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ABSTRACT: Astragalin (kaempferol-3-O-β-D-glucopyranoside, Ast) glucosides were synthesized by the acceptor reaction of a dextransucrase produced by Leuconostoc mesenteroides B-512FMCM with astragalin and sucrose. Each glucoside was purified and their structures were assigned as kaempferol-3-O-β-D-glucopyranosyl-(1→3)-O-α-D-glucopyranoside (or kaempferol-3-O-β-D-nigeroside, Ast-G1') and kaempferol-3-O-β-D-glucopyranosyl-(1→6)-O-α-D-glucopyranoside (or kaempferol-3-O-β-D-isomaltoside, Ast-G1) for one glucose transferred, and kaempferol-3-O-β-D-isomaltooligosacharide (Ast-IMO or Ast-Gn; n=2-8). The astragalin glucosides exhibited 8.3-60.6% higher inhibitory effects on matrix metalloproteinase-1 expression, 18.8-20.3% increased antioxidant effects, and 3.8-18.8% increased inhibition activity of melanin synthesis compared to control (without the addition of compound), depending on the number of glucosyl residues linked to astragalin. These novel compounds could be used to further expand the industrial applications of astragalin glucosides, in particular in the cosmetics industry.
Enzyme and microbial technology. 01/2012; 50(1):50-6.
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ABSTRACT: Bacillus subtilis TD6 was isolated from Takifugu rubripes, also known as puffer fish. Cellulase from this strain was partially purified by ammonium sulphate precipitation up to 80% saturation, entrapped in calcium alginate beads, and finally characterized using CMC as the substrate. For optimization, various parameters were observed, including pH maximum, temperature maximum, sodium alginate, and calcium chloride concentration. pH maximum of the enzyme showed no changes before and after immobilization and remained stable at 6.0. The temperature maximum showed a slight increase to 60 °C. Two percent sodium alginate and a 0.15 M calcium chloride solution were the optimum conditions for acquisition of enzyme with greater stability. K (m) and V (max) values for the immobilized enzyme were slightly increased, compared with those of free enzyme, 2.9 mg/ml and 32.1 μmol/min/mL, respectively. As the purpose of immobilization, reusability and storage stability of the enzyme were also observed. Immobilized enzyme retained its activity for a longer period of time and can be reused up to four times. The storage stability of entrapped cellulase at 4 °C was found to be up to 12 days, while at 30 °C, the enzyme lost its activity within 3 days.
Bioprocess and Biosystems Engineering 09/2011; 35(1-2):29-33. · 1.81 Impact Factor
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ABSTRACT: Pretreatment of lignocellulosic biomass has gained attention for production of biofuels. In this study, pretreatment by soaking in aqueous ammonia was adopted for pretreatment of biomass for ethanol production. A central composite design of response surface methodology was used for optimization of the pretreatment condition of rapeseed straw, with respect to catalyst concentration, pretreatment time, and pretreatment temperature. The most optimal condition for pretreatment of rapeseed straw by soaking in aqueous ammonia was 19.8% of ammonia water, 14.2 h of pretreatment time, and a pretreatment temperature of 69.0 °C. Using these optimal factor values under experimental conditions, 60.7% of theoretical glucose was obtained, and this value was well within the range predicted by the model. SEM results showed that SAA pretreatment of rapeseed straw resulted in increased surface area and pore size, as well as enhanced enzymatic digestibility.
Bioprocess and Biosystems Engineering 09/2011; 35(1-2):77-84. · 1.81 Impact Factor
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Gwi-Taek Jeong,
Kyoung-Min Lee,
Hee-Seung Yang,
Seok-Hwan Park,
Jae-Hee Park, Changshin Sunwoo,
Hwa-Won Ryu,
Doman Kim,
Woo-Tae Lee,
Hae-Sung Kim,
Wol-Seog Cha,
Don-Hee Park
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ABSTRACT: Hydrogels are materials with the ability to swell in water through the retention of significant fractions of water within their structures. Owing to their relatively high degree of biocompatibility, hydrogels have been utilized in a host of biomedical applications. In an attempt to determine the optimum conditions for hydrogel synthesis by the free-radical polymerization of sorbitan methacrylate (SMA), the hydrogel used in this study was well polymerized under the following conditions: 50% (w/v) SMA as monomer, 1% (w/w) alpha, alpha'-azo-bis(isobutyro-nitrile) as thermal initiator, and 1% (w/w) ethylene glycol dimethacrylate as cross-liking agent. Under these conditions, the moisture content of the polymerized SMA hydrogel was higher than in the other conditions. Moreover, the moisture content of the poly(SMA) hydrogel was also found to be higher than that of the poly(methyl methacrylate [MMA]) hydrogel. When the Fourier transform-infrared spectrum of poly(SMA) hydrogel was compared with that of poly(MMA) hydrogel, we noted a band at 1735-1730/cm, which did not appear in the Fourier transform-infrared spectrum of poly(MMA). The surface of the poly(SMA) hydrogel was visualized through scanning electron microscopy, and was uniform and clear in appearance.
Applied biochemistry and biotechnology 05/2007; 137-140(1-12):935-46. · 1.94 Impact Factor
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ABSTRACT: A pretreatment method using aqueous ammonia was investigated with the intent of minimizing the liquid throughput. This process uses a flowthrough packed column reactor (or percolation reactor). In comparison to the ammonia recycle percolation (ARP) process developed previously in our laboratory, this process significantly reduces the liquid throughput to one reactor void volume in packed bed (2.0-4.7 mL of liquid/g of corn stover) and, thus, is termed low-liquid ARP (LLARP). In addition to attaining short residence time and reduced energy input, this process achieves 59-70% of lignin removal and 48-57% of xylan retention. With optimum operation of the LLARP to corn stover, enzymatic digestibilities of 95, 90, and 86% were achieved with 60, 15, and 7.5 filter paper units/g of glucan, respectively. In the simultaneous saccharification and fermentation test of the LLARP samples using Saccharomyces cerevisiae (NREL-D5A), an ethanol yield of 84% of the theoretical maximum was achieved with 6% (w/v) glucan loading. In the simultaneous saccharification and cofermentation (SSCF) test using recombinant Escherichia coli (KO11), both the glucan and xylan in the solid were effectively utilized, giving an overall ethanol yield of 109% of the theoretical maximum based on glucan, a clear indication that the xylan content was converted into ethanol. The xylooligomers existing in the LLARP effluent were not effectively hydrolyzed by cellulase enzyme, achieving only 60% of digestibility. SSCF of the treated corn stover was severely hampered when the substrate was supplemented with the LLARP effluent, giving only 56% the overall yield of ethanol. The effluent appears to significantly inhibit cellulase and microbial activities.
Applied Biochemistry and Biotechnology 05/2006; 133(1):41-57. · 1.94 Impact Factor
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ABSTRACT: Corn stover was pretreated with aqueous ammonia in a flow-through column reactor, a process termed ammonia recycled percolation (ARP). This method was highly effective in delignifying of the biomass, reducing the lignin content by 70-85%. Most lignin removal occurred within the first 20 min of the process. Lignin removal by ARP was further confirmed by FTIR analysis and lignin staining. The ARP process solubilized 40-60% of the hemicellulose but left the cellulose intact. The solubilized carbohydrate existed in oligomeric form. Carbohydrate decomposition during the pretreatment was insignificant. Corn stover treated for 90 min exhibited enzymatic digestibility of 99% with 60 FPU/g of glucan enzyme loading, and 92.5% with 10 FPU/g of glucan. The digestibility of ARP treated corn stover was substantially higher than that of alpha-cellulose. The enzymatic digestibility was related with the removal of lignin and hemicellulose, perhaps due to increased surface area and porosity. The SEM pictures indicated that the biomass structure was deformed and its fibers exposed by the pretreatment. The crystallinity index increased with pretreatment reflecting removal of the amorphous portion of biomass. The crystalline structure of the cellulose in the biomass, however, was not changed by the ARP treatment.
Bioresource Technology 11/2003; 90(1):39-47. · 4.98 Impact Factor
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ABSTRACT: “Biomaterials” is a generic term which refers to a variety of medical material which is designed to be in direct contact with living tissue. Clearly, biomaterials must be carefully and microscopically fabricated for optimal acceptance within the living organism, in both functional and structural senses. In this study, the enzymatic synthesis of sorbitan methacrylate from 1,4-sorbitan via the manipulation of an immobilized biocatalyst (Novozym 435) and acryl donors (methacrylic acid and vinyl methacrylate) was evaluated. The conversion yield of sorbitan methacrylate was found to be 80.4% under the following experimental conditions: 1:3 molar ratio of 1,4-sorbitan and vinyl methacrylate, reaction temperature of 50 °C, initial sorbitan concentration of 50 g/L, and 3% (w/v) Novozym 435.
Biochemical Engineering Journal.
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ABSTRACT: Corn stover was pretreated with aqueous ammonia in a flow-through column reactor, a process termed ammonia recycled percolation (ARP). This method was highly effective in delignifying of the biomass, reducing the lignin content by 70–85%. Most lignin removal occurred within the first 20 min of the process. Lignin removal by ARP was further confirmed by FTIR analysis and lignin staining. The ARP process solubilized 40–60% of the hemicellulose but left the cellulose intact. The solubilized carbohydrate existed in oligomeric form. Carbohydrate decomposition during the pretreatment was insignificant. Corn stover treated for 90 min exhibited enzymatic digestibility of 99% with 60 FPU/g of glucan enzyme loading, and 92.5% with 10 FPU/g of glucan. The digestibility of ARP treated corn stover was substantially higher than that of α-cellulose. The enzymatic digestibility was related with the removal of lignin and hemicellulose, perhaps due to increased surface area and porosity. The SEM pictures indicated that the biomass structure was deformed and its fibers exposed by the pretreatment. The crystallinity index increased with pretreatment reflecting removal of the amorphous portion of biomass. The crystalline structure of the cellulose in the biomass, however, was not changed by the ARP treatment.
Bioresource Technology.
