Lyophilized Powder of Catalpol and Puerarin

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Lyophilized Powder of Catalpol and Puerarin Protects Neurovascular Unit from Stroke

Lyophilized Powder of Catalpol and Puerarin Protects Neurovascular Unit from Stroke

Hunting for an effective medicine for brain stroke has been a medical task in neuroscience for decades. The present research showed that the lyophilized Powder of Catalpol and Puerarin (C-P) in all the tested doses (65.4 mg/kg, 32.7 mg/kg, 16.4 mg/kg) significantly reduced the neurological deficiency, infarct volume and apoptotic cells in ischemic/reperfusion (I/R) rats. It also promoted astrocyte processes and prolonged neuron axons in infarct area. Further, it decreased MDA, NO, NF-κB/p65, TNF-α, IL-1β and IL-6 and enhanced the EPOR and GAF-43. 65.4 mg/kg and 32.7 mg/kg C-P could up-regulated EPO and VEGF significantly. In vitro, 49 μg/mL and 24.5 μg/mL C-P decreased the leakage of sodium fluorescein and increased the activity of γ-GTP. Additionally, it increased SOD and decreased MDA, NO, and LDH and decreased NF-κB/p65, TNF-α, IL-1β and IL-6 and unregulated EPO, EPOR, VEGF, and GAP-43. Only the dose of 49 μg/mL increased TEER and Claudin-5 and turned the typically damaged morphologies of neurons, astrocytes and endo- thelium into a favorable trend. These data imply that C-P improved the recovery of neurological deficiency in motor, sense, balance and reflex, and protected the whole NVU by anti-oxidative stress, anti-inflammation and up-regulating some protective factors. This research provides a candidate medicine for brain stroke and, at the same time, a pattern for drug study targeting NVU in vitro.
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Lyophilized Powder of Catalpol and Puerarin Protected Cerebral Vessels from Ischemia by Its Anti-apoptosis on Endothelial Cells

Lyophilized Powder of Catalpol and Puerarin Protected Cerebral Vessels from Ischemia by Its Anti-apoptosis on Endothelial Cells

Catalpol and puerarin are two monomers of Rehmannia glutinosa and Lobed Kudzuvine Root, which are two herbs commonly used together in ancient prescriptions of traditional Chinese medicine for cerebral ischemia. Our previous study shows that the lyophilized powder of the two monomers improved the outcome of cerebral ischemia excellently in rodents. However, if it protects vessels from ischemia is unknown. The present research studied the protection of lyophilized powder of catalpol and puerarin (CP) on endothelial cells and the relative mechanism in vivo and in vitro. Middle cerebral artery occlusion (MCAO) rats were used to study the improvement of CP on neurological deficiency, regional cerebral blood flow (rCBF), and infarct volume. The morphology of vessels and the apoptosis of brain vascular endothelial cells (BVECs) were observed and detected by immunohistochemistry approaches. To study how CP protected primary BVECs (pBVECs) from ischemic penumbra, oxygen glucose deprivation (OGD)-damaged pBVECs were cultured in the condition of insufficient nutrition and low oxygen which recapitulate the low perfusion of ischemic penumbra. Using the cell model, the mechanism by which CP protected pBVECs was studied by shRNA and pathway inhibitors. CP at the dose of 65.4 mg/kg increased regional cerebral blood flow (rCBF), reduced infarct volume, protected vessel integrity and inhibited endothelial cell apoptosis in vivo. But it only improved rCBF, vessel integrity and BVECs apoptosis at the dose of 32.7 mg/kg. In vitro, the protection of CP on pBVECs was proved to be ERK/HIF-1a- and PI3K/AKT/mTOR/HIF-1a-dependent. This study indicates a possibility of CP being a new drug for cerebral ischemia. Besides, this research provides an alternative cell model for penumbra ECs study.
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Amelioration of Stroke-Induced Neurological Deficiency by Lyophilized Powder of Catapol and Puerarin

Amelioration of Stroke-Induced Neurological Deficiency by Lyophilized Powder of Catapol and Puerarin

Catalpol and puerarin are active ingredients isolated from Rehmannia glutinosa Libosch and Radix Puerariae, respectively. They are popular in research for their poly-pharmacological effects. This research focused on effect of anti-stroke by lyophilized powder of catalpol and puerarin (C-P) and potential mechanisms. At the beginning of research, C-P was identified and analyzed by HPLC. Neurological function was evaluated by Longa score, neurological complex function score and beam balance score after permanent middle cerebral artery occlusion (PMCAO) in mice. Infarct volume and water content were evaluated after treatment of C-P. Anti-oxidative stress, an- ti-apoptosis, angiogenesis and neurogenesis were investigated by ELISA, WB and immunohisto- chemical stain respectively. With treatment of C-P, neurological deficiency of PMCAO mice was ameliorated. Morphologically, infarct volume and water content in ischemic hemisphere were significantly reduced by C-P. In vivo and in vitro, oxidative stress injury was extenuated by C-P. Meanwhile, Caspase-3 was down-regulated and Bxl-2 was up-regulated by C-P in vivo. In addition, C-P enhanced angiogenesis around the infarct of cortex and neurogenesis in the Hippocampal Dentate Gyrus (DG). Hence, C-P ameliorated stroke-induced neurological deficiency through its multiple neuroprotections. What’s more, this article provides us a novel formula of active ingre- dients for stroke.
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Puerarin promotes osteogenesis and inhibits adipogenesis in vitro

Puerarin promotes osteogenesis and inhibits adipogenesis in vitro

MC3T3-E1 osteoblastic cells were cultured in puerarin at various concentrations (0, 0.1, 1, 10 and 20 μM) for 48 h. As shown in Figure 2A, those treated with puerarin promoted MC3T3-E1 osteoblastic cells prolif- eration at concentrations of 1 (P = 0.012), 10 (P = 0.015) and 20 μM (P = 0.050). As shown in Figure 2B, puerarin demonstrated a dose-dependent effect by visually deter- mined on promoting ALP activity. It significantly in- creased the ALP activity by 59.3% at the concentrations of 20 μM, compared to the control group (P = 0.008). Calcium nodule formation was examined by Alizarin Red S staining. Figure 2C and 2D show that puerarin in- creased mineralized nodule formation in a dose- dependent manner by visually determined, where the maximal and significant effects were observed at a con- centration of 20 μM (P = 0.011). Compared with the control group without osteogenic induction (ctl-), the in- duction group (ctl+) significantly increased OC levels ex- pression. Puerarin further increased the OC levels expression to 36.4% at 10 μM dosage (P = 0.003), and 42.2% at 20 μM dosage (P = 0.004), compared with ctl+ group (Figure 2E). These results suggested that puerarin could promote proliferation, ALP activity, mineralization and OC protein secretion in MC3T3-E1 cells.
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Lyophilized Ethinylestradiol Nanosuspension: Fabrication, Characterization and Evaluation of in vitro Anticancer and Pharmacokinetic Study

Lyophilized Ethinylestradiol Nanosuspension: Fabrication, Characterization and Evaluation of in vitro Anticancer and Pharmacokinetic Study

Hence EE particles might have dispersed in a uniform matrix and the drug released by diffusion process based on Fick’s law. The EENS showed a dramatic increase in dissolution rate as compared to EE coarse powder. Moreover, EENS displayed more than 60 % increase in dissolution rate compared to EE coarse powder (15 %) within 60 min indicating a distinctly superior dissolution profile of EENS relative to EE. This enhancement in dissolution of EE could be attributed to the reduction in particle size, especially in nanometre range with an effective increase in surface area that increased dissolution. This phenomenon is better explained by Noyes-Whitney Eqn. 3, dC/dt = DS–(C s –C t )/h, where h denotes thickness of the dissolution boundary layer, D is the diffusion coefficient of the solute, C s is saturation
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Hypolipidemic Effect of Puerarin and Underlying Mechanism Investigation

Hypolipidemic Effect of Puerarin and Underlying Mechanism Investigation

is the dry root of the leguminous plant Pueraria lobata (Willd.) Ohwi, is one of the common vegetables in some provinces of southern China. Pueraria lobata (Willd.) Ohwi tastes sweet, cool and delicious, and is usually utilized to prepare soups. Starch comprises major of Radix Puerariae, 12% of which is composed of flavonoids including more than ten active ingredients such as daidzein, daidzin, puerarin, puerarin-7-xyloside, etc. Besides, puerarin also contains dausterols, amino acids, coumarins, etc [4, 5]. Drug use of puerarin can improve the regeneration capability of liver cells, recover the normal liver functions, stimulate the secretion of bile, prevent the accumulation of fat in the liver, facilitate the metabolism, alleviate myocardial ischemia and cerebral arteriosclerosis, and enhance the immune functions of hepatobiliary cells [6, 7].
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<p>Advanced Mg, Zn, Sr, Si Multi-Substituted Hydroxyapatites for Bone Regeneration</p>

<p>Advanced Mg, Zn, Sr, Si Multi-Substituted Hydroxyapatites for Bone Regeneration</p>

Atomic force microscopy, AFM images were obtained for all synthesized nanomaterials. Different areas from 10 μ m x 10 μ m to 0.5 μ m x 0.5 μ m were scanned on a particular nanomaterial, adsorbed from its aqueous dis- persion on optically polished glass plates. 74–76 As an exam- ple, the AFM images, ie, 2D-topography (A) and phase image (B), as well as cross-section pro fi les (C) for noncal- cined, lyophilized powders of hydroxyapatites: HAP, HAPc, HAPc-5% Sr and HAPc-10% Sr are presented in Figure 5. AFM images on needles, rods or spindle-shaped particles of HAP and ms-HAPs gave spherical or oval shapes of nanoparticles, as exempli fi ed in Figure 5. The average size of particles is 41 ± 3 nm for HAP, 38 ± 2 nm for HAPc, 36 ± 2 nm for HAPc-5%Sr, and 35 ± 3 nm for HAPc-10%Sr, as determined from cross-section pro fi les of each noncalcined sample. These values are comparable with those given by XRD (Table 2). A similar trend is also found for the average size of particles in calcined, lyophilized HAP and ms-HAPs.
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Comparison of preference and safety of powder and liquid lactulose in adult patients with chronic constipation

Comparison of preference and safety of powder and liquid lactulose in adult patients with chronic constipation

Cumberland Pharmaceuticals Inc., Nashville, TN, USA) was provided in 10 g pouches and liquid lactulose syrup ( Generlac, Morton Grove Pharmaceuticals Inc., Morton Grove, IL, USA) was provided in a 473 mL (pint) bottle. Patient preference was assessed on a questionnaire administered by study staff in the days following completion of the study. Both treatment groups received both drugs in a crossover design (drug sequence determined by randomization), and then preference was evalu- ated after patients had been exposed to both treatments in this prospective study. The study sponsor developed the patient questionnaire and two versions were developed and utilized equally to avoid bias. One version of the questionnaire listed powder first as an answer selection for all of the questions, while the other listed liquid first as an answer selection for all of the questions. Each question on the questionnaire had three possible answers, ie, liquid, powder, or no preference. Spanish translations of the questionnaire and other study documents were made available at the request of the Brooklyn, NY site. Upon completion of the study, patients were allowed a seven- day window (total study duration including questionnaire visit = 21 days) to return to the study site and complete the questionnaire, and adverse events were monitored throughout the entire study period (Figure 1).
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Complex of Tris(Phenanthroline)Cobalt(II)Trifluoroacetate: Characterisation and Powder XRD Analysis

Complex of Tris(Phenanthroline)Cobalt(II)Trifluoroacetate: Characterisation and Powder XRD Analysis

The powder complex of [Co(phen) 3 ] (CF 3 COO) 2 •5H 2 O has been successfully prepared. The equivalent conductance confirms the ionic nature of this complex and the magnetic moment supports strongly the electronic configuration of high-spin Co(II) with three unpaired electrons, indicating an octahedral weak ligand field of tris-phenantroline ligand surrounding Co(II). The electronic spectral property of this complex reveals the d-d transitions with metal-ligand charge transfer (MLCT) and intraligand transition band. The infrared spectral property indicates clearly the main mode of vibrations of the ligand phen and TFA within the complex which support strongly formula of the complex. The corresponding powder X-ray diffraction which was analysed using Le Bail method of Rietica
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PHARMACEUTICAL STUDY ON EXTENDED RELEASE LYOPHILIZED MILK TREATED IBUPROFEN BEADS

PHARMACEUTICAL STUDY ON EXTENDED RELEASE LYOPHILIZED MILK TREATED IBUPROFEN BEADS

www.wjpr.net Vol 4, Issue 1, 2015. 659 formulations. Various approaches available to improve drug solubility as well as drug dissolution of poorly aqueous soluble drugs include micronization [5] , formation of inclusion complexes with cyclodextrins, [6] formation of amorphous drugs [7] , and formation solid dispersions of drugs using various hydrophilic carriers [8-10] , fast dissolving applying freeze- drying [11] . In recent years newer oral drug delivery systems like sustained, controlled dosage forms are formulated and evaluated in order to solve the problems of conventional therapy. These are able to maintain steady drug plasma levels for extended periods of time and minimize drug related side effects [12] . The aim of this work was to prepare beads containing lyophilized milk treated Ibuprofen as a model of a poorly soluble drug formulated in extended release Chitosan beads by applying lyophilized milk to enhance its solubility within Chitosan matrix. Hence, reducing the frequency of administration of the drug and elimination of its irritant effect on gastrointestinal tract in solid drug delivery dosage forms.
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Original Article Puerarin protects against myocardial ischemia/reperfusion injury via the AMPK/Akt/GSK-3β/Nrf2 signaling pathway

Original Article Puerarin protects against myocardial ischemia/reperfusion injury via the AMPK/Akt/GSK-3β/Nrf2 signaling pathway

HO-1 and other antioxidants [18]. Therefore, it is of particular interest to determine whether Puerarin can activate Nrf2 in association with HO-1 up-regulation. In this study, Puerarin sig- nificantly upregulated Nrf2 activation, and such was correlated with a significant upregulation of HO-1 expression in heart issues. this result demonstrated that Puerarin mediated its car- dioprotective effects against oxidative insults through activation of the Nrf2 pathway. Glycogen synthase kinase 3 beta (GSK-3β ), a multifunctional serine/threonine kinase, con- trols switching off of Nrf2 activation of gene expression. Our data displayed that GSK-3β phosphorylation was induced by Puerarin treat- ment. The modulation of AMPK activity in the heart may improve cardiac function and over- come the increased susceptibility of the heart to I/R injury. In this study, the cytoprotective effect of Puerarin against I/R injury depended on AMPK activation. The serine survival kinase Akt is activated downstream of phosphati- dylinositol 3-kinase (PI3K). The PI3K/Akt path- way plays a critical role in promoting cell sur- vival in the heart, and there is increasingly evidence to indicate cross talk between the Nrf2 and PI3K/Akt pathways in response to oxi- dative insults [19, 20]. In the present study, I/R decreased Akt phosphorylation and Puerarin pretreatment augmented Akt phosphorylation significantly. Puerarin not only induced phos- phorylation of AMPK but also caused the phos- phorylation of Akt and GSK-3β in an AMPK- dependent manner. These results indicated that the AMPK/Akt/GSK-3β pathway is respon- sible for Puerarin’s pharmacological action. In summary, this study demonstrated that Puerarin possesses cardioprotective proper- ties against oxidative injury and myocardium I/R. The underlying mechanisms of Puerarin mediated cardioprotection may be attributable to activation and cross-talk between the AMPK/ Akt and GSK-3β/Nrf2 signaling pathways.
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Characterization of the Immunochemical Forms of Calcitonin Released by a Medullary Thyroid Carcinoma in Tissue Culture

Characterization of the Immunochemical Forms of Calcitonin Released by a Medullary Thyroid Carcinoma in Tissue Culture

Lyophilized pools of immunoreactive calcitonin obtained by gel filtration of medullary carcinoma tissue culture medium or lyophilized synthetic human calcitonin monomer were each dissolv[r]

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Hypolipidemic and Antiobesity Impact of Cuminum Cyminum Powder in Overweight and Obese Females

Hypolipidemic and Antiobesity Impact of Cuminum Cyminum Powder in Overweight and Obese Females

 Whole cumin seeds were grinded into powder and pack in plastic pouches to prevent lose volatile compounds. Whole cumin seeds were grinded into powdered. Cumin powder was subjected for proximate analysis. And analysis showed that C.Cyminum powder contain 7.56±0.55% of moisture content. The protein content, crude fat, crude fiber, ash and nitrogen free extract(NFE) 19.22±0.1%, 23.3±0.6%, 11.43±0.4%, 7.08±0.08%, 30.55±0.29% respectively. On the basis of significant results, it can be concluded that ant- obesity and hypolipidemic effect of C.cyminum on females. It has potential to raise HDL levels and decrease the LDL, cholesterol and triglycerides levels in the body. It contains high fiber and antioxidant that help in weight loss and raise HDL level. Overall results revealed that Cuminum cyminum has a huge medicinal potential to be use in treatment of obese patients and to reduce the different body fats contents and weight as well. It can be a better substitute of other traditionally used chemicals for the treatments of these body problems
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Catalpol Increases Brain Angiogenesis and Up-Regulates VEGF and EPO in the Rat after Permanent Middle Cerebral Artery Occlusion

Catalpol Increases Brain Angiogenesis and Up-Regulates VEGF and EPO in the Rat after Permanent Middle Cerebral Artery Occlusion

To investigate the role and mechanism of catalpol in brain angiogenesis in a rat model of stroke, the effect of catalpol (5 mg/kg; i.p) or vehicle administered 24 hours after permanent middle cerebral artery occlusion (pMCAO) on behavior, angiogenesis, ultra-structural inte- grity of brain capillary endothelial cells, and expression of EPO and VEGF were assessed. Repeated treatments with Catalpol reduced neurological deficits and significantly improved angiogenesis, while significantly increasing brain levels of EPO and VEGF without worsening BBB edema. These results suggested that catalpol might contribute to infarcted-brain angi- ogenesis and ameliorate the edema of brain capillary endothelial cells (BCECs) by upregulating VEGF and EPO coordinately.
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Protective Effect of Catalpol on Myocardium in Rats with Isoprenaline Induced Myocardial Infarcts via Angiogenesis through Endothelial Progenitor Cells and Notch1 Signaling Pathway

Protective Effect of Catalpol on Myocardium in Rats with Isoprenaline Induced Myocardial Infarcts via Angiogenesis through Endothelial Progenitor Cells and Notch1 Signaling Pathway

In this study, we injected INN subcutaneously to prepare the infract rat model. This is a widely used method. Myocardium infarction is a common and severe disease clinically. One of the most important methods to examine the myocardial injury is thorough the detection of bio- markers in blood [11,12]. In normal condition, LDH, an important enzyme involved in energy metabolism, exists widely in cardiac tissues. When the tissues are injured, the enzyme is released into blood, resulting in high se- rum LDH level. SOD plays important role in balancing the oxidation and antioxidation activities, and is a major oxygen free radical scavenger. The final product of lipid oxidation is MDA, which is an indirect indictor of cell injury, and therefore can be used to measure the damage in the cardiac tissues. Results from our study indicated that in the infracted rats, serum activities of LDH and CK increased significantly, while those of SOD reduced sig- nificantly. After feeding with medium or high dose of the prescription, the activities and levels of LDH, CK, SOD and MDA were all returned to normal, indicating that catalpol was able to scavenge oxygen free radicals, re- duce the production of oxidized products from lipids and the damage in cardiac tissues. TTC staining can visualize the infract areas. Using TTC staining, we found that catalpol effectively reduced the infract areas and improve the pathological status of the infracted tissues. We also
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Original Article Catalpol enhances neurogenesis in the SVZ in a rat model of strokes

Original Article Catalpol enhances neurogenesis in the SVZ in a rat model of strokes

Addressing this problem, the current study fo- cused on potential neurogenic effects of catal- pol. The current study examined its mecha- nisms and evaluated anti-apoptotic effects on new-formed neurons. This study also assessed neuronal functional recovery after treatment with catalpol in a rat model of permanent mid- dle cerebral artery occlusion (pMCAO) [6, 7]. Results suggest that catalpol may enhance neurogenesis and promote neuronal stem cell differentiation into neurons by suppressing do- wnregulation of Bcl-2 and upregulation of Bax, enhancing BDNF following strokes [9].
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Design, synthesis, and preliminary biological evaluation of catalpol propionates as antiaging drugs

Design, synthesis, and preliminary biological evaluation of catalpol propionates as antiaging drugs

In this paper, catalpol propionylated analogs (CPs) were designed as drug ligands of glutathione peroxidase (GSH-Px) based on molecular docking (MD) using Surflex-Docking method. The calculated total scores (Total_score) and C log P of CPs are higher than that of catalpol, which show that the CPs maybe served as potential lead compounds as new antiaging drugs. Furthermore, the maximum Total_score of isomers in one group CPs is often not that the molecule with minimum energy structure. These show that the CPs docking with GSH-Px maybe not only affected by the molecular energy, but also affected by their conformations. The CPs were synthesized by esterification of catalpol with propionic anhydride using pyridine as solvent and acid banding agent, DMAP as catalyst, reaction at specific tempera- ture. The synthesized perpropionylated catalpol analog (CP-6) was determined by NMR, FT-IR, HRMS, and HPLC, and the synthesis process was optimized by means of orthogonal experimental design. Subsequently, CP-6 was screened for cells viability by MTT assay, the results show that the CP-6 can effectively reversed STZ-induced reduction of cells viability, and CP-6 has potential antiaging activity.
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<p>Molecular Mechanisms of Anticancer Activities of Puerarin</p>

<p>Molecular Mechanisms of Anticancer Activities of Puerarin</p>

Cancer is a major cause of mortality worldwide; therefore, the development of cancer treatment is highly important. Natural products (NPs) are widely used in cancer treatment because of their low toxicity and high level of success. 1 Medicinal plants proven to get active compounds contain NPs. 2 In the recent era, medicinal plants have been explored for the treatment of a wide spectrum of physiological diseases. 3–8 Common medicinal plant-derived NPs are iso fl avones with a 3-phenylchroman skeleton. 9 Legumes of the Leguminosae and Fabaceae families, including lupine, kudzu, barley, cauli fl ower, soy, and fava beans, are a major source of plant-based iso fl avones. 9,10 Puerarin (Pue), depicted in Figure 1, is an important bioactive iso fl a- vone glycoside. 11,12 Pue has been isolated from several leguminous plants of the genus Pueraria, including Pueraria tuberosa (Willd.), 13 – 15 Pueraria lobata (Willd.) Ohwi (Gegen in Chinese), 16,17 and Pueraria thomsoniiBenth. 13,18,19 Pueraria plants have been interlinked with Asian culture because of their use in decoration, cooking, and disease treatment. 13 Systematic biology is an emerging approach that focuses on molecular interactions with biological systems. 20 Pue has molecular weight 416, 21 possesses several pharmacological activities against osteoporosis, 22 cardiovascular diseases, 23 fever, 24 neurological dysfunction, 25 liver injury, 26 and hangover, and they have been used in clinical treatments and experimental research. 27 Pue injections are used extensively in China, 16,28,29 but their effects on human health remain unclear to
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<p>Catalpol Promotes the Proliferation and Differentiation of Osteoblasts Induced by High Glucose by Inhibiting KDM7A</p>

<p>Catalpol Promotes the Proliferation and Differentiation of Osteoblasts Induced by High Glucose by Inhibiting KDM7A</p>

As shown in Figure 2A, there is no statistical difference in calcium nodules between control group and HM group. The calcium nodules were decreased in HG- induced MC3T3-E1 cells while the formation of miner- alized nodules was increased when HG-induced MC3T3-E1 cells were treated with the increase of cat- alpol. The expression of cell differentiation-related pro- teins was analyzed by Western blot (Figure 2B). The expression of RUNX2, Collagen I, OCN, BMP4 and BMP7 in HG-induced MC3T3-E1 cells was obviously decreased compared with the control group and HM group. However, catalpol treatment promoted the expression of RUNX2, Collagen I, OCN, BMP4 and BMP7 in HG-induced MC3T3-E1 cells and the promo- tion role of catalpol in the expression of these proteins was enhanced with the increase of catalpol. The ALP activity in the control group was not statistically differ- ent from the HM group. HG signi fi cantly inhibited the ALP activity in MC3T3-E1 cells and the ALP activity in HG-induced MC3T3-E1 cells was gradually increased when the concentration of catalpol was increased (Figure 2C).
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Electrochemical Determination of Catalpol in Rehmannia Glutinosa Based on Polyaniline-Graphene Modified Glassy Carbon Electrode

Electrochemical Determination of Catalpol in Rehmannia Glutinosa Based on Polyaniline-Graphene Modified Glassy Carbon Electrode

bare GCE, GR/GCE and GR-PANI/GCE, respectively. For all the electrodes described above in BR buffer solution with a concentration of 0.1 M when pH was 7.0, no responses were observed without adding catalpol. However, it was obvious in the cyclic voltammograms that the background current at GR/GCE and GR-PANI/GCE was larger than that of GCE, which indicated that both GR and GR- PANI had been coated on the bare GCE efficiently. Besides, the electroactive surface area of these two materials were more effective compared with the bare GCE. After adding catalpol, the oxidation peak observed at the bare GCE and GR/GCE in 0.1 M BR buffer solution with a pH of 7.0 was around 0.70 V and 0.61 V, respectively. However, for the GR-PANI/GCE in 0.1 M BR buffer with a pH of 7.0, a pair of definite redox peaks was obtained after adding catalpol, where the potentials of the reduction and oxidation peak were 0.34 and 0.54 V, respectively. Especially, the oxidation peak current observed at the GR-PANI/GCE was 80 times higher than that of the bare GCE, which indicated that the electroactive surface area and the electrocatalytic capacity of the GR-PANI to catalpol were relatively higher. However, compared with the bare GCE and GR/GCE, the oxidation peak potential of catalpol at the GR-PANI/GCE was relatively lower, which indicated that the GR-PANI/GCE exhibited an efficiently electrocatalysis performance for the redox reaction of catalpol. The observed enhancement in the anodic peak current as well as lowering of the overpotential can be attributed not only to the enlargement of microscopic surface area of the electrode, but also to the contribution of GR as electron conductor that promoted the conductivity of the modifier film [31]. In order to testify these assumptions, the microscopic surface areas of GR-PANI/GCE was calculated by CV method using K 3 Fe(CN) 6 as a redox probe at different potential scan rates. Randles-Sevick equation is used to obtain
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