羟丙基—β—环糊精的冷冻干燥

羟丙基－β－环糊精只有采用冷冻干燥的方法才能得到松散的粉末物料。本论文测定羟丙基－β－环糊精的各种冷冻干燥的物理性质和传递性质,得到了羟丙基－β－环糊精的冷冻干燥工艺条件,为羟丙基－β－环糊精的冷冻干燥操作控制奠定了良好的基础。     

响应面优化羟丙基-β-环糊精对血根碱的包合工艺

本文采用溶液搅拌法制备血根碱与羟丙基-β-环糊精包合物。以羟丙基-β-环糊精和血根碱包合比、包合温度、包合时间为考察因素,在单因素试验基础上,应用Box-Behnken中心组合方法进行3因素3水平的试验设计,以血根碱和羟丙基-β-环糊精包合率为响应值,采用响应面法对包合条件进行进一步优化。结果表明:最佳条件为:包合比10:1,包合温度60℃,包合时间190 min,血根碱和羟丙基-β-环糊精包合率为73.55%,与预测值(72.43%)接近(相对误差1.5%)。该方法稳定、重复性好,是一种高效制备血根碱羟丙基-β-环糊精包合物的方法。     

羟丙基-β-环糊精的结构

用红外光谱法对羟丙基-β-环糊精的结构进行了定性分析,用气相色谱-质谱联用方法,通过对质谱图解析,详细研究了羟丙基-β-环糊精中羟丙基的分布。此羟丙基-β-环糊精以C2位取代为主,计算得到其平均取代度为6.41。     

虾青素/羟丙基-β-环糊精包合物制备工艺优化

应用均匀设计法,选取羟丙基-β-环糊精浓度、主客比、反应温度和搅拌速度4个因素对虾青素/羟丙基-β-环糊精包合物制备工艺进行了优化。得到的最佳工艺参数是：羟丙基-β-环糊精浓度3.00mol/L,主客体摩尔比60,反应温度20℃,搅拌速度1000r/min,此时预测的包合率是54.0%（±5.91%）,在此条件下实际测定的包合率为51.6%,优化工艺切实可靠。     

羟丙基-β-环糊精在药剂学中的应用与研究

综述羟丙基-β-环糊精的特性、优势以及近年来在药剂学中的应用和研究进展。     

相溶解度法研究环糊精对纳他霉素的包合作用

目的:研究β-环糊精(β-CD)和羟丙基β-环糊精(HP-β-CD)对纳他霉素的增溶作用。方法:采用紫外分光光度测定纳他霉素含量,相溶解度法研究β-环糊精(β-CD)和羟丙基β-环糊精(HP-β-CD)对纳他霉素的包合作用、增溶作用及包合过程中热力学参数变化。结果:纳他霉素的溶解度随着β-环糊精浓度的增加而呈线性增加,相溶解度图呈AL型;纳他霉素的溶解度与羟丙基β-环糊精浓度在一定范围内呈线性,但随着羟丙基β-环糊精浓度的增加呈负向偏离型,相溶解度图呈AN型。纳他霉素与2种环糊精在包合过程中的吉布斯自由能变化(ΔG)、焓变(ΔH)均为负值,纳他霉素与β-CD在包合过程中的熵变(ΔS)为负值,而与HP-β-CD包合过程中的熵变(ΔS)为正值。结论:纳他霉素与2种环糊精增溶作用明显。     

羟丙基-β-环糊精的热稳定性及分解动力学

用热重/差热分析研究了羟丙基-β-环糊精的热稳定性,其分解温度为367℃左右。通过动力学分析确定其活化能为EA=149.15kJ/mol,指前因子k0=2.19×1010min-1。对比β-环糊精、羟丙基-β-环糊精的热重/差热曲线发现,羟丙基-β-环糊精的热稳定性优于β-环糊精,热分解温度提高32℃左右。     

羟丙基-β-环糊精分子识别能力研究

以复合物稳定常数为指标对羟丙基-β-环糊精（HP-β-CD）的分子识别能力进行了研究。通过还原-裂解法和甲基化分析确定了HP-β-CD样品的取代度和取代基分布。选取酚酞和甲基红分别作为大、小客体模型与HP-β-CD作用,用红外和紫外-可见光谱确定复合物的形成和复合形式,用分光光度法分别研究了两种复合物的稳定性,结合HP-β-CD的结构特性,总结出了HP-β-CD对客体的分子识别规律。对较大的客体,HP-β-CD的识别能力低于母体-βCD;对较小的客体,HP-β-CD有较高的分子识别能力,特别是取代度3.5左右,取代基分布较平均的HP-β-CD与客体结合的稳定常数远大于母体β-CD。     

环糊精模拟酶的研究进展

由于环糊精分子空腔能与客体分子形成包络物，对客体分子具有一定的选择识别能力，使它具有模拟酶的功能。对环糊精单体、修饰环糊精和环糊精聚合物模拟酶的情况进行了综述。     

β-环糊精及衍生物在食品工业中的应用研究

β-环糊精是环糊精的一种,是引人注目的一种新型包合材料。 β-环糊精及衍生物因其独特的理化性质及包合作用在食品工业中的应用研究日益广泛,本文主要介绍了 β-环糊精的特性以及 β-环糊精衍生物羧甲基-β-环糊精、乙基化 β-环糊精、羟丙基- β-环糊精、甲基- β-环糊精的制备方法及特性。对制备 β-环糊精包合物的液相法,半固相法,固相法以及其在食品工业中的应用前景也做了一定的介绍,以期对 β-环糊精及衍生物的进一步开发研究提供一定的帮助。     

β-环糊精及其衍生物增加客体分子水溶性的研究进展

β-环糊精及其衍生物对不同结构的客体分子的包合稳定性会因包合介质、包合温度、客体分子大小及氢键的形成等诸多因素的影响而产生较大差异,而环糊精包合物的形成不仅对疏水性客体分子的溶解度、生物利用度、安全性和稳定性有显著影响,还在减小疏水性客体分子刺激性、去除和掩盖其不良气味以及控制其释放速率等方面发挥重要作用。本文对常见β-环糊精衍生物的特点进行了归纳,并重点讨论了黄酮类化合物、多酚类化合物、香豆素类化合物和萜类化合物等客体分子与β-环糊精及其衍生物形成稳定包合物时包合方式的差异以及β-环糊精及其衍生物在增溶方面的应用,为β-环糊精及其衍生物在食品相关领域对不同疏水性功效成分增溶作用的探究提供理论参考。     

环糊精超分子自组装包合机制研究进展

环糊精因具有独特的“外亲水、内疏水”结构,可作为一种优良的包合载体对性质活泼、易挥发、易氧化分解的活性组分进行保护,从而达到提高其溶解度、稳定性和生物利用率的效果。本文从环糊精的结构与性质出发,首先对其包合机理进行探究,即分析主体环糊精与客体分子之间的相互作用和影响因素,包括环糊精单体与客体之间的包合反应、环糊精单体之间的自组装行为以及该行为下所形成的超分子体系与客体分子的包合机制;接着阐述有无表面活性剂存在的情况下环糊精界面稳定机制、表面活性剂与环糊精自组装形成复合乳化剂协同稳定客体机制等;然后,对环糊精包合物中客体分子的释放机制、缓释动力学模型及相应的影响因素进行解析;最后,从分子模拟及界面稳定机制方面对环糊精在超分子领域的研究进行展望,以期为后续研究提供参考。     

角鲨烯/γ-环糊精包合物制备及分子模拟

采用水溶液法结合冷冻干燥法制备角鲨烯/γ-环糊精包合物,应用相溶解度法、傅里叶变换红外光谱及氢谱核磁共振对包合物进行表征,并对包合物分子结构进行模拟。结果表明,当角鲨烯过量时,形成的包合物主客物质的量比大多为1∶1;而当γ-环糊精过量时,可形成平均主客物质的量比为3.45∶1的包合物。包合物的分子结构为角鲨烯链状分子将γ-环糊精环状分子均匀地“串联”在一起,且随着主客物质的量比增加,包合物分子结构趋于稳定。由于角鲨烯分子链长所限,理论上最佳主客物质的量比为4∶1。包合物的包合常数随温度升高而增大,在55 ℃条件下最大可达1 778.086 L/mol,且在此温度下最大可使角鲨烯的水溶性提高为原来的309 倍。根据能量变化推断,熵增加是角鲨烯分子进入γ-环糊精空腔的主要驱动力。     

Characterization and Chemical Modification of Amylose Complexes

Complexes of amylose with various organic guest molecules have been studied by means of c. d. spectroscopy and microcalorimetry in aqueous solution. From the results the structure of the complexes and the mechanism of their formation are deduced. It is concluded that amylose can adjust its helix conformation to the shape and structure of the guest molecule included. Investigations about intramolecular and intermolecular crosslinking of amylose indicate that the complexing behaviour of amylose can be manipulated specifically.     

Application of Cyclodextrins in the Chromatography

The central cavity of the cylinder-shaped cyclodextrin molecules behaves as an empty molecular capsule: it can accomodate so called ‘guest molecules’ of appropriate size, shape and polarity. The stability of the formed inclusion complexes is however very different. This is the basis of the separation of various substances by cyclodextrins. The separation can be realized by non-chromatographic methods or by chromatographic methods. The present review summarizes the utilization of cyclodextrins and their derivatives in gas-liquid and gas-solid-, gel-, inclusion-, thin-layer-, affinity-, and high performance liquid chromatography.     

High Relative Humidity In‐Package of Fresh‐Cut Fruits and Vegetables: Advantage or Disadvantage Considering Microbiological Problems and Antimicrobial Delivering Systems?

ABSTRACT:  This hypothesis article states that the high relative humidity (RH) of packaged fresh-cut fruits or vegetables that is associated with spoilage can be used as an advantageous way to deliver antimicrobial compounds using cyclodextrins (CDs) as carriers. CDs can function as antimicrobial delivery systems as they can release antioxidant and antimicrobial compounds (guest molecules) as the humidity levels increase in the headspace. Hydrophobic antimicrobial guests can be complexed with CDs due to the amphiphatic nature of the host. Then, at high RH values, due to the water–CDs interaction, host–guest interactions are weakened; consequently, the antimicrobial molecule is released and should protect the product against the microbial growth. Potential antimicrobial compounds capable of forming complexes with CDs are discussed, as well as possible applications to preserve fresh-cut produce and future research in this area.     

Encapsulation of cinnamon and thyme essential oils components (cinnamaldehyde and thymol) in β-cyclodextrin: Effect of interactions with water on complex stability

Thymol and cinnamaldehyde formed inclusion complexes with β-cyclodextrin (β-CD) upon mixing the components in aqueous media and subsequent freeze–drying, as confirmed by differential scanning calorimetry. The samples were stored at constant relative humidities (RH) from 22% to 97%, at 25 °C. The release of encapsulated compounds was determined following the melting enthalpy of each guest. Water sorption isotherms for β-CD and the complexes showed constant and low water sorption at RH < 80%, then the uptake of water increased abruptly. The amount of sorbed water at each RH was smaller for the complexes than for β-CD. The guest molecules displaced water molecules from inside the cavity of β-CD. No thymol or cinnamaldehyde release was detected at RH < 84%, and it increased abruptly from 84% RH, coincidentally with the abrupt increase of sorbed water. Water sorption significantly affects β-CD complexes stability, which is thus governed by the shape of the water sorption isotherm.     

槲皮素与环糊精衍生物包合物的理化性质和分子对接研究

槲皮素具有较强的抗氧化活性,对呼吸道炎症和心血管疾病具有一定疗效,在医药行业中受到广泛关注。 但是,槲皮素的水溶性和热稳定性较低,使其在医药行业的应用受到限制。环糊精（cyclodextrins,CDs）是一种 大环分子,能够与客体分子包合形成包合物,从而有效提高客体分子的溶解性、稳定性和生物利用率。本实验制备 槲皮素与β-CD、G-β-CD及G2-β-CD的包合物,利用相溶解度法研究环糊精与槲皮素的包合效果,利用紫外光谱、 傅里叶变换红外光谱、扫描电子显微镜、X射线衍射、热重及差示扫描量热技术表征槲皮素与G-β-CD包合物,借 助分子对接研究槲皮素与G-β-CD包合物的超分子结构。结果显示：槲皮素的溶解度与环糊精的浓度呈线性关系, G-β-CD与槲皮素的包合效果最好,且包合后槲皮素的热稳定性提高。分子对接结果表明槲皮素的C环嵌入G-β-CD 的空腔中形成包合物。     

Cyclodextrins and Antioxidants

In recent years, the growth of the functional foods industry has increased research into new compounds with high added value for use in the fortification of traditional products. One of the most promising functional food groups is those enriched in antioxidant compounds of a lipophilic nature. In spite of the numerous advantages reported for such antioxidant molecules, they may also have disadvantages that impede their use in functional foods, although these problems may well avoided by the use of encapsulant agents such as cyclodextrins. This explains the recent increase in the number of research papers dealing with the complexation of different guest molecules possesing important antioxidant properties using natural and modified cyclodextrins. This paper presents a review of the most recent studies on the complexes formed between several important types of antioxidant compounds and cyclodextrins, focusing on the contradictory data reported in the literature concerning to the antioxidant activity of the host/guest molecule complexes, the different complexation constants reported for identical complexes, the bioavailability of the antioxidant compound in the presence of cyclodextrins and recommendation concerning the use of natural or modified cyclodextrins. Moreover, the use of cyclodextrins as antibrowning agents to prevent enzymatic browning in different foods is revised. Finally, we look at studies which suggest that cyclodextrins act as ‘‘secondary antioxidants,” enhancing the ability of traditional antioxidants to prevent enzymatic browning.     

Extraction of Lycopene from Tomato Paste by Ursodeoxycholic Acid Using the Selective Inclusion Complex Method

Lycopene, a precursor of β‐carotene with well‐known antioxidant activity and powerful health properties, can be found in many natural products such as tomato (Lycopersicon esculentum), watermelon, red pepper, and papaya. Many separation methods have been reported for extracting lycopene from its sources. The inclusion complex is an effective method for extraction and purification of organic chemicals. This procedure has 2 main components: host and guest molecules. In this study, lycopene (guest) was extracted from tomato paste by ursodeoxycholic acid, the inclusive agent (host). The molecular structure of the extracted lycopene was then confirmed by ¹HNMR and its purity was evaluated using high‐performance liquid chromatography and UV‐Vis spectrophotometry methods, in comparison with a standard product. The results indicated that the proposed separation method was very promising and could be used for the extraction and purification of lycopene from tomato paste.