Probing the binding of the flavonoid diosmetin to human serum albumin by multispectroscopic techniques

The binding mechanism of molecular interaction between diosmetin and human serum albumin (HSA) in a pH 7.4 phosphate buffer was studied using atomic force microscopy (AFM) and various spectroscopic techniques including fluorescence, resonance light scattering (RLS), UV-vis absorption, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by diosmetin was a static quenching procedure. The binding constants and number of binding sites were evaluated at different temperatures. The RLS spectra and AFM images showed that the dimension of the individual HSA molecules were larger after interaction with diosmetin. The thermodynamic parameters, ΔH° and ΔS° were calculated to be -24.56 kJ mol(-1) and 14.67 J mol(-1) K(-1), respectively, suggesting that the binding of diosmtin to HSA was driven mainly by hydrophobic interactions and hydrogen bonds. The displacement studies and denaturation experiments in the presence of urea indicated site I as the main binding site for diosmetin on HSA. The binding distance between diosmetin and HSA was determined to be 3.54 nm based on the F?rster theory. Analysis of CD and FT-IR spectra demonstrated that HSA conformation was slightly altered in the presence of diosmetin.     

Deactivation of ferrylmyoglobin by vanillin as affected by vanillin binding to β-lactoglobulin

Vanillin was found to be efficient as a deactivator of ferrylmyoglobin with a second-order rate constant of k(2) = 57 ± 1 L mol(-1) s(-1) for reduction to metmyoglobin with ΔH(?) = 58.3 ± 0.3 kJ mol(-1) and ΔS(?) = -14 ± 1 J mol(-1) K(-1) in aqueous pH 7.4 solution at 25 °C. Binding to β-lactoglobulin (βLG) was found to affect the reactivity of vanillin at 25 °C only slightly to k(2) = 48 ± 2 L mol(-1) s(-1) (ΔH(?) = 68.4 ± 0.4 kJ mol(-1) and ΔS(?) = 17 ± 1 J mol(-1) K(-1)) for deactivation of ferrylmyoglobin. Binding of vanillin to βLG was found to have a binding stoichiometry vanillin/βLG > 10 with K(A) = 6 × 10(2) L mol(-1) and an apparent total ΔH° of approximately -38 kJ mol(-1) and ΔS° = -55.4 ± 4 J mol(-1) K(-1) at 25 °C and ΔC(p, obs) = -1.02 kJ mol(-1) K(-1) indicative of increasing ordering in the complex, as determined by isothermal titration microcalorimetry. From tryptophan fluorescence quenching for βLG by vanillin, approximately one vanillin was found to bind to each βLG far stronger with K(A) = 5 × 10(4) L mol(-1) and a ΔH° = -10.2 kJ mol(-1) and ΔS° = 55 J mol(-1) K(-1) at 25 °C. The kinetic entropy/enthalpy compensation effect seen for vanillin reactivity by binding to βLG is concluded to relate to the weakly bound vanillin oriented through hydrogen bonds on the βLG surface with the phenolic group pointing toward the solvent, in effect making both ΔH(?) and ΔS(?) more positive. The more strongly bound vanillin capable of tryptophan quenching in the βLG calyx seems less or nonreactive.     

Covalent binding of the flavonoid quercetin to human serum albumin

Quercetin is an abundant flavonoid in the human diet with numerous biological activities, which may contribute to the prevention of human disease but also may be potentially harmful. Quercetin is oxidized in cells to products capable of covalently binding to cellular proteins, a process that may be important for its biological activities. In the present study, using radiolabeled drug and quantifying the products after electrophoretic separation, proteins to which oxidized quercetin is binding irreversibly were identified. The binding of quercetin to human serum albumin (HSA) in human blood and the effect of stimulation of neutrophilic myeloperoxidase on this binding were also measured. The in vitro binding of quercetin to eight proteins in the presence of catalytic amounts of horseradish peroxidase and hydrogen peroxide was highly selective for HSA. For all proteins the binding was dramatically decreased by reduced L-glutathione. In the blood samples, the release of neutrophilic myeloperoxidase by phorbol ester caused a 3-fold increase in the binding of quercetin to HSA. This study shows that quercetin in the presence of peroxidase/hydrogen peroxide covalently links to proteins with a particularly high affinity for HSA and that this also may occur in vivo after exposure to quercetin. This provides further insights into the complex behavior of this major dietary flavonoid.     

Sorption behavior of prochloraz in different soils.

The sorption behavior of the imidazole fungicide prochloraz [PCZ; N-propyl-N-[2-(2,4,6-trichlorophenoxy)ethyl]imidazole-1-carboxamide] was studied in batch experiments with different soils. The soil organic matter content was found to control the amount sorbed by different soils. K(d) values ranged from 56 +/- 0 to 552 +/- 10 (mean = 221 +/- 5) and K(OC) values from 7273 +/- 0 to 16250 +/- 1300 (mean = 11829 +/- 303). As calculated from a linear regression of K(d) versus %OC, K(OC) was 12900 +/- 1300. Additionally, the pH value of the soil had considerable influence on the sorption of the weakly basic PCZ (pK(a) = 3.8), giving rise to stronger sorption at lower pH. K(d) values determined on pH-modified soils confirmed the pH dependency. Sorption isotherms on two soils were recorded, initial concentrations ranging from 0.09 to 5.71 mg L(-)(1). The Freundlich isotherm was fitted to the values measured. The Freundlich exponents calculated were significantly smaller than unity, indicating nonlinear sorption. Sorption experiments with two metabolites of PCZ (PCZ-formylurea and PCZ-urea) revealed K(d) values one-fourth to one-third those for PCZ on two soils.     

连续解吸中离子强度对可变电荷土壤和高岭石体系pH的影响

研究了两种可变电荷土壤中在去离子水中和0.1 mol L-1 Na NO3溶液中吸附铜离子和钙离子后依次被浓度从低到高的Na NO3溶液连续解吸时,离子强度变化对每次解吸前后体系p H变化(Δp H)的影响,为了进一步了解其相关机理,作为对照,也研究了各种条件下,离子强度变化对高岭石Δp H的影响。结果表明,无论是否有吸附性二价阳离子的存在,或者吸附性阳离子属性(专性吸附型离子或电性吸附型离子)如何,当样品依次被去离子水、0.01 mol L-1 Na NO3、0.1 mol L-1 Na NO3以及1 mol L-1 Na NO3解吸时,在去离子水中和Na NO3溶液中的解吸过程对Δp H的影响截然不同。总体而言,如果解吸时体系离子强度趋于降低,Δp H将为正值,反之则为负值,且Δp H变幅开始增大时的起始点所对应的p H吸附基本相同,该起始点应该与高岭石ZPC(电荷零点)紧密相关。对上述结果的分析表明,解吸过程中,引起上述Δp H变化规律的根本原因之一是连续解吸过程中的离子强度变化导致的可变电荷表面的表面电位变化。     

Exploring the denaturation of whey proteins upon application of moderate electric fields: a kinetic and thermodynamic study

Thermal processing often results in disruption of the native conformation of whey proteins, thus affecting functional properties. The aim of this work was to evaluate the effects of moderate electric fields on denaturation kinetics and thermodynamic properties of whey protein dispersions at temperatures ranging from 75 to 90 °C. Application of electric fields led to a lower denaturation of whey proteins, kinetically traduced by lower values of reaction order (n) and rate constant (k) (p < 0.05), when compared to those from conventional heating under equivalent heating rates and holding times. Furthermore, the application of electric fields combined with short come-up times has reduced considerably the denaturation of proteins during early stages of heating (>30% of native soluble protein than conventional heating) and has determined also considerable changes in calculated thermodynamic properties (such as E(a), ΔH(?), ΔS(?)). In general, denaturation reactions during moderate electric fields processing were less dependent on temperature increase.     

Effects of dietary α-linolenic acid (18:3n-3)/linoleic acid (18:2n-6) ratio on fatty acid metabolism in Murray cod (Maccullochella peelii peelii)

Global shortages in fish oil are forcing the aquaculture feed industry to use alternative oil sources, the use of which negatively affects the final fatty acid makeup of cultured fish. Thus, the modulation of fatty acid metabolism in cultured fish is the core of an intensive global research effort. The present study aimed to evaluate the effects of various dietary α-linolenic acid (ALA, 18:3n-3)/linoleic acid (LA, 18:2n-6) ratios in cultured fish. A feeding trial was implemented on the freshwater finfish Murray cod, in which fish were fed either a fish oil-based control diet or one of five fish oil-deprived experimental diets formulated to contain an ALA/LA ratio ranging from 0.3 to 2.9, but with a constant total C?? PUFA (ALA+LA) content. The whole-body fatty acid balance method was used to evaluate fish in vivo fatty acid metabolism. The results indicate that dietary ALA was more actively β-oxidized and bioconverted, whereas LA appears to be more efficiently deposited. LA was β-oxidized at a constant level (~36% of net intake) independent of dietary availability, whereas ALA was oxidized proportionally to dietary supply. The in vivo apparent Δ-6 desaturase activity on n-3 and n-6 PUFA exhibited an increasing and decreasing trend, respectively, in conjunction with the increasing dietary ALA/LA ratio, clearly indicating that this enzymatic activity is substrate dependent. However, the maximum Δ-6 desaturase activity acting on ALA peaked at the substrate level of 3.2186 (μmol g fish?1 day?1), suggesting that additional inclusion of ALA is not only wasteful but counterproductive in terms of n-3 LC-PUFA production. Despite a constant total supply of ALA+LA, the recorded total in vivo apparent Δ-6 desaturase activity on both substrates (ALA and LA) increased in synchrony with the ALA/LA ratio, peaking at 1.54, and a 3.2-fold greater Δ-6 desaturase affinity toward ALA over LA was recorded.     

二苯-α-吡喃酮类链格孢霉毒素和人血清白蛋白的相互作用及机理探究

为探究链格孢酚单甲醚(AME)和链格孢酚(AOH)这两种二苯-α-吡喃酮类链格孢霉毒素与人血清白蛋白(HSA)之间的分子相互作用及机理,本研究模拟血液生理pH值,采用稳态荧光光谱、同步荧光光谱、3D荧光光谱以及圆二色光谱等方法研究两者之间的相互作用。结果表明,AME和AOH与HSA相互作用均发生了静态猝灭,具有较高亲和力,以氢键和范德华力(ΔH<0,ΔS<0)结合形成1:1复合物,互作过程中这两种类毒素破坏了人血清白蛋白中稳定二级结构的氢键网络,使蛋白二级结构展开,且AME和AOH使人血清白蛋白中的α-螺旋结构含量从48.93%分别减少至39.41%和44.01%,并使色氨酸残基极性降低、疏水性增加,但酪氨酸残基极性变化不大,即结合位点可能位于色氨酸残基所在的空腔(即结合位点I);AME对HSA的猝灭程度、猝灭常数(K_sv)及结合常数(K_a)均大于AOH,结合距离也更小(r_AME=2.56 nmAOH=2.60 nm)。本研究结果为进一步探究二苯-α-吡喃酮类链格孢霉毒素的毒代动力学和药代动力学,完善丰富其毒理学相关资料,以及进行风险评估和在食品中限量标准的制定提供了参考依据。     

Crocetin, dimethylcrocetin, and safranal bind human serum albumin: stability and antioxidative properties

Crocetin (CRT) and dimethylcrocetin (DMCRT) are derived from crocins which are found in the stigmas of saffron (Crocus sativus L.), while safranal is the main component of saffron's essential oil. The aim of the present study was to examine their interaction with human serum albumin in aqueous solution at physiological conditions using constant protein concentration and various ligand contents. FT-IR and UV-visible spectroscopic methods were used to determine the ligands' binding mode, the binding constant, and the effects of ligand complexation on protein secondary structure. Structural analysis showed that crocetin, dimethylcrocetin, and safranal bind nonspecifically (H-bonding) via protein polar groups with binding constants of Kcrt =2.05 (+/-0.30) x 103 M-1, Kdmcrt = 9.60 (+/-0.35) x 104 M-1, and Ksaf = 2.11 (+/-0.35) x 103 M-1. The protein secondary structure showed no major alterations at low ligand concentrations (1 microM), whereas at higher content (1 mM), decrease of alpha-helix from 55% (free HSA) to 43-45% and increase of beta-sheet from 17% (free HSA) to 18-22% and random coil 7% (free HSA) to 10-14% occurred in the ligand-HSA complexes. The results point to a partial unfolding of protein secondary structure at high ligand content. The antioxidant activity of CRT, DMCRT, and safranal was also tested by the DPPH* antioxidant activity assay, and their IC50 values were compared to that of well-known antioxidants such as Trolox and butylated hydroxy toluene (BHT). The IC50 values of CRT and safranal were 17.8 +/- 1 microg/mL and 95 +/- 1 microg/mL, respectively, while the inhibition of DMCRT reached a point of 38.8%, which corresponds to a concentration of 40 microg/mL, and then started to decrease. The IC50 values of Trolox and BHT were 5.2 +/- 1 microg/mL and 5.3 +/- 1 microg/mL, respectively.     

Binding of phthalate plasticizers to human serum albumin in vitro: a multispectroscopic approach and molecular modeling

As endocrine-disrupting chemicals, a few frequently used phthalate plasticizers were banned or restricted for use as additives in food in some countries. The interaction mechanisms between three phthalate plasticizers with human serum albumin (HSA) were studied by fluorescence (quenching, synchronous, and three-dimensional), UV-vis absorption, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy, in combination with molecular modeling under simulative physiological conditions, respectively. The results obtained from fluorescence quenching data revealed that the plasticizers-HSA interaction altered the conformational strcture of HSA. Meanwhile, the alterations of HSA secondary structure in the presence of phthalate plasticizers were investigated. The binding distances for the plasticizers-HSA system were provided by the efficiency of fluorescence resonance energy transfer. Furthermore, the thermodynamic analysis implied that hydrophobic forces were the main interaction for the plasticizers-HSA system, which agreed well with the results from the molecular modeling study.     

Acetylation of 5-amino-1H-[1,2,4]triazole revisited

The products of the acetylation reactions of the common herbicide 5-amino-1H-[1,2,4]triazole were investigated using HPLC, GC-MS, 1H NMR, and FTIR spectroscopy. The conventional annular monoacetylation procedures with acetyl chloride are not regioselective and furnish a mixture of isomers. Traditional diacetylation in neat acetic anhydride under reflux produces a mixture of di-, mono-, and triacetylated derivatives. By using equivalent amounts of acetic anhydride in a dimethylformamide solution, a rapid and selective annular monoacetylation of 5-amino-1H-[1,2,4]triazole was achieved. The monoacetylation proceeds via the formation of the intermediate, 1-acetyl-3-amino-1H-[1,2,4]triazole, which had not been observed previously and which undergoes transformation into the known 1-acetyl-5-amino-1H-[1,2,4]triazole. Neat acetic anhydride at room temperature affords the diacetylated derivative, 1-acetyl-3-(acetylamino)-1H-[1,2,4]triazole both from 5-amino-1H-[1,2,4]triazole itself and from either 1-acetyl-5-amino-1H-[1,2,4]triazole or 5-(acetylamino)-1H-[1,2,4]triazole. The atypical product of the second acetylation, 1-acetyl-5-(acetylamino)-1H-[1,2,4]triazole, has been identified. These results may be useful in the development of effective and selective preparative procedures for the acetylation of 5-amino-1H-[1,2,4]triazole.     

三唑类农药的微生物降解研究进展

三唑类农药是一种广泛使用的防治植物病害的杀菌剂和植物生长调节剂，可通过抑制麦角甾醇的合成阻碍病原菌的细胞壁形成，从而起到防治作物病害的作用，也能抑制植物赤霉素合成延缓植物生长；但因大范围应用及其难以降解的特性，污染环境和影响人类健康。为给三唑类农药的微生物降解提供参考，基于文献研究，梳理总结了三唑类农药降解菌的种类、影响降解的环境因素和降解机理方面的研究进展，明确了微生物在不同环境中能有效降解三唑类农药，微生物降解技术有望应用于治理三唑类农药造成的环境污染。     

Characterizing the Interaction between tartrazine and two serum albumins by a hybrid spectroscopic approach

Tartrazine is an artificial azo dye commonly used in food products. The present study evaluated the interaction of tartrazine with two serum albumins (SAs), human serum albumin (HSA) and bovine serum albumin (BSA), under physiological conditions by means of fluorescence, three-dimensional fluorescence, UV-vis absorption, and circular dichroism (CD) techniques. The fluorescence data showed that tartrazine could bind to the two SAs to form a complex. The binding process was a spontaneous molecular interaction procedure, in which van der Waals and hydrogen bond interactions played a major role. Additionally, as shown by the UV-vis absorption, three-dimensional fluorescence, and CD results, tartrazine could lead to conformational and some microenvironmental changes of both SAs, which may affect the physiological functions of SAs. The work provides important insight into the mechanism of toxicity of tartrazine in vivo.     

Bioevaluation of human serum albumin-hesperidin bioconjugate: insight into protein vector function and conformation

Hesperidin is a flavanone glycoside widely available for dietary intake in citrus fruits or citrus fruit derived products; however, exhaustive and reliable data are scarcely available for biological activity when it exerts protective health effects in humans. The principal intent of this work is to check binding domain and structural changes of human serum albumin (HSA), the primary carrier of flavonoids, in blood plasma association with hesperidin by employing molecular modeling, steady state and time-resolved fluorescence, and circular dichroism (CD) methods. From molecular modeling simulations, subdomains IIA and IIIA, which correspond to Sudlow's sites I and II, respectively, were earmarked to possess affinity for hesperidin, but the affinity of site I with flavanone is greater than that of site II. This corroborates the site-specific probe and hydrophobic 8-anilino-1-naphthalenesulfonic acid (ANS) displacement results placing the hesperidin at warfarin-azapropazone and indole-benzodiazepine sites. Steady state and time-resolved fluorescence manifested that static type, due to HSA-hesperidin complex formation (1.941 × 10(4) M(-1)), is the operative mechanism for the diminution in the tryptophan (Trp)-214 fluorescence. Moreover, via alterations in three-dimensional fluorescence and CD spectral properties, we can securely draw the conclusion that the polypeptide chain of HSA is partially destabilized after conjugation with hesperidin. We anticipate that this study can provide better knowledge of bioavailability such as absorption, biodistribution, and elimination, of hesperidin in vivo, to facilitate the comprehension of the biological responses to physiologically relevant flavanones.     

Polymerization kinetics of wheat gluten upon thermosetting. A mechanistic model

Size exclusion high-performance liquid chromatography analysis was carried out on wheat gluten-glycerol blends subjected to different heat treatments. The elution profiles were analyzed in order to follow the solubility loss of protein fractions with specific molecular size. Owing to the known biochemical changes involved during the heat denaturation of gluten, a mechanistic mathematical model was developed, which divided the protein denaturation into two distinct reaction steps: (i) reversible change in protein conformation and (ii) protein precipitation through disulfide bonding between initially SDS-soluble and SDS-insoluble reaction partners. Activation energies of gluten unfolding, refolding, and precipitation were calculated with the Arrhenius law to 53.9 kJ x mol(-1), 29.5 kJ x mol(-1), and 172 kJ x mol(-1), respectively. The rate of protein solubility loss decreased as the cross-linking reaction proceeded, which may be attributed to the formation of a three-dimensional network progressively hindering the reaction. The enhanced susceptibility to aggregation of large molecules was assigned to a risen reaction probability due to their higher number of cysteine residues and to the increased percentage of unfolded and thereby activated proteins as complete protein refolding seemed to be an anticooperative process.     

鹰嘴豆α-淀粉酶抑制剂基因CL-AI的原核表达、纯化及生物学特性

为研究鹰嘴豆种子中新贮藏蛋白类型α-淀粉酶抑制剂CL-AI的抑制活性、生物活性以及三级结构,本研究利用前期克隆的α-淀粉酶抑制剂基因CL-AI及其2个亚基CL-AI-α、CL-AI-β分别构建原核表达载体p E-SUMO3,经诱导表达获得了CL-AI、CL-AI-α的可溶性融合蛋白和CL-AI-β包涵体融合蛋白,其中CL-AI-β通过构建含不同标签的表达载体,最终实现了可溶性表达。人唾液淀粉酶(HSA)抑制活性试验结果表明,CL-AI,CL-AI-α,CL-AI-β3个蛋白对HAS都有一定的抑制作用。发芽试验表明,CL-AI蛋白对小麦、玉米、水稻种子发芽过程中的发芽势、根长和芽长影响显著,与加入无菌水的处理相比,种子的简化活力指数显著下降。本研究结果为CL-AI蛋白的后续研究与应用奠定了基础。     

Development of monoclonal immunoassays for the determination of triazole fungicides in fruit juices

Enzyme-linked immunosorbent assays (ELISAs) based on monoclonal antibodies for the detection of triazole fungicides have been developed. With this aim, hapten-protein conjugates, containing the common triazole and chlorinated aromatic moieties, were prepared. From mice immunized with these conjugates, several monoclonal antibodies (MAbs) with the ability to sensitively bind several triazoles with different specificity were obtained. Both analyte- and class-specific ELISAs were developed. The hexaconazole-specific immunoassay can determine this fungicide with a limit of detection of 0.3 mug/L in standard buffer. The so-called triazole-specific immunoassay allowed for the detection of tetraconazole, penconazole, cyproconazole, and myclobutanil, with limits of detection in the 0.1-0.7 mug/L range. These immunoassays were applied to the determination of triazoles in spiked fruit juices. Samples were adequately diluted to minimize the matrix effects. Coefficients of variation were below 30%, and recoveries ranged from 62 to 135%. Therefore, the developed immunoassays can determine triazole fungicides in fruit juices down to the maximum residue limits currently legislated, without any sample treatment other than dilution.     

Conformational study of red kidney bean (Phaseolus vulgaris L.) protein isolate (KPI) by tryptophan fluorescence and differential scanning calorimetry

Fluorescence and differential scanning calorimetry (DSC) were used to study changes in the conformation of red kidney bean (Phaseolus vulgaris L.) protein isolate (KPI) under various environmental conditions. The possible relationship between fluorescence data and DSC characteristics was also discussed. Tryptophan fluorescence and fluorescence quenching analyses indicated that the tryptophan residues in KPI, exhibiting multiple fluorophores with different accessibilities to acrylamide, are largely buried in the hydrophobic core of the protein matrix, with positively charged side chains close to at least some of the tryptophan residues. GdnHCl was more effective than urea and SDS in denaturing KPI. SDS and urea caused variable red shifts, 2-5 nm, in the emission λ(max), suggesting the conformational compactness of KPI. The result was further supported by DSC characteristics that a discernible endothermic peak was still detected up to 8 M urea or 30 mM SDS, also evidenced by the absence of any shift in emission maximum (λ(max)) at different pH conditions. Marked decreases in T(d) and enthalpy (ΔH) were observed at extreme alkaline and/or acidic pH, whereas the presence of NaCl resulted in higher T(d) and ΔH, along with greater cooperativity of the transition. Decreases in T(d) and ΔH were observed in the presence of protein perturbants, for example, SDS and urea, indicating partial denaturation and decrease in thermal stability. Dithiothreitol and N-ethylmaleimide have a slight effect on the thermal properties of KPI. Interestingly, a close linear relationship between the T(d) (or ΔH) and the λ(max) was observed for KPI in the presence of 0-6 M urea.     

鲐鱼软骨糖胺聚糖的硫酸软骨素的结构及其与生长因子的相互作用

为了开发具有药用价值的硫酸软骨素(chondroitin sulfate,CS)的新资源,从鲐鱼(Pneumatophorus japonicus Houttuyn)软骨蛋白聚糖(proteoglycan,PG)制备了糖胺聚糖(glycosaminoglycan,GAG),用酶降解和阴离子交换HPLC法测定了GAG的CS的组成及其含量,用凝胶层析法测定了GAG的分子量,用表面等离子体谐振(surface plasmon resonance,SPR)法测定了其与多效生长因子(PTN)、中期因子(MK)和肝细胞生长因子(HGF)相互作用的动力学参数结合速率常数(ka)、解离速率常数(kd)和平衡解离常数(KD)。结果显示,鲐鱼软骨GAG含量约为651μg/mgPG或1.09μmol/mgPG(按照二糖单位计算),主要含CS(1.03μmol/mgPG,按照二糖单位计算),CS酶解产生的主要二糖单位是ΔDi-6S(38.8%)和ΔDi-4S(46.3%),有少量的ΔDi-0S(8.4%)和ΔDi-diSD(6.5%)。GAG(CS)的分子量为78kD。GAG(CS)与生长因子的相互作用的动力学参数ka((mol/L)-1.s-1)、kd(s-1)和KD(nmol/L)分别为(2.77±0.17)×105、(7.74±1.56)×10-5和(0.28±0.06)(MK),(1.05±0.22)×104、(4.16±0.80)×10-3和(417±131.3)(PTN),(7.04±0.94)×105、(7.84±2.82)×10-3和(11.1±3.80)(HGF)。该GAG同MK、HGF和PTN有高的或较高的亲和性,暗示鲐鱼软骨GAG的CS有可能通过调节生长因子的信号转导途径而对某些疾病发挥治疗作用,具有潜在进一步药用开发价值。     

Ciprofloxacin Adsorption on ZnO Supported on SBA-15

Most drugs are synthesized by human medicine both for the treatment of men and animals and are also produced to maintain their physical and chemical properties for a time sufficient to serve a therapeutic purpose in treatments of some kind of illness. Ciprofloxacin is an antibiotic synthetically obtained in 1987 and belongs to the family of fluoroquinolones and is currently prescribed in certain treatments. This work was developed with the objective of evaluating the adsorption of the ciprofloxacin antibiotic in solution on zinc oxide (ZnO) supported on SBA-15-type mesoporous silica. The results showed that the post-synthesis method is effective in impregnating zinc oxide in SBA-15 and its structure has not been damaged and has not lost its organization in the hexagonal 2D planes. The ZnO-SBA-15 (10%) sample adsorbed 69.10% of ciprofloxacin (25 mg/L) in 180 min. Freundlich adsorption model was observed with the correlation factor of R²?=?0.9999, for the adsorbent ZnO-SBA-15 (10%), which showed the best sample. The kinetics was classified as pseudo-second order, as well as the thermodynamic parameters were determined, showing that the process has a spontaneous nature and a value of ΔH°?=?4.677 kJ/mol, evidencing that the process has the nature of physiosorption.