Significance of benzylic hydroxymethylene group in the reaction of lignin side-chain with active oxygen species under oxygen bleaching conditions

2013 ◽  
Vol 59 (4) ◽  
pp. 337-343 ◽  
Author(s):  
Satoshi Ohmura ◽  
Tomoya Yokoyama ◽  
Yuji Matsumoto
Holzforschung ◽  
2005 ◽  
Vol 59 (3) ◽  
pp. 269-275 ◽  
Author(s):  
Tomoya Yokoyama ◽  
Yuji Matsumoto ◽  
Gyosuke Meshitsuka

Abstract The reactivities of active oxygen species toward a non-phenolic lignin model compound, 1-(3,4-dimethoxyphenyl)-1,2-ethanediol (veratryl glycol, VG), and a carbo-hydrate model compound, methyl β-D-glucopyranoside (MGP), were examined and compared under practical oxygen bleaching conditions. In this study, active oxygen species were generated in situ by subjecting a phenolic compound, 2,4,6-trimethylphenol, to oxygen oxidation to faithfully simulate practical oxygen bleaching. The results indicated that the time-dependent reaction selectivity of active oxygen species between VG and MGP, k VG(t)/k MGP(t), in the early stage of the reaction is 2.1 and 0.3–0.7 at initial pH values of 11.8 and 13.1, respectively. By comparing this value with the of hydroxyl radical obtained by Ek et al. [Holzforschung 43 (1989) 391] we conclude that the active oxygen species in the early stage of the reaction are hydroxyl radicals. The reaction selectivity at higher pH was much lower, which is explained by the fact that an oxyl anion radical, the conjugate base of the hydroxyl radical, predominantly abstracts hydrogen from aliphatic substructures. Chain-type reactions could be mainly responsible for degradation of the model compounds after the middle stage of the reaction. We suggest that the operation of chain-type reactions is not greatly dependent on the pH of the medium, but on the structure of the substrate.


2014 ◽  
Vol 4 (1) ◽  
pp. 1 ◽  
Author(s):  
Takeshi Nagai ◽  
Misuzu Tamai ◽  
Masato Sato ◽  
Yasuhiro Tanoue ◽  
Norihisa Kai ◽  
...  

Background: In recent years, a new everbearing strawberry cultivar, ‘Summertiara’ was cultivated to supply the strawberries in pre-harvest season from July to October in Japan. For highly research and development of processing of this cultivar, ‘Summertiara’ berries, the objective of this study was to characterize these berries, with relation to chemical parameters, total phenols, total flavonoids, total vitamin C, and total anthocyanins, and was to investigate the solubility and the stability of anthocyanins from the berries. Moreover, the functional properties such as antioxidative activity, active oxygen species scavenging activity, and antihypertensive activity were also evaluated.Methods: Chemical analysis, colour measurement, and sensory evaluation of new everbearing strawberry cultivar, ‘Summertiara’ berries were performed. Next, the solubility of anthocyanins from the berries and stability of these against pH, temperature, and an incandescent lighting were investigated. Moreover, functional properties of the extracts prepared from berries were elucidated using 5 different methods.Results: The contents of water, proteins, lipids, carbohydrates, and ash were the same as those of other cultivar berries. The sugar-acid ratio in the berries was low; these were acidulous. By sensory evaluation, the main factors were vivid red colour, aroma, and acidity. The berries were rich in phenols, flavonoids, vitamin C, and anthocyanins. The anthocyanins of the berries became unstable by heat treatment and light exposures such as visible rays. On the other hand, the extracts prepared from the berries showed the functionalities such as antioxidant activity, active oxygen species scavenging activities, and antihypertensive activity.  Conclusions: The strawberry cultivar, ‘Summertiara’ berries were the most suitable for processing ingredient of strawberry-derived products with superior health promoting functionalities.Keywords: Summertiara, everbearing strawberry cultivar, characterization, sensory evaluation, color and storage, functional property


2015 ◽  
Vol 119 (21) ◽  
pp. 11792-11799 ◽  
Author(s):  
David Degler ◽  
Susanne Wicker ◽  
Udo Weimar ◽  
Nicolae Barsan

1983 ◽  
Vol 18 ◽  
pp. 47
Author(s):  
B.J. Phillips ◽  
T.E.B. James ◽  
D. Anderson

Surgery Today ◽  
1995 ◽  
Vol 25 (9) ◽  
pp. 774-777 ◽  
Author(s):  
Katsuhisa Tanjoh ◽  
Atsuyuki Shima ◽  
Mitsuhiro Aida ◽  
Ryouichi Tomita ◽  
Yasuhiko Kurosu

2020 ◽  
Vol 10 (20) ◽  
pp. 7067-7067
Author(s):  
Ningqiang Zhang ◽  
Lingcong Li ◽  
Rui Wu ◽  
Liyun Song ◽  
Lirong Zheng ◽  
...  

Correction for ‘Activity enhancement of Pt/MnOx catalyst by novel β-MnO2 for low-temperature CO oxidation: study of the CO–O2 competitive adsorption and active oxygen species’ by Ningqiang Zhang et al., Catal. Sci. Technol., 2019, 9, 347–354, DOI: 10.1039/C8CY01879K.


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