Quinine Groups Research Articles

Tannic acid-aminopropyltriethoxysilane co-deposition modified polymer membrane for α-glucosidase immobilization

Mussel-inspired catechol-amine co-deposition is an effective modification strategy for various materials. In this work, polyvinylidene fluoride (PVDF) membrane was employed as the carrier for α-glucosidase immobilization. By virtue of the co-polymerization of tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) and the hydrolysis of APTES, a hierarchical layer-colloidal nanospheres coating was decorated on the surface of PVDF membrane. Subsequently, α-glucosidase was covalently bound to the modified PVDF membrane through Schiff base reaction and Michael addition reaction between the residual quinine groups in the coating and the amino groups in enzyme molecules. Several parameters affecting the immobilization procedure were investigated thoroughly. The morphology and functional groups of the prepared composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared-Attenuated total reflectance spectroscopy (FTIR-ATR), and X-ray photoelectron spectroscopy (XPS). Combined with capillary electrophoresis (CE) analysis, the performance, enzyme reaction kinetics and inhibition kinetics of PVDF-immobilized α-glucosidase were studied. The immobilized enzyme exhibited the enhanced tolerance to temperature and pH value. In addition, it possessed good reusability maintaining 77.1% of initial relative activity after 11 recycles, and batch-to-batch reproducibility with RSD of 4.3% (n = 10). The Michaelis-Menten constant (Km) of immobilized enzyme was calculated to be 4.16 mM, and IC50 value of acarbose was 0.10 µM. Finally, the PVDF-immobilized α-glucosidase was applied to screening potential inhibitors from 13 kinds of traditional Chinese medicines (TCMs), among which Sanguisorba Radix exhibited the strongest inhibitory activity. The positive results suggested that TA/APTES co-deposition was a simple and mild functionalization method for chemically inert polymer membrane and the proposed screening method was a reliable approach for discovering enzyme inhibitors from TCMs.

Effect of gap junction blockers on hippocampal ripple energy expression in rats with status epilepticus.

To study the effect of gap junction blockers, quinine (QUIN) and carbenoxolone (CBX), on hippocampal ripple energy expression in rats with status epilepticus (SE). A total of 24 rats were randomly divided into four groups: model, QUIN, valproic acid (VPA), and CBX (n=6 each). A rat model of SE induced by lithium-pilocarpine (PILO) was prepared. The QUIN, VPA, and CBX groups were given intraperitoneal injection of QUIN (50 mg/kg), VPA by gavage (200 mg/kg), and intraperitoneal injection of CBX (50 mg/kg) respectively, at 3 days before PILO injection. Electroencephalography was used to analyze the change in hippocampal ripple energy before and after modeling, as well as before and after chloral hydrate injection to control seizures. Ripple expression was observed in the hippocampal CA1, CA3, and dentate gyrus regions of normal rats. After 10 minutes of PILO injection, all groups had a gradual increase in mean ripple energy expression compared with 1 day before modeling, with the highest expression level before chloral hydrate injection in the model, VPA and CBX groups (P<0.05). The QUIN group had the highest expression level of mean ripple energy 60 minutes after PILO injection. The mean ripple energy returned to normal levels in the three intervention groups immediately after chloral hydrate injection, while in the model group, the mean ripple energy returned to normal levels 1 hour after chloral hydrate injection. The mean ripple energy remained normal till to day 3 after SE in the four groups. The changing trend of maximum ripple energy was similar to that of mean ripple energy. The change in ripple energy can be used as a quantitative indicator for early warning of seizures, while it cannot predict seizures in the interictal period. Gap junction blockers can reduce ripple energy during seizures.

Effects of monosodium glutamate on testicular structural and functional alterations induced by quinine therapy in rat: An experimental study.

Background Quinine (QU) as an anti-malarial drug induces alterations in testicular tissue. Toxic effects of monosodium glutamate (MSG) on the male reproductive system have been recognized.ObjectiveTo investigate the impact of MSG administration on the intensity of gonadotoxicity of QU.Materials and MethodsSixty eight-wk old Wistar rats weighing 180-200 gr were divided into six groups (n = 10/each): the first group as a control; the second and third groups received low and high doses of MSG (2 & 4 gr/kg i.p.), respectively, for 28 days; the fourth group received QU for seven days (25 mg/kg); and in the fifth and sixth groups, QU was gavaged following the MSG administration (MSG + QU) from day 22 to day 28. Serum testosterone and malondialdehyde (MDA) levels were measured. Testes samples were prepared for tissue MDA levels, histomorphometry, and immunohistochemistry of p53. Sperm analysis was performed on cauda epididymis.ResultsSerum and tissue MDA levels were increased in treated groups compared to the control group. This increment was higher in the MSG + QU groups. The testosterone levels were reduced significantly (p 0.0001) in all treated groups. In addition, histomorphometric indices and tubular epithelium population were reduced significantly (p 0.0001) in QU, MSG + QU, and consequently in high-dose MSG, QU, MSG + QU groups. All spermatogenic indices were reduced in the treated groups, particularly in the MSG + QU groups. Sperm motility and viability indices were reduced significantly (p = 0.003) in the MSG + QU groups. Finally, the overexpression of p53 was observed in the MSG + QU groups.Conclusion The administration of MSG before and during QU therapy may intensify testicular tissue alterations.

Administration of Nicotine Exacerbates the Quinine-induced Structural and Functional Alterations of Testicular Tissue in Adult Rats: An Experimental Study.

In this study the role of nicotine (NCT) administration on the intensity of rat testicular tissue alterations induced by quinine (QU) was evaluated. Forty adult Wistar rats were divided into four groups. Control (CON), NCT administrated (4 mg/kg) (NCT), QU treated (25 mg/kg for 7 days) (QU), and nicotine with quinine received (NCT+QU). After 28 days, serum testosterone and malondialdehyde (MDA) levels were measured. Testes and epididymides samples were prepared for determining tissue MDA levels, histomorphometry, microscopic indices of spermatogenesis, immunohistochemistry of p53 and sperm analysis. Testosterone levels were decreased significantly (P = .0004) in treated groups compared to CON group. Serum MDA levels were increased significantly (P = .0004) in NCT and QU groups compared to CON group. Tissue MDA levels were increased significantly (P = .0012) in NCT+QU group in comparison to CON group. These parameters were changed significantly in NCT+QU group compared to QU group. Seminiferous tubules diameter decreased significantly (P < .0001) in treated groups compared to CON group and in NCT+QU group compared to QU group. The height of germinal epithelium decreased significantly (P = .0001) in NCT and NCT+QU groups compared to CON and QU groups. The number of Sertoli cells, spermatocytes, and spermatids decreased significantly in treated groups compared to CON group. The number of spermatogonia decreased significantly (P = .0017) in NCT and NCT+QU groups compared to CON group. The number of Sertoli cells, spermatogonia, and spermatocytes decreased significantly in NCT+QU group compared to QU group. All indices of spermatogenesis decreased in treated groups compared to CON group. The lowest mean of these indices was observed in NCT+QU group. The sperm viability decreased significantly (P < .0001) in treated groups compared to CON group. Sperm count and motility decreased significantly in NCT and NCT+QU groups compared to CON group. All experimental groups showed the over-expression of p53 compared to CON group. The administration of nicotine could be involved in the exacerbation of testicular tissue alterations related to quinine therapy.

Artesunate compared with quinine for the treatment of severe malaria in adult patients managed in an intensive care unit: A retrospective observational study.

There are limited South African data on the outcomes of patients with severe malaria treated with quinine compared with those treated with artesunate in the intensive care unit (ICU). To compare the outcomes of adult patients treated with artesunate against those treated with quinine in the ICU. Primary outcome variables are length of stay (LOS) in the ICU and mortality. Secondary outcomes include the incidence of hypoglycaemic episodes and neurological outcomes. This was a retrospective cohort study of patients with severe malaria treated at a multidisciplinary ICU with artesunate or quinine from 1 January 2008 to 31 December 2012. Of the 92 patients included in the study, 63 (69.2%) were male. The mean age in the quinine and artesunate groups was 36.2 years and 40.5 years, respectively (p=0.071). Most (98.6%) of the patients with a positive travel history had visited a malaria-endemic region. Of the 53 patients tested for HIV infection, 71.7% tested positive (p=0.520). The average CD4+ cell count of HIV-positive patients treated with quinine was 200 cells/µL compared with 217.17 cells/µL for those treated with artesunate (p=0.875). The mean APACHE II score at admission was 20.85 and 19.62 in the quinine group and artesunate group, respectively (p=0.380). The median LOS was 5 days (range 1 - 27). Mortality was 15.4% in the quinine group and 7.7% in the artesunate group (p=0.246). A statistically insignificant mortality difference was observed in outcomes of the two treatment groups in this retrospective, single-centre cohort study. Intravenous artesunate is currently the preferred treatment in the management of patients with severe malaria. However, there are limited local data on the outcomes of artesunate v. quinine therapy for the management of severe malaria in highly monitored clinical environments in non-endemic regions of South Africa.We describe clinical characteristics, management and outcomes of patients with severe malaria treated with quinine and those treated with artesunate in the ICU in a non-endemic region.

Inhibition of the bioavailability of heavy metals in sewage sludge biochar by adding two stabilizers.

Agricultural application of sewage sludge (SS) after carbonization is a plausible way for disposal. Despite its benefits of improving soil fertility and C sequestration, heavy metals contained in sewage sludge biochars (SSB) are still a concern. In this study, two types of heavy metal stabilizers were chosen: fulvic acid (FA) and phosphogypsum (with CaSO4, CS, as the main component). The two stabilizers were incorporated into SS prior to 350°C carbonization for 1 h at the rates of 1%, 2%, or 4%. The obtained SSBs were then analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Total and available concentrations of four heavy metals, i.e., Zn, Pb, Cd, and Ni, in the SSBs were determined. In addition, a series of pot soil culture experiments was conducted to investigate the effects of stabilizers incorporation into SSB on heavy metal bioavailability and the uptake by plants (corn as an indicator) and plant biomass yield, with SS and SSB (no stabilizers) as controls. The results showed that incorporation of both FA and CS increased functional groups such as carboxyl, phenol, hydroxyl, amine and quinine groups in the SSBs. The percentage of heavy metals in sulfuric and oxidizable state and residual state of SSBs were significantly increased after carbonization, and hence the mobility of the heavy metals in SSBs was decreased. The introduction of the stabilizers (i.e., FA or CS) significantly lowered the total and available concentrations of Zn, Pb, Cd, and Ni. The reduction in available heavy metal concentration increased with incorporation rate of the stabilizers from 1% to 4%. In the treatments with FA or CS incorporated SSB, less heavy metals were taken up by plants and more plant biomass yields were obtained. The mitigating effects were more pronounced at higher rates of FA or CS stabilizer. These findings provide a way to lower bioavailability of heavy metals in SS or SSB for land application or horticulture as a peat substitute.

A review: role of interfacial adhesion between carbon blacks and elastomeric materials

Abstract Carbon blacks (CBs) have been widely used as reinforcing materials in advanced rubber composites. The mechanical properties of CB-reinforced rubber composites are mostly controlled by the extent of interfacial adhesion between the CBs and the rubber. Surface treatments are generally performed on CBs to introduce chemical functional groups on its surface. In this study, we review the effects of various surface treatment methods for CBs. In addition, the preparation and properties of CB-reinforced rubber composites are discussed. Key words: rubber, carbon blacks, surface treatments, interfacial adhesion 1. Introduction Rubber exhibits superior viscoelastic properties and improves the lifespan of products which continue to be transformed. At first, natural rubber (NR), which is composed of isoprene monomers, was obtained from nature. Later, as industries developed, synthetic rubbers were produced to supplement the production of NR. In particular, studies have been conducted on a new kind of rubber that is made of butadiene, namely, a copolymer of acrylonitrile butadiene rubber (NBR) and styrene butadiene rubber (SBR) as shown in Fig. 1 [1-6].However, rubber lacks sufficient physical strength, which makes it unsuitable for various applications. For this reason, fillers, such as carbon materials and silica, are added to rubber to form rubber composites with improved mechanical behaviors [7-27].In recent years, carbon materials have been widely used as reinforcing agents in high-per -formance composite materials [28-35], adsorbents [36], electrochemistry [37], and energy storage materials [38]. Among various carbon materials used as reinforcing agents, carbon blacks (CBs) are the oldest carbon derivatives produced by the incomplete combustion of petroleum products, such as fluid catalytic cracking tar and coal tar. Moreover, the particle size, structure, and surface conditions of CBs (Fig. 2) make them popular reinforcing agents [19-21].CBs contain more than 95% amorphous carbon, and their particle sizes vary from 5 to 500 nm. The physical properties of CBs vary with the production method and the raw materials used, which makes them suitable for applications in various fields. The mixing ratio of CBs in automobile tires is 50%, while that in other rubber products is approximately 30%. Rela-tively large amounts of reinforced CBs should be added to NR to attain acceptable mechani-cal properties. Cohesion occurs between CB particles due to chemical and physical bonds. The chemical composition of CB aggregates is 90%–99% carbon, 0.1%–1.0% hydrogen, 0.2%–2.0% oxygen, and a small amount of sulfur and ash. In addition, oxygen-containing functional groups, such as the carboxyl, hydroxyl, and quinine groups, exist on the surfaces of CBs. These are called surface functional groups. These surface functional groups increase the chemical and physical bonding between the CBs particles and the rubber matrix [39-43]. Therefore, the addition of CBs to rubber results in the formation of composites with im-

Multifunctional Electrochemical Platforms Based on the Michael Addition/Schiff Base Reaction of Polydopamine Modified Reduced Graphene Oxide: Construction and Application.

In this paper, a new strategy for the construction of multifunctional electrochemical detection platforms based on the Michael addition/Schiff base reaction of polydopamine modified reduced graphene oxide was first proposed. Inspired by the mussel adhesion proteins, 3,4-dihydroxyphenylalanine (DA) was selected as a reducing agent to simultaneously reduce graphene oxide and self-polymerize to obtain the polydopamine-reduced graphene oxide (PDA-rGO). The PDA-rGO was then functionalized with thiols and amines by the reaction of thiol/amino groups with quinine groups of PDA-rGO via the Michael addition/Schiff base reaction. Several typical compounds containing thiol and/or amino groups such as 1-[(4-amino)phenylethynyl] ferrocene (Fc-NH2), cysteine (cys), and glucose oxidase (GOx) were selected as the model molecules to anchor on the surface of PDA-rGO using the strategy for construction of multifunctional electrochemical platforms. The experiments revealed that the composite grafted with ferrocene derivative shows excellent catalysis activity toward many electroactive molecules and could be used for individual or simultaneous detection of dopamine hydrochloride (DA) and uric acid (UA), or hydroquinone (HQ) and catechol (CC), while, after grafting of cysteine on PDA-rGO, simultaneous discrimination detection of Pb(2+) and Cd(2+) was realized on the composite modified electrode. In addition, direct electron transfer of GOx can be observed when GOx-PDA-rGO was immobilized on glassy carbon electrode (GCE). When glucose was added into the system, the modified electrode showed excellent electric current response toward glucose. These results inferred that the proposed multifunctional electrochemical platforms could be simply, conveniently, and effectively regulated through changing the anchored recognition or reaction groups. This study would provide a versatile method to design more detection or biosensing platforms through a chemical reaction strategy in the future.

Organocatalytic Synthesis of Quinine-Functionalized Poly(carbonate)s

The ring-opening polymerization of substituted cyclic carbonates with 1-(3,5-bis-trifluoromethyl-phenyl)-3-cyclohexyl-thiourea (TU)/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) organocatalysts afford highly functionalized oligocarbonates. The fluorescent alkaloid quinine can be readily incorporated into the oligocarbonates either by initiation from quinine or by ring-opening polymerization of a quinine-functionalized cyclic carbonate (MTC-Q). Copolymerization of MTC-Q with a boc-protected guanidinium cyclic carbonate affords, after deprotection, highly water-soluble cationic copolymers functionalized with both quinine and pendant guanidinium groups. When multiple quinine groups are attached to the oligomers, they exhibit minimal fluorescence due to self-quenching. Upon hydrolysis, the fluorescence intensity increases, providing a potential strategy for monitoring the hydrolysis rates in real time.

Surface modified activated carbon with β-cyclodextrin – Part I. Synthesis and characterization

Surface functional groups produced from oxidation (carboxylic acid, lactone, quinine, phenol, and nitro groups), reduction (alcohol and amine groups), and grafting (imine and hemi-acetal) reactions were characterized (using surface analysis and chemical methods) and compared with unmodified activated carbon (AC) materials. The untreated, surface-modified, and grafted activated carbon materials were characterized by various surface sensitive methods: Diffuse Reflectance Infrared Fourier Transform Spectroscopy, Scanning Electron Microscopy, Raman spectroscopy, thermogravimetry analysis, and Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) mass spectrometry. A chemical method (Boehm titration) was used for estimating the amount of surface bound acidic and basic functional groups. Nitrogen porosimetry was used to analyze the surface area (95–1350 m2/g) and pore volume (0–0.31 cm3/g) characteristics of AC, surface modified AC, and AC materials grafted with β-cyclodextrin.

Comparison of artesunate and quinine in the treatment of Sudanese children with severe Plasmodium falciparum malaria

Sixty-six children presenting to Singa hospital, Sudan with different manifestations of severe Plasmodium falciparum malaria were randomly divided into two well-matched groups (33 in each arm) to receive either intravenous artesunate 2·4 mg/kg at 0, 12, and 24 hours, then daily, or intravenous quinine 20mg/kg initially then 10mg/kg three times a day. There was no significant difference in the fever, parasite clearance, and coma resolution times. Three patients died, one in the artesunate and two in the quinine groups. One patient developed hypoglycaemia following quinine infusion. Thus, artesunate can be used for the treatment of severe falciparum malaria.

Dialysis Leg Cramps

A controlled randomized double-blind study was done to determine the frequency and severity of leg cramps in 40 patients on dialysis with a history of leg cramps. All patients entered a 2 month placebo washout and were randomized into a 2 month double-dummy phase of quinine 325 mg at bedtime versus vitamin E 400 IU at bedtime. Of the 29 patients completing the study, 16 received quinine and 13 vitamin E. During placebo washout, the vitamin E group had a mean of 10.4 leg cramps per month, and the quinine group had a mean of 10.9. The vitamin E and quinine groups had a 1 month reduction in leg cramps to 3.3 and 3.6, respectively (p < 0.0005 for both groups combined); this was sustained at 2 months. A severity of pain index showed a statistically significant decrease for both groups. The 95% confidence interval for the difference between the number of leg cramps after vitamin E versus quinine treatment (95% confidence interval, -3.8, +3.2) suggests similar efficacy. Quinine and vitamin E were effective treatments for leg cramps in these patients. Considering the potential toxicity of quinine, vitamin E is recommended as the initial treatment of choice for patients on dialysis with leg cramps.