Dioxygen Affinities and Catalytic Epoxidation Performanceof Transition-Metal Hydroxamates

The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.

Dioxygen affinities and catalytic oxidation performance of cobalt(Ⅱ) hydroxamates with benzo-15-crown-5 pendants

The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （ΔH^0 and ΔS^0） were calculated based on these （Ko2） values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.

Synergistic Catalytic Action of Cobalt(Ⅱ) Hydroxamates and N-Hydroxyphthalimide in the Aerobic Oxidation of p-Xylene

The catalytic performance of a series of cobalt(Ⅱ) hydroxamates (CoL2) and the synergistic catalytic action of the cobalt complexes combined with N-hydroxyphthalimide (NHPI) in the aerobic oxidation of p-xylene to p-toluic acid (PTA) were investigated. The results showed that the existing synergistic action in the catalytic oxidation can shorten the induction period of the radical reaction and improve the yield of PTA.

Synthesis, Characterization and in vitro Antitumour Activity of the Di-n-butyltin(IV) Complexes of Some Arylhydroxamates

Fourteen new di n butyltin(IV) complexes of hydroxamic acids of the formula Bu 2 SnL 2 (HL=hydroxamic acids) were synthesized by the reaction of Bu 2 SnO and hydroxamic acids in dry toluene and ethanol media. The compounds were characterized by elemental analyses, molecular weight, IR and 1 H NMR spectroscopy. The results indicate that n Bu 2 SnL 2 have distorted trans octahedral structure. The antitumor activity in vitro against human A 549 tumor cells and P388 leukemia was presented, and their structure activity relationship was discussed.

Synthesis,3D-QSAR and Molecular Docking of Hydroxamate Inhibitors

In search of natural renewable resource-based bioactive molecules,20 hydroxamate inhibitors were designed and synthesized using cinamaldehyde as the starting material.Their structures were characterized by FT-IR,^(1)HNMR,^(13)C NMR,and HRMS.And in vitro antifungal activity of the target compounds against 8 tested fungi was preliminarily evaluated by the agar dilution method.The bioassay results revealed that at the concentration of 50 mg/L,the target compounds exhibited certain inhibitory activity against 8 tested fungi,in which compounds 5r(R=o,o-Cl),5c(R=m-F),5b(R=o-F)and 5p(R=o,p-Cl)displayed better inhibitory activity of 93.3%,76.8%,75.3%and 72.3%,respectively,against P.piricola than that of the positive control chlorothalonil.At the same time,3D-quantitative structure-activity relationship(3D-QSAR)study was carried out to explore the relationship of the molecular structures with their antifungal activity against P.piricola.And a reasonable and effective 3D-QSAR model(r^(2)=0.980,q^(2)=0.501)has been established.Besides,molecular docking was also performed to reveal the binding mode of the target compound 5r(R=o,o-Cl)with succinate dehydrogenase(SDH).It was found that compound 5r could be well embedded in the active pocket of the receptor protein.This showed a similar mode with SDH inhibitors(SDHI)carboxin.

MMP-2和Hydroxamate类抑制剂绝对自由能的计算

采用基于线性响应近似的自由能计算方法计算了一类hydroxamate抑制剂和MMP 2的绝对结合自由能 .计算中 ,催化锌离子和MMP 2以及配体之间采用了非键模型 .分子动力学模拟结果显示 ,采用非键模型时 ,催化Zn离子采用五配位的形式 ,但配位键的形式和初始结构比较有很大的差别 .通过拟合 ,分别得到了单参数、双参数以及三参数的自由能预测模型 ,其中 ,含有常数校正项的三参数模型具有最佳的预测能力 ,预测自由能和实际自由能之间平均绝对误差仅为 2 .38kJ/mol.

Hydroxamate类抑制剂与MMP—3的结合自由能的计算

用自由能微扰方法(FEP)计算了两种hydroxamate类的抑制剂和MMP-3的相对结合自由能.在计算中,对于催化区的锌离子与其共价结合的配体(包括抑制剂和组氨酸)采用了键合的模型,抑制剂和周围配体的部分电荷的计算采用两步静电势收敛方法.自由能计算采用了慢增长(Slow growth)和固定窗口增长(Fixed width window growth)两种方法,并且在每次计算中都采用了双向采样(Double-wide sampling)的策略.两种方法计算得到的相对结合自由能都能和实验值很好的符合.同时从动力学模拟的得到的分子轨迹得到了抑制剂和受体之间相互作用模式,抑制剂的P1部分可以和受体的S1′口袋形成很强的范德华和疏水相互作用,P1上的苯环可以和Tyr223上的苯环形成较好的π键堆积相互作用.

Hydroxamate类抑制剂与MMP—2的分子对接研究

通过分子动力学模拟研究了MMP-2和hydroxamate抑制剂之间的作用模式.在分子动力学模拟中,对于催化区的锌离子和其共价结合的配体(包括抑制剂和组氨酸)采用了键合的模型.从模拟的结果可以看到,R1取代基和MMP-2的S1疏水口袋中的部分残基能形成很好的几何匹配,从而可以产生很强的范德华和疏水相互作用.模拟结果也表明,两个抑制剂和MMP-2之间分别能形成5个和8个氢键,抑制剂B比A活性更高的原因就是能够形成更加有利的氢键作用模式.在整个模拟过程中,催化锌都能保持好的五配位形式,配位键的长度也处于稳定的状态.预测得到的MMP-2和其抑制剂的相互作用模式对于全新抑制剂的设计提供了非常重要的结构信息.

Dioxygen Affinities and Catalytic Oxidation Performance of Cobalt (Ⅱ)Complexes with N—Aryl Hydroxamic Acid

The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.

新显色剂PMNHA的合成、分析鉴定及其在分光光度测定钒中的应用

用１－甲基－２－萘甲酰基替换Ｎ－苯甲酰苯基羟胺（ＢＰＨＡ）的苯甲酰基，合成了一种新显色剂Ｎ－苯基－１－甲氧基－２－萘甲酰氧肟酸（Ｎ－ｐｈｅｎｙｌ－１－ｍｅｔｈｏｘｙ－２－ｎａｐｈｔｈｏｙｌｈｙｄｒｏｘａｍｉｃａｃｉｄ，缩写为ＰＭＮＨＡ）。根据元素分析、差热分析、质谱分析、核磁共振、红外光谱分析，确定ＰＭＮＨＡ的组成和结构为：ＯＣＨ３ＣＯＮＯＨＣ６Ｈ５。该试剂的三氯甲烷溶液能很快从２．２５—４．５０ｍｏｌ／ＬＨＣｌ中萃取钒（Ⅴ）的紫色配合物，其配合物最大吸收在５４０ｎｍ，很多外来离子，特别是大量的钛不干扰钒的测定，钒含量在０—２８μｇ·ｇ－１范围遵守比耳定律。

The soil fungi producing siderophores of Mt.Yangbew,Tawang,La Trinidad,Benguet

Siderophores,being iron-chelators,have received much attention in environmental research,medicine,and biotechnology because of their high affinity and specificity to a wide range of metals.This study aimed to investigate siderophore production of culturable soil fungi from Mt.Yangbew,Tawang,La Trinidad,Benguet and to determine their chemical characteristics.Siderophore production was detected and quantified using Chrome Azurol Sulphonate assay while the siderophore characterization was through FeCl_(3),Csáky’s and Arnow’s tests.It was found that 11 out of 20 pure cultures,which showed positive CAS assay results,produce hydroxamates.ITS primers were used in PCR amplification for the molecular identification of the top-four siderophore-producers.Based on BLASTn analyses of their sequences,the isolates were found to be most homologous to species of Talaromyces,Byssochlamys,Paecilomyces,and Penicillium.The identified species were subjected to phylogenetic analysis using MEGA 7 to the show evolutionary history and relationship among the fungal species.

Flotation performance of anisic hydroxamic acid as new collector for tungsten and tin minerals

In order to improve the recovery of tungsten ores containing tin minerals,anisic hydroxamic acid(p-methoxy benzohydroxanic acid,PMOB)was synthesized and introduced as novel collector in the flotation of scheelite,wolframite and cassiterite.The flotation performance and adsorption mechanism were investigated by micro/batch flotation,zeta potential measurements and density functional theory(DFT).The micro flotation results showed that the recoveries of scheelite,wolframite and cassiterite using PMOB as collector are 97.45%,95.77% and 90.08%,respectively,and the corresponding recoveries are 91.00%,84.30% and 84.67% for benzohydroxamic acid(BHA).The batch flotation results revealed that the collector dosage could be reduced by about 45% for PMOB compared with BHA,in the case of similar flotation indicators.Zeta potential measurements indicated that PMOB could be adsorbed on the mineral surfaces by chemisorption.Moreover,density functional theory(DFT)calculation results showed that the substituent group—OCH_(3)endues PMOB stronger electron donation ability and hydrophobicity compared with benzohydroxamic acid(BHA),pmethyl benzohydroxamic acid(PMB)and p-hydroxyl benzohydroxamic acid(PHB).

A Simple Method for the Isolation and Purification of 2,4-Dihydroxy-7-Methoxy-2H-1,4-Benzoxazin-3(4H)-One (DIMBOA) from Maize (Zea mays L.) Seedlings

2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3（4H）-one （DIMBOA）, the dominant benzoxazinoid hydroxamic acid in maize （Zea Mays L.）, serves as important factors of resistance against insects and microbial diseases, allelochemicals used in competition with other plants. In this paper, a novel and simple method for the isolation and purification of DIMBOA from maize seedlings was developed. Frozen shoots from 7-d-old maize seedlings （1 000×g） were firstly defrosted and then were directly homogenized and extracted with ethyl acetate. The macerate was allowed to stand at room temperature （25±2）°C for 1 h to allow enzymatic release of DIMBOA from DIMBOA-glucoside. Then the ethyl acetate phase was filtered, dried and evaporated to dryness. The resulting light-tan, semicrystalline residue was stored at -20°C for 24 h. Upon recrystallization from acetone-hexane, a relative higher yield （0.58 g） of pure DIMBOA crystals was obtained compared with the yield afforded by Woodward methodology （0.26 g）.

Flotation behavior and adsorption mechanism of fine wolframite with octyl hydroxamic acid

Flotation behavior and adsorption mechanism of octyl hydroxamic acid(OHA)on wolframite were investigated through flotation experiments,adsorption tests,zeta-potential measurements,infrared spectroscopy and solution chemistry calculations.Results of flotation and adsorption experiments show that the maximum values of flotation recovery and adsorption capacity occur around p H 9.In term of the solution chemistry calculations,the concentration of metal hydroxamate is greater than that of metal tungstate and metal hydroxyl,and metal hydroxamate compounds are identified to be the main species on wolframite surface at p H region of 8-10,contributing to the increase of OHA adsorption and flotation performance.Results of zeta-potential and IR spectra demonstrate that OHA adsorbs onto wolframite surface by chemisorptions.Hydroxamate ions can bond with Mn_2+/Fe_2+cations of wolframite surface,forming metal hydroxamate compounds,which is a key factor in inducing the hydrophobicity of wolframite under the conditions of maximum flotation.

Studies of benzyl hydroxamic acid/calcium lignosulphonate addition order in the flotation separation of smithsonite from calcite

Flotation separation of smithsonite from calcite is difficult due to their similar surface properties.In the present study,a reagent scheme of depressant calcium lignosulphonate(CLS) and collector benzyl hydroxamic acid(BHA) was introduced in the flotation of smithsonite from calcite.Microflotation tests revealed that the efficient flotation of smithsonite from calcite could only be obtained with the addition order of BHA before CLS,which was opposite to the widely-used order that adding depressant prior to the collector.The zeta potential measurements indicated that BHA selectively adsorbed onto smithsonite surface,then not allowed the CLS adsorption onto the smithsonite surface rather than calcite surface because of the steric hindrance,thereby the smithsonite surface remained hydrophobic while calcite surface became more hydrophilic after the addition of CLS.As a result,the calcite flotation was completely depressed while the smithsonite flotation recovery was still in high value,leading to the optimal flotation separation performance.

Effect of hydroxamic acid polymers on reverse flotation of bauxite

The effect of hydroxamic acid starch (HAS) and hydroxamic acid polyacrylamide (HPAM) on the flotation of diaspore and kaolinite was investigated by flotation test. It is found that HAS depresses diaspore but activates kaolinite in acidic pulp,while HPAM activates both diaspore and kaolinite in the pH range of 2.010.5. The measurement of zeta potential shows that both HAS and HPAM can increase zeta potential of negatively charged diaspore, which indicates the existence of chemical bonding or hydrogen bonding between the reagents and diaspore. By covering the collector dodecyl amine(DDA) on diaspore surface,HAS increases the hydrophilicity of minerals and depresses the flotation of diaspore,however HPAM activates the flotation of diaspore by increasing the adsorption of DDA on diaspore surface.

Histone deacetylase inhibitor suberoylanilide hydroxamic acid alleviates liver fibrosis by suppressing the transforming growth factor-β1 signal pathway

Background: Histone deacetylases(HDACs) inhibitors are new anti-fibrotic drugs that inhibit the activity of hepatic stellate cells. The present study focused on the anti-fibrotic function of HDAC inhibitor suberoylanilide hydroxamic acid(SAHA) by suppressing transforming growth factor-β1(TGF-β1) signaling. Methods: Male Sprague-Dawley rats were used to induce liver fibrosis with carbon tetrachloride(CCl 4) and LX2 cell(human hepatic stellate cell line) was stimulated by TGF-β1. Both animals and cells were treated with SAHA. The Smad7 and connective tissue growth factor(CTGF) mRNA levels were detected by real-time polymerase chain reaction(PCR). Western blotting was used to examine the protein levels of CTGF, Histone H3(H3), Smad7, Smad2/3, Acetyl-Histone H3(AH3), HDAC2, α-smooth muscle actin( α-SMA), HDAC6, p-Smad2/3 and HDAC8. In addition, the TGF-β1 and liver enzyme levels from rat serum were detected. Histopathological changes were examined by hematoxylin and eosin(HE), Sirius red and Masson trichrome staining. The α-SMA expression was detected by immumohistochemical staining. Results: Compared with control group, the TGF-β1 and liver enzyme levels from rat serum, together with the mRNA levels of CTGF and protein levels of CTGF, HDAC2, α-SMA, HDAC6, p-Smad2/3 and HDAC8 were elevated in fibrotic rats( P < 0.01). But the Smad7 mRNA and AH3 protein levels were notably suppressed in the fibrotic rats( P < 0.01). Pathological examination showed the typical changes of liver fibrosis in the fibrotic rats. After the treatment with SAHA, the levels of liver enzymes, TGF-β1, CTGF, HDAC2, α-SMA, HDAC6, p-Smad2/3 and HDAC8 were reduced( P < 0.01) and Smad7 and AH3 protein contents were elevated in liver fibrotic rats( P < 0.01). Moreover, immumohistochemistry showed that SAHA significantly suppressed the α-SMA protein content in fibrotic liver( P < 0.01). Conclusion: The HDAC inhibitor SAHA alleviated liver fibrosis by suppressing the TGF-β1 signaling.

Depressing effect of hydroxamic polyacrylamide on pyrite

The performance of hydroxamic polyacrylamide(HPAM) in mineral flotation was tested on the samples of calcite, diaspore and pyrite. It is found that HPAM expresses intensive depression on pyrite and can be used as effective depressants for pyrite. The depression mechanism of HPAM to pyrite was investigated by the determination of contact angle, zeta potential, adsorptive capacity for collectors and infrared spectrum. A lower contact angle, more negative zeta potential, less xanthate adsorptive capacity, and the formation of chemical bonding were determined, which reveals that the strong chemical interactions exist between HPAM and pyrite surface. The group electronegativity of HPAM was calculated to explain the differences of interaction between reagent and minerals.

Effects of SAHA on proliferation and apoptosis of hepatocellular carcinoma cells and hepatitis B virus replication

AIM: To investigate the effects of suberoylanilide hydroxamic acid(SAHA) on proliferation and apoptosis of a human hepatocellular carcinoma cell line(HepG2.2.15) and hepatitis B virus(HBV) replication.METHODS: HepG2.2.15 cells were treated with different concentrations of SAHA.Cell morphology was examined by confocal laser scanning microscopy,and cell proliferation was determined using a MTT colorimetric assay.Flow cytometry was used to detect apoptosis and determine cell cycle phase,while hepatitis B surface antigen and hepatitis B e antigen content were measured using chemiluminescence.Reverse transcription polymerase chain reaction was performed to measure HBV DNA in cell lysate.RESULTS: Cell proliferation rates were significantly reduced by the addition of SAHA.The inhibitory effect of SAHA on cell proliferation was both time-and dosedependent.After 24 h of treatment with SAHA,the early cell apoptotic rate increased from 3.25% to 21.02%(P = 0.041).The proportion of G0 /G1 phase cells increased from 50.3% to 65.3%(P = 0.039),while that of S phase cells decreased from 34.9% to 20.6%(P = 0.049).After 48 h of treatment,hepatitis B surface antigen and hepatitis B e antigen content increased from 12.33 ± 0.62 to 25.42 ± 2.67(P = 0.020) and 28.92 ± 1.24 to 50.48 ± 1.85(P = 0.026),respectively.Furthermore,HBV DNA content increased from 4.54 ± 0.46 to 8.34 ± 0.59(P = 0.029).CONCLUSION: SAHA inhibits HepG2.2.15 cell proliferation,promotes apoptosis,and stimulates HBV replication.In combination with anti-HBV drugs,SAHA may potentially be used cautiously for treatment of hepatocellular carcinoma.

Extraction Separation of Germanium with Hydroxamic Acid HGS98

The extraction separation of germanium from indium raffinate in hydrometallurgical zinc process was discussed. The conditions and mechanism of the extraction with hydroxamic acid HGS98 have been investigated in detail. The results show that u sing 2% (mass fraction) hydroxamic acid HGS98 and 5% D 2EHPA as synergist, germanium is extracted (1 stage) over 99% in 5 min at phase ratio ( V o∶ V a) of 1∶5 from indium raffinate with original acidity. Then, using 2 mol·L -1 NH 4F as strip liquor, the stripping recovery is over 98% in 15 min at phase ratio of 1∶1. This process has the following advantages:easy to operate, high recovery and selectivity, and lower investment cost. It provides a new way to recover rare metal-germanium from metallurgical spent residues.