r² > 0.995, respectively. The precision was evaluated by intra- and inter-day tests, and relative standard deviation (R.S.D.) values were reported within the range of 1.14–4.42% and 0.37–4.00%. The recovery studies for the quantified compounds were observed over the range of 92.1–105.6% with R.S.D. values less than 4.55%. It demonstrated that the method developed was successfully applied for identification and quantification of 11 coumarins in Radix Angelicae Dahuricae. The results showed that the contents of coumarins in Radix Angelicae Dahuricae were processed differently and varied significantly.     

Compressional Characterization of Two Dextrose-Based Directly Compressible Excipients Using an Instrumented Tablet Press

The main objective of this work was to evaluate the compaction behavior and record the work and the force involved in the compaction of blends and granules of two dextrose-based directly compressed excipients using a single-punch instrumented tablet press. The second objective was to identify the predominant form of deformation for the two different directly compressible excipients. Anhydrous theophylline (10% w/w) was used as a drug model, Emdex and/or Maltrin M 510 (89.5% w/w) were used as diluent, and magnesium stearate (0.5% w/w) was used as lubricant. All formulations were compressed at four different compressional forces and at a target tablet weight of 450 mg ± 5%. Results show that compacts prepared from Emdex using the direct compression method produced the lowest elastic work and die wall friction, and the best degree of lubrication. Wet granulation for Maltrin M 510 decreased elastic work, frictional work, and ejection force, and enhanced both net work and degree of lubrication. In general, wet granulation for both Emdex and Maltrin M 510 decreased the crushing strength of the tablets and enhanced the degree of lubrication, compared to direct compression formulations. All formulations showed similar shape pattern for plastic deformation, suggesting that the predominant mechanism of deformation is plastic deformation type a Heckel plots.     

Comparative study on production,purification of penicillin by Penicillium chrysogenum isolated from soil and citrus samples

Objective

To explore various unexplored locations where Penicillium spp. would be available and study the production of penicillin from the isolated Penicillium spp. in different media with altered carbohydrate source.

Methods

The collected soil samples were screened for the isolation of Penicillium chrysogenum (P. chrysogenum) by soil dilution plate. The isolated Penicillium species were further grown in different production media with changes in the carbohydrate source. The extracted penicillin from various isolates was analyzed by HPLC for the efficacy of the product. Further the products were screened with various bacterial species including methicillin resistant Staphylococcus aureus (MRSA). And the work was extended to find the possible action on MRSA, along with characterization using other pathogens.

Results

From the various soil and citrus samples used for analysis, only the soil sample from Government General Hospital of Bangalore, India, and Sanjay Gandhi Hospital, Bangalore, India, showed some potential growth of the desired fungi P. chrysogenum. Different production media showed varied range of growth of Penicillium. Optimum production of penicillin was obtained in maltose which proved maximum zone of inhibition during assay. Characterization of penicillin on pathogens, like wild Escherichia coli strain, Klebsiella spp., and MRSA, gave quite interesting results such as no activity on the later strain as it is resistant. HPLC data provided the analytical and confirmation details of the penicillin produced. Accordingly, the penicillin produced from the soil sample of Government General Hospital had the high milli absorbance unit of 441.5 mAu compared with that of the penicillin produced from Sanjay Gandhi Hospital sample, 85.52 mAu. Therefore, there was a considerable change in quantity of the penicillin produced from both the samples.

Conclusions

The Penicillium spp. could be possibly rich in hospital contaminants and its environments. This research focuses on various unexplored sources of medical ailments, and also shows that the growth of penicillin is high in maltose rich media that could possibly enhance the growth.