花生壳提取物的体外抗氧化活性研究

为研究花生壳提取物的体外抗氧化活性,测定了花生壳提取物的还原能力、抗脂质过氧化作用、抑制油脂过氧化作用以及清除超氧阴离子自由基、羟基自由基、DPPH自由基的能力,并与抗坏血酸进行了比较.结果表明,花生壳提取物具有较好的总抗氧化活性和总还原性,能抑制脂质过氧化和油脂过氧化作用以及清除自由基.它对DPPH自由基、羟基自由基、超氧阴离子自由基的IC50分别为27.82μg/ml、183μg/ml、89μg/ml.研究表明,花生壳提取物具有较强的综合抗氧化能力,是一种很有开发价值的天然抗氧化剂.     

不同溶剂的竹叶提取物抗氧化活性研究

采用石油醚、氯仿、乙醇和水作为提取溶剂,对竹叶提取物的抗氧化活性进行了研究,表明不同溶剂的竹叶提取物对羟自由基和超氧阴离子自由基具有一定的清除能力,且随着浓度的增大而增强。对羟自由基的清除能力大小依次为石油醚〉氯仿〉乙醇〉水,对超氧阴离子自由基清除能力大小依次为氯仿〉乙醇〉石油醚〉水,还原能力大小依次为石油醚〉氯仿〉水〉乙醇。     

花生壳中黄酮物质的提取及对油脂的抗氧化作用

对花生壳中黄酮物质的提取工艺进行了优化研究,并对提取物的抗氧化性进行了初步研究。用单因素试验分别对提取溶剂乙醇体积分数、料液比、提取时间及提取温度进行了研究。在此基础上,通过正交试验确定上述4个因素的最佳组合。优化后花生壳中黄酮的最大提取率为92．32％,花生壳中黄酮类化合物的适宜提取条件为乙醇体积分数60％、料液比1：30、提取时间150min、提取温度60℃。花生壳中黄酮类化合物对猪油有明显的抗氧化作用,当添加量为0．2％时抗氧化效果与0．2％BHT接近。     

蜈蚣草总黄酮体外抗氧化作用的研究

通过回流法提取蜈蚣草黄酮类化合物,利用分光光度法测定总黄酮的含量,并分析了它对羟基自由基、超氧阴离子自由基的清除作用和总抗氧化能力。结果表明,蜈蚣草总黄酮含量为6.15%,且具有较好的抗氧化能力。     

柳树乙醇提取物体外抗氧化活性

通过Fenton反应产生.OH,邻苯三酚自氧化产生O2.-模型,研究了柳树乙醇提取物体外清除自由基的作用。结果显示,柳茎和柳叶乙醇提取物在3.125—50 mg/ml浓度范围内具有清除O2.-的作用。随着浓度升高,其清除作用增大。在浓度达到50mg/ml时,柳茎提取物的清除率为75.62%,柳叶提取物的清除率为88.53%;柳茎乙醇提取物在3.125—25 mg/ml浓度范围内,清除.OH的能力随着其浓度的增加而逐渐增强。当浓度为25mg/ml时,其清除率为60.63%;柳叶提取物在浓度3.125—25mg/ml内清除.OH的作用不明显。当浓度达到50mg/ml时,对羟基自由基的清除率为60.63%。     

三种中药复方体外抗氧化活性研究

采用体外实验,通过对超氧阴离子自由基(0·-)和羟自由基(·OH)的清除作用检测3种中药复方的抗氧化活性,同时对3种复方的还原力进行了测定.结果表明,3种中药复方对羟自由基和氧自由基均有一定的清除作用,清除率与中药方剂溶液的浓度成正相关,3种中药复方均具有抗氧化活性.     

乳苣总黄酮的提取及抗氧化作用研究

通过乙醇回流提取乳苣中的黄酮类化合物,利用分光光度法测定总黄酮的含量,并分析了对羟基自由基的清除作用和总抗氧化能力。结果表明,乳苣中总黄酮含量为16.8%,具有较好的抗氧化能力。     

西藏红景天植物的生态分布调查与资源的合理保护

红景天属植物是一类具有重要药用价值的经济植物.根据相关历史资料和对西藏地区红景天属植物的野外调查与记录,已知西藏红景天属植物有36个种2个亚种.作为红景天属植物的现代分布中心,青藏高原上的红景天植物种类多、分布广、蕴藏量大.在生态习性方面,红景天表现为适应性强、喜光照,但只有在具备适宜的小生境时才能生长.适宜的小生境有林下、灌丛边缘、高山草甸和高山流石滩等,阳坡环境更有利于红景天属植物的生长,其种类与数量较多.红景天植物资源较脆弱,合理采挖与保护才有利于可持续利用.     

黑木耳和茶叶黄酮复配物的抗氧化活性

研究了黑木耳和茶叶黄酮复合对两种自由基体系的活性清除。结果表明,黑木耳和茶叶黄酮复合对羟基自由基（OH.）和超氧阴离子自由基（O2-.）均有较强的清除作用,且随着用量的增加清除效果增强。在同样用量的情况下,其清除作用明显强于单种黄酮的抗氧化作用,初步说明两种黄酮的复合可增强清除自由基的活性。     

高原人参—红景天的适生环境

高原人参──红景天的适生环境黄德昌，岳安云，张启碧，张清华（甘孜州气象局，康定６２６０００）红景天属景天科，生长在号称世界屋脊的青藏高原海拔４０００ｍ以上高寒带的寒漠上中，是一种天然的多年生草本植物，藏名苏罗玛布。红景天生长在高寒缺氧、人迹罕至的“净...     

Clove as antioxidant additive in diesel–biodiesel fuel blends in diesel engines

Increased NOx emission from usage of biodiesel is a burning issue to be dealt with. Many techniques have been adopted to reduce NOx emissions from diesel engines. The present experimental study deals with the analysis of performance and emission characteristics of Cotton Seed oil biodiesel with the addition of natural antioxidant extract of clove. FTIR analysis characterized the antioxidant by the presence of hydroxyl groups denoted by the corresponding wave number. The oxidation stability of the test samples was determined in terms of induction period by means of Rancimat test. The induction periods of the test fuel samples B100, B20, B20+CL1000, and B20+CL2000 were found to be 2.20 h, 2.73 h, 10.19 h, and 11.12 h, respectively. Thus, the addition of Clove antioxidant increased the oxidation stability of the biodiesel. Results show that the addition of antioxidant to biodiesel blend has increased the Brake Thermal Efficiency to a maximum of 4.71% and decreased the Brake Specific Fuel Consumption to a maximum of 6.25% at full-load conditions compared to Cotton Seed biodiesel blend. The addition of Clove extract antioxidant at a concentration of 1000 ppm and 2000 ppm decreases the NOx emission by 23.03% and 26.7%, respectively, at full-load conditions. However, CO emissions increased by 1.12% and 4.49% with the addition of CL1000 and CL2000 to B20, respectively. Similarly, HC emissions increased by 4.19% and 7.35% by the addition of CL1000 and CL2000 to B20, respectively. The increases in smoke with the addition of CL1000 and CL2000 to B20 were 42.48% and 47.71%, respectively.     

Germination tests for assessing biochar quality

Definition, analysis, and certification of biochar quality are crucial to the agronomic acceptance of biochar. While most biochars have a positive impact on plant growth, some may have adverse effects due to the presence of phytotoxic compounds. Conversely, some biochars may have the ability to adsorb and neutralize natural phytotoxic compounds found in soil. We evaluated the effects of biochars on seedling growth and absorption of allelochemicals present in corn ( L.) residues. Corn seeds were germinated in aqueous extracts of six biochars produced from varied feedstocks, thermochemical processes, and temperatures. Percent germination and shoot and radicle lengths were evaluated at the end of the germination period. Extracts from the six biochars had no effect on percent germination; however, extracts from three biochars produced at high conversion temperatures significantly inhibited shoot growth by an average of 16% relative to deionized (DI) water. Polycyclic aromatic hydrocarbons detected in the aqueous extracts are believed to be at least partly responsible for the reduction in seedling growth. Repeated leaching of biochars before extract preparation eliminated the negative effects on seedling growth. Biochars differ significantly in their capacity to adsorb allelochemicals present in corn residues. Germination of corn seeds in extracts of corn residue showed 94% suppression of radicle growth compared to those exposed to DI water; however, incubation of corn residue extracts with leached biochar for 24 h before initiating the germination test increased radicle length 6 to 12 times compared to the corn residue extract treatments. Germination tests appear to be a reliable procedure to differentiate between effects of different types of biochar on corn seedling growth.     

Phosphorus fractionation in manure from swine fed traditional and low-phytate corn diets

Traditional corn (Zea mays L.) (TC), the primary grain used in swine (Sus scrofa) diets, stores a majority of its P as phytate, which is largely unavailable for digestion by nonruminant animals. Low-phytate corn (LPC) contains similar amounts of total P but a smaller percentage of P as phytate. When fed to swine, LPC increases P utilization and reduces P content of manure. While differences in P content between manure from animals fed TC and LPC diets have been documented, solubility and lability of manure P have not been compared. Manure P was characterized in manure from swine fed either LPC or TC diets in 2000 and 2001. Total P was lower (20 vs. 34 g kg(-1)) and N to P ratio was higher (4.5 vs. 3.3) in LPC manure than in TC manure. Manures were sequentially extracted with deionized water, 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl. Extracts were analyzed for inorganic and total P. Most P (approximately 80%) in the extracts was in the inorganic form. Concentration of P in the water-extractable fraction was lower for LPC manure (10.2 g kg(-1) in 2000 and 9.7 g kg(-1) in 2001) than for TC manure (13.6 g kg(-1) in 2000 and 17.0 g kg(-1) in 2001). Percentage of total P in each extract was in the order of: H2O (60%), HCl (22%), NaHCO3 (12%), NaOH (8%), and residue (<1%). Total P and distribution of P in extracts indicates swine are able to utilize more P contained in LPC feed but the composition of P excreted in LPC manure is similar to TC manure. Solubility, crop availability, and lability of P in LPC manure should be similar to that of TC manure.     

Photochemistry and photoinduced toxicity of acifluorfen, a diphenyl-ether herbicide

Photochemistry studies can be helpful in assessing the environmental fate of chemicals. Photochemical reactions lead to the formation of by-products that can exhibit different toxicological properties from the original compound. For this reason the photochemical behavior of the herbicide acifluorfen (5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid) in the presence of different solvents was studied. Photochemical reactions were carried out using a high-pressure mercury arc and a solar simulator. Kinetic parameters and quantum yields were determined. The identification of photoproducts was performed by mass spectrometry and [1H] nuclear magnetic resonance (NMR). Nitrofluorfen, hydroxy-nitrofluorfen, 2-chloro-4-(trifluoromethyl)phenol, 5-trifluoromethyl-5'-nitrodibenzofuran, and other derivatives were identified. The photochemical reactions were also carried out in the presence of either a singlet or a triplet quencher, and in the presence of either a radical initiator or a radical inhibitor. Substances used as inhibitors of the excited levels T1 and S1 showed that photodegradation of acifluorfen begins from a singlet state S1 through a pi,pi* transition. The role of free radicals in the photodegradation of acifluorfen was determined and a radical mechanism was proposed. Toxicity tests against Daphnia magna Strauss showed that acifluorfen was not toxic at a concentration of 0.1 mM; however, photoproducts formed after 36 h of UV exposure of the herbicide induced a remarkable toxicity to the test organism.     

Multinuclear magnetic resonance analysis of two humic acid fractions from lowland rice soils

To determine the effects of intensive cropping of tropical lowland rice (Oryza sativa L.) and the associated long-term soil submergence on chemical properties of soil organic matter, we used solid-state 13C and 15N and solution 31P nuclear magnetic resonance (NMR) spectroscopy to analyze the labile mobile humic acid (MHA) and the more recalcitrant calcium humate (CaHA) fractions extracted from a series of soils supporting several long-term field experiments in the Philippines. The soils varied mainly in degree of submergence and cropping intensity, ranging from a rainfed rice field without soil submergence to irrigated double- and triple-cropped fields in which soil remains submerged almost all year long. As reported previously, all analyses associated increasing intensity of rice cropping with larger proportions of less humified material in the MHA and CaHA, such as diester phosphorus (P), amide nitrogen (N), and phenolic carbon (C). We established significant correlations between proportions of various spectral areas as well as between some spectral areas and other humic acid (HA) properties such as visible light absorption and free radical concentration (positive indices of humification) and hydrogen (H) concentration (negative index of humification). For example, spectral proportions of heterocyclic N were positively, and proportions of amide N and phenolic C negatively, correlated with visible light absorption and free radical concentration, and each of these spectral proportions had an opposite sign when correlated with H concentration. The correlations of N-alkyl C proportions were the strongest with these properties and with other functional group proportions.     

中草药提取物对致病弧菌抑菌活性的筛选

为了寻找高效植物源杀菌剂,实验采用平板扩散法研究了8种中草药醇提物对致鱼病菌的体外抑菌试验。通过双倍试管稀释法,测定了最小抑菌浓度(MIC)和最低杀菌浓度(MBC)。结果显示,这8种中草药醇提物对致病弧菌均有不同程度的抑制作用,其中以臭椿和盐肤木醇提物对所有供试菌均有较高的抑制活性,臭椿醇提物对病菌的MIC均在7.81mg/mL以下,表明中草药杀菌剂具有较高的开发价值和应用前景。