Riboflavin concentration in corneal stroma after intracameral injection

AIM:To evaluate the enrichment of riboflavin in the corneal stroma after intracameral injection to research the barrier ability of the corneal endothelium to riboflavin in vivo.METHODS:The right eyes of 30 New Zealand white rabbits were divided into three groups. Different concentrations riboflavin-balanced salt solutions (BSS) were injected into the anterior chamber (10 with 0.5%, 10 with 1%, and 10 with 2%). Eight corneal buttons of 8.5 mm in diameter from each group were dissected at 30min after injection and the riboflavin concentrations in the corneal stroma were determined using high-performance liquid chromatography (HPLC) after removing the epithelium and endothelium. The other two rabbits in every group were observed for 24h and sacrificed. As a comparison, the riboflavin concentrations from 16 corneal stromal samples were determined using HPLC after instillation of 0.1% riboflavin-BSS solution for 30min on the corneal surface (8 without epithelium and 8 with intact epithelium).RESULTS: The mean riboflavin concentrations were 11.19, 18.97, 25.08, 20.18, and 1.13 μg/g for 0.5%, 1%, 2%, de-epithelialzed samples, and the transepithelial groups, respectively. The color change of the corneal stroma and the HPLC results showed that enrichment with riboflavin similar to classical de-epithelialized corneal collagen crosslinking (CXL) could be achieved by intracameral1% riboflavin-BSS solution after 30min; the effect appeared to be continuous for at least 30min.CONCLUSION:Riboflavin can effectively penetrate the corneal stroma through the endothelium after an intracameral injection in vivo, so it could be an enhancing method that could improve the corneal riboflavin concentration in transepithelial CXL.     

Application of HPLC mixed‐mode chromatography in determining radiochemical purity of [14C] labeled metformin hydrochloride

Metformin is currently prescribed worldwide to treat type 2 diabetes, and therefore, radiolabeled [¹⁴C] metformin is often prepared for clinical comparisons of new drug candidates. Prior to using the radiolabeled metformin, the purity needs to be determined to ensure the quality of the material. While typical reversed‐phase LC methods are often the first choice for purity analysis, they are not suitable for this determination because the compound is poorly retained under these conditions. Mixed‐mode chromatography has been demonstrated to overcome these retention issues, and therefore, this methodology was utilized for the purity determination of radiolabeled metformin.     

α-突触核蛋白与Cu~(2+)相互作用的研究进展

帕金森病是一种慢性中枢神经系统退行性疾病,其主要的病理特征是黑质致密部多巴胺能神经元丢失,残存神经元胞质中出现路易小体,其主要成分是异常聚集的α-synuclein蛋白(α-突触核蛋白)。α-synuclein的聚集与多种因素有关,其中金属离子与α-synuclein结合可导致蛋白构象发生变化引起蛋白发生聚集。近年的研究发现,Cu2+能够特异地结合α-synuclein蛋白,并诱导α-synuclein的聚集。该文就Cu2+与α-synuclein相互作用的的结合位点、结合模式以及Cu2+在α-synuclein毒性形式中可能发挥的作用作一综述。     

薄荷水质量控制方法的研究

目的 完善薄荷水的质量控制方法。方法 采用薄层色谱法鉴别薄荷水中的薄荷素油,用气相色谱法测定薄荷水中薄荷脑的含量。结果 薄层色谱法鉴别专属性强;气相色谱法中,薄荷脑线性范围为5.0~80.0μg/ml(r=0.999 9),平均回收率为103.16%,RSD为1.81%。结论 该法操作简便,结果准确,灵敏度高,重复性好,可有效地控制薄荷水的质量。     

刺五加叶中金丝桃苷的薄层鉴别和含量测定

目的：以金丝桃苷为指标成分,建立刺五加叶的薄层定性和含量测定的方法。方法：采用薄层色谱法对刺五加叶中金丝桃苷进行定性鉴别,并用高效液相色谱法进行含量测定,色谱柱：Kromasil 100-5C18色谱柱（4.6mm×250mm）;流动相：甲醇-0.1％冰醋酸水溶液(35：65);流速：0.8mL/min;检测波长：360nm;柱温：30℃;进样量：10μL。结果：刺五加叶金丝桃苷的薄层鉴别特征明显,金丝桃苷在0.13～0.78μg范围内具有良好线性关系,r=0.9994,平均回收率为98.17％,RSD为1.02％（n=5）。结论：此方法简便、快速、准确,可用于刺五加叶的质量控制。     

Separation and Identification of Phenolic Acid and Flavonoids from Nerium indicum Flowers

Four major compounds were separated and identified from the methanol extracts of Nerium indicum flowers (Arali) using HPLC and mass spectral data. Through mass data, the chemical structures were elucidated as: trans5-O-caffeoylquinic acid (1), quercetin-3-O- rutinoside (2), luteolin-5-O-rutinoside (3) and luteolin-7-O-rutinoside (4). In addition, the cis isomers of 5-O-caffeoylquinic acid in Nerium indicum flowers were confirmed by Mass, HPLC and UV. The structures of these compounds confirmed with the help of liquid chromatography mass spectrometry.     

Cost-Effective Isolation of a Process Impurity of Pregabalin

Cost-effective isolation methods were developed on preparative HPLC, flash LC, and simulated moving bed (SMB) to prepare the process impurity, 3-(aminomethyl)-5-methylhex-4-enoic acid (4-ene impurity), of pregabalin. By a thorough experimental study on the different isolation techniques available, it was concluded that SMB was the most cost-effective. Hence, it was a continuous chromatography that utilized the advantage of SMB so that a high quantity of the impurity was generated in a short period of time. SMB was equipped with eight reversed-phased columns and was used to separate the process impurity of pregabalin. The effects of flow rate in zone 2 (Q2) and 3 (Q3), as well as switching time, on the operating performance parameters like purity, productivity, and desorbent consumption were studied. Operating conditions leading to more than 90% purity in the raffinate outlet stream were identified, together with those achieving optimal performance. All of these developed methods are novel, cost-effective, and can be applied to the isolation of other process- and stability-related impurities of pregabalin.     

肝纤维化食蟹猴血浆丙泊酚浓度的HPLC测定

目的 建立血浆丙泊酚浓度的高效液相色谱(HPLC)测定方法,探讨肝纤维化食蟹猴丙泊酚血浆浓度变化.方法 选择肝纤维化S0、S1、S2、S3、S4期的雄性食蟹猴各12只,持续输注丙泊酚8mg·kg-1·h1 30min.于输注1、10、20、30 min和苏醒时采血,采用Agilent 1100型HPLC仪测定血浆丙泊酚浓度.血浆样品经6％高氯酸沉淀蛋白处理;色谱柱为Hypersil C18,流动相为甲醇-水(68∶32);流速1 ml/min;紫外检测波长为258 nm;柱温为室温;内标为麝香草酚,进样量:20μl.结果 丙泊酚与血浆中其他成分分离良好,在0.1-10 μg/ml范围内线性关系良好,回归方程为Ai/As=0.23C-0.045(r=0.995,n=5).方法回收率为98.69％ 100.10％,提取回收率为86.86％-89.48％.日内、日间精密度均小于5％.S4期肝纤维化组各时间点的血浆丙泊酚浓度均高于S0-S3期(P＜0.05).结论 HPLC法检测血浆丙泊酚浓度,灵敏度高,结果准确.丙泊酚代谢随食蟹猴肝纤维化程度加重而减慢.     

Toxicology of 3-epi-deoxynivalenol,a deoxynivalenol-transformation product by Devosia mutans 17-2-E-8

Microbial detoxification of deoxynivalenol (DON) represents a new approach to treating DON-contaminated grains. A bacterium Devosia mutans 17-2-E-8 was capable of completely transforming DON into a major product 3-epi-DON and a minor product 3-keto-DON. Evaluation of toxicities of these DON-transformation products is an important part of hazard characterization prior to commercialization of the biotransformation application. Cytotoxicities of the products were demonstrated by two assays: a MTT bioassay assessing cell viability and a BrdU assay assessing DNA synthesis. Compared with DON, the IC₅₀ values of 3-epi-DON and 3-keto-DON were respectively 357 and 3.03 times higher in the MTT bioassay, and were respectively 1181 and 4.54 times higher in the BrdU bioassay. Toxicological effects of 14-day oral exposure of the B6C3F₁ mouse to DON and 3-epi-DON were also investigated. Overall, there were no differences between the control (free of toxin) and the 25 mg/kg bw/day or 100 mg/kg bw/day 3-epi-DON treatments in body and organ weights, hematology and organ histopathology. However, in mice exposed to DON (2 mg/kg bw/day), white blood cell numbers and serum immunoglobulin levels were altered relative to controls, and lesions were observed in adrenals, thymus, stomach, spleen and colon. Taken together, in vitro and in vivo studies indicate that 3-epi-DON is substantially less toxic than DON.