槲皮素酯类衍生物研究进展

健康生活方式特别强调食物质量,多酚在这方面发挥了关键作用。槲皮素是一种天然多酚,是多种植物性食品中发现最丰富的类黄酮类化合物之一。槲皮素是天然的抗氧化剂,可以保护细胞免受自由基造成的损害。槲皮素是一种亲脂性化合物,能够穿过细胞膜,可调节众多与疾病进展、化学预防有关的细胞内和细胞外信号通路。槲皮素具有广泛的药理活性,抗炎、抗菌、抗癌和预防心脑血管疾病,但是它低溶解度和生物利用度限制了在临床上的应用。对槲皮素的结构进行优化修饰获得了溶解性能好、生物利用度高、活性明显改善、抗癌活性增强的槲皮素衍生物。综述了近年来槲皮素酯衍生物的研究进展,为槲皮素衍生物的进一步开发提供参考。     

MIL-101 (Cr)-表面辅助激光解吸电离-质谱法快速检测血样中的芦丁

本文采用金属有机骨架(Metal Organic Frameworks,MOFs)化合物MIL-101(Cr)作为基质辅助激光解吸电离(MALDI)的基质,将其与传统基质进行对比分析黄酮类小分子化合物,可以实现对黄酮类药物小分子的无背景干扰检测,并据此建立了快速检测芦丁的MIL-101 (Cr)-表面辅助激光解吸电离-...     

高效液相色谱法测定复方芦丁片中芦丁和维生素C的含量

采用反相高效液相离子对色谱法,以对氨基苯甲酸为内标,测定了复方芦丁片中芦丁和维生素Ｃ的含量。色谱柱为μ－ＢｏｎｄａｐａｋＣ_（１８）,流动相为甲醇－水（５０：５０）配制的樟脑磺酸溶液（０．００２５ｍｏｌ／Ｌ）,检测波长为２５４ｎｍ。并做了线性范围和回收率测定。     

芦丁钙的合成及降低胆固醇的作用

在碱溶液中,芦丁与钙离子反应生成了芦丁钙,通过元素分析、紫外光谱、红外光谱、薄层层析对芦丁钙进行了表征．大鼠实验证明芦丁钙能降低总胆固醇（TC）、甘油三酯（TG）,并升高高密度脂蛋白（HDL）,从而发挥调节血脂的作用．     

木犀草素衍生物研究进展

木犀草素属于黄酮类化合物,主要以糖苷的形式存在于蔬菜、水果和中草药中。木犀草素属于天然抗氧化剂,具有丰富的生物活性,可调节众多与疾病进展有关的细胞内和细胞外信号通路,具有抗氧化、抗炎、抗糖尿病、抗癌等作用。越来越多的证据表明,摄入木犀草素可能有益于影响糖脂代谢紊乱,特别是胰岛素抵抗、糖尿病和肥胖。木犀草素低溶解度和较低的生物利用度限制了在临床上的应用。然而,木犀草素的低分子质量和易修饰的化学基团,使其具有药物开发的吸引力。因此,研究人员通过各种方法设计合成了木犀草素衍生物,以改善其不利因素,进而发挥预防和治疗疾病的作用。木犀草素衍生物溶解性能好、生物利用度高、活性明显改善、抗癌活性增强,本文综述了木犀草素衍生物的研究进展,为天然产物的研究、开发及利用提供参考。     

RP-HPLC法测定唐古特铁线莲中芦丁的含量

建立了唐古特铁线莲中芦丁含量测定的RP-HPLC方法.色谱条件:采用C18柱 (4.6 mm×250 mm,5 μm),流动相:V(甲醇)∶V(0.4% H3PO4)=55∶45,流速:1.0 mL/min,柱温:30 ℃,检测波长:360 nm,芦丁在0.24～1.2 μg范围内成良好的线性关系,r=0.9992,回收率RSD=1.0%,对青海省不同地区唐古特铁线莲中芦丁进行了定量分析,测定结果:不同产地该药材中芦丁的含量有较大差异,含量在0.119%～0.317%之间.     

新黄酮类化合物的脱甲基反应及其抗氧化活性

以3,4-二甲氧基苯甲醛(1)为起始原料,使用文献已报道的三氟乙酸法合成了3个含两个甲氧基取代基的新黄酮类化合物4a-4c,在新制碘化铝的催化下发生脱甲基反应,合成了3个含多个羟基取代基的新黄酮类化合物5a-5c,产率均高于90%.所有目标化合物均经过IR,~1H NMR,ESI-MS对其进行了结构确认.通过测定羟基自由基和DPPH自由基清除活性两个方面评价其抗氧化活性,结果发现,脱甲基后产物活性均增强.     

一种低成本高含量曲克芦丁的制备方法

本文以市售芦丁为原料,在吡啶中经醋酸酐酰化后再水解得外标含量为99.7%的高纯度芦丁;然后以此高纯度芦丁为原料,以3代聚酰胺-胺树枝状聚合物为催化剂,在甲醇中经环氧乙烷羟乙基化反应,精制后得高含量曲克芦丁。本文系统研究了以高纯度芦丁为原料,反应温度、时间和压强对曲克芦丁合成的影响。实验表明,芦丁经酰化后再水解可得到纯度为99.7%的高纯度芦丁,在高压釜内,压强0.2MPa、温度80℃条件下反应5 h,得到的粗品曲克芦丁只需简单纯化便可得到外标纯度大于98.5%的曲克芦丁。     

芦丁的电化学伏安行为及其应用

芦丁在0.1mol/L Tris-HCl缓冲溶液(pH=8.3)中产生灵敏的线性扫描极谱峰,峰电位EP=-1.10V(vs.Ag/AgCl).峰电流与芦丁浓度在7×10-7~9.8×10-6mol/L范围内呈良好的线性关系.可用于乌拉尔甘草内黄酮含量的测定.线性扫描和循环伏安法测试表明,该体系属具有吸附性的准可逆过程体系.     

介孔碳纳米纤维修饰电极用于黄酮类化合物芦丁的电化学测定

制备了新型的介孔碳纳米纤维修饰热解石墨电极(MCNF/PGE),并将其用于芦丁含量的测定。用循环伏安法、交流阻抗谱法、示差脉冲伏安法研究了该修饰电极膜性能及芦丁在该修饰电极上的电化学行为。结果表明,修饰电极可有效促进探针离子[Fe(CN)6]3-/4-在电极表面的电子传递;芦丁在该修饰电极表面的电化学过程受扩散控制。由于MCNFs大量的石墨边缘缺陷、大比表面积以及介孔结构,与裸电极相比,该修饰电极对芦丁呈现出很高的电催化活性,芦丁阳极峰电流约为裸电极上的18倍。在最佳实验条件下,芦丁的氧化峰电流(Ipa)与其浓度(c)在2.0×10-8～1.2×10-6mol/L范围内呈良好的线性关系,检出限(S/N=3)为5.0×10-9mol/L,线性系数r2=0.999。此外,计算了电荷转移系数(α)、标准速率常数(ks),并推测了芦丁的电化学氧化还原机理。该修饰电极易于制备、可再生,重复性及稳定性良好,可作为一种高灵敏度的电化学传感器应用于芦丁片剂中芦丁的含量测定。     

毛细管区带电泳法测定复方芦丁片中芦丁和维生素C的含量

考察了缓冲溶液的pH、背景电解质浓度及分离电压对芦丁、维生素C及苯甲酸分离的影响，建立了以苯甲酸为内标，毛细管区带电泳法快速测定复方芦丁片中芦丁和维生素C含量的新方法。以3g/L硼砂－4g/L硼酸(pH8.18）为运行缓冲液，苯甲酸为内标，在分离电压为25kV，检测波长为254nm的电泳条件下，芦丁、维生素C和内标可在5min实现分离。芦丁的线性方程为：y=2．65x＋0．095（r＝0．9994），线性范围为0．025mg/mL－0．4mg/mL，维生素C的线性方程为：y＝3．1343x＋0．565（r＝0．9991），线性范围0．125mg/mL－1．0mg/mL。方法可用于复方芦丁片的质量控制。     

Therapeutic Importance of Kaempferol in the Treatment of Cancer through the Modulation of Cell Signalling Pathways

Plant-derived flavonoids are considered natural nontoxic chemo-preventers and have been widely studied for cancer treatment in recent decades. Mostly all flavonoid compounds show significant anti-inflammatory, anticancer and antioxidant properties. Kaempferol (Kmp) is a well-studied compound and exhibits remarkable anticancer and antioxidant potential. Kmp can regulate various cancer-related processes and activities such as cell cycle, oxidative stress, apoptosis, proliferation, metastasis, and angiogenesis. The anti-cancer properties of Kmp primarily occur via modulation of apoptosis, MAPK/ERK1/2, P13K/Akt/mTOR, vascular endothelial growth factor (VEGF) signalling pathways. The anti-cancer property of Kmp has been recognized in several in-vivo and in-vitro studies which also includes numerous cell lines and animal models. This flavonoid possesses toxic activities against only cancer cells and have restricted toxicity on healthy cells. In this review, we present extensive research investigations about the therapeutic potential of Kmp in the management of different types of cancers. The anti-cancer properties of Kmp are discussed by concentration on its capability to target molecular-signalling pathway such as VEGF, STAT, p53, NF-κB and PI3K-AKT signalling pathways. The anti-cancer property of Kmf has gained a lot of attention, but the accurate action mechanism remains unclear. However, this natural compound has a great pharmacological capability and is now considered to be an alternative cancer treatment.     

Spectrophotometric investigation of protolytic equilibria of rutin

The dissociation constants of rutin in aqueous-methanol medium (6040 v/v), the values of which are pK₁=–2.92±0.06, pK₂=6.72±0.11, pK₃=8.26±0.05, pK₄=12.57±0.09, were estimated by using the spectrophotometric method. They were ascribed to the dissociation of protonated oxygen atom at position 1 and then to hydroxyl groups at positions 7, 4', 5, respectively. Resonance structures of H₃L^– ion of rutin were suggested and, by using them, the greater dissociability of the hydroxyl group at position 7 in relation to the –OH group at position 4' was explained.     

Antioxidant and Anti-Inflammatory Activities of Six Flavonoids from Smilax glabra Roxb

This study aimed to isolate, prepare and identify the main flavonoids from a standardized Smilax glabra flavonoids extract (SGF) using preparative HPLC, MS, ¹H NMR and ¹³C NMR, determine the contents of these flavonoids using UPLC, then compare their pharmacological activities in vitro. We obtained six flavonoids from SGF: astilbin (18.10%), neoastilbin (11.04%), isoastilbin (5.03%), neoisoastilbin (4.09%), engeletin (2.58%) and (−)-epicatechin (1.77%). The antioxidant activity of six flavonoids were evaluated by determining the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2′-Azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS⁺) radical scavenging activity and ferric reducing antioxidant power (FRAP). In addition, the anti-inflammatory activity of six flavonoids were evaluated by determining the production of cytokines (IL-1β, IL-6), nitric oxide (NO) using enzyme linked immunosorbent assay and the NF-κB p65 expression using Western blotting in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The results showed that (−)-epicatechin, astilbin, neoastilbin, isoastilbin and neoisoastilbin had strong antioxidant activities, not only in DPPH and ABTS⁺ radicals scavenging capacities, but in FRAP system. Furthermore, all the six flavonoids could significantly inhibit the secretion of IL-1β, IL-6, NO (p < 0.01) and the protein expression of NF-κB p-p65 (p < 0.01) in LPS-stimulated RAW264.7 cells. This study preliminarily verified the antioxidant and anti-inflammatory activities of six flavonoids in S. glabra.     

Phenylethyl Isothiocyanate: A Bioactive Agent for Gastrointestinal Health

The incidence of gastrointestinal pathologies (cancer in particular) has increased progressively, with considerable morbidity and mortality, and a high economic impact on the healthcare system. The dietary intake of natural phytochemicals with certain bioactive properties has shown therapeutic and preventive effects on these pathologies. This includes the cruciferous vegetable derivative phenylethyl isothiocyanate (PEITC), a bioactive compound present in some vegetables, such as watercress. Notably, PEITC has antioxidant, anti-inflammatory, bactericidal, and anticarcinogenic properties. This review summarized the current knowledge on the role of PEITC as a potential natural nutraceutical or an adjuvant against oxidative/inflammatory-related disorders in the gastrointestinal tract. We also discussed the safe and recommended dose of PEITC. In addition, we established a framework to guide the research and development of sustainable methodologies for obtaining and stabilizing this natural molecule for industrial use. With PEITC, there is great potential to develop a viable strategy for preventing cancer and other associated diseases of the gastrointestinal tract. However, this topic still needs more scientific studies to help develop new PEITC products for the nutraceutical, pharmaceutical, or food industries.     

Determination of rutin using a CeO2 nanoparticle-modified electrode

CeO₂ nanoparticles approximately 12 nm in size were synthesized and subsequently characterized by XRD, TEM and UV-vis spectroscopy. Then, a gold electrode modified with CeO₂ nanoparticles was constructed and characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The modified electrode demonstrated strong catalytic effects with high stability towards electrochemical oxidation of rutin. The anodic peak currents (measured by differential pulse voltammetry) increased linearly with the concentration of rutin in the range of 5.0 × 10⁻⁷–5.0 × 10⁻⁴ mol · L⁻¹. The detection limit (S/N = 3) was 2.0 × 10⁻⁷ mol · L⁻¹. The relative standard deviation (RSD) of 8 successive scans was 3.7% for 5.0 × 10⁻⁶ mol · L⁻¹ rutin. The method showed excellent sensitivity and stability, and the determination of rutin in tablets was satisfactory.     

Chitosan Elicitation Impacts Flavonolignan Biosynthesis in Silybum marianum (L.) Gaertn Cell Suspension and Enhances Antioxidant and Anti-Inflammatory Activities of Cell Extracts

Silybum marianum (L.) Gaertn is a rich source of antioxidants and anti-inflammatory flavonolignans with great potential for use in pharmaceutical and cosmetic products. Its biotechnological production using in vitro culture system has been proposed. Chitosan is a well-known elicitor that strongly affects both secondary metabolites and biomass production by plants. The effect of chitosan on S. marianum cell suspension is not known yet. In the present study, suspension cultures of S. marianum were exploited for their in vitro potential to produce bioactive flavonolignans in the presence of chitosan. Established cell suspension cultures were maintained on the same hormonal media supplemented with 0.5 mg/L BAP (6-benzylaminopurine) and 1.0 mg/L NAA (α-naphthalene acetic acid) under photoperiod 16/8 h (light/dark) and exposed to various treatments of chitosan (ranging from 0.5 to 50.0 mg/L). The highest biomass production was observed for cell suspension treated with 5.0 mg/L chitosan, resulting in 123.3 ± 1.7 g/L fresh weight (FW) and 17.7 ± 0.5 g/L dry weight (DW) productions. All chitosan treatments resulted in an overall increase in the accumulation of total flavonoids (5.0 ± 0.1 mg/g DW for 5.0 mg/L chitosan), total phenolic compounds (11.0 ± 0.2 mg/g DW for 0.5 mg/L chitosan) and silymarin (9.9 ± 0.5 mg/g DW for 0.5 mg/L chitosan). In particular, higher accumulation levels of silybin B (6.3 ± 0.2 mg/g DW), silybin A (1.2 ± 0.1 mg/g DW) and silydianin (1.0 ± 0.0 mg/g DW) were recorded for 0.5 mg/L chitosan. The corresponding extracts displayed enhanced antioxidant and anti-inflammatory capacities: in particular, high ABTS antioxidant activity (741.5 ± 4.4 μM Trolox C equivalent antioxidant capacity) was recorded in extracts obtained in presence of 0.5 mg/L of chitosan, whereas highest inhibitions of cyclooxygenase 2 (COX-2, 30.5 ± 1.3 %), secretory phospholipase A2 (sPLA2, 33.9 ± 1.3 %) and 15-lipoxygenase (15-LOX-2, 31.6 ± 1.2 %) enzymes involved in inflammation process were measured in extracts obtained in the presence of 5.0 mg/L of chitosan. Taken together, these results highlight the high potential of the chitosan elicitation in the S. marianum cell suspension for enhanced production of antioxidant and anti-inflammatory silymarin-rich extracts.     

Hypoglycemic and Antioxidant Properties of Extracts and Fractions from Polygoni Avicularis Herba

Our research focused on the hypoglycemic capability and the possible mechanisms of extract and fractions from Polygoni Avicularis Herba (PAH) based on α-glucosidase, α-amylase inhibition assays, glucose uptake experiment, HPLC-MS analysis, and molecular docking experiment. In addition, DPPH, ABTS, and FRAP assays were used for determining the antioxidant capability. The results of total flavonoids and phenolics contents showed that ethyl acetate fraction (EAF) possessed the highest flavonoids and phenolics with values of 159.7 ± 2.5 mg rutin equivalents/g and 107.6 ± 2.0 mg galic acid equivalents/g, respectively. The results of in vitro hypoglycemic activity showed that all samples had effective α-glucosidase inhibition capacities, and EAF possessed the best inhibitory effect with IC₅₀ value of 1.58 ± 0.24 μg/mL. In addition, n-butanol fraction (NBF) significantly promoted the glucose uptake rate of 3T3-L1 adipocytes. HPLC-MS analysis and molecular docking results proved the interactions between candidates and α-glucosidase. The results of antioxidation capacities showed that EAF possessed the best antioxidation abilities with DPPH, ABTS, and FRAP. In summary, the hypoglycemic activity of PAH might be related to the inhibition of α-glucosidase (EAF > PEF > NBF) and the promotion of glucose uptake in 3T3-L1 adipocytes (NBF). Simultaneously, the antioxidation capacity of PAH might be related to the abundant contents of flavonoids and other phenolics (EAF > PEF > NBF).     

Flavonoids: biological activities and therapeutic potential

Abstract

Flavonoids have aroused much interest in research, since they present a great diversity of biological activities observed in vitro, such as: antioxidant effect, modulation of the enzymatic activity and inhibition of cellular proliferation, exerting beneficial effects on the organism, as well as the use of its therapeutic potential. With wide distribution in the plant kingdom represent a class of phenolic compounds that differ in their chemical structure and particular characteristics. The objective of this review was to describe the relevant aspects of flavonoids, reporting the different known groups, the probable mechanisms by which they act, their pharmacological properties and to gain a better understanding of the reported beneficial health effects of these substances. This systematic review consisted of research using scientific databases such as Scopus, Science Direct, PubMed, SciVerse and SciELO, without time limitation. Some pharmacological properties of some flavonoids and their health benefits have been confirmed by previous studies.     

Pulse radiolysis study on the mechanisms of reactions of CCl_3OO radical with quercetin, rutin and epigallocatechin gallate

The mechanisms of reactions between CCI3OO radical and quercetin, rutin and epigal-locatechin gallate (EGCG) have been studied using pulse radiolytic technique. It is suggested that the electron transfer reaction is the main reaction between CCI3OO radical and rutin, EGCG, but there are two main pathways for the reaction of CCI3OO" radical with quercetin, one is the electron transfer reaction, the other is addition reaction. The reaction rate constants were determined. It is proved that quercetin and rutin are better CCI3OO radical scavengers than EGCG.