蛹虫草菌产生的胞外多糖及其理化性能和抗氧化活性的初步研究

蛹虫草菌Cordycepsmilitaris在液体发酵条件下可产生胞外多糖,其粗多糖的蛋白含量在14．31％左右,氨基酸含量为13．8％,共有17种氨基酸,水分5％左右,多糖含量大约占80％。蛹虫草菌胞外多糖具有良好的增稠性、触变性、抗盐耐热和对广泛pH的稳定性能。蠕虫草菌丝体及其胞外多糖具有一定的抗氧化活性,在60℃的促进氧化条件下放置7天,0．05％含量的菌丝体及其胞外多糖降低油脂氧化率分别达到18．8％和19．8％。     

Effect of nitrogen limitation on foliar antioxidants in relationship to other metabolic characteristics

The long-term effect of limiting soil nitrogen (N) availability on foliar antioxidants, thermal energy dissipation, photosynthetic and respiratory electron transport, and carbohydrates was investigated in Spinacia oleracea L. Starch, sucrose, and glucose accumulated in leaves of N-limited spinach at predawn, consistent with a downregulation of chloroplast processes by whole-plant sink limitation in response to a limited supply of N-based macromolecules throughout the plant. On a leaf-area or dry-weight basis, levels of chlorophyll, carotenoid pools, photosynthetic electron transport capacity, as well as activities for the predominantly chloroplast-localized antioxidant enzymes ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2) were much lower in N-limited versus N-replete plants. When expressed on a chlorophyll basis, foliar levels of all of these parameters were similar in N-replete versus N-limited plants. However, on a total-protein basis, antioxidant enzyme activities were higher in N-limited plants. Nitrogen-limited spinach showed higher levels of thermal energy dissipation and of zeaxanthin and antheraxanthin at midday, as well as slightly higher ascorbate contents relative to chlorophyll. These results indicate that strong, long-term N limitation led not only to alterations in the balance between different processes but also to an overall downregulation of light collection, photosynthetic electron transport capacity, and chloroplast-based antioxidant enzymes. This is further supported by the finding that glucose-feeding of excised leaves led to strong concomitant decreases in photosynthetic electron transport capacity and ascorbate peroxidase activity. On a leaf-area basis, neither superoxide dismutase (EC 1.15.1.1) activity nor dark repiration rates showed a treatment effect. This indicates that overall mitochondrial electron transport activity does not decrease under long-term N limitation and is consistent with localization of an important fraction of foliar superoxide dismutase in mitochondria. Received: 19 March 1999 / Accepted: 13 April 1999     

抗氧化乳酸菌在体外结肠环境清除羟自由基的研究

目的利用鼠肝匀浆经Fe^2＋ -VitC诱导产生丙二醛（MDA）为模型研究29株乳酸菌的抗氧化活性。方法建立体外模拟结肠发酵体系,分析3株具有不同抗氧化能力的乳酸菌（Lactobacillus paracasei Fn032,Laaobacillus rhamnosus GG,Lactobacillus sp．Fn001）在正常结肠和铁过载结肠模型中清除羟自由基效果及对肠球菌增殖的的影响,并检测3株菌螯合亚铁离子能力及其无细胞提取物超氧化物歧化酶（SOD）活性。结果体外结肠体系中羟自由基含量与肠球菌数量有显著相关性。在正常结肠环境中,3株乳酸菌清除羟自由基能力与其SOD活性一致,但与其抑制肠球菌增殖能力和螯合亚铁离子能力不一致。在高铁结肠环境中,3株乳酸菌清除羟自由基能力与它们抑制肠球菌增殖能力和螯合亚铁离子能力一致,但与SOD活性不一致。结论正常条件下乳酸菌可通过产生抗氧化酶来清除结肠自由基,铁过载条件则可增强具有铁螯和能力乳酸菌的抗氧化活性。     

熊果苷对小鼠脑缺血再灌注损伤的影响

目的：本研究旨在探讨中药熊果苷对缺血再灌注损伤后脑细胞的影响,为中药熊果苷的临床应用提供理论依据。方法：昆明种小鼠40只,随机分成4组,即空白组、模型组、药物预防组和药物治疗组。根据缺血时脑损伤原理制成脑缺血再灌注损伤模型,以TTC染色、HE染色观察细胞形态学变化,并检测脑组织中超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量及谷胱甘肽过氧化物酶（GSH-Px）活性的变化。结果：与模型组相比,药物预防组和药物治疗组分别TTC染色缺血区域都不如模型组坏死明显,HE染色显示细胞损伤程度减轻,SOD、GSH—Px活性提高有显著性差异,MDA含量减少（均P〈0．05）。结论：药物熊果苷具有抗氧化作用,能有效地预防和保护脑细胞损伤。     

Effect of cadmium on the growth and antioxidant enzymes in two varieties of Brassica juncea

Increasing contamination and higher enrichment ratio of non-essential heavy metal cadmium (Cd) induce various toxic responses in plants when accumulated above the threshold level. These effects and growth responses are genotype and Cd level dependent. An experiment was conducted to analyze the effect of Cd toxicity in Brassica juncea [L] Czern and Coss by selecting its two varieties Varuna and RH-30. Cadmium (0, 25, 50 or 100 mg CdCl₂ kg⁻¹ of soil) fed to soil decreased the values of growth characteristics, activity of nitrate reductase and leaf water potential, whereas activities of antioxidant enzymes and proline content increased with the increasing concentration of Cd, observed at 30 and 60 day stages of growth, in both the varieties. Moreover, Cd uptake by the roots was higher in RH-30 than Varuna. Also the activity of antioxidant enzymes and proline accumulation were higher in Varuna with increasing soil level of Cd. Out of the two varieties, Varuna was more tolerant than RH-30 to Cd stress.     

桐花树叶醇提取物乙酸乙酯部位对大鼠皮肤抗氧化与抗衰老能力的影响

萃取法获得桐花树叶75%乙醇提取物的石油醚、二氯甲烷、乙酸乙酯、正丁醇和水部位(醇沉),从中筛选出多酚与总黄酮含量均较高、DPPH自由基清除能力较强的乙酸乙酯部位作为辅料试配成膏状体,并通过对SD大鼠背部皮肤进行连续外涂实验,测定其皮肤组织匀浆的总超氧化物歧化酶(T-SOD)活性、羟基自由基清除能力、丙二醛(MDA)含量、羟脯氨酸(HYP)和胶原蛋白含量。结果表明:2.0%桐花树叶乙酸乙酯部位膏状体处理组的皮肤组织T-SOD活性、羟基自由基清除能力、HYP和胶原蛋白含量均极显著高于,但MDA含量极显著低于阴性对照组(仅含化妆品基质的膏状体)、阳性对照组(2.0%熊果苷膏状体)与1.0%、0.5%乙酸乙酯部位膏状体处理组(P0.01)。说明桐花树叶乙酸乙酯部位是一种潜在的抗氧化或抗衰老化妆品辅料,2.0%乙酸乙酯部位含量是试配该化妆品的有效添加剂量。增强T-SOD活性、提高自由基清除能力、降低MDA含量、促进胶原蛋白合成可能是桐花树叶乙酸乙酯部位预防或延缓皮肤衰老的作用机制。     

大孔树脂纯化嘉宝果叶片多酚及其生物活性和组成分析

为探讨嘉宝果(Myrciaria cauliflora)叶片多酚的分离纯化方法,对4种树脂(NKA-2、NKA-9、HPD-826和HPD-400A)进行了筛选,并分析了其多酚的抗氧化、体外降糖活性和组成成分。结果表明,NKA-9树脂适于嘉宝果叶片多酚纯化,最佳工艺条件为:上样液质量浓度2.00 mg/mL、洗脱液乙醇体积分数70%、上样流速1.0 mL/min、上样量204 mL、洗脱流速0.9 mL/min、洗脱量70 mL。嘉宝果叶多酚纯度可达69.86%。嘉宝果叶片纯化后的多酚抗氧化及α-葡萄糖苷酶抑制活性高于纯化前,但α-淀粉酶抑制活性低于纯化前。HPLC结果表明,嘉宝果叶片中含有杨梅苷、芦丁、金丝桃苷和鞣花酸,其中鞣花酸含量最高[(16.15±0.49) mg/g]。因此,NKA-9树脂适合分离纯化嘉宝果叶片多酚,纯化后的多酚抗氧化及α-葡萄糖苷酶抑制活性增强。     

Synthesis,radioprotective activity and pharmacokinetics characteristic of a new stable nitronyl nitroxyl radical-NIT2011

A new stable nitronyl nitroxyl radical NIT2011 was synthesized and characterized. The radioprotective effect and pharmacokinetics profiles of NIT2011 were investigated. The results showed that when irradiation exposure dose was 6.5 Gy gama radiation, the survival rate in the irradiation-only group was 20% on 30th day. The survival rate was 70%, 80%, and 90% on 30th day when mice were pretreated with 0.25, 0.5 and 1.0 mmol/kg NIT2011, respectively. The pretreatment of NIT2011 increased number of spleen colonies, the numbers of bone marrow cells and protein level in bone marrow cells. Pretreatment with NIT2011 prior to radiation exposure increased the plasma SOD (superoxide dismutase) activity. 24 h after irradiation exposure, level of plasma MDA (malondialdehyde) in irradiation-only mice was 14.8 ± 2.8 nmol/mL, level of plasma MDA in NIT2011 (1 mmol/kg) pretreated mice was 9.8 ± 2.0 nmol/mL. Three days after irradiation exposure, the micronucleus ratio in irradiation-only mice is 40.2 ± 3.6, the micronucleus ratio in NIT2011 (1 mmol/kg) pretreated mice was 11.7 ± 1.2. NIT2011 was easily absorbed in mice after it was oral administrated. Compared with the intraperitoneal injection, the relative oral bioavailability of the NIT2011 was 27.5% in mice. The LD₅₀ of NIT2011 was 1510 mg/kg in mice by oral administration. Thus, NIT2011 has potential in being developed as an oral dosage form, safe and effective radioprotective agent.     

Optimization, purification, characterization and antioxidant activity of an extracellular polysaccharide produced by Paenibacillus polymyxa SQR-21

The optimization, purification and characterization of an extracellular polysaccharide (EPS) from a bacterium Paenibacillus polymyxa SQR-21 (SQR-21) were investigated. The results showed that SQR-21 produced one kind of EPS having molecular weight of 8.96 × 10⁵ Da. The EPS was comprised of mannose, galactose and glucose in a ratio of 1.23:1.14:1. The ratio of monosaccharides and glucuronic acid was 7.5:1. The preferable culture conditions for EPS production were pH 6.5, temperature 30 °C for 96 h with yeast extract and galactose as best N and C sources, respectively. The maximum EPS production (3.44 g L⁻¹) was achieved with galactose 48.5 g L⁻¹, Fe³⁺ 242 μM and Ca²⁺ 441 μM. In addition, the EPS showed good superoxide scavenging, flocculating and metal chelating activities while moderate inhibition of lipid peroxidation and reducing activities were determined. These results showed the great potential of EPS produced by SQR-21 to be used in industry in place of synthetic compounds.     

Structure and protective effect of exopolysaccharide from P. Agglomerans strain KFS-9 against UV radiation

The water-soluble exopolysaccharide (WSEPS) from Pantoea agglomerans strain KFS-9 isolated from mangrove forest was prepared by removing bacterial cell from the fermentation liquid following by concentration and cold ethanol precipitation of the supernatant. The polysaccharide material was purified by gel permeation chromatography on a Sephacryl S-300HR column and characterized using chemical and spectral methods. The results show that WSEPS is protein-bound polysaccharide, and it is composed of arabinose, glucose galactose and gulcuronic acid in the molar ratio of 1.0:2.2:2.8:0.9. Their antioxidant activities in vitro were studied by various antioxidant assays, including hydroxyl radical scavenging, superoxide radical scavenging and antilipid peroxidation. The results show that the WSEPS extracted had a high antioxidant activity in a concentration-dependent manner (except the activity of antilipid peroxidation). WSEPS quenched hydroxyl radicals, superoxide radicals at low amounts, the IC(50) of which were 0.07 and 0.15 mg/ml, respectively. These results indicate that the protective effect of WSEPS against UV radiation is most likely to be due to the free radicals-scavenging ability.