Synthesis of stable genipin derivatives and studies of their neuroprotective activity in PC12 cells

Modifications at C1, C7, C8, and C10 of genipin were conducted, and the neurotrophic effects of all derivatives were studied. Genipin derivatives 1-4 were obtained in mild to high yield. Compounds 1 and 4 are more stable than genipin if exposed to nucleophiles. All the derivatives display higher neurotrophic activities than genipin. Compound 4 is the most active, with the least optimal dose. Both genipin and 4 up-regulated the activity of nNOS in PC12 cells. The effect of 4 is inhibited not only by 7-NI, a specific inhibitor of nNOS, but also by L-NIO, a specific inhibitor of eNOS; in the case of genipin, its effect is only inhibited by 7-NI. All the results indicate that 4 is a promising lead compound for the development of new drugs in the treatment of neurodegenerative diseases with the ability to address multiple drug targets.     

京尼平的分离纯化及高效液相色谱法测定

研究了用β-葡萄糖苷酶水解栀子苷制备京尼平及京尼平的分离纯化方法,同时还建立了京尼平的高效液相色谱检测法。静态吸附实验表明,HPD700对京尼平的吸附率可达96.50%,动态吸附及洗脱实验结果表明,上样流速以1.5BV/h为宜,采用无水乙醇对京尼平的洗脱率最高,达到94.32%。高效液相色谱法对京尼平的分析结果为:京尼平进样量在0.2~2.0μg范围内,峰面积与进样量呈良好的线性关系,京尼平的回归方程为Y=3.81×106X-19261,相关系数R2为0.9994,方法精密度为1.06%,回收率为98.5%~102.2%。结论:本实验制备的京尼平纯度可达98%以上,为制备高端栀子蓝色素创造了条件。     

大豆蛋白基复合水凝胶的制备及其体外释放

利用天然无毒的京尼平交联大豆蛋白(SB)和壳聚糖(CS)制备复合水凝胶(HD)控释载体,以茶碱(TP)作为药物模型,结合扫描电镜和核磁共振研究了复合凝胶的表观形态和结构,并对其在模拟胃肠液中的控释特性进行研究。结果表明:复合水凝胶中大豆蛋白和壳聚糖通过京尼平发生了明显的交联作用,并呈现紧密的网络结构。在pH1.2模拟胃液中,复合水凝胶的溶胀度和茶碱释放率较低,但在pH6.8模拟肠液中,却呈现较高的溶胀度和释放率。复合水凝胶在模拟胃肠液中120h内可实现对茶碱的可控释放。复合凝胶的释放特性不仅与SB/CS比例相关,而且还取决于添加的京尼平的含量。本实验结果说明了这种京尼平交联的复合凝胶较为适合用作药物在胃肠道中的定向运送载体。     

Release of indomethacin from a novel chitosan microsphere prepared by a naturally occurring crosslinker: Examination of crosslinking and polycation–anionic drug interaction

Novel chitosan microspheres with lower cytotoxicity were fabricated in this study and their drug release characteristics were investigated. Genipin, a naturally occurring crosslinking reagent that has been used in herbal medicine and in the production of food dye, was used to prepare crosslinked chitosan microspheres by a water‐in‐oil dispersion method. The crosslinking mechanism examined by FTIR and ¹³C–NMR suggests that the crosslinking of chitosan by genipin leads to the formation of secondary amide and heterocyclic amino linkage. The polycation–anionic drug interaction between chitosan and indomethacin was pH dependent and could affect the dissolution property of indomethacin. By examination of the release profiles of the crosslinked chitosan microsphere, it was found that the release of indomethacin from the microsphere was sustainable and influenced by factors such as crosslinking of microsphere and chitosan–indomethacin interaction, thus establishing crosslinked chitosan microsphere as a very promising polymeric carrier for drug release. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1700–1711, 2001     

京尼平交联大豆蛋白/壳聚糖复合凝胶的控释

利用天然无毒的京尼平交联大豆蛋白(SB)和壳聚糖(CS)制备复合水凝胶(HD)并用作茶碱的控释载体。同时对其在模拟胃肠液和pH7.4缓冲液（PBS）中的控释特性进行了研究。结合扫描电镜和红外光谱以及核磁共振表征了复合凝胶的表观形态和结构。结果表明,复合水凝胶中大豆蛋白和壳聚糖通过京尼平发生了明显的交联作用,并呈现致密的片层结构。复合凝胶在模拟胃肠液和pH7.4PBS中均呈现溶胀现象,在模拟胃液中的溶胀度较低。而且凝胶在pH1.2模拟胃液中的释放量比模拟肠液和pH7.4PBS液中的低,并发现该凝胶具有pH响应,在120 h内可实现对茶碱的可控释放。因此,这种京尼平交联的复合凝胶具有作为药物在胃肠道中定向运送载体的潜力。     

栀子黄A238nm/A440nm 值与西红花苷和栀子苷相关性研究

目的：采用TLC、HPLC 和紫外分光光度法(UV)研究栀子黄OD 值(栀子黄中栀子苷的最大吸光度A238nm 与西红花苷的最大吸光度A440nm 的比值)与栀子苷含量的关系。方法：采用硅胶柱层析从栀子中分离西红花苷纯品,然后分别采用TLC、HPLC 和UV 来定性和定量分析栀子乙醇提取部位和经大孔吸附树脂精制的栀子黄,并计算波长238nm 和440nm 处的百分比吸光系数及OD 值。结果：经过对以上数据的分析,发现西红花苷本身在波长238nm处有明显紫外吸收,采用OD 值来控制栀子黄中的栀子苷将高估栀子苷含量。结论：栀子黄中栀子苷的控制不宜采用OD 值作为评价指标,而应采用具有分离功能的高效液相色谱法来作为质量控制的手段。     

Novel Findings regarding the Bioactivity of the Natural Blue Pigment Genipin in Human Diseases

Genipin is an important monoterpene iridoid compound isolated from Gardenia jasminoides J.Ellis fruits and from Genipa americana fruits, or genipap. It is a precursor of a blue pigment which may be attractive alternative to existing food dyes and it possesses various potential therapeutic properties such as anti-cancer, anti-diabetic and hepatoprotective activity. Biomedical studies also show that genipin may act as a neuroprotective drug. This review describes new aspects of the bioactivity of genipin against various diseases, as well as its toxicity and industrial applications, and presents its potential mechanism of action.     

Effects of coacervation acidity on the genipin crosslinking action and intestine-targeted delivery potency of the O-carboxymethyl chitosan–gum arabic coacervates

O-carboxymethyl chitosan (O-CMC)–gum arabic (GA) coacervates separated in different acidities were crosslinked by genipin and subjected to FTIR analysis, viscoelasticity measurement, DSC characterization, pH response evaluation, and in vitro BSA release profiling to explore the influence of coacervation acidity on genipin crosslinking and intestine-targeted delivery potency of the coacervates. Genipin crosslinking greatly improved the stability of the coacervates against various simulated gastrointestinal fluids and the coacervation acidity exerted different effects on the pH response of coacervates and BSA-loaded microcapsules. It was concluded that genipin-crosslinked O-CMC–GA coacervates could be used to deliver hydrophobic compounds to the intestine.     

Preparation,characterization, and pharmacokinetics of the inclusion complex of genipin-β-cyclodextrin

Objective: The aim of this study was to prepare the inclusion complex of genipin (GP) and β-cyclodextrin (β-CD) with improved stability, solubility, and bioavailability and to study the pharmacokinetics of β-CD inclusion complex in mice. Methods: Lyophilization was employed in the preparation of the inclusion complex of GP–β-CD, whose formation was confirmed by infrared, ultraviolet, differential scanning calorimetry, X-ray diffraction, and phase solubility method. Comparative studies on the in vitro solubility and stability and in vivo evaluation of GP in mice were investigated. Liquid–liquid extraction was used for the isolation of GP in the assay of its concentration. After injection in the caudal vein at equal doses of the inclusion complex of free GP, the drug concentration in mice plasma at fixed time after administration was determined by high-performance liquid chromatography method. Results: The results demonstrated that GP–β-CD solid powders showed improved stability and solubility in aqueous solution, when comparing with free GP. The results of the in vivo study showed that the inclusion complex of GP–β-CD exhibited the dissimilar pharmacokinetics from that of free GP after intravenous administration. The inclusion complex of GP–β-CD displayed longer MRT_0–∞ and higher AUC_0–∞ than free GP did. Conclusions: The relative bioavailability of the inclusion complex of GP–β-CD to free GP was 305.3%, which demonstrated that GP formulations containing β-CD significantly increased the bioavailability.     

Thermosensitive elastin-derived polypeptide hydrogels crosslinked by genipin

In this paper, first, elastin-derived peptides (EPs) with low molecular weight were prepared by acid degradation. Second, elastin-derived peptide hydrogels were fabricated by crosslinking EP with genipin. EP exhibited an inverse transition temperature, and the inverse transition temperature (T_t) could be adjusted by changing the concentration and molecular weight of EP, pH, and adding salt. The freeze-dried EP hydrogels were obviously three-dimensional network structure and the property of EP hydrogel can be optimized by dosage of genipin. Differential scanning calorimetry (DSC) tests and the swelling ratio changing with temperature showed the crosslinked EP hydrogels were still thermosensitive and exhibited a negative swelling behavior. The compression modulus of EP hydrogels can even reach 39.4?kPa, surpassing many other elastin-based hydrogels. This genipin crosslinked EP hydrogel is a good biological material and has great potentiality in tissue engineering.