Effect of Additives on the Activity of Tannase from <Emphasis Type="Italic">Aspergillus awamori</Emphasis> MTCC9299

Tannase from Aspergillus awamori MTCC 9299 was purified using ammonium sulfate precipitation followed by ion-exchange chromatography. A purification fold of 19.5 with 13.5% yield was obtained. Temperature of 30 °C and pH of 5.5 were found optimum for tannase activity. The effects of metals and organic solvents on the activity of tannase were also studied. Metal ions Mg⁺², Mn⁺², Ca⁺², Na⁺, and K ⁺ stimulated the tannase activity, while Cu⁺², Fe⁺³, and Co⁺² acted as inhibitors of the enzyme. The addition of organic solvents like acetic acid, isoamylalcohol, chloroform, isopropyl alcohol, and ethanol completely inhibited the enzyme activity. However, butanol and benzene increased the enzyme activity.     

Synthesis and Antioxidant Activities of Novel 4,4′‐Arylmethylene‐bis(1H‐pyrazole‐5‐ol)s from Lignin

A series of novel bispyrazoles joined by arylmethylene at C‐4 position were synthesized with aromatic aldehydes obtained from lignin and screened for their in vitro antioxidant activities by N,N‐diphenyl‐N′‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis(3‐ethylenzothiazoline‐sulphonic acid) diammonium salt (ABTS⁺) radical scavenging assays. All of these compounds exhibited good DPPH and ABST⁺ radical scavenging activities as compared to the standard, Trolox, which suggested their potential as promising agents for curing tumors or other free radical‐related diseases.     

Synthesis,Structure Elucidation and H+/K+‐ATPase Inhibitory Activity of Bisabolangelone Reduction Derivatives

Nine bisabolangelone reduction derivatives were synthesized and separated as potential anti‐ulcer agent. Their structures were characterized by 2D NMR, IR, ESI‐MS, elemental analysis and single‐crystal X‐ray diffraction analysis. Preliminarily H⁺/K⁺‐ATPase activity evaluation indicated that all the target compounds had a certain inhibitory effect, and compounds II and IV exhibited the better inhibitory activity against H⁺/K⁺‐ATPase than bisabolangelone and the commercial omeprazole with the IC₅₀ of 23.21 and 65.32 μmol/L, respectively. The initial structure‐activity analysis suggested that the presence of carbonyl group in six‐membered ring and double bond in side‐chain seemed to be necessary to the activity.     

Purification and Characterization of Lectins from Jute (Chorchorus olitorius) Leaves

Three lectins were isolated from an extract of jute leaves (Chorchorus olitorius) and purified by gel filtration on Sephadex G‐50 of the 100% ammonium sulfate saturated crude extract, followed by ion‐exchange chromatography on DEAE‐cellulose were designated as JLL‐1, JLL‐2 and JLL‐3. All the lectins were homogeneous as judged by SDS‐polyacrylamide slab gel electrophoresis and gave single bands. The molecular weights of the three lectins were estimated by the same method were 35000, 38000 and 42000, respectively. The lectins specifically agglutinated rat red blood cells. The agglutination of JLL‐1 was inhibited by D‐mannose/D‐glucose and their derivatives, whereas D‐galactose was found to be the potent inhibitor for the agglutination of JLL‐2 and JLL‐3. The lectins were glycoprotein in nature with a neutral sugar content of 1.3%, 1.2% and 0.8% for JLL‐1, JLL‐2 and JLL‐3, respectively. The hemagglutinating activity of JLL‐2 was also investigated after the treatment of physico‐chemical agents. The lectin showed maximum activity between the range of pH 7.2–8.0 and the range of temperature of 20‐30 °C. The activity of lectin decreased after treatment with a higher concentration of acetic acid and urea. In the presence EDTA the activity was inhibited while the presence of Ca⁺², Mn⁺² and K⁺ increased the activity of the lectin moderately.     

Purification and characterization of a microbial dehydrogenase

Pseudomonas fluorescens (strain BTP9) was found to have at least two NAD(P)-dependent vanillin dehydrogenases: one is induced by vanillin, and the other is constitutive. The constitutive enzyme was purified by ammonium sulfate fractionation, gel-filtration, and Q-Sepharose chromatography. The subunit Mr value was 55,000, determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The native M _r value estimated by gelfiltration chromatography gave a value of 210,000. The enzyme made use of NAD⁺ less effectively than NADP⁺. Benzaldehyde, 4-hydroxybenzaldehyde, hexanal, and acetaldehyde were not oxidized at detectable rates in the presence of NAD⁺ or NADP⁺. The ultraviolet absorption spectrum indicated that there is no cofactor or prosthetic group bound. The vanillin oxidation reaction was essentially irreversible. The pH optimum was 9.5 and the pI of the enzyme was 4.9. Enzyme activity was not affected when assayed in the presence of salts, except FeCl₂. The enzyme was inhibited by the thiol-blocking reagents 4-chloromercuribenzoate and N-ethylmaleimide. NAD⁺ and NADP⁺ protected the enzyme against such a type of inhibition along with vanillin to a lesser extent. The enzyme exhibited esterase activity with 4-nitrophenyl acetate as substrate and was activated by low concentrations of NAD⁺ or NADP⁺. We compared the properties of the enzyme with those of some well-characterized microbial benzaldehyde dehydrogenases.     

Characterization of xylitol dehydrogenase from debaryomyces hansenii

The xylitol dehydrogenase (EC 1.1.1.9) from xylose-grown cells ofDebaryomyces hansenii was partially purified in two Chromatographic steps, and characterization studies were carried out in order to inves tigate the role of the xylitol dehydrogenase-catalyzed step in the regu lation of D-xylose metabolism. The enzyme was most active at pH 9.0–9.5, and exhibited a broad polyol specificity. The Michaelis con stants for xylitol and NAD⁺ were 16.5 and 0.55 mM, respectively. Ca²⁺, Mg²⁺, and Mn²⁺ did not affect the enzyme activity. Conversely, Zn²⁺, Cd²⁺, and Co²⁺ strongly inhibited the enzyme activity. It was concluded that NAD⁺-xylitol dehydrogenase from D.hansenii has similarities with other xylose-fermenting yeasts in respect to optimal pH, substrate specificity, and K_m value for xylitol, and therefore should be named L-iditol:NAD⁺-5-oxidoreductase (EC 1.1.1.14). The reason D.hansenii is a good xylitol producer is not because of its value of K_m for xylitol, which is low enough to assure its fast oxidation by NAD⁺ xylitol dehydrogenase. However, a higher K_m value of xylitol dehydro genase for NAD⁺ compared to theK _m values of other xylose-ferment ing yeasts may be responsible for the higher xylitol yields.     

Purification and Characterization of Extracellular Inulinase from a Marine Yeast <Emphasis Type="Italic">Cryptococcus aureus</Emphasis> G7a and Inulin Hydrolysis by the Purified Inulinase

The extracellular inulinase in the supernatant of the cell culture of the marine yeast Cryptococcus aureus G7a was purified to homogeneity with a 7.2-fold increase in specific inulinase activity compared to that in the supernatant by ultrafiltration, concentration, gel filtration chromatography (Sephadex™ G-75), and anion exchange chromatography (DEAE sepharose fast flow anion exchange). The molecular mass of the purified enzyme was estimated to be 60.0 kDa. The optimal pH and temperature of the purified enzyme were 5.0 and 50 °C, respectively. The enzyme was activated by Ca²⁺, K⁺, Na⁺, Fe²⁺, and Zn²⁺. However, Mg²⁺, Hg²⁺, and Ag⁺ acted as inhibitors in decreasing the activity of the purified inulinase. The enzyme was strongly inhibited by phenylmethanesulphonyl fluoride (PMSF), iodoacetic acid, EDTA, and 1,10-phenanthroline. The K _m and V _max values of the purified enzyme for inulin were 20.06 mg/ml and 0.0085 mg/min, respectively. A large amount of monosaccharides were detected after the hydrolysis of inulin with the purified inulinase, indicating the purified inulinase had a high exoinulinase activity.     

Knudsen effusion mass spectrometric determination of mixing thermodynamic data of liquid Ag–In–Sn alloy

The vaporisation of a liquid Ag–In–Sn system has been investigated at 1273–1473 K by Knudsen effusion mass spectrometry (KEMS) and the data fitted to a Redlich–Kister–Muggianu (RKM) sub-regular solution model. Nineteen different compositions have been examined at six fixed indium mole fractions, X_In = 0.10, 0.117, 0.20, 0.30, 0.40 and 0.50. The ternary L-parameters, the thermodynamic activities and the thermodynamic properties of mixing have been evaluated using standard KEMS procedures and from the measured ion intensity ratios of Ag⁺ to In⁺ and Ag⁺ to Sn⁺, using a mathematical regression technique described by us for the first time. The intermediate data obtained directly from the regression technique are the RKM ternary L-parameters. From the obtained ternary L-parameters the integral molar excess Gibbs free energy, the excess chemical potentials, the activity coefficients and the activities have been evaluated. Using the temperature dependence of the activities, the integral and partial molar excess enthalpies and entropies were determined. In addition, for comparison, for some compositions, also the Knudsen effusion isothermal evaporation method (IEM) and the Gibbs–Duhem ion intensity ratio method (GD-IIR) were used to determine activities and good agreement was obtained with the data obtained from fitting to the RKM model.     

Metal-containing polyurethanes from tetradentate Schiff bases: synthesis,characterization, and biocidal activities

N,N′-bis(salicylidene)thiosemicarbazide Schiff base has been synthesized by the reaction of thiosemicarbazide with salicylaldehyde and then reacted with formaldehyde to generate phenolic groups, resulting in the formation of Schiff-base monomeric ligand. It was further incorporated with transition metals, Mn⁺², Co⁺², Ni⁺², Cu⁺², and Zn⁺², to form Schiff-base metal complex, which was then polymerized with toluene 2,4-diisocyanate to form metal-chelated polyurethanes. Monomeric ligand, its metal complexes, and its metal polychelates were characterized and compared by elemental analysis, FT-IR, ¹H NMR, thermal, and biocidal activities to evaluate the enhancement in physical and chemical properties on coordination with metal and on polymerization. SEM images of ligand and polymer metal complexes showed changes in surface morphology, while electronic spectra of polymer metal complexes were used to predict the geometry. Antimicrobial activities were determined by using agar-diffusion method with Staphylococcus aureus, Escherichia coli, Bacillus subtilis (bacteria), Aspergillus niger, Candida albicans, and Aspergillus flavus (yeast). The polymeric ligand had varied antibacterial and antifungal activities, enhanced after chelation and polymerization. Comparative results show that coordination of metal to the ligand enhances its physical and chemical properties which were meliorated on polymerization.     

Kinetics and mechanism of silver(I) catalysed autoxidation of aqueous sulphur(IV) in acetate buffered medium

The kinetics of the silver(I) catalysed autoxidation of aqueous sulphur(IV) an acetate buffered medium obey the rate law: –d[S^IV]/dt = D[Ag^I][S^IV]²[H⁺]^–1/(B+C[S^IV]). The rate is independent of [O₂] but strongly inhibited by EtOH. A free radical mechanism is proposed.     

Decreased Activity of Ca++-ATPase and Na+/K+-ATPase during Aging in Humans

Aging is a biological process characterized by a progressive functional impairment which is associated with increased susceptibility to a variety of diseases. The main purpose of this study is to understand the gender-based relationship between human aging and activities of two erythrocyte membranes bound enzymes, Ca⁺⁺-ATPase and Na⁺/K⁺-ATPase. Ca⁺⁺-ATPase and Na⁺/K⁺-ATPase activities were determined as per the previous reports. Statistical differences were analyzed with Student’s t test. Our results show a significant (p?<?0.0001) decrease in the Ca⁺⁺-ATPase and Na⁺/K⁺-ATPase activities in males and females as a function of age. We also correlate the activities of ATPases with total antioxidant capacity of the plasma in term of ferric reducing ability of plasma values. The Ca⁺⁺-ATPase and Na⁺/K⁺-ATPase activities positively correlated with ferric reducing ability of plasma value. No significant differences in the ATPase activity between males and females were observed. Decreased activity of Ca⁺⁺-ATPase and Na⁺/K⁺-ATPase during human aging may be due to increased free radical generation which leads to oxidative stress and alter the erythrocyte membrane transport function and other activities. Our results emphasize the need to establish age-dependent reference values for membrane bound enzymes in studies involving its role in different disease conditions.     

Magnesium chloride supported catalysts for olefin polymerization. XIX. Titanium oxidation states,catalyst deactivation,and active site structure

A precise method for the determinations of Ti⁺², Ti⁺³ and Ti⁺⁴ was developed. The CW-procatalyst before activation contains mostly Ti⁺⁴ ions with 6% Ti⁺³ and 4% Ti⁺² ions. Activation with AlEt₃ alone at room temperature reduced all the titaniums to lower valence states consisting of 71% Ti⁺³ and 29% Ti⁺². Reduction is incomplete when methyl-p-toluate was present as external Lewis base during activation: at 25°C the distribution of Ti⁺⁴ : Ti⁺³ : Ti⁺² is 36% : 25% : 38%; the distribution at 50°C is 37% : 22% : 40%. Aging of the activated catalyst caused little or no changes in the distribution of [Ti⁺ⁿ]; whereas the catalytic activity decays rapidly with aging. The aged catalysts have polymerization activity comparable to the decreased activity of the catalyst during a polymerization. The [Ti⁺ⁿ] was determined for the CW-catalyst during the course of a decene polymerization; they were found to be Ti⁺⁴ : Ti⁺³ : Ti⁺² = 30% : 27% : 43%, which did not change with polymerization time. These results suggest that the reducibility of Ti⁺⁴ species by AlEt₃ or 3AlEt₃/MPT to different valence states is predicated by their structures. These species do not undergo further changes in their oxidation states during either aging or polymerization. Their decays probably involve nonreductive metathesis reactions like those known for zirconium alkyls. Possible structures for the stereospecific and nonspecific sites are proposed.     

Design,Synthesis and Biological Evaluation of Novel N‐(4‐([2,2′:5′,2′′‐Terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) Benzamide Derivatives

On the basis of the principle of combination of active groups, a series of novel N‐(4‐([2,2′:5′,2′′‐terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) benzamide derivatives were designed, synthesized and systematically evaluated for their antiviral activity against tobacco mosaic virus (TMV). The bioassay results showed that most of these compounds displayed good anti‐TMV activity, and some of them exhibited higher antiviral activity than commercial Ningnanmycin. Especially, compound 8e with excellent anti‐TMV activity (inactivation activity, 92.3%/500 µg·mL^?1; curative activity, 85.7%/500 µg·mL^?1 and protection activity, 64.7%/500 µg·mL^?1) emerged as a potential inhibitor of plant virus TMV. Quantitative structure‐activity relationship studies proved that the van der Waals volume (V) and electronic parameter (∑(∑σ_o+σ_p) and ∑σ_m) for the substituent R¹ were very important for antiviral activities in this class of compounds.     

Potassium‐Ion‐Assisted Regeneration of Active Cyano Groups in Carbon Nitride Nanoribbons: Visible‐Light‐Driven Photocatalytic Nitrogen Reduction

As a metal‐free nitrogen reduction reaction (NRR) photocatalyst, g‐C₃N₄ is available from a scalable synthesis at low cost. Importantly, it can be readily functionalized to enhance photocatalytic activities. However, the use of g‐C₃N₄‐based photocatalysts for the NRR has been questioned because of the elusive mechanism and the involvement of N defects. This work reports the synthesis of a g‐C₃N₄ photocatalyst modified with cyano groups and intercalated K⁺ (mCNN), possessing extended visible‐light harvesting capacity and superior photocatalytic NRR activity (NH₃ yield: 3.42 mmol g^?1 h^?1). Experimental and theoretical studies suggest that the ‐C≡N in mCNN can be regenerated through a pathway analogous to Mars van Krevelen process with the aid of the intercalated K⁺. The results confirm that the regeneration of the cyano group not only enhances photocatalytic activity and sustains the catalytic cycle, but also stabilizes the photocatalyst.     

Synthesis,antimicrobial activity,and molecular docking study of formylnaphthalenyloxymethyl‐triazolyl‐N‐phenylacetamides

In the present study, substituted formylnaphthalenyloxymethyl‐triazolyl‐N‐phenylacetamide derivatives ( 6a – k ) have been designed and synthesized employing click chemistry approach and evaluated for their in vitro antifungal and antibacterial activities. All the newly synthesized compounds were thoroughly characterized by ¹H NMR, ¹³C NMR, and HRMS spectral techniques. Among the screened compounds, 6d , 6e , 6j , and 6k have shown good antifungal and antibacterial activities. Compound 6k has shown very effective antimicrobial activity. We further performed exploratory docking studies on microbial DNA gyrase to rationalize the in vitro biological data and to demonstrate the mechanism of antimicrobial activity. This is the first report to demonstrate the formylnaphthalenyloxymethyl, triazole, and N‐phenylacetamide hybrids as potential antimicrobial agents.     

Purification and Characterization of Cell Suspensions Peroxidase from Cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.)

Two peroxidases, cPOD-I and rPOD-II, have been isolated and purified from cotton cell suspension and their biochemical characteristics studied. rPOD-II from R405-2000, a non-embryogenic cultivar, has higher activity than cPOD-I derived from Coker 312, which developed an embryogenic structure. The cPOD-I and rPOD-II had molecular mass of 39.1 and 64 kDa respectively, as determined by SDS-PAGE. Both enzymes showed high efficiency of interaction with the guaiacol at 25 mM. The optimal pH for cPOD-I and rPOD-II activity was 5.0 and 6.0, respectively. The enzyme had an optimum temperature of 25 °C and was relatively stable at 20–30 °C. The isoenzymes were highly inhibited by ascorbic acid, dithiothreitol, sodium metabisulfite, and β-mercaptoethanol. Their activities were highly enhanced by Al³⁺, Fe³⁺, Ca²⁺, and Ni²⁺, but they were moderately inhibited by Mn²⁺ and K⁺. The enzyme lost 50% to 62% of its activity in the presence of Zn²⁺ and Hg²⁺.     

Isolation and Characterization of a Novel Thermophilic-Organic Solvent Stable Lipase From <Emphasis Type="Italic">Acinetobacter baylyi</Emphasis>

The benzene tolerant Acinetobacter baylyi isolated from marine sludge in Angsila, Thailand could constitutively secrete lipolytic enzymes. The enzyme was successfully purified 21.89-fold to homogeneity by ammonium sulfate precipitation and gel-permeable column chromatography with a relative molecular mass as 30 kDa. The enzyme expressed maximum activity at 60°C and pH 8.0 with p-nitrophenyl palmitate as a substrate and found to be stable in pH and temperature ranging from 6.0-9.0 to 60-80°C, respectively. A study on solvent stability revealed that the enzyme was highly resisted to many organic solvents especially benzene and isoamyl alcohol, but 40% inhibited by decane, hexane, acetonitrile, and short-chain alcohols. Lipase activity was completely inhibited in the presence of Fe²⁺, Mn²⁺, EDTA, SDS, and Triton X-100 while it was suffered detrimentally by Tween 80. The activity was enhanced by phenylmethylsulfonyl fluoride (PMSF), Na⁺, and Mg²⁺ and no significant effect was found in the presence of Ca²⁺ and Li⁺. Half of an activity was retained by Ba²⁺, Ag⁺, Hg⁺, Ni²⁺, Zn²⁺, and DTT. The enzyme could hydrolyze a wide range of p-nitrophenyl esters, but preferentially medium length acyl chains (C₈-C₁₂). Among natural oils and fats, the enzyme 11-folds favorably catalyzed the hydrolysis of rice bran oil, corn oil, sesame oil, and coconut oil in comparison to palm oil. Moreover, the transesterification activity of palm oil to fatty acid methyl esters (FAMEs) revealed 31.64 ± 1.58% after 48 h. The characteristics of novel A. baylyi lipase, as high temperature stability, organic solvent tolerance, and transesterification capacity from palm oil to FAMEs, indicate that it could be a vigorous biocatalyzer in the prospective fields as bioenergy industry or even in organic synthesis and pharmaceutical industry.     

Isolation and structural elucidation of novel antimicrobial compounds from maggots of Chrysomyis megacephala Fabricius

The excretions/secretions from the maggot of Chrysomyis megacephala Fabricius are traditionally used to treat serious infections in China. In this study, bioassay-guided fractionation led to the isolation of three novel antibacterial compounds (1–3), including important fluorinated compounds (3 and 5), together with other nine known compounds from 70% methanol extract of C. megacephala. The structures of the new compounds were elucidated by NMR spectroscopic analysis and high-resolution mass spectroscopy. The antibacterial activities of the isolated compounds were evaluated using agar disc diffusion method. New compounds 1 and 2 exhibited moderate activity against Bacillus subtilis with a minimum inhibitory concentration (MIC) of 250 μg mL^? 1. The most active compounds 3 and 5 displayed a broad spectrum of antimicrobial activity with an MIC of 125 μg mL^? 1 against G⁺ and G^?  bacteria. The structure of the above-mentioned novel compounds and their antimicrobial activities are herein reported for the first time from the natural product of insects.     

Antimalarial activity in Xylocarpus granatum (Koen)

The antimalarial activity of Xylocarpus granatum fruits and their active constituents gedunin and xyloccensin-I were investigated using an in?vitro model in this study. The chloroform fraction of X. granatum fruits was found to show promising antimalarial activity using an in?vitro model of Plasmodium falciparum. On purification of the active fraction, four pure compounds were isolated and characterised, namely gedunin, photogedunin, xyloccensin-I and palmitic acid. Out of these only gedunin and xyloccensin-I were found to show activity equivalent to the parent active fraction in?vitro model.     

Lipophilic Di- and Triamides as Ionophores for Alkaline Earth Metal Cations

Different electrically neutral lipophilic di- and triamides were prepared and their ion selectivity in membranes studied. In membranes the ionophore N, N′-diheptyl-N, N′-dimethyl-succinamide prefers Ca²⁺ over Mg²⁺ by a factor of 20 but rejects Na⁺ and K⁺ in respect to Mg²⁺ by a factor of 100 and 10, respectively. This selectivity suffices to perform useful intracellular Mg²⁺ activity studies.