槲皮素表面分子印迹聚合物的制备及其应用研究

以接枝双键的凹凸棒土(TM)为载体,槲皮素为模板分子,采用表面印迹技术制备对槲皮素具有特异吸附性能的分子印迹聚合物(MIP)。利用光谱法选择实验条件及对化合物表征。采用静态法研究聚合物对槲皮素的结合性能与识别性能。结果表明,该分子印迹材料对槲皮素具有特异的识别特性和优良的亲和性,提高了传统聚合物的结合率。以该印迹聚合物为固相萃取材料,结合高效液相色谱法,对白菜中的槲皮素进行分离富集,方法回收率为84.0%~90.6%,相对标准偏差低于5.6%。     

槲皮素在聚L-络氨酸修饰电极上的电化学行为及测定

采用电聚合方法制备了聚L-络氨酸修饰电极。利用循环伏安法(CV)探究了pH值、扫描速率对槲皮素电化学行为的影响。用差分脉冲伏安法(DPV)对槲皮素进行测定。结果表明:聚L-络氨酸修饰电极在pH值为6.0的磷酸盐缓冲溶液中对槲皮素表现出良好的电催化能力。在6.21×10~(-5)～6.9×10~(-4) mol/L范围内槲皮素的浓度与相应的检测信号呈现出良好的线性关系,线性方程为:I(10~(-6) A)=-1.034 8-0.099 39c(10~(-4) mol/L),线性相关系数R=-0.987 87,检出限为2.07×10~(-5) mol/L(S/N=3)。电化学分析方法简易快捷、重现性和稳定性高。     

Synthesis and characterization of a novel quercetin magnetic molecularly imprinted polymer via reversible addition fragmentation chain transfer strategy

Molecularly imprinted polymer (MIP) will be modified on the surface of the core-shell structure silica magnetic nanoparticles, during which quercetin is used as a template molecule, acrylamide as a functional monomer, azo-bisisobutyronitrile as an initiator and ethylene glycol dimethacrylate as a cross-linker, to synthesize highly efficient and selective quercetin magnetic molecularly imprinted nanoparticles via Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. FT-IR and X-ray diffraction (XRD) patterns are used to monitor the reaction and show the characteristic groups of each reaction step. Compared with the conventional bulk polymerization (2.7029 mg/g), the adsorption test showed that the MMIP by RAFT activity controlled polymerization had better absorption capacity for quercetin which the saturated adsorption amount was 4.8471 mg/g. Kinetic studies indicate that pseudo first order model is suitable to describe the adsorption mechanism. Thermodynamics experiment revealed that Langmuir model was more applied for explains the adsorption of quercetin onto magnetic molecularly imprinted polymer.     

银杏叶提取物中黄酮类成分的高效液相色谱分析

Quantitative reversed-phase high performance liquid chromatographic method has been developed for theseparation and determination of the flavonoids found in the extracts of the leaves of ginkgo biloba L. (EGb).Procedure includes hydrolysis of the flavonoids and subsequent quantitative chromatographic assay of the ob-tained aglycones on a C_(18) column with methanol-0.4% orthophosphoric acid (55:45) as eluent. The detec-tion was effected at 360nm.     

锌-槲皮素配位分子印迹聚合物膜渗透特性的研究

采用紫外光引发原位聚合的方法制备了以聚偏氟乙烯管状微孔滤膜为支撑膜的锌离子配位分子印迹聚合物膜. 通过膜渗透实验表明, 在一定浓度锌离子存在下, 印迹膜对模板分子槲皮素表现出良好的渗透选择性. 分别考察了阳离子和阴离子对印迹膜渗透模板分子的影响. 本工作对分子印迹技术应用于实际样品中槲皮素的分离与富集具有重要意义.     

钒－槲皮素－氯酸盐体系极谱催化波的研究

在醋酸盐缓冲底液中，钒能与槲皮素形成络合物，并吸附在汞电极上，在氯酸盐存在下，在Ⅴ（Ⅳ）还原至Ⅴ（Ⅲ）过程中，形成催化波。用单扫二阶导数极谱法测定时，钒浓度在１．０×１０￣（－９）～５．０×１０￣（－６）ｍｏｌ／Ｌ与峰高有正比关系，检出下限为５．０×１０￣（－１０）ｍｏ１／ｍＬ。测得电活性络合物的组成为Ⅴ（Ⅳ：Ｑｕ＝１：２。平行催化反应的速率常数Ｋ＝１．５×１０￣（４）（ｍｏｌ／Ｌ）￣（－１）ｓ（－１）。     

Rp-HPLC Determination of Quercetin in a Novel D-α-Tocopherol Polyethylene Glycol 1000 Succinate Based SNEDDS Formulation: Pharmacokinetics in Rat Plasma

Despite its proven efficacy in diverse metabolic disorders, quercetin (QU) for clinical use is still limited because of its low bioavailability. D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) is approved as a safe pharmaceutical adjuvant with marked antioxidant and anti-inflammatory activities. In the current study, several QU-loaded self-nanoemulsifying drug delivery systems (SNEDDS) were investigated to improve QU bioavailability. A reversed phase high performance liquid chromatography (RP-HPLC) method was developed, for the first time, as a simple and sensitive technique for pharmacokinetic studies of QU in the presence of TPGS SNEDDS formula in rat plasma. The analyses were performed on a Xterra C₁₈ column (4.6 × 100 mm, 5 µm) and UV detection at 280 nm. The analytes were separated by a gradient system of methanol and phosphate buffer of pH 3. The developed RP-HPLC method showed low limit of detection (LODs) of 7.65 and 22.09 ng/mL and LOQs of 23.19 and 66.96 ng/mL for QU and TPGS, respectively, which allowed their determination in real rat plasma samples. The method was linear over a wide range, (30–10,000) and (100–10,000) ng/mL for QU and TPGS, respectively. The selected SNEDDS formula, containing 50% w/w TPGS, 30% polyethylene glycol 200 (PEG 200), and 20% w/w pumpkin seed oil (PSO), showed a globule size of 320 nm and −28.6 mV zeta potential. Results of the pharmacokinetic studies showed 149.8% improvement in bioavailability of QU in SNEDDS relative to its suspension. The developed HPLC method proved to be simple and sensitive for QU and TPGS simultaneous determination in rat plasma after oral administration of the new SNEDDS formula.     

In Vitro Bioaccessibility and Anti-Inflammatory Activity of a Chemically Characterized Allium cepa L. Extract Rich in Quercetin Derivatives Optimized by the Design of Experiments

Allium cepa L. is a highly consumed garden crop rich in biologically active phenolic and organosulfur compounds. This study aimed to assess the in vitro bioaccessibility and anti-inflammatory effect of a chemically characterized A. cepa extract rich in quercetin and its derivatives. Different varieties of A. cepa were studied; based on the highest total phenolic content, the “Golden” variety was selected. Its extracts, obtained from the tunicate bulb, tunic, and bulb, were subjected to determination of quercetin and its derivatives with LC-MS analysis and based on the highest total quercetin content, the tunic extract was utilized for further experiments. The extraction method was optimized through a design of experiment (DoE) method via full factorial design, which showed that 40% ethanol and 1 g tunic/20 mL solvent are the best extraction conditions. HPLC analysis of the optimized tunic extract identified 14 flavonols, including 10 quercetin derivatives. As far as in vitro bioaccessibility was concerned, the increases in some quercetin derivatives following the gastro-duodenal digestion process support the bioaccessibility of these bioactive compounds. Moreover, the extract significantly inhibited the production of PGE2 in stimulated J774 cell lines, while no effects of the tunic extract were observed against the release of IL-1β, TNF-α, and nitrites. The study provided insights into the optimized extraction conditions to obtain an A. cepa tunic extract rich in bioavailable quercetin derivatives with significant anti-inflammatory effects against PGE2.     

Selected Plant-Derived Polyphenols as Potential Therapeutic Agents for Peripheral Artery Disease: Molecular Mechanisms,Efficacy and Safety

Vascular diseases, such as peripheral artery disease (PAD), are associated with diabetes mellitus and a higher risk of cardiovascular disease and even death. Surgical revascularization and pharmacological treatments (mainly antiplatelet, lipid-lowering drugs, and antidiabetic agents) have some effectiveness, but the response and efficacy of therapy are overly dependent on the patient’s conditions. Thus, the demand for new cures exists. In this regard, new studies on natural polyphenols that act on key points involved in the pathogenesis of vascular diseases and, thus, on PAD are of great urgency. The purpose of this review is to take into account the mechanisms that lead to endothelium dysfunction, such as the glycoxidation process and the production of advanced glycation end-products (AGEs) that result in protein misfolding, and to suggest plant-derived polyphenols that could be useful in PAD. Thus, five polyphenols are considered, baicalein, curcumin, mangiferin, quercetin and resveratrol, reviewing the literature in PubMed. The key molecular mechanisms and preclinical and clinical studies of each selected compound are examined. Furthermore, the safety profiles of the polyphenols are outlined, together with the unwanted effects reported in humans, also by searching the WHO database (VigiBase).     

Anti-Inflammatory,Antioxidative, and Nitric Oxide-Scavenging Activities of a Quercetin Nanosuspension with Polyethylene Glycol in LPS-Induced RAW 264.7 Macrophages

Quercetin (Qu) is a dietary antioxidant and a member of flavonoids in the plant polyphenol family. Qu has a high ability to scavenge reactive oxygen species (ROS) and reactive nitrogen species (RNS) molecules; hence, exhibiting beneficial effects in preventing obesity, diabetes, cancer, cardiovascular diseases, and inflammation. However, quercetin has low bioavailability due to poor water solubility, low absorption, and rapid excretion from the body. To address these issues, the usage of Qu nanosuspensions can improve physical stability, solubility, and pharmacokinetics. Therefore, we developed a Qu and polyethylene glycol nanosuspension (Qu-PEG NS) and confirmed its interaction by Fourier transform infrared analysis. Qu-PEG NS did not show cytotoxicity to HaCaT and RAW 264.7 cells. Furthermore, Qu-PEG NS effectively reduced the nitrogen oxide (NO) production in lipopolysaccharide (LPS)-induced inflammatory RAW 264.7 cells. Additionally, Qu-PEG NS effectively lowered the levels of COX-2, NF-κB p65, and IL-1β in the LPS-induced inflammatory RAW 264.7 cells. Specifically, Qu-PEG NS exhibited anti-inflammatory properties by scavenging the ROS and RNS and mediated the inhibition of NF-κB signaling pathways. In addition, Qu-PEG NS had a high antioxidant effect and antibacterial activity against Escherichia coli and Bacillus cereus. Therefore, the developed novel nanosuspension showed comparable antioxidant, anti-inflammatory, and antibacterial functions and may also improve solubility and physical stability compared to raw quercetin.