Antioxidant activity of polyaniline nanofibers

Well-confined uniform polyaniline (PANI) nanofibers were synthesized by using photo-assisted chemical oxidative polymer- ization of aniline in the presence of different dopant acids,and the radical scavenging ability of the produced PANI nanofibers was determined by the DPPH assay.It was found that the antioxidant activity of PANI nanofibers was higher than conventional PANI, and increased with decreasing of averaged diameter of the nanofibers.The enhanced antioxidant activity was concerned with increased surface area of PANI nanofibers.     

Regulation of β-amylase activity by alkylresorcinols

The effects of two alkylresorcinols, namely, methylresorcinol (MR) and hexylresorcinol (HR), which are chemical analogues of the natural anabiosis factors of some bacteria, on the catalytic activity of β-amylase has been investigated. When water-soluble potato starch is used as a substrate, MR in a concentration ranging from 0.8 to 12.9 mmol/L raises the activity of β-amylase to 170%. HR at a concentration ranging from 0.05 to 0.35 mmol/L stimulates a weak increase in the activity of β-amylase to 115%. A further increase in the concentration (0.75 mmol/L) leads to inhibition by 50%. The interaction of MR with β-amylase allows one to increase the general yield of the hydrolysis products of potato and malt starch by 1.5 to 1.6 times, to enhance the rate of hydrolysis by 4 to 5 times, and to extend the temperature and pH ranges of catalysis. Non-competitive activation in the presence of MR and non-competitive inhibition in the presence of HR are observed upon determining the kinetic parameters of the starch hydrolysis by β-amylase modified with alkylresorcinols.     

Prediction of the activity of β-lactam antibiotics

The pharmacological properties of penam, 3-cepheme, and semisynthetic penicillins were predicted by means of the ORAKUL automated system. A comparative evaluation of the similarity between the structures of these compounds and the structures of 8800 biologically active substances in the data base of the system made it possible to uncover the high probability of the manifestation of anti-inflammatory, analgesic, antitumorigenic, antiallergic, and anticoagulant activity by structural analogs of -lactam antibiotics.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 555–564, April, 1992.     

Defect-rich and ultrathin nitrogen-doped carbon nanosheets with enhanced peroxidase-like activity for the detection of urease activity and fluoride ion

Although carbon nanozymes have attracted great interest due to their good biocompatibility, low cost,and high stability, designing high-active carbon nanozymes still faces great challenges. Herein, ultrathin nitrogen-doped carbon nanosheets with rich defects(d-NC) were prepared through a high-temperature annealing process, using potassium chloride and ammonium chloride as templates. Owing to the large specific surface area, rich defects and the high exposure of active sites, the proposed d-NC na...     

Neat synthesis and antioxidant activity of α-aminophosphonates

A simple, efficient, and environmentally benign method for a three-component reaction of an amine, an aldehyde and diethyl phosphite catalyzed by Amberlyst-15 has been developed to afford α-amino phosphonates in high yields and short reaction times under solvent-free reaction conditions using microwave irradiation. The major advantages of the present method are inexpensive, ecofriendly and reusable catalyst and also studied their antioxidant activity of synthesized compounds.     

Synthesis and antimycobacterial activity of N-isonicotinoyl-N′-alkylideneferrocenecarbohydrazides

Russian Chemical Bulletin - Acylation of ferrocenoylhydrazones with isonicotinoyl chloride hydrochloride in pyridine was used to obtain a number of new...     

Synthesis and antitumor activity of 9-methyl-10-hydroxycamptothecin

A novel camptothecin analogue, 9-methyl-10-hydroxycamptothecin （4）, was unexpectedly synthesized from 10-hydroxycamptothecin in two steps. The key step included an efficient Mannich-type reaction. The overall yield was 47.2%. An ether analogue of 4, 9-methyl-10-benzylaminomethoxycamptothecin （5）, was also prepared. These new camptothecin analogues were evaluated for in vitro cytotoxicity against four human cancer cell lines, and exhibited more potent antitumor activities than contrals camptothecin and topotecan against several cancer cells.     

AuPt core–shell nanocatalysts with bulk Pt activity

In the presented work, the evaluation of an unsupported AuPt core–shell catalyst for the oxygen reduction reaction is introduced. Applying only basic chemicals in an upscalable synthesis route, it is demonstrated that uniform, flat, and complete Pt layers around a spherical Au core are obtained. The electrocatalytic measurements show that the surface area specific activity of the AuPt core–shell catalyst towards the important oxygen reduction reaction equals the one of polycrystalline bulk Pt. To our knowledge, this is the first time that the unfavorable particle size effect of Pt nanoparticles could be by-passed for a nanoscale catalyst.     

Synthesis and α-amylase inhibitory activity of glucose-deoxynojirimycin conjugates

Inhibitors of α-amylase have attracted attention for their putative effects against diabetes mellitus. Although numerous studies have explored natural small molecule inhibitors, acarbose is currently the only compound with sufficient inhibitory potency and drug-like characteristics to be considered as a potential therapeutic agent. We have synthesized conjugates of the potent glucosidase inhibitor, 1-deoxynojirimycin, and glucose, with the aim of enhancing inhibitory activity against α-amylase. This synthetic conjugate showed increased inhibition of α-amylase compared to 1-deoxynojirimycin alone, suggesting that similar modifications of existing glucosidase inhibitors may yield more potent α-amylase inhibitors.     

Synthesis and NHE1 inhibitory activity of ligustrazine derivatives

A series of novel derivatives of ligustrazine linked with substituted benzoyl guanidine were synthesized. These compounds have not been reported in literature, and their chemical structures were confirmed by IR, 1H NMR and MS. The results of NHE1 inhibitory activity test showed that compounds I2, I3, I4, I6, and I7 possess more potent NHE1 inhibitory activity than cariporide.     

Anticancer β-hairpin peptides: membrane-induced folding triggers activity

Several cationic antimicrobial peptides (AMPs) have recently been shown to display anticancer activity via a mechanism that usually entails the disruption of cancer cell membranes. In this work, we designed an 18-residue anticancer peptide, SVS-1, whose mechanism of action is designed to take advantage of the aberrant lipid composition presented on the outer leaflet of cancer cell membranes, which makes the surface of these cells electronegative relative to the surface of noncancerous cells. SVS-1 is designed to remain unfolded and inactive in aqueous solution but to preferentially fold at the surface of cancer cells, adopting an amphiphilic β-hairpin structure capable of membrane disruption. Membrane-induced folding is driven by electrostatic interaction between the peptide and the negatively charged membrane surface of cancer cells. SVS-1 is active against a variety of cancer cell lines such as A549 (lung carcinoma), KB (epidermal carcinoma), MCF-7 (breast carcinoma), and MDA-MB-436 (breast carcinoma). However, the cytotoxicity toward noncancerous cells having typical membrane compositions, such as HUVEC and erythrocytes, is low. CD spectroscopy, appropriately designed peptide controls, cell-based studies, liposome leakage assays, and electron microscopy support the intended mechanism of action, which leads to preferential killing of cancerous cells.     

Inhibition of cyclodextrins on the activity of α-amylase

α-amylase activity influences both flour fermentation process and the quality of the fermented products due to its ability of breaking starch into smaller units. The inhibition of cyclodextrins on α-amylase activity was investigated in this paper. Experiment results showed that hydrophobic cavity size was an intrinsic factor during the inhibition processing. Among three types of cyclodextrin (α-, β- and γ-), β-type exhibited the most significant inhibitory activity toward α-amylase. The optimal inhibitory parameters were indicated to be pH 5.9, concentration of β-cyclodextrins 1 mmol/L, reaction temperature 45 °C and reaction time 60 min. Results suggested that the endogenous fluorescence of α-amylase was inhibited by cyclodextrins. Circular dichroism spectrum indicated that the secondary structure of α-amylase, including α-helices, β-sheets and random coils, was changed by cyclodextrins. All the results in this paper aim to provide a further understanding for α-amylase in the industry application.     

α-Amino acid-derived 2-phenylimidazoles with potential antimycobacterial activity

α-Amino acid-derived 2-phenylimidazole derivatives were designed, synthesized, and further investigated as potential antimycobacterial agents. The synthesis of target imidazole derivatives involved the transformation of Cbz-protected α-amino acids (Ala, Val, Phe, Leu, iLe, and Pro) into α-diazoketones and α-bromoketones, respectively. Subsequent treatment of α-bromoketones with (4-nitro)benzamidine afforded imidazole derivatives bearing α-amino acid residue appended to the imidazole C4 and (4-nitro)phenyl ring in the position C2. Antimycobacterial activities of both series of compounds against M. tuberculosis, M. avium, and M. kansasii were screened and basic structure-activity relationships were further evaluated.      

Off-target activity of TNF-α inhibitors characterized by protein biochips

Tumor necrosis factor-alpha inhibitors are widely and successfully used to treat rheumatic diseases. However, significant side effects have been reported. To detect the potential off-target activities of such inhibitors we characterized two therapeutic antibodies (adalimumab, infliximab) and one receptor fusion protein (etanercept) on protein biochips (UNIchip AV-400) containing a printed serial dilution of tumor necrosis factor-alpha and about 384 different human proteins. Etanercept binds to ten proteins (affinity: 20-33% of tumor necrosis factor-alpha recognition), and six of these proteins are related to ribosomal proteins. Interestingly, adalimumab binds to the same six proteins related to ribosomal proteins (affinity: 12-18%) as well as to four proteins crucially involved in ribosomal protein synthesis. Alignment of protein sequences indicates no significant sequence homology between these ten proteins bound by the biological drugs with the highest off-target activities. Taken together, our in vitro results demonstrate that a significant number of proteins are recognized by tumor necrosis factor-alpha inhibitors and are related to ribosome biogenesis.     

Synthesis and antitumor activity of derivatives of 23-hydroxybetulinic acid

A series of natural product 23-hydroxybetulinic acid derivatives were prepared.In the preparation of mono-O-benzoyl ester derivative,it was observed that benzoyl group migrated from 3-O-to 23-O-position during the detritylation.     

A novel mass spectrometry-based assay for GSK-3β activity

Background  

As a component of the progression from genomic to proteomic analysis, there is a need for accurate assessment of protein post-translational modifications such as phosphorylation. Traditional kinase assays rely heavily on the incorporation of γ-P³² radiolabeled isotopes, monoclonal anti-phospho-protein antibodies, or gel shift analysis of substrate proteins. In addition to the expensive and time consuming nature of these methods, the use of radio-ligands imposes restrictions based on the half-life of the radionucleotides and pose potential health risks to researchers. With the shortcomings of traditional assays in mind, the aim of this study was to develop a high throughput, non-radioactive kinase assay for screening Glycogen Synthase Kinase-3beta (GSK-3β) activity.     

Magic angle Raman optical activity: β-pinene and nopinone

Applying the Stokes—Mueller formalism to the case of right angle scattering of chiral molecules randomly oriented in an optically isotropic phase, orientations of the polarization analyzer in the scattered beam at the ‘magic angle’ of ∼ ±35.26° to the vertical have been identified to isolate the pure magnetic dipole contribution to the ROA intensity. Magic angle ROA spectra of(−) β-pinene and (+) nopinone from 350 to 1350 cm⁻¹ are presented as first examples. Comparing the magic angle ROA spectra of both terpenes with their corresponding depolarized spectra, the origin of the couplet at 716 and 765 cm⁻¹ in the magic angle ROA spectrum of β-pinene is ascribed to interactions between deformations and torsions of the olefinic group with a skeletal mode of the pinane structure.     

Dissociation and catalytic activity of oligomer forms of β-galactosidases

The dissociation of oligomer forms of bacterial Escherichia coli, yeast Kluyveromices fragilis, and bovine liver β-galactosidases was studied. The catalytic constants for the dimers and tetramers of the bacterial enzyme, dimers and monomers of the animal enzyme, and dimers of the yeast enzyme in the reaction of hydrolysis of 2-nitrophenyl-β-D-galactopyranoside were determined. At 25°C, these values were found to be 180 and 400 s^?1 for the bacterial enzyme, 0.01 and 0.08 s^?1 for the bovine liver enzyme, and 45.4 s^?1 for the yeast enzyme, respectively. The other oligomer forms of the β-galactosidases were inactive under conditions of these experiments.