Capillary electrophoresis for simultaneous determination of emodin,chrysophanol, and their 8-beta-D-glucosides

The simultaneous separation and determination of the major anthraquinones, emodin, chrysophanol, and their glucosides, of Rumex japonicus HOUTT., and emodin and emodin glucoside, of Cassia tora L., Rhamnus purshiana DC., Polygonum multiflorum THUNB., and P. cuspidatum SIEB. et ZUCC., were achieved by cyclodextrin modified capillary zone electrophoresis. The running electrolyte used in this method was 0.005 M alpha-cyclodextrin in 0.03 M borate buffer (pH 10.5) containing 10% acetonitrile, with an applied voltage of 20 kV.     

Studies of interaction of emodin and DNA in the presence of ethidium bromide by spectroscopic method

Emodin interacting with deoxyribonucleic acid (DNA) has been studied by different spectroscopic techniques, such as fluorescence, ultraviolet and visible (UV-vis), and fourier transform infared (FT-IR) spectroscopies, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of emodin shows that the fluorescence quenching of DNA-EB complex by emodin occurs. The binding constants of emodin with DNA in the presence of EB are 6.02x10(4), 9.20x10(4) and 1.17x10(5)Lmol(-1) at 20, 35 and 50 degrees C, respectively. FT-IR spectrum further suggests that both the phosphate groups and the bases of DNA react with emodin. The reaction of DNA with emodin in the presence of EB is affected by ionic strength and temperature. The values of melting temperature (T(m)) of DNA-EB complex and emodin-DNA-EB complexes were determined, respectively. From the experiment evidences, the major binding mode of emodin with DNA should be the groove binding.     

Analysis of the pharmacokinetics and metabolism of aloe‐emodin following intravenous and oral administrations in rats

Aloe‐emodin, a natural polyphenolic anthraquinone, has shown various beneficial bioactivities in vitro. The aim of this study was to investigate the pharmacokinetics and metabolism of aloe‐emodin. Aloe‐emodin was intravenously and orally administered to rats. The concentrations of aloe‐emodin and rhein, a metabolite of aloe‐emodin, were determined by HPLC method prior to and after hydrolysis with β‐glucuronidase and sulfatase/β‐glucuronidase. The results showed that the systemic exposures of aloe‐emodin and its metabolites were ranked as aloe‐emodin glucuronides (G) > rhein sulfates (S) > aloe‐emodin > rhein and rhein G when aloe‐emodin was given intravenously. In contrast, when aloe‐emodin was administered orally, the parent form of aloe‐emodin was not absorbed per se, and the systemic exposures of its metabolites were ranked as aloe‐emodin G > rhein G > rhein. In conclusion, the metabolites of aloe‐emodin are more important than the parent form for the bioactivities in vivo. Copyright © 2016 John Wiley & Sons, Ltd.     

Simultaneous determination by UPLC-ESI-MS of scoparone, capillarisin, rhein, and emodin in rat urine after oral administration of Yin Chen Hao Tang preparation

A simple, sensitive, and validated method was developed for simultaneous determination of scoparone, capillarisin, rhein, and emodin in rat urine by ultra-performance liquid chromatography/electrospray ionization quadruple time-of-flight mass spectrometry (UPLC-MS). The urinary samples were analyzed on an Acquity UPLC BEH C18 1.7 microm 2.1x50 mm column. Scoparone, capillarisin, rhein, and emodin in rat urine were simultaneously analyzed with good separation. The lower limits of detection were 6.0, 9.0, 7.0, and 3.0 ng/mL, and the lower limits of quantification were 20.0, 33.0, 24.0, and 12.0 ng/mL for scoparone, capillarisin, rhein, and emodin, respectively. The intra- and inter-day precisions (RSD) were less than 9%. The intra- and inter-accuracies were found to be in the range of 94.14-104.54% for scoparone, 101.72-107.34% for capillarisin, 95.24-103.59% for rhein, and 101.32-107.82% for emodin at three concentration levels. The absolute recoveries for scoparone, capillarisin, rhein, and emodin were not less than 77.0%. The developed method has been applied to determine scoparone, capillarisin, rhein, and emodin in rat urine after oral administration of Yin Chen Hao Tang preparation, a traditional Chinese medicine formulation widely used in China for treatment of jaundice and liver disorders.     

Photochemistry and phototoxicity of aloe emodin

Photochemical pathways leading to the phototoxicity of the aloe vera constituent aloe emodin were studied. The results indicate a photochemical mechanism involving singlet oxygen to be the most likely pathway responsible for the observed phototoxicity. Aloe emodin was found to efficiently generate singlet oxygen when irradiated with UV light (phidelta = 0.56 in acetonitrile). The survival of human skin fibroblast cells in the presence of aloe emodin was found to decrease upon irradiation with UV light. A further decrease in cell survival was observed in D2O compared with H2O, suggesting the involvement of singlet oxygen as the primary pathway. Laser flash photolysis experiments were also carried out on aloe emodin alone and in the presence of various biological substrates. Aloe emodin proved to be relatively photostable (phi = 1 x 10(-4)) and a poor photo-oxidant (E*red = +1.02 V). Only absorption bands caused by the triplet state of aloe emodin (lambdamax = 480 nm) and the aloe emodin conjugate base (lambdamax = 520 nm) were observed in the transient spectra.     

Application of an efficient strategy based on liquid–liquid extraction,high‐speed counter‐current chromatography,and preparative HPLC for the rapid enrichment,separation, and purification of four anthraquinones from Rheum tanguticum

This study presents an efficient strategy based on liquid–liquid extraction, high‐speed counter‐current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum. A new solvent system composed of petroleum ether/ethyl acetate/water (4:2:1, v/v/v) was developed for the liquid–liquid extraction of the crude extract from R. tanguticum. As a result, emodin, aloe‐emodin, physcion, and chrysophanol were greatly enriched in the organic layer. In addition, an efficient method was successfully established to separate and purify the above anthraquinones by high‐speed counter‐current chromatography and preparative HPLC. This study supplies a new alternative method for the rapid enrichment, separation, and purification of emodin, aloe‐emodin, physcione, and chrysophanol.     

Phosphorylation of emodin

A convenient method has been developed for the interaction of dialkyl phosphites with 1,6,8-trihydroxy-3-methylanthraquinone (emodin) under the conditions of the Todd—Atherton reaction. It has been shown that the α-hydroxy groups of emodin are not phosphorylated at an equimolar ratio of emodin and dialkyl phosphite. The phosphorylation of 7-bromo-1,6,8-trihydroxy-3-methylanthraquinone with potassium dialkyl phosphorothioates has been studied. The reaction takes place at the sulfur atom, with the formation of of the product of S-alkylation.     

Synthesis and antibacterial activity of emodin and its derivatives against methicillin-resistant Staphylococcus aureus

Synthesis of the antibacterial emodin was improved using Friedel-Crafts acylation as a key step leading to 37% overall yield. In addition, 21 analogues were synthesized by structural modification of the hydroxyl and methyl groups, as well as the aromatic ring of emodin. Antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and cytotoxicity against noncancerous Vero cells were evaluated. A structure-activity relationship (SAR) study indicated that the hydroxyl groups and the methyl group in the emodin skeleton were crucial for anti-MRSA activity. Furthermore, the presence of an iodine atom or ethylamino group on the aromatic ring enhanced the anti-MRSA activity with higher selectivity indices, while derivatives containing bromine, chlorine atoms or quaternary ammonium salt were as active as emodin. The quaternary ammonium group on the aromatic ring also led to non-cytotoxicity against Vero cells.     

Optimized protocol for multigram preparation of emodin anthrone,a precursor in the hypericin synthesis

Emodin reduction to emodin anthrone comprise one of three process steps involved in the hypericin synthesis, a powerful natural photosensitiser found in plants of the genus Hypericum. In this communication, an optimized protocol was established for emodin reduction enabling an efficient multigram preparation of emodin anthrone. A screening of reducing agent (SnCl₂·2H₂O and HCl_conc) under different reaction times was employed in micro-scale and monitored by electronic absorption spectroscopy technique. Data showed lower yields of emodin anthrone when some experimental conditions previously described in the literature were reproduce. However, using the optimized protocol for the emodin reduction these yields were overcoming, and a gram-scale supply experiment was reproducible for the preparation of 10 grams of emodin anthrone with excellent yield.     

Semi-Preparative Scale Separation of Emodin from Plant Extract by Using Molecularly Imprinted Polymer as Stationary Phase

In this work, a core–shell molecularly imprinted polymer (MIP) was synthesized through sol–gel coating procedure by using silica beads, emodin, 3-aminopropyltriethoxysilane, tetraethoxysilane and tetrahydrofuran as supporting matrix, template, functional monomer, cross-linker and solvent, respectively. The selective recognition property for emodin and its analogues (physcion and aloe emodin) of the resultant MIP was evaluated in a chromatographic column for high-performance liquid chromatography (HPLC). The retention time and imprinted factor of MIP column for emodin, physcion and aloe emodin were 5.11, 0.63, 0.69 min and 4.69, 0.75, 1.38, respectively. It showed that the MIP beads had a good binding ability for emodin. Finally, one-step separation of emodin from alcohol extract of Rheum palmatum L. at semi-preparative scale was achieved and 380 mg of emodin was collected in 5 days. The product was characterized by mass spectrometry and HPLC and its purity was 95 %.     

大黄素与DNA相互作用方式的研究

通过分子荧光分析、紫外可见吸收光谱及粘度分析以及与溴化乙锭的竞争性实验对大黄素与DNA之问的作用模式进行了考察.在pH 7.4,低离子强度(30 mmol/L NaCl)及恒温37℃条件下反应35 min,大黄素的荧光强度随DNA加入浓度的增加而递减,紫外可见吸收光谱在380、475 nm处出现等吸收点并红移5nm,表...     

Qualitative and quantitative analyses of aloe-emodin,rhein, and emodin in qi yin granules by high-performance thin-layer chromatography

The aim of this study was to perform qualitative and quantitative analyses of aloe-emodin, rhein, and emodin in three prepared samples of compound qi yin granules by high-performance thin-layer chromatography (HPTLC) and to establish an analytical method. TLC was used to qualitatively analyze the three major components of the compound: aloe-emodin, rhein, and emodin. HPTLC was performed to determine the contents of the three components. HPTLC analysis showed that using Anhui Liangchen high-efficiency silica gel G plate was the optimal stationary phase and the upper layer solution of a petroleum ether–ethyl acetate–formic acid (15.5:5:1, V/V) mixed solution was the optimal developing agent. The composition of the samples for testing was basically the same, but the content was different. In summary, this study used HPTLC to qualitatively and quantitatively analyze aloe-emodin, rhein, and emodin in compound qi yin granules. It can lay the foundation for improving the quality control and standards of compound qi yin granules.

     

相溶解度法研究芦荟大黄素和环糊精及其衍生物的包结作用

本文用相溶解度法研究了芦荟大黄素与β－环糊精（ＣＤ）衍生物的包结作用,测定了包结物的包结常数,表明β－ＣＤ衍生物对芦蔡大黄素有较好的增溶作用,有应用价值。     

Emodin ameliorates high-glucose induced mesangial p38 over-activation and hypocontractility via activation of PPAR��

Early stage diabetic nephropathy is characterized by elevated glomerular filtration. Recent studies have identified high-glucose induced p38 MAPK (p38) over-activation in mesangial cells. Mesangial hypocontractility is the major underlying mechanism, however, no ameliorating agents are currently available. We investigated the protective effects of emodin on high-glucose induced mesangial cell hypocontractility. Mesangial cells were cultured under normal (5.6 mM) and high glucose (30 mM) conditions. Emodin was administrated at doses of 50 mg/l and 100 mg/l. Angiotension II stimulated cell surface reductions were measured to evaluate cell contractility. p38 activity was detected using Western blotting. To further explore the possible mechanism of emodin, expression of the peroxisome proliferator-activated receptor γ (PPARγ) was measured and its specific inhibitor, gw9662, was administrated. Our results showed: (1) high-glucose resulted in a 280% increase in p38 activity associated with significant impairment of mesangial contractility; (2) emodin treatment dose-dependently inhibited high-glucose induced p38 over-activation (a 40% decrease for 50 mg/l emodin and a 73% decrease for 100 mg/l emodin), and mesangial hypocontractility was ameriolated by emodin; (3) both the PPARγ mRNA and protein levels were elevated after emodin treatment; (4) inhibition of PPARγ using gw9662 effectively blocked the ameliorating effects of emodin on high-glucose induced p38 over-activation and mesangial hypocontractility. Emodin effectively ameliorated p38 over-activation and hypocontractility in high-glucose induced mesangial cells, possibly via activation of PPARγ.     

Simultaneous determination and pharmacokinetic studies of aloe emodin and chrysophanol in rats after oral administration of Da-Cheng-Qi decoction by high-performance liquid chromatography

A validated high-performance liquid chromatography (HPLC) method was developed for simultaneous determination and pharmacokinetic study of aloe emodin and chrysophanol in rats. It was performed on a reverse-phase C(18) column and a mobile phase made up of methanol and 0.2% acetic acid (83:17, v/v). The ultraviolet detection was 254 nm. 1,8-dihydroxyanthraquinone was used as the internal standard. The assay was linear over the range 28-2800 ng/mL (r(2) = 0.9993) for aloe emodin and 25.6-2560 ng/mL (r(2) = 0.9991) for chrysophanol. The average percentage recoveries of three spiked plasmas were 98.8-104.8% and 97.7-103.2% for aloe emodin and chrysophanol, respectively. Their RSD of intra-day and inter-day precision at concentrations of 56, 280 and 1400 ng/mL for aloe emodin and 51.6, 258 and 1290 ng/mL for chrysophanol were less than 3.5%. This method was applied for the first time to simultaneously determinate aloe emodin and chrysophanol in rats following oral administration of traditional Chinese medicine of Da-Cheng-Qi decoction. The pharmacokinetic parameters showed that chrysophanol was better absorbed with higher concentrations in plasma than aloe emodin did. They both eliminated slowly in male rats. The assay is suitable for identifying the plasma and tissue levels of aloe emodin and chrysophanol in preclinical investigations.     

Comparison of dispersive liquid-liquid microextraction based on organic solvent and ionic liquid combined with high-performance liquid chromatography for the analysis of emodin and its metabolites in urine samples

In this paper, two methods based on organic solvent dispersive liquid-liquid microextraction (OS-DLLME) and ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) coupled with high-performance liquid chromatography have been critically compared for analyzing emodin and its metabolites (aloe-emodin, anthraquinone-2-carboxylic acid, rhein, danthron, chrysophanol and physcion) in urine samples. Several important parameters influencing the extraction recoveries of DLLME were carefully optimized. Under optimal conditions, the enrichment factors (EFs) for emodin and its metabolites by OS-DLLME and IL-DLLME were within the range of 90-295 and 63-192 respectively; the relative standard deviations (RSDs, n=3) for intra-day and inter-day precision were lower than 7.2 and 8.7% by OS-DLLME, and lower than 5.7 and 6.4% by IL-DLLME; the recoveries of emodin and its metabolites were from 87.1 to 105% for OS-DLLME and from 94.8 to 103% for IL-DLLME, respectively. There were no significant deviations between the two methods for the determination of emodin and its metabolites. From the results of HPLC/UV of urine sample after DLLME, the metabolites aloe-emodin, rhein, chrysophanol and physcion were identified by comparing the retention times with the standards. From the results of HPLC/MS, anthraquinone-2-carboxylic acid and danthron as unreported metabolites of emodin were found.     

Induction of primary cutaneous melanomas in C3H mice by combined treatment with ultraviolet radiation, ethanol and aloe emodin

The role of ultraviolet (UV) radiation in the induction of nonmelanoma skin cancer is widely accepted, although its precise contribution to the development of primary cutaneous melanoma skin cancer requires further definition. We found that painting aloe emodin, a trihydroxyanthraquinone from Aloe barbadensis, in ethyl alcohol vehicle on the skin of mice in conjunction with exposure to UVB (280-320 nm) radiation results in the development of melanin-containing skin tumors. C3H/HeN mice were treated thrice weekly with aloe emodin in a 25% ethanol in water vehicle and exposed to 15 kJ/m2 UV radiation. Neither ethanol vehicle nor aloe emodin alone induced skin tumors in the absence of UV radiation. In two separate experiments, 20-30% of the mice treated with a combination of UV radiation and ethanol vehicle and 50-67% of the UV-irradiated animals given aloe emodin in ethanol vehicle developed primary cutaneous melanin-containing tumors. The diagnosis of melanoma was established using Fontana silver stain for melanin; these tumors were negative for vimentin and keratin. Melanin-containing melanosomes were observed by transmission electron microscopy in tumors diagnosed as melanomas. Although the mechanism of carcinogenesis in these mice is currently unknown, our findings have led to the development of the first facile murine model for the induction of primary melanoma. This model has the potential to clarify the role of UV radiation in the etiology of malignant melanoma.     

多壁碳纳米管表面大黄素印迹材料制备及吸附性能研究

以表面硅烷修饰的碳纳米管为基材,甲基丙烯酸为功能单体,二甲基丙烯酸乙二醇酯为交联剂,采用表面印迹技术成功制备了大黄素印迹复合材料。采用扫描电镜和透射电镜研究该印迹复合材料的形貌,结果表明,在碳纳米管表面接枝了1层稳定的约40nm厚的印迹层。在pH=8.5时,该印迹材料对大黄素具有较大吸附容量和良好选择吸附性能,最大理论吸附量(Qmax)为20.8mg/g。以该印迹材料作为固相萃取吸附剂,在85%乙醇水溶液淋洗和10%乙酸的乙醇溶液洗脱下,可实现对猕猴桃根样品粗提取液中大黄素固相萃取分离富集,回收率达到85%以上。     

芦荟大黄素在水和非水溶剂中的电化学性质

在HAc-NaAc水溶液或二甲亚砜(DMSO)非水溶剂中,芦荟大黄素于铂电极上均显示一个准可逆的双电子转移过程,与HAc-NaAc溶液相比,芦荟大黄素在DMSO溶剂中的峰电位明显负移,且波形改变很大;HAc-NaAc溶液中,峰电流Ipa与芦荟大黄素的浓度在1.0×10-5~6.0×10-4mol/L范围内成线性关系,检测限为1.0×10-6mol/L.溶剂对芦荟大黄素的电化学性能有甚大的影响.     

虎杖中主要蒽醌的提取分离及HPLC分析测定

高压液相色谱法;虎杖中主要蒽醌的提取分离及HPLC分析测定