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1.
The oxidative degradation of β-cyclodextrin (β-CD) induced by autoxidation of linoleate has been investigated in the solid system composed of β-CD and linoleate. β-CD was oxidized with a propagative oxidation of linoleate to induce the cleavage of its glucosidic linkage and this degradation proceeded proportionally with the moisture content in the solid system. The oxidative cleavage of β-CD gave several kinds of oligosaccharides which were composed of D -erythrose, D -arabinose, D -erythropentosulose, D -xylopentdial-dose, D -glucose and deoxyunsaturated hexose as their reducing terminals. These degradation of β-CD seemed to be initiated by certain radical species formed from the peroxidation of linoleate. 相似文献
2.
Recently, we have reported that anthocyanins show strong antioxidative activity, but no attention has been paid to anthocyanins
from the viewpoint of the reaction mechanism of alkylperoxyl radicals; therefore, we investigated the reaction products of
antioxidative anthocyanins (cyanidin 3-O-β-d-glucoside). Cyanidin 3-O-β-d-glucoside was reacted with 2,2′-azobis(2,4-dimet hylvaleronitrile) to generate the alkylperoxyl radicals, and the reaction
products were isolated by high-performance liquid chromatography. The products were identified as 4,6-dihydroxy-2-O-β-d-glucosyl-3-oxo-2,3-dihydrobenzofuran and protocatechuic acid. Based on reaction products, the antioxidative mechanism of
cyanidin 3-O-β-d-glucoside may be different from that of α-tocopherol; cyanidin 3-O-β-d-glucoside would produce another radical scavenger, as it would break down the structure and scavenge the radicals. 相似文献
3.
Kiyoko Sakamoto Shunro Yamaguchi Atsushi Nakahira Motoki Kaneno Masayuki Okazaki Junko Ichihara Yoshiaki Tsunawaki James C. Elliott 《Journal of Materials Science》2002,37(5):1033-1041
Hydrolyses of -tricalcium bis(orthophosphate) Ca3(PO4)2 (-TCP) were carried out in a heterogeneous solvent system (hydrophobic organic solvent-water). The hydroxyapatites (HAp) formed were deficient in calcium (Ca/P = 1.56–1.61, a-axis = 0.9440 nm, c-axis = 0.6880 nm) and contained acid phosphate (and sometimes carbonate depending on the organic solvent used). The HAp was in the form of needles with a length (1–4 m) that depended on the polarity of the hydrophobic organic solvent. The aspect ratio was highest in 1-octanol with a polarity of E
T = 48.3. On the other hand, in a hydrophobic organic solvent system without OH groups such as n-octane (E
T = 31.1), HAp formed fine particles that are similar to HAp prepared in a system without an organic solvent. Thus, hydrophobicity and OH groups of organic solvents affect the crystal growth of HAp. 相似文献
4.
The deterioration of corn starch and γ-cyclodextrin (γ-CD) as a model compound by coexisting of methyl linolate (ML) has been studied in the solid system. With the elapse of oxidation time of ML, the reducing values of above the sugars increased and the value of γ-CD with Silica Gel done more largely than without the one. The molecular weight of corn starch may decrease slightly, the glycosidic linkages of amylopectin and amylose molecules in the starch may be cleaved partially and the crystalline structure of the starch will be deteriorted a little by some active radicals formed by the autoxidation of ML. The propagative autoxidation of ML induced the deterioration of γ-CD giving the two processes of the hydrolysis and the depolymerization in the similar way as observed in the reaction of γ-CD with OH radicals. 相似文献
5.
6.
Narasimhan Ramarathnam Toshihiko Osawa Mitsuo Namiki Shunro Kawakishi 《Journal of the American Oil Chemists' Society》1989,66(1):105-108
Accelerated aging effects, induced by y irradiation, were investigated on the fatty acid composition of lipids and on the
content of endogenous antioxidants of four Indica and four Japonica rice seeds with and without intact hull. While the linoleic
acid content of the phospholipids decreased gradually with the increase in irradiation doses, there was a corresponding increase
in the linoleic acid content of the free fatty acids. Such changes were drastic, especially in the case of Japonica rice seeds
irradiated without intact hull. However, the neutral lipids were found to be resistant to γ irradiation.
The α-tocopherol content was found to decrease (markedly) in rice seeds irradiated with or without hull, especially in the
Japonica rice seeds. At a dose of 15 kGy only traces of a-tocopherol could be detected in Japonica and Indica rice seeds irradiated
with and without intact hull. Oryzanol, a relatively weaker anti-oxidant, was found to be more resistant to oxidative damage
than a-tocopherol. At 15 kGy, the oryzanol content ranged from 59 μg to 170 μg/g lipid in rice seeds irradiated with intact
hull, while the corresponding value for rice seeds irradiated without hull was 52 μg to 153 μg/g lipid.
The overall susceptibility to oxidative damage was less in Indica rice seeds, indicating that the antioxidative defense system
offered better protection in overcoming oxidative stress in Indica rice hull than in Japonica rice hull. 相似文献
7.
This paper considers a 1-unit system; the unit is repaired upon failure. The failure and repair rates need not be constant. The system fails if the unit is not repaired within a fixed time, or if the number of failures during the mission exceeds a fixed number. As a special case, that number is allowed to be ``infinite.' The Laplace transforms of the reliability and mean time to system failure are derived; they are not easily solved. The special case of constant failure and repair rates is treated. The results are compared with those of Calabro. 相似文献
8.
Takanori Tsuda Toshihiko Osawa Tsutomu Nakayama Shunro Kawakishi Katsumi Ohshima 《Journal of the American Oil Chemists' Society》1993,70(9):909-913
Antioxidative activity of pea bean (Phaseolus vulgaris L.) extract was evaluated by using a linoleic acid system, and the methanol extract exhibited strong antioxidative activity
as measured by the thiocyanate method. The crude methanol extract was partitioned between then-butanol phase (BP) and the water phase (WP). Then, the antioxidative activity of the BP and the WP was determined by using
a linoleic acid system. The WP showed strong antioxidative activity, while BP showed only weak activity as measured by the
thiocyanate method. Next, the synergistic antioxidative action of WP with α-tocopherol was examined by using linoleic acid
and liposome systems. The WP had a synergistic effect with α-tocopherol in both the food model and liposome systems. For purification
and isolation of the antioxidative substances of the pea bean, preparative high-performance liquid chromatography was carried
out with an octadecylsilyl column. Five fractions were collected, and antioxidative activity was determined in a linoleic
acid system. Although fraction 1 had strong activity by the thiocyanate method, the purification of this active fraction was
difficult; therefore, the partly characterized active fraction was investigated. The contents of total phenolics and sugars
were 0.31±0.01 mg/g of fraction 1 and 406.1±0.1 mg/g, respectively. The ninhydrin chromogenic reaction was positive, and the
ultraviolet absorption spectral λ max value in distilled water was 264.0 nm, indicating that the water-soluble antioxidative
components from pea bean may be a new type of antioxidant. Isolation and identification are currently being investigated. 相似文献
9.
Atsushi Nakahira Kiyoko Sakamoto Shunro Yamaguchi Motoki Kaneno Shinichi Takeda Masayuki Okazaki 《Journal of the American Ceramic Society》1999,82(8):2029-2032
A novel and simple nonhydrothermal method was developed for synthesizing hydroxyapatite whiskers under mild conditions. Hydroxyapatite whiskers were synthesized by the hydrolysis of alpha-tricalcium phosphate at 80°C and atmospheric pressure. The effect of aliphatic alcohols on the transformation of alpha-tricalcium phosphate to hydroxyapatite in water-alcohol systems was examined. When the hydroxyapatite was characterized by XRD and TEM observation, its morphology and size were found to vary with the specific alcohol used during hydrolysis. The effect of reaction time on hydrolysis of alpha-tricalcium phosphate to hydroxyapatite also was studied. 相似文献
10.
Nomoto T Haraguchi K Yamaguchi S Sugano N Nakayama H Sekino T Niihara K 《Journal of materials science. Materials in medicine》2006,17(4):379-385
Hydrolysis of calcium phosphates cement- allografts composite in calf serum and that in saline were examined in comparison
with those of the calcium phosphates cement in both the solutions. The calcium phosphates cement consists of α-tricalcium
phosphate (α-TCP), tetracalcium phosphate (TetCP), dicalcium phosphate dihydrate (DCPD), and hydroxyapatite (HAP), which is
clinically used as Biopex. In the hydrolyses of Biopex-allografts composite in both the solutions, the calcium phosphates
cement was transformed into HAP. On the other hand, in the hydrolyses of Biopex, HAP was formed after 1 day and octacalcium
phosphate (OCP) was gradually formed after 7 days. In the presence of allografts, plate-like crystals were deposited and in
the absence of allografts, needle-like crystals were deposited in both the solutions. By the addition of allografts, the hydrolysis
process of the calcium phosphates cement was significantly changed. 相似文献