H2O2 production by copper amine oxidase, a component of the ecto-apyrase (ATPase)-containing protein complex(es) in the pea cell wall, is regulated by an elicitor and a suppressor from Mycosphaerella pinodes

Blue native PAGE analysis for cell wall proteins from pea epicotyls demonstrated that cell wall-associated ecto-apyrase (ATPase) formed a large protein complex(es) ranging from 450 to 900?kDa; one of the components of the complex was copper amine oxidase (CuAO), which catalyzes the oxidation of amines with the subsequent generation of ammonia and hydrogen peroxide. CuAO activity was coordinately regulated in vitro with ATP-hydrolyzing activity by an elicitor and a suppressor from Mycosphaerella pinodes. Moreover, treatment of cell wall proteins with the suppressor caused the appearance of the apyrase monomer. On the basis of these results, M. pinodes may target the apyrase-containing protein complex(es) of the host to attenuate cell wall-based, extracellular defense(s) including the production of hydrogen peroxide.     

稻壳资源化新工艺的研究

根据纤维素、半纤维素、木质素在高温高压水中分解速度相差很大的特点，提出了一条稻壳资源化的新工艺，以便减少废弃物、最大限度地得到糖类化合物。新工艺主要包括连续水蒸汽蒸煮爆碎处理、连续近临界水处理和燃烧三步。研究了连续近临界水处理过程中温度和停留时间对液相分解产物的收率和残渣组成的影响，并得到了较优的操作条件。通过对新工艺中固形物组成变化的研究得知：水蒸汽蒸煮爆碎处理过程主要分解半纤维素，而连续近临界水处理同时水解纤维素和含硅化合物。新工艺可将约80%的碳源转化为水溶性物质，其中多聚糖和单糖的收率可达40%（wt）以上。新工艺为稻壳的全面综合利用提供了一条新途径。     

Urinary excretion of 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone, a ring-fission metabolite of (-)-epicatechin, in rats and its in vitro antioxidant activity

There is great interest in the nutritional potential of (-)-epicatechin, a common polyphenolic constituent of many foods and beverages, because of its potent antioxidant capacity. To better evaluate the biological role of (-)-epicatechin, we studied the urinary excretion of 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone, a ring-fission metabolite of (-)-epicatechin by intestinal microflora, in rats as well as its antioxidant activity in vitro. The method for measuring the urinary levels of (-)-epicatechin and 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone was based on the enzymatic hydrolysis of beta-glucuronidase and sulfatase, and was subsequently determined by HPLC coupled to an electrochemical detector. Following administration of (-)-epicatechin at doses of 0, 20, 40, and 80 mumol per rat, (-)-epicatechin and 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone were excreted into the urine within 24 h in a dose-dependent manner. Urinary 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone was mostly in the conjugated form, with a higher ratio of conjugation than (-)-epicatechin. We assessed the relative antioxidant potentials for scavenging radicals in the aqueous phase as expressed in the Trolox equivalent antioxidant capacity (TEAC). The results demonstrated that the degradation of (-)-epicatechin into 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone attenuated the antioxidant ability of the former. However, 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone showed stronger antioxidant activity than l-ascorbic acid. These results led us to suppose that 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone, a microbial metabolite of (-)-epicatechin, circulating in the body may also at least be biologically active in terms of contributing to its combined antioxidant effect.