人体衰老与抗氧化营养素保健功能的研究

为了解中老年人群膳食中抗氧化营养素的摄入状况及体内抗氧化功能水平 ,对上海某社区2 2 9名 4 5～ 79岁老年前期和老年期人群开展营养学调查和血清学分析 ,结果表明两组人群从膳食中摄入的抗氧化营养素不能满足需要 ,体内血清超氧化物歧化酶 (SOD)普遍降低 ,而脂质过氧化产物则普遍升高 ,说明衰老与年龄、抗氧化营养素摄入不足有关。建议中老年人群应增加抗氧化营养素的摄入 ,抗衰老应从中年人开始。     

氧化应激在糖代谢紊乱中的作用

为探讨氧化应激和糖尿病发生／发展的相互关系,由四氧嘧啶诱导建立糖尿病大鼠模型,进行抗氧化干预。动物经此化学诱导剂处理后,血糖／血脂和硫代巴比妥酸反应产物升高,ＳＯＤ降低,再经抗氧化干预,即可发生逆转恢复。试验结果表明糖／脂代谢调节和氧化应激密切相关。     

Assessment of the Antioxidant and Free Radical Scavenging Activities of Methanolic Extract of Diplazium esculentum

The present study was carried out to determine the antioxidant and different free radical scavenging activities of 70% methanolic extract of Diplazium esculentum. Total antioxidant activity of the extract was evaluated as trolox equivalent antioxidant capacity value. The IC₅₀ values for scavenging of different free radicals indicated its efficient free radical scavenging properties. The extract acted as an iron chelator and also possessed reducing power. It also inhibited lipid peroxidation. Moreover, the extract yielded high phenolic and flavonoid content. Therefore, the results indicated that 70% methanolic extract of D. esculentum acted as a potential antioxidant and free radical scavenger.     

Analysis and metabolite profiling of glucosinolates,anthocyanins and free amino acids in inbred lines of green and red cabbage (Brassica oleracea L.)

We profiled and quantified glucosinolates (GSLs), anthocyanins and free amino acids in thirty-seven inbred lines green and red cabbage. Analysis of these distinct cabbages revealed the presence of 8 GSLs, 13 anthocyanins and 12 free amino acids. GSL contents were varied among the different lines of cabbage. The maximum levels of glucoraphanin (14.91 μmol/g DW) and glucobrassicin (12.37) were found in FX 1-28 and FX 1-32 lines, respectively. Total GSLs in red cabbage lines were 50% higher than those of green cabbage. Anthocyanin contents in red cabbage were ranged from 4.11 to 6.81 mg/g DW in FX 2-3 and FX 1-34 lines, respectively. Among the 13 anthocyanins, both cyanidin 3-(feruloyl) (sinapoyl)diglucoside-5-glucoside and cyanidin 3-(sinapoyl) (sinapoyl)diglucoside-5-glucoside levels were the highest amounts. The amounts of total free amino acids were ranged from 523.5 to 1308 mg/100 g fresh weight (FW) in green cabbage and 484.8 to 1271 in red cabbage, respectively. In red cabbage lines, 9.4% of the total free amino acids accounted essential amino acids such as valine, threonine, isoleucine, leucine and lysine. Thus, the amounts of GSLs, anthocyanins, and amino acids varied widely, and the variations in these compounds between the lines of cabbage were significant.     

Radical scavenging by dietary flavonoids. A kinetic study of antioxidant efficiencies

The rate of scavenging of peroxyl radicals and of diphenylpicrylhydrazyl radicals by flavanones, flavones, flavanols and flavonols commonly occurring in foods was found, when determined by ESR spin trapping and by stopped-flow spectroscopy, respectively, to be the highest for the most reducing of the flavonoids. Among 12 flavonoids investigated a threshold potential of approximately +0.4 V seems to exist, above which the flavonoids become ineffective radical scavengers, as determined by ESR spectroscopy using 5,5-dimethyl-1-pyrroline-N-oxide as spin trap. Scavenging of diphenylpicrylhydrazyl radicals showed (pseudo) first order kinetics for excess of flavonoids, and the reaction half-life could also be determined for the less effective flavonoids. For kaempferol and eriodictyol, flavonoids with very similar reduction potentials for their phenoxyl radicals, rate constants for the bimolecular scavenging could be determined in methanol and had the value (7.0 ±0.7)×10² s⁻¹ M⁻¹ and 33±1 s⁻¹ M⁻¹ at 25°C, respectively, showing that other factors than the driving force, such as hydrophilic/lipophilic balance are important, as was further confirmed in an oxygen consumption assay based on a linoleic acid emulsion, where decreasing antioxidant efficiency followed the order: (+)-catechin>(±)-taxifolin≥luteolin>kaempferol>quercetin>>naringenin. Received: 5 November 1999     

Differential antioxidant and quinone reductase inducing activity of American,Asian, and Siberian ginseng

The antioxidant and quinone reductase (QR) inducing activities of American, Asian, and Siberian ginseng have been reported using various plant materials, solvents, and assays. To directly establish their comparative bioactivity, the effects of extracts obtained from acidified methanol (MeOH), a gastrointestinal mimic (GI), and hexane (Hex) on free radical scavenging and QR induction were tested. Siberian ginseng-MeOH had the highest total phenolic content at 52.6 μmol gallic acid equivalents/g. GI liberated ?50% more phenolics than MeOH and Hex from American and Asian ginseng. Siberian ginseng-Hex was most effective at inducing QR activity in Hepa1c1c7 cells. GI and MeOH extracts of American and Asian ginseng exhibited comparable HOCl scavenging activity, but were ?4.6-fold more potent than Siberian ginseng. Siberian ginseng was the most effective scavenger of ONOO⁻. Siberian-MeOH had the highest ferric reducing antioxidant power (FRAP), and American ginseng-GI had the highest oxygen radical absorbance capacity (ORAC). Thus, the components in ginseng have antioxidant and QR-inducing activity which are dependent upon the dose, method of extraction, radical species, and plant species.     

Antioxidative characteristics of aqueous and ethanol extracts of glossy privet fruit

Non-enzymatic antioxidant activities of aqueous extract, 50% ethanol extract and 75% ethanol extract of glossy privet fruit were examined. Aqueous and ethanol extracts contained various concentrations of phenolic acids, flavonoids, oleanolic acid and ursolic acid. Each extract scavenged superoxide anion, hydroxyl radical and nitric oxide (P < 0.05) in a concentration-dependent manner and the effect of 75% ethanol extract was significantly greater than other extracts (P < 0.05). Each extract showed a concentration-dependent effect on chelating effect, xanthine oxidase inhibition activity and reducing power (P < 0.05). Compared with controls, each extract significantly decreased malondialdehyde formation in low density lipoprotein (LDL) and 8-epi-PGF_2α formation in plasma (P < 0.05). Aqueous extract exerted a greater effect than ethanol extract on increasing catalase and glutathione peroxidase activities in plasma (P < 0.05). These data suggest that using glossy privet fruit extracts may enhance lipid stability in food systems, and provide antioxidative protection for LDL and plasma.