• Journal of Microbiology and Biotechnology
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• v.21 no.10
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• pp.1036-1042
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• 2011

The exopolysaccharide botryosphaeran ($EPS_{GLC}$; a ($1{\rightarrow}3$)($1{\rightarrow}6$)-${\beta}$-D-glucan from Botryosphaeria rhodina MAMB-05) was sulfonated to produce a water-soluble fraction ($EPS_{GLC}$-S) using pyridine and chlorosulfonic acid in formamid. This procedure was then repeated twice to produce another fraction ($EPS_{GLC}$-RS) with a higher degree of substitution (DS, 1.64). The purity of each botryosphaeran sample (unsulfonated and sulfonated) was assessed by gel filtration chromatography (Sepharose CL-4B), where each polysaccharide was eluted as a single symmetrical peak. The structures of the sulfonated and re-sulfonated botryosphaerans were investigated using ultraviolet-visible (UV-Vis), Fourier-transform infrared (FT-IR), and $^{13}C$ nuclear magnetic resonance ($^{13}C$ NMR) spectroscopies. $EPS_{GLC}$ and $EPS_{GLC}$-RS were also assayed for anticoagulation activity, and $EPS_{GLC}$-RS was identified as an anticoagulant.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.200-208
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• 2017

Actinobacteria are prolific producers of a large number of natural products with diverse biological activities. In the present study, an actinobacterium isolated from sunflower rhizosphere soil sample collected from Medak, Andhra Pradesh, South India was identified as Amycolatopsis thermoflava strain SFMA-103. A pigmented secondary metabolite in culture broth was extracted by using methanol and it was further purified by silica gel column chromatography with methanol-chloroform solvent system. Structural elucidation studies based on UV-visible, 1D and 2D-NMR, FT-IR, and mass spectroscopic analyses confirmed the structure as 1-methoxy-3-methyl-8-hydroxy-anthraquinone. It showed significant in vitro anticancer activity against lung cancer and lymphoblastic leukemia cells with $IC_{50}$ values of 10.3 and $16.98{\mu}M$, respectively. In addition, 1-methoxy-3-methyl-8-hydroxy-anthraquinone showed good free radical scavenging activity by DPPH method with an $EC_{50}$ of $18.2{\mu}g/ml$. It also showed other promising superoxide radical scavenging, nitric oxide radical scavenging and inhibition of lipid peroxidation activities. This is a first report of anti-proliferative and antioxidant activities of 1-methoxy-3-methyl-8-hydroxy-anthraquinone isolated from A. thermoflava strain SFMA-103 which may find potential application in biotechnological and pharmaceutical fields.

• Macromolecular Research
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• v.9 no.2
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• pp.116-121
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• 2001

A series of poly(1,4-phenylenevinylene-alt-3-alkyl-2,5-thienylenevinylene)s (alkyl = hexyl [PPV-alt-6-TV] and octyl (PPV-alt-8-TV] group) have been synthesized by the Heck coupling reaction. These polymers were characterized using $^1$H-NMR, FT-IR spectroscopy, and thermogravimetric analysis (TCA). They are solvent processible and have obviously copolymeric structure. The photophysical properties of the polymers were investigated using UV-visible and steady-state photoluminescence(PL) spectroscopy. We studied the change of light-emitting properties by incorporating the thiophene group into the PPV polymer backbone using alternating copolymer system. The properties of two synthesized polymers are very similar, but they exhibited apparent changes of light-emitting properties compared with other PPV backbone based polymers. The broad absorption bands from 350 to 570 nm are due to $\pi$-$\pi$* transitions of the polyconjugated systems. The absorption maxima of the two polymers were found at about 452 and 448 nm for PPV-alt-6-TV and PPV-alt-8-TV, respectively. The copolymers showed broad PL spectra between 550 and 700 nm without vibronic bands and PL emission maxima of PPV-alt-6-TV and PPV-alt-8-TV are about 620 and 605 nm, respectively. The copolymers exhibited the red emission (PPValt-6-TV), but more red shifted emissions are needed to obtain real red color.

• Macromolecular Research
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• v.15 no.4
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• pp.363-369
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• 2007

Novel biodegradable elastic hydrogels, based on hydrophilic and hydrophobic polymer blocks, were synthesized via the radical crosslinking reaction of diacrylates of poly(ethylene glycol) (PEG) and poly(${\varepsilon}-caprolactone$) (PCL). PEG and PCL diols were diacrylated with acryloyl chloride in the presence of triethylamine, with the reaction confirmed by FT-IR and $^1H-NMR$ measurements. The diacrylate polymers were used as building-blocks for the syntheses of a series of hydro gels, with different block compositions, by simply varying the feed ratios and molecular weights of the block components. The swelling ratio of the hydrogels was controlled by the balance between the hydrophilic and hydrophobic polymer blocks. Usually, the swelling ratio increases with increasing PEG content and decreasing block length within the network structure. The hydrogels exhibited negative thermo-sensitive swelling behavior due to the coexistence of hydrophilic and hydrophobic polymer components in their network structure, and such thermo-responsive swelling/deswelling behavior could be repeated using a temperature cycle, without any significant change in the swelling ratio. In vitro degradation tests showed that degradation occurred over a 3 to 8 month period. Due to their biodegradability, biocompatibility, elasticity and functionality, these hydrogels could be utilized in various biomedical applications, such as tissue engineering and drug delivery systems.

• Polymer(Korea)
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• v.34 no.1
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• pp.69-73
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• 2010

Effects of reaction time and temperature on the isomerization and dehydrobromination reactions of brominated butyl rubber were investigated. The structural composition of brominated butyl rubber was determined by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy($^1H$-NMR), Density functional theory (DFT) was used to study on the isomerization and dehydrobromination mechanisms of model compounds. The geometries for model compounds of 3-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-1-octylene (3BrOE), 1-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-2-octylene (1Br2OE) and 5,5,7,7-tetramethyl-2(2',2', 4',4'-tetramethyl)pentyl-1,3-octadiene (CD) had been optimized by using density functional theory at B3LYP/3-21G and B3LYP/6-31G levels. The predicted energy of 3BrOE lies higher than that of 1Br2OE which suggests that 1Br2OE configuration is more stable than the 3BrOE configuration. Compared with the energy barrier, the pathway of dehydrobromination is less competitive than that of isomerization. This is qualitatively consistent with the experimental results.

• Tribology and Lubricants
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• v.30 no.4
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• pp.224-233
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• 2014

We prepared polyester-polyamines to improve the effect of carbon black dispersibility for use in thermal transfer ink, and synthesized polymeric dispersing agents by two-step reactions. In the first step, we made polyester by polycondensing 1,6-hexanediol and adipic acid. The resulting polymers had carboxylic acid, which was linked with polyamine via an acid-base reaction. We then characterized the polyester-polyamine structure by NMR spectroscopy and Fourier transform infrared spectroscopy (FT-IR). We also determined the basic characterizations such as total acid numbers (TAN) (5.0-67.5 mgKOH/g), hydroxyl values (27.1-67.5 mgKOH/g), and molar masses ($M_n=1.6-8.4kg\;mol^{-1}$) for the polyester and total base numbers (TBN) (15.3-57.1 mgKOH/g), hydroxyl values (33.0-79.8 mgKOH/g), and nitrogen contents (1.02-3.48%) for the polyester-polyamine polymers. We thus prepared thermal transfer ink using carbon blacks and the polyester-polyamine dispersing agents, and evaluated the resulting mixtures for printability, adhesive force, storage stability, ink appearance, ink gloss, and processability. These mixtures showed significant dispersibility for carbon black in the ink. Thus, we concluded that the dispersibility of the polymeric materials depended on the polyamine structure and the hydrophilicity-hydrophobicity distribution of the polymeric dispersants.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2537-2543
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• 2011

A self-assembled Al-bridged diiminopyridine-based ligand (3) was synthesized and characterized by FT-IR, ESI-MS and NMR spectroscopy. Electron spectral titrations were performed to confirm the formation of a novel trinuclear bis(imino)pyridyl iron(II) complex (4) upon addition of $FeCl_2$ into Al-bridged ligand 3 in methanol solution. Simultaneously, a typical bis(imino)pyridine-iron(II) complex (2) was synthesized and fully characterized. The X-ray crystal study of the iron(II) complex 2 disclosed a five-coordinate, distorted square-pyramidal structure with the tridentate N^N^N ligand and chlorides. The optimal molecular structure of 4 was obtained by means of molecular mechanics, which showed that each iron atom in the complex 4 is surrounded by two chlorides, a tridentate N^N^N ligand and one oxygen atom, supporting considerations about the possibility of six-coordinate geometry from MMAO or the ethylene access. A comparison of 4 with the reference 2 revealed a remarkable decrease of the catalytic activity and MMAO consumption (activity up to $0.41{\times}10^3\;kg\;{mol_{Fe}}^{-1}h^{-1}bar^{-1}$, Al/Fe = 650 for 4 and $7.02{\times}10^3\;kg\;{mol_{Fe}}^{-1}h^{-1}bar^{-1}$, Al/Fe = 1600 for 2).

• The Journal of Advanced Prosthodontics
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• v.6 no.5
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• pp.333-345
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• 2014

PURPOSE. Bonding agents (BA) are the crucial weak link of composite restorations. Since the commercial materials' compositions are not disclosed, studies to formulize the optimum ratios of different components are of value. The aim of this study was to find a proper formula of BAs. MATERIALS AND METHODS. This explorative experimental in vitro study was composed of 4 different sets of extensive experiments. A commercial BA and 7 experimental formulas were compared in terms of degree of conversion (5 experimental formulas), shear bond strength, mode of failure, and microleakage (3 experimental formulas). Statistical analyses were performed (${\alpha}$=.05). The DC of selected formula was tested one year later. RESULTS. The two-way ANOVA indicated a significant difference between the shear bond strength (SBS) of two tissues (dentin vs. enamel, P=.0001) in a way that dentinal bonds were weaker. However, there was no difference between the four materials (P=.283). The adhesive mode of failure was predominant in all groups. No differences between the microleakage of the four materials at occlusal (P=.788) or gingival (P=.508) sites were detected (Kruskal-Wallis). The Mann-Whitney U test showed a significant difference between the microleakage of all materials (3 experimental formulas and a commercial material) together at the occlusal site versus the gingival site (P=.041). CONCLUSION. A formula with 62% bisphenol A-glycidyl methacrylate (Bis-GMA), 37% hydroxy ethyl methacrylate (HEMA), 0.3% camphorquinone (CQ), and 0.7% dimethyl-para-toluidine (DMPT) seems a proper formula for mass production. The microleakage and SBS might be respectively higher and lower on dentin compared to enamel.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.707-712
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• 1991

N'-phenyl-N-(2-chloroethyl)-N-aminourea has been prepared from N'-phenyl-N-(2-chloroethyl)-N-nitrosourea by means of the electrochemical reduction with the mercury pool electrolytic cell. In order to find out the optimum condition of the reaction, the voltammetric behaviors for N'-aryl-N-(2-chloroethyl)-N-nitrosourea derivatives have been investigated by the cyclic voltammetry and polarography. The peak potentials was shifted to the negative direction as the pH value of the solution decrease. The substituent effects of phenyl ring on the peak potential were not observed in this case. (5:3) EtOH/4 N-HCl mixed solution was employed for the electrolysis. The applied potential was -0.7 V vs. Ag/AgCl/4 N-HCl electrode. The number of electrons participated to the reduction process was 4, respectively. The product was identified by FT-IR, NMR, mass and/or elemental analysis data.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2260-2266
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• 2011

4-Chlorotetrazolo[1,5-a]quinoxaline (III) was synthesized by azide (2+3) cycloaddition of 2,3-dichloroquinoxaline (II). Compound (III) on further refluxing with hydrazine hydrate furnished 4-hydrazinotetrazolo[1,5-a]quinoxaline (IV). Further refluxing of (IV) with different aromatic aldehydes in methanol yielded corresponding Schiff's bases V(a-j). Various 4-aminotetrazolo[1,5-a]quinoxaline based azetidinones VII(a-j) were synthesized by stirring the compounds V(a-j), at low temperature, with equimolar mixture of chloroacetylchloride & triethylamine in dry benzene, while 4-aminotetrazolo[1,5-a]quinoxaline based thiazolidinones VIII(a-j) were synthesized by refluxing Schiff's bases V(a-j) with thioglycolic acid in oil-bath. The structures of all the compounds were confirmed on the basis of $^1H$-NMR & FT-IR spectral data. All the newly synthesized compounds were screened for in-vitro antimicrobial activity against E. coli, S. aureus, K. pneumoniae & P. aeruginosa & antifungal activity against C. albicans. Few of them have exhibited the promising activity.