槲皮素苯磺酸酯前药的设计与合成

为了提高槲皮素的生物利用度以改善其抗肿瘤等活性,本论文根据其体内基本传递特性,利用前药原理成功设计合成了3个新型槲皮素磺酸酯衍生物(1,3～4),所有化合物的结构均经IR,MS,元素分析和1H NMR等确证.对目标产物进行溶解度测定,发现三种目标化合物的脂溶性与水溶性均有显著的提高.     

Development of Antioxidant-Loaded Nanoliposomes Employing Lecithins with Different Purity Grades

This work focused on comparing the ability of lecithins with two purity grades regarding their performance in the development of nanoliposomes, as well as their ability to contain and release polar (trans-aconitic acid) and non-polar (quercetin) antioxidant compounds. First, the chemical characterization of both lecithins was carried out through infrared spectroscopy (FTIR), electrospray ionization mass spectrometry (ESI/MS), and modulated differential scanning calorimetry (mDSC). Second, nanoliposomes were prepared by the ethanol injection method and characterized by means of particle size, polydispersity, and zeta potential measurements. Third, the encapsulation efficiency and in vitro release profiles of antioxidants were evaluated. Finally, the antioxidant effect of quercetin and trans aconitic acid in the presence and absence of nanoliposomes was assessed through the oxygen radical absorbance capacity (ORAC) assay. The results showed that, although there are differences in the chemical composition between the two lecithins, these allow the development of nanoliposomes with very similar physicochemical features. Likewise, nanoliposomes elaborated with low purity grade lecithins favored the encapsulation and release of trans-aconitic acid (TAA), while the nanoliposomes made with high purity lecithins favored the encapsulation of quercetin (QCT) and modified its release. Regarding the antioxidant effect, the vehiculization of TAA and QCT in nanoliposomes led to an increase in the antioxidant capability, where QCT showed a sustained effect over time and TAA exhibited a rapidly decaying effect. Likewise, liposomal systems were also found to have a slight antioxidant effect.     

用高效液相色谱法测定灯盏花中槲皮素的含量

分别采用溶剂回流提取和超声提取两种方法对灯盏花样品中的槲皮素进行提取,优化了提取条件,并用高效液相色谱进行了定量分析,采用扫描电镜分析了提取样品的表面形貌.结果表明:两种方法的提取率分别为0.048 7mg/g和0.042 3mg/g,溶剂回流的提取效果略优于超声提取;回流提取时的高温有利于提取物的溶出,而超声提取节能、快速.与此同时,采用两种方法提取的样品表面都受到明显的侵蚀,且回流提取时的机械搅拌促进样品的破碎,这些都有利于槲皮素的溶出.     

~(18)F标记前体3'-甲氧基-7-对甲苯磺酰氧丙氧基槲皮素的合成

以槲皮素为起始原料,经酰化、醚化、苄醚化、脱苄、甲基化、水解6步反应合成了18F标记前体3'-甲氧基-7-对甲苯磺酰氧丙氧基槲皮素,其结构经1H NMR,13C NMR和HR-MS(ESI)确证。     

槲皮素-锆-SDS荧光光度法的研究及其应用

槲皮素与锆形成二元荧光络合物,SDS对体系有强烈的增敏作用,研究并建立了测定槲皮素的荧光光度法。在0．48mol／LHCl介质中,槲皮素浓度在0．072～7．76μg／mL范围内与其荧光强度呈良好的线性关系,其线性回归方程为γ=7．1829x＋5．4025,相关系数r=0．9958,检出限为0．046μg／mL。该法用于银杏叶片制剂中总黄酮醇苷含量（以槲皮素计）的测定,其回收率为97．60％-102．2％,结果较为理想。     

Synthesis,Antiproliferative Activity and Radical Scavenging Ability of 5-O-Acyl Derivatives of Quercetin

Quercetin is a flavonoid that is found in many plant materials, including commonly eaten fruits and vegetables. The compound is well known for its wide range of biological activities. In this study, 5-O-acyl derivatives of quercetin were synthesised and assessed for their antiproliferative activity against the HCT116 colon cancer and MDA-MB-231 breast cancer cell lines; and their radical scavenging activity against the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical species. Four derivatives were found to have improved the antiproliferative activity compared to quercetin whilst retaining radical scavenging activity.     

Polyphenols of the Mediterranean Diet and Their Metabolites in the Prevention of Colorectal Cancer

The Mediterranean diet is a central element of a healthy lifestyle, where polyphenols play a key role due to their anti-oxidant properties, and for some of them, as nutripharmacological compounds capable of preventing a number of diseases, including cancer. Due to the high prevalence of intestinal cancer (ranking second in causing morbidity and mortality), this review is focused on the beneficial effects of selected dietary phytophenols, largely present in Mediterranean cooking: apigenin, curcumin, epigallocatechin gallate, quercetin-rutine, and resveratrol. The role of the Mediterranean diet in the prevention of colorectal cancer and future perspectives are discussed in terms of food polyphenol content, the effectiveness, the plasma level, and the importance of other factors, such as the polyphenol metabolites and the influence of the microbiome. Perspectives are discussed in terms of microbiome-dependency of the brain-second brain axis. The emergence of polyphenol formulations may strengthen the efficiency of the Mediterranean diet in the prevention of cancer.     

Quantum-Mechanical and Solvatochromic Characterization of Quercetin

ABSTRACT

Quercetin was subjected to a quantum-mechanical analysis and energetic and electro-optic parameters were evaluated. A solvatochromic study was used to estimate the dipole moment of quercetin in the excited state and to determine the angle between the dipole moments of this molecule in the electronic states responsible for the visible absorption band. The contribution of each type of intermolecular interactions to the total spectral shift experimentally recorded in quercetin solution was also established in this study.     

Ordered macroporous quercetin molecularly imprinted polymers: Preparation,characterization, and separation performance

Ordered macroporous molecularly imprinted polymers were prepared by a combination of the colloidal crystal templating method and the molecular imprinting technique by using SiO₂ colloidal crystal as the macroporogen, quercetin as the imprinting template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross‐linker and tetrahydrofuran as the solvent. Scanning electron microscopy and Brunauer–Emmett–Teller measurements show that the ordered macroporous molecularly imprinted polymers have a more regular macroporous structure, a narrower pore distribution and a greater porosity compared with the traditional bulk molecularly imprinted polymers. The kinetic and isothermal adsorption behaviors of the polymers were investigated. The results indicate that the ordered macroporous molecularly imprinted polymers have a faster intraparticle mass transfer process and a higher adsorption capacity than the traditional bulk molecularly imprinted polymers. The ordered macroporous molecularly imprinted polymers were further employed as a sorbent for a solid‐phase extraction. The results show that the ordered macroporous molecularly imprinted polymers can effectively separate quercetin from the Gingko hydrolysate.     

Two new quercetin glycoside derivatives from the fruits of Gardenia jasminoides var. radicans

Two new quercetin glycoside derivatives named quercetin-3-O-[2-O-trans-caffeoyl-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside] (1) and quercetin-3-O-[2-O-trans-caffeoyl-β-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside] (2) along with three known flavonoids, 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavone (3), 5,7-dihydroxy-8-methoxyflavone (4) and kaempferol 3-O-β-d-glucopyranoside (5), were isolated from the fruits of Gardenia jasminoides var. radicans. The structures of the new compounds were determined by means of extensive spectroscopic analysis (1D, 2D NMR and HR-ESI-MS), glycoside hydrolysis and sugar HPLC analysis after derivatisation. This is the first report on the isolation of a pair of compounds with α or β-l-rhamnopyranosyl configuration from plant and the first detail assignment of their NMR data.