• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.2
• /
• pp.246-252
• /
• 1993

Melanoidins, as brown colored polymers, are formed through the diversified reaction systems of Maillard type and other reactions. Melanoidins are important components in relation to food quality and also are known to have antioxidative, mutagenic and antimutagenic activities. Since these aspects have been extensively reviwed elsewhere, only the recent studies regarding to their antioxidative and antimutagenic activities are discussed in this review. Even though their mechanisms are not clearly identified, melanoidins or specific fractions isolated from their mixtures have shown varied antioxidative activities depending on the reaction systems and reaction conditions. Those activities presumely are derived from the complex functional properties of hydrogen / electron donors and metal chelating power, which are originated from their reductone structure and others. It is considered that pyrolysate and other mutagens are formed by the given conditions in some cases during browning reaction, whereas melanoidins and their fractions have antimutagenic effects on chemical and other mutagens. There are positive correlationship among the color intensity, antioxidative activity and antimutagenicity of melanoidins or their fractions. These suggest that the antimutagenicity of melanoidins could be attributed to their antioxidative properties, however, it might also be due to other factors, because the relevant responses for antimutagenicity are very complicate and not clear. Accordingly, further studies are required to determine the actual acitivities and mechanisms involved in antioxidation and (anti)mutagenicity of melanoidins by reaction systems / conditions and by the isolated fractions. And also, additional studies are needed to evaluate the applications of melanoidins and their relevant effects to food and human health.

• Asian-Australasian Journal of Animal Sciences
• /
• v.32 no.12
• /
• pp.1864-1872
• /
• 2019

Objective: This study was conducted to evaluate the effects of Ecklonia stolonifera (E. stolonifera) extract addition on in vitro ruminal fermentation characteristics, methanogenesis and microbial populations. Methods: One cannulated Holstein cow ($450{\pm}30kg$) consuming timothy hay and a commercial concentrate (60:40, w/w) twice daily (09:00 and 17:00) at 2% of body weight with free access to water and mineral block were used as rumen fluid donors. In vitro fermentation experiment, with timothy hay as substrate, was conducted for up to 72 h, with E. stolonifera extract added to achieve final concentration 1%, 3%, and 5% on timothy hay basis. Results: Administration of E. stolonifera extract to a ruminant fluid-artificial saliva mixture in vitro increased the total gas production. Unexpectedly, E. stolonifera extracts appeared to increase both methane emissions and hydrogen production, which is contrasts with previous observations with brown algae extracts used under in vitro fermentation conditions. Interestingly, real-time polymerase chain reaction indicated that as compared with the untreated control the ciliate-associated methanogen and Fibrobacter succinogenes populations decreased, whereas the Ruminococcus flavefaciens population increased as a result of E. stolonifera extract supplementation. Conclusion: E. stolonifera showed no detrimental effect on rumen fermentation characteristics and microbial population. Through these results E. stolonifera has potential as a viable feed supplement to ruminants.

• Bulletin of the Korean Chemical Society
• /
• v.13 no.4
• /
• pp.363-367
• /
• 1992

The crystal structure of (1,3,6,9,11,14-hexaazatricycol[12.2.1.$1^{6,9}$]octadecane)copper(Ⅱ) perchlorate, Cu($C_{12}H_{26}N_6$)$(ClO_4)_2$, has been determined by the X-ray diffraction methods. The crystal data are as follows: Mr=516.9, triclinic, ${\alpha}=8.572\;(2)$, b=8.499 (3), c=15.204 (3) ${\AA}$, ${\alpha}=80.42\;(5),\;{\beta}=73.57\;(3),\;{\gamma}=69.82\;(4)^{\circ},\;V=994.2\;{\AA}^3,\;D_C=1.726\;gcm^{-3}$, space group $P{\tilde{1}},\;Z=2,\;{\mu}=21.27\;cm^{-1}&, F(000)=534 and T=297 K. The structure was solved by direct methods and refined by full-matrix least-squares methods to and R value of 0.081 for 1608 observed reflections measured with graphite-mono-chromated Mo Ka radiation on a diffractometer. There are two independent complexes in the unit cell. The two copper ions lie at the special positions (1/2, 0, 0) and (0, 1/2, 1/2)and each complex possesses crystallographic center of symmetry. Each Cu ion is coordinated to four nitrogen donors if the hexaazamacrotricyclic ligand and weakly interacts with two oxygen atoms of the perchlorate ions to form a tetragonally distorted octahedral coordination geometry. The Cu_N (sec), Cu_N(tert) and Cu_O coordination distances are 1.985 (14), 2.055 (14) and 2.757 (13) ${\AA}$ for the complex A and 1.996 (10), 2.040 (11) and 2.660 (13) ${\AA}$ for the complex B, respectively. The macrocycles in the two independent cations assume a similar conformation with the average r.m.s. deviation of 0.073 ${\AA}$. Two 1,3-diazacyclopentane ring moieties of the hexaazamacrotricyclic ligand are placed oppositely and almost perpendicularly to the square coordination plane of the ruffled 14-membered macrocycle. The secondary N atoms are hydrogen-bonded to the perchlorate O atoms with distances of 3.017 (23) and 3.025 (19) ${\AA}$ for the complexes A and B, respectively.

• Applied Chemistry for Engineering
• /
• v.28 no.4
• /
• pp.467-472
• /
• 2017

In this study, the reforming reaction of vacuum residue (VR) was carried out using aquathermolysis reaction. VR showed a prone to decrease the amount of resins and asphaltenes in the constituents, and to increase saturates and aromatics when reacting with steam at 30 bar and above $300^{\circ}C$ for 24 h. This tendency became more evident when the amount of steam used was excessive than the amount of VR. When the aquathermolysis reaction was performed at $300^{\circ}C$ and 30 bar for 48 h, the VR composition was changed from the initial state (S/A/R/A = 7.3%/43.7%/25.6%/23.5%) to final state (S/A/R/A = 6.8%/57%/12.2%/24.0%), and the contents of the resins decreased by 13% and the aromatic compounds increased by 13%. The viscosity decreased from 880,000 cp to 290,000 cp by 68%. When 10% of decalin, which is easy to provide hydrogen, was added, the viscosity decreased by 68% in 24 h. The VR composition showed a reduction in the contents of resins and asphaltenes from 49% to 17% from the initial state (S/A/R/A = 7.3%/43.7%/25.6%/23.5%) to the final state (S/A/R/A = 4.5%/63.5%/12.5%/20.0%), and the content of aromatics was maximized to 63.5%. The gas layer formed by the aquathermolysis reaction in the reactor chamber was collected and analyzed by GC-MS spectroscopy. As a result, various hydrocarbon compounds such as ethylbenzene, octane and dimethylbenzene were detected.

• Journal of the Mineralogical Society of Korea
• /
• v.15 no.3
• /
• pp.231-240
• /
• 2002

Microbial metal reduction influences the biogeochemical cycles of carbon and metals as well as plays an important role in the bioremediation of metals, radionuclides, and organic contaminants. The use of bacteria to facilitate the production of magnetite nanoparticles and the formation of carbonate minerals may provide new biotechnological processes for material synthesis and carbon sequestration. Metal-reducing bacteria were isolated from a variety of extreme environments, such as deep terrestrial subsurface, deep marine sediments, water near Hydrothemal vents, and alkaline ponds. Metal-reducing bacteria isolated from diverse extreme environments were able to reduce Fe(III), Mn(IV), Cr(VI), Co(III), and U(VI) using short chain fatty acids and/or hydrogen as the electron donors. These bacteria exhibited diverse mineral precipitation capabilities including the formation of magnetite ($Fe_3$$O_4$), siderite ($FeCO_3$), calcite ($CaCO_3$), rhodochrosite ($MnCO_3$), vivianite [$Fe_3$($PO_4$)$_2$ .$8H_2$O], and uraninite ($UO_2$). Geochemical and environmental factors such as atmospheres, chemical milieu, and species of bacteria affected the extent of Fe(III)-reduction as well as the mineralogy and morphology of the crystalline iron mineral phases. Thermophilic bacteria use amorphous Fe(III)-oxyhydroxide plus metals (Co, Cr, Ni) as an electron acceptor and organic carbon as an electron donor to synthesize metal-substituted magnetite. Metal reducing bacteria were capable of $CO_2$conversion Into sparingly soluble carbonate minerals, such as siderite and calcite using amorphous Fe(III)-oxyhydroxide or metal-rich fly ash. These results indicate that microbial Fe(III)-reduction may not only play important roles in iron and carbon biogeochemistry in natural environments, but also be potentially useful f3r the synthesis of submicron-sized ferromagnetic materials.

• Asian-Australasian Journal of Animal Sciences
• /
• v.31 no.1
• /
• pp.71-79
• /
• 2018

Objective: Gelidium amansii (Lamouroux) is a red alga belonging to the family Gelidaceae and is commonly found in the shallow coasts of many East Asian countries, including Korea, China, and Japan. G. amansii has traditionally been utilized as an edible alga, and has various biological activities. The objective of this study was to determine whether dietary supplementation of G. amansii could be useful for improving ruminal fermentation. Methods: As assessed by in vitro fermentation parameters such as pH, total gas, volatile fatty acid (VFA) production, gas profile (methane, carbon dioxide, hydrogen, and ammonia), and microbial growth rate was compared to a basal diet with timothy hay. Cannulated Holstein cows were used as rumen fluid donors and 15 mL rumen fluid: buffer (1:2) was incubated for up to 72 h with four treatments with three replicates. The treatments were: control (timothy only), basal diet with 1% G. amansii extract, basal diet with 3% G. amansii extract, and basal diet with 5% G. amansii extract. Results: Overall, the results of our study indicate that G. amansii supplementation is potentially useful for improving ruminant growth performance, via increased total gas and VFA production, but does come with some undesirable effects, such as increasing pH, ammonia concentration, and methane production. In particular, real-time polymerase chain reaction indicated that the methanogenic archaea and Fibrobacter succinogenes populations were significantly reduced, while the Ruminococcus flavefaciens populations were significantly increased at 24 h, when supplemented with G. amansii extracts as compared with controls. Conclusion: More research is required to elucidate what G. amansii supplementation can do to improve growth performance, and its effect on methane production in ruminants.

• The Korean Journal of Pharmacology
• /
• v.27 no.2
• /
• pp.155-166
• /
• 1991

In order to evaluate a potential role of mitochondria in the mediation of toxicity of paraquat (PQ), submitochondrial particle and microsome of mouse liver were compared by oxygen radical generation and lipid peroxidation. With NADH in submitochondrial particle and NADPH in microsome as electron donors, PQ stimulated production of superoxide anion and $H_2O_2$ in both fractions. Under the same conditions, PQ enhanced the generation of ethylene from methional suggestiong stimulation of OH production by PQ. But these effects by PQ were somewhat lower in submitochondrial particle than in microsome. In addition, lipid peroxidation(measured as MDA production) was stimulated by PQ in both fractions. The stimulation of lipid peroxidation in both fractions seemed to occur by the same mechanism probably through perferryl ion. This was supported by the following findings: i) The lipid peroxidation in both fractions was partially inhibited by SOD and completely inhibited by DETAPAC(an iron chelator) but not by catalase or OH scavenger. ii) Addition of $ADP-Fe^{3+}$ further increased PQ-induced lipid peroxidation but decreased ethylene production from methional suggesting no correlation between OH production and lipid peroxidation. The redox-cycling of PQ in mitochondria appeared to be linked to NADH dehydrogenase, not to CoQ since all of the observed stimulations by PQ in submitochondrial particle were inhibited by p-hydroxymercuribenzoate(a NADH dehydrogenase inhibitor) but not affected by other respiratory chain blockers. The above results demonstrate that redox-cycling properties of PQ leading to oxygen radical generation and lipid peroxidation can also occur in mitochondria in the same manner as in microsome. Therefore, the observed actions of PQ in mitochondria suggest that mitochondria may also contribute to toxicity of this drug in vivo.