Determination of low levels of perchlorate in lettuce and spinach using ion chromatography-electrospray ionization mass spectrometry (IC-ESI-MS)

A sample preparation method was developed to quantify environmentally relevant (low micrograms per liter) concentrations of perchlorate (ClO4(-)) in leafy vegetables using IC-ESI-MS. Lettuce and spinach were macerated, centrifuged, and filtered, and the aqueous extracts were rendered water-clear using a one-step solid-phase extraction method. Total time for extraction and sample preparation was 6 h. Ion suppression was demonstrated and was likely due to unknown organics still present in the extract solution after cleanup. However, this interference was readily eliminated using a Cl(18)O4(-) internal standard at 1 microg/L in all standards and samples. Hydroponically grown perchlorate-free butterhead lettuce was spiked to either 10.3 or 37.7 microg/kg of fresh weight (FW), and recoveries were between 91 and 98% and between 93 and 101%, respectively. Five types of lettuce and spinach from a local grocery store were then analyzed; they contained from 0.6 to 6.4 microg/kg of FW. Spike recoveries using the store-bought samples ranged from 89 to 100%. The method detection limit for perchlorate in plant extracts is 40 ng/L, and the corresponding minimum reporting limit is 200 ng/L or 0.8 microg/kg of FW.     

Perchlorate in soybean sprouts (Glycine max L. Merr.), water dropwort (Oenanthe stolonifera DC.), and lotus (Nelumbo nucifera Gaertn.) root in South Korea

The occurrence of perchlorate in soybean sprouts (Glycine max L. Merr), water dropwort (Oenanthe stolonifera DC.), and lotus (Nelumbo nucifera Gaertn.) root, which are commonly consumed by people in South Korea, was determined by using an ion chromatograph coupled with a tandem mass spectrometer. For soybean sprouts (11 samples), perchlorate was detected in most (91%) of the samples at various concentrations of up to 78.4 μg/kg dry weight (DW); the mean concentration was 35.2 μg/kg DW. For water dropwort, of the 13 samples examined, four showed concentrations that were above the limit of quantification (LOQ). The mean perchlorate concentration was 20.7 μg/kg DW, and the highest perchlorate value was 39.9 μg/kg DW. Of the six lotus root samples examined, only one exhibited a detectable perchlorate concentration (17.3 μg/kg DW). For the accumulation experiments with artificially contaminated solutions, the concentrations of perchlorate in soybean sprouts gradually increased with the increase of perchlorate concentration in the solution. However, there was a decrease in the bioconcentration factor as the perchlorate concentration in the solution increased.     

Predicting perchlorate exposure in milk from concentrations in dairy feed

Perchlorate has been detected in U.S. milk samples from many different states. Applying data from a recently reported 9-week experiment in which 16 Holstein dairy cows were administered perchlorate allowed us to derive an equation for the dose-response relationship between perchlorate concentrations in feed/drinking water and its appearance in milk. Examination of background concentrations of perchlorate in the total mixed ration (TMR) fed in addition to the variable dose supplied to treated cows as a ruminal infusate revealed that cows receive significant and variable exposure to perchlorate from the TMR. Weekly examination of the TMR disclosed that a change in ingredients midway through the experiment caused a significant (78%) change in TMR perchlorate concentration. Analyses of the ingredients comprising the TMR revealed that 41.9% of the perchlorate came from corn silage, 22.9% came from alfalfa hay and 11.7% was supplied by sudan grass. Finally, USDA Food and Nutrition Survey data on fluid milk consumption were used to predict potential human exposure from milk that contained concentrations of perchlorate observed in our previous dosing study. The study suggests that reducing perchlorate concentration in dairy feed may reduce perchlorate concentrations in milk as well as the potential to reduce human exposure to perchlorate in milk.     

Cr(Ⅲ)胁迫对大豆、小麦生长及铬吸收和转运的影响

利用系统发育和根系形态不同的大豆与小麦,采用盆栽试验,研究了不同添加量铬对两种作物生长及铬吸收和转运的影响,并对两种作物铬耐受能力进行比较。结果表明,当土壤铬含量大于287.9 mg/kg(添加量为250 mg/kg)时,大豆植株生长变慢,无豆荚产生,且后期易枯萎死亡;大豆根系铬含量和富集系数超过小麦,而转移系数随铬添加量增加而逐渐降低,说明大豆对土壤中铬胁迫的耐性低于小麦;小麦籽粒铬含量超过规定的临界值。在土壤铬含量小于287.9 mg/kg时,小麦根系铬浓度和富集系数高于大豆,小麦根系比大豆具有更强的铬吸收能力;大豆茎叶富集系数高于小麦。     

Perchlorate in the feed-dairy continuum of the southwestern United States

Perchlorate has the potential to cause thyroid dysfunction by inhibiting iodide uptake by the sodium iodide symporter. Perchlorate-contaminated waters may lead to human exposure through drinking water and food chain transfer in crops by way of irrigation water. Perchlorate has been found in dairy milk collected nationally and internationally. This study was conducted to evaluate perchlorate in the feed-dairy continuum in the southwestern United States. All feed products collected at dairies in this study had detectable levels of perchlorate as analyzed by ion chromatography-tandem mass spectrometry. The calculated total perchlorate intake across dairies ranged from 1.9 to 12.7 mg/cow per day. The variation in total perchlorate intake across dairies was largely associated with variation in forage and silage products. Alfalfa products were the single most important source of perchlorate intake variability among dairies. The estimated perchlorate intake from drinking water ranged from 0.01 mg per cow per day and was generally less than 2% of the total perchlorate intake. The perchlorate content of milk ranged from 0.9 to 10.3 microg/L and was similar to levels reported by the Food and Drug Administration's Total Diet Study. The perchlorate content of milk was significantly related to the presence of perchlorate in feed but the variation of perchlorate in milk could not be explained by feed intake alone.     

Tissue distribution, elimination, and metabolism of sodium [36Cl]perchlorate in lactating goats

Perchlorate has contaminated water sources throughout the United States but particularly in the arid Southwest, an area containing large numbers of people and few water sources. Recent studies have demonstrated that perchlorate is present in alfalfa and that perchlorate is secreted into the milk of cows. Studies in lactating cows have indicated that only a small portion of a perchlorate dose could be accounted for by elimination in milk, feces, or urine. It was hypothesized that the remainder of the perchlorate dose was excreted as chloride ion. The purpose of this study was to determine the fate and disposition of (36)Cl-perchlorate in lactating dairy goats. Two goats (60 kg) were each orally administered 3.5 mg (16.5 muCi) of (36)Cl-perchlorate, a dose selected to approximate environmental perchlorate exposure but that would allow for adequate detection of radioactive residues after a 72 h withdrawal period. Blood, milk, urine, and feces were collected incrementally until slaughter at 72 h. Total radioactive residue (TRR) and perchlorate concentrations were measured using radiochemical techniques and liquid chromatography mass spectrometry (LC-MS-MS). Peak blood levels of TRR occurred at 12 h ( approximately 195 ppb) postdose; peak levels of parent perchlorate, however, occurred after only 2 h, suggesting that perchlorate metabolism occurred rapidly in the rumen. The serum half-life of perchlorate was estimated to be 2.3 h. After 24 h, perchlorate was not detectable in blood serum but TRR remained elevated (160 ppb) through 72 h. Milk perchlorate levels peaked at 12 h (155 ppb) and were no longer detectable by 36 h, even though TRRs were readily detected through 72 h. Perchlorate was not detectable in skeletal muscle or liver at slaughter (72 h). Chlorite and chlorate were not detected in any matrix. The only radioactive residues observed were perchlorate and chloride ion. Bioavailability of perchlorate was poor in lactating goats, but the perchlorate that was absorbed intact was rapidly eliminated in milk and urine.     

Perchlorate, nitrate, thiocyanate, and iodide levels in chicken feed, water, and eggs from three farms

Perchlorate is an inhibitor of iodide uptake that is found widely in the environment. Given the potential for perchlorate accumulation during egg formation and the widespread consumption of eggs, it is important to examine eggs as a source of exposure to perchlorate and other potential inhibitors of iodide uptake (nitrate and thiocyanate). This study was conducted to determine potential human exposure to perchlorate from eggs produced by chicken flocks consuming differing amounts of perchlorate. The mean concentrations of perchlorate (7.16 ( 1.99 microg/kg of dry weight), nitrate (2820 ( 2100 microg/kg of dry weight), thiocyanate (574 +/- 433 microg/kg of dry weight), and iodide (2980 ( 1490 microg/kg of dry weight) in eggs (n = 180) from 15 chicken houses on 3 U.S. farms were determined. Chickens secreted into eggs an average of 23% of the perchlorate ingested from feed and water. Perchlorate levels in eggs were positively correlated with perchlorate intake (p < 0.001). Increased intake of perchlorate, nitrate, and thiocyanate was associated with decreased iodide levels in eggs, possibly indicating a competitive transport mechanism, such as sodium-iodide symporter. It was estimated that egg consumption contributes minimal perchlorate (approximately 0.040 microg) compared to the average total intake of approximately 10.5 microg for U.S. adults. Additionally, it was found that egg consumption was not associated with increased perchlorate exposure in 2820 individuals from the National Health and Nutrition Examination Survey (p value for the difference of least-squares means, pDiff = 0.225). From these findings it was concluded that, although chickens secrete perchlorate in eggs, eggs do not appear to be a significant source of perchlorate exposure for adults in the United States.     

磷和土霉素对小麦和紫花苜蓿幼苗生长和根系发育的影响

采用盆栽试验的方法,研究不同磷添加量(0,20,80 mg/kg)和土霉素添加量(0,40,160 mg/kg)对小麦和紫花苜蓿幼苗生物量及根系发育的影响。结果表明:所有水平土霉素处理中,20,80 mg/kg磷处理的小麦地上部生物量均比不加磷时高,分别高22.7%～34.1%,10.0%～30.0%和9.1%～18.3%。除160 mg/kg土霉素加80 mg/kg磷的处理外,所有处理的苜蓿根生物量均小于不加磷和土霉素的对照。小麦的根长和根表面积随着土霉素添加量的增加总体上呈减少的趋势。总体来看,施磷显著促进了小麦幼苗地上部的生长,但对苜蓿幼苗生长的影响不显著。土霉素对苜蓿幼苗的根系发育有抑制作用。研究结果可为评价土壤中土霉素残留对作物早期生长的影响和指导合理施用磷肥提供理论依据。     

3种作物对盐碱性防护林地改良效果分析

通过盐碱性防护林地播种大麦、小麦和大豆的试验,结果显示:夏季高温干旱期间,实施播种大豆防护林地土表(0~20 cm)层的可溶性盐分和PH值分别为0.65 g﹒kg-1和7.04,与实施播种大麦和小麦无明显差异,有机质(29.88 g﹒kg-1)、速磷(91.10 mg﹒kg-1)、速钾(23.10 mg﹒kg-1)和速氮(134.43 mg﹒kg-1)则分别比实施播种大麦和小麦有明显增高,并且存在极显著差异;3种作物播种后,防护林地没有出现“返盐碱”(发白)现象.表明:实施播种大豆对改善林地土壤条件的效果最好,其次是播种大麦和小麦.     

Formation of high levels of acrylamide during the processing of flour derived from sulfate-deprived wheat

When wheat was grown under conditions of severe sulfate depletion, dramatic increases in the concentration of free asparagine were found in the grain of up to 30 times as compared to samples receiving the normal levels of sulfate fertilizer. The effect was observed both in plants grown in pots, where the levels of nutrients were carefully controlled, and in plants grown in field trials on soil with poor levels of natural nutrients where sulfate fertilizer was applied at levels from 0 to 40 kg sulfur/Ha. Many of the other free amino acids were present at higher levels in the sulfate-deprived wheat, but the levels of free glutamine showed increases similar to those observed for asparagine. In baked cereal products, asparagine is the precursor of the suspect carcinogen acrylamide, and when flours from the sulfate-deprived wheat were heated at 160 degrees C for 20 min, levels of acrylamide between 2600 and 5200 microg/kg were found as compared to 600-900 microg/kg in wheat grown with normal levels of sulfate fertilization.     

Perchlorate Distribution, Excretion, and Depuration in Prairie Voles and Deer Mice

A study on perchlorate distribution was conducted in male adult prairie voles (Microtus ochrogaster). Excretion via urine was the major pathway for perchlorate fate in the body, with the highest concentrations of perchlorate detected in urine after exposure to perchlorate through drinking water [250 μg/ml Mg(ClO₄)₂], and an average of 34% and 88% of perchlorate intake recovered in urine in the 4- and 8-h exposure groups, respectively. Perchlorate mass in kidney, thyroid, blood, and urine were related to perchlorate intake (254.5–2687.7 μg). Perchlorate excretion and depuration patterns via urine were tested further using male adult deer mice (Peromyscus maniculatus). Animals were exposed to perchlorate through dosed drinking water (0, 17, 165, and 1600 ng/ml). Perchlorate concentrations in urine showed a significant difference among the three dosed groups during a 28-day exposure period. However, no difference was found in urine among the three dosages in terms of mass percentage of perchlorate intake from water at each sampling time over the 28-day exposure period. Both concentrations of perchlorate and mass percentage in urine reached a steady state after 1 day in all treatments. On average 46%, 46%, and 61% of perchlorate intake from water was recovered in urine over the exposure period in high, medium, and low dose groups, respectively. Including perchlorate consumption from rodent chow (1.44 ng/g), less than 46% of perchlorate intake was recovered in urine in the high and medium dose groups, and <61% in the low dose group. Three parameter first-order decay models fit the depuration curve very well, with r?>?0.99 in both the low and high dose groups; half-lives of perchlorate in deer mice were estimated as 9.12 and 7.25 h in the low and high dose groups, respectively. Endogenous generation of perchlorate and/or some degree of retention or metabolism of perchlorate may occur in deer mice, based in part on the uncompleted mass balance in the excretion and depuration experiments. The data reported herein should provide additional insight for perchlorate fate determination in animals and humans and valuable information for perchlorate risk assessment in the environment, especially wildlife.     

广州市蔬菜和菜地土壤砷含量及其健康风险研究

测定了广州市郊区菜地土壤(n=120)、菜地蔬菜(n=109)和市售蔬菜(n=237)中砷含量,结合广州居民蔬菜消费情况,分析了砷对广州居民的健康风险影响.结果表明:不同类型菜地土壤砷含量不同,为菜园土(12.94±9.78)mg/kg>水稻土(8.67±10.24)mg/kg>赤红壤(4.17±3.70)mg/kg,土壤质量主要属于二级标准以内;菜地蔬菜砷含量范围为ND～0.179 mg/kg,均值为(0.017±0.024)mg/kg;市售蔬菜砷含量范围为ND-0.314 mg/kg,含量变化为豆类(0.038±0.047)mg/kg)>根茎类(0.027±0.031)mg/kg>茄类(0.025±0.030)mg/kg>叶菜类(0.024±0.022)mg/kg>葱蒜类(0.019±0.025)mg/kg>瓜类(0.017±0.020)mg/kg,所有蔬菜均没有超过我国食品中砷的限量卫生标准(GB-4810-94).广州市居民从蔬菜中摄入的砷为0.045 mg/d,叶菜类和根茎类蔬菜是主要的贡献者.     

Adding selenium‐enriched plant tissue to soil causes the accumulation of selenium in alfalfa

Greenhouse experiments were conducted to determine selenium (Se) uptake by alfalfa (Medicago sativa L.) grown in soils amended with Se‐laden mustard plant tissue. The experimental design was a completely randomized block with treatments consisting of 5, 10, 20, and 40 g of added dried Se‐containing mustard tissue to the soil, which resulted in soil Se concentrations of 1.0, 1.6, 3.0, and 5.7 mg Se/kg, respectively. Four clippings of alfalfa were made and the vegetative portions analyzed for dry weight and total Se. Plant dry weight yields and heights of plants were significantly reduced only at the highest Se treatment rate. Mean tissue Se concentrations increased from 1.8 mg Se/kg DM at the 5 g treatment rate to 6.0 mg Se/kg DM at the 40 g treatment rate. Based on this study, alfalfa can accumulate Se during establishment year when Se‐laden mustard plant tissue is added to the soil.     

Evaluation of fumonisin contamination in cornflakes on the Belgian market by "flow-through" assay screening and LC-MS/MS analyses

A total of 205 cornflake samples collected in Belgian retail stores during 2003-2004 were surveyed for the natural occurrence of fumonisin B1 (FB1), B2 (FB2), and B3 (FB3). These cornflake samples, originating from conventional as well as from organic production, were analyzed using an intralaboratory-validated LC-MS/MS method. Additionally, 90 cornflake samples were subjected to rapid screening using a flow-through enzyme immunoassay method to demonstrate the practicability of a screening test coupled to a validated confirmatory LC-MS/MS method for the management of food safety risks. FB(1) concentrations ranged from not detected (nd) [LOD (FB1) = 20 microg/kg] to 464 microg/kg with mean and median concentrations of respectively 104 +/- 113 and 54 microg/kg. For FB2 and FB3, the concentration ranges varied respectively from nd [LOD (FB2) = 7.5 microg/kg] to 43 microg/kg and from nd [LOD (FB3) = 12.5 microg/kg] to 90 microg/kg. Mean concentrations for FB2 and FB3 were respectively 12 +/- 8 and 21 +/- 15 microg/kg, while the median concentration was 11 microg/kg for FB2 and 19 microg/kg for FB3. From the statistical tests (chi2 and ANOVA model III), it could be concluded that the agricultural practice did not have any significant effect on the fumonisin concentrations but that the variation between different batches was significant (p < 0.0001).     

A study on perchlorate exposure and absorption in beef cattle

Perchlorate exposure and potential effects were evaluated in large mammals by monitoring heifer calves placed on a site with access to streamwater fed by a perchlorate-contaminated groundwater spring ( approximately 25 ng/mL). Blood was collected from the two calves on the site (and two control calves from an uncontaminated site) approximately every 2 weeks for analysis of perchlorate residues and thyroid hormones. During the 14 week study, perchlorate was detected (detection limit = 13.7 ng/mL) in blood plasma twice (15 ng/mL and 22 ng/mL) in one of the heifer calves drinking perchlorate-contaminated water on consecutive sampling periods 4 and 6 weeks after the beginning of perchlorate exposure. Constant exposure to 25 ppb perchlorate in drinking water had no effect on circulating thyroid hormones (T(3) and T(4)) in the heifer calves.     

Phytochemical quantification and total antioxidant capacities of emmer (Triticum dicoccon Schrank) and einkorn (Triticum monococcum L.) wheat landraces

In this study, samples of 18 ancient wheat (12 emmer, 6 einkorn) and 2 bread wheat varieties grown in different regions of Turkey were examined for their total phenolics and flavonoids, phenolic acids, lutein, total yellow pigment, and total radical scavenging capacities against ABTS cation. Results showed that health beneficial phytochemicals and total antioxidant capacities were generally significantly different in emmer and einkorn wheat groups. Remarkably higher total antioxidant activity (18.31 +/- 1.31 micromol Trolox equiv/g), total phenolics (6.33 +/- 0.98 micromol gallic acid equiv/g), ferulic acid (662.95 +/- 61.07 microg/g), and flavonoids (1.61 +/- 0.34 micromol catechin equiv/g) content were detected in emmer wheat samples (n = 12), suggesting that they may have high potential for utilization as a novel grain, rich in natural antioxidants. In addition, quite high levels of lutein (7.33 +/- 2.43 microg/g) of einkorn samples (n = 6) hold the potential of developing high-lutein bakery products to considerably raise the dietary intake of carotenoids. These findings for ancient wheat varieties are considered to be very useful in breeding programs for selecting and breeding wheat varieties for higher concentration and better composition of health-beneficial phytochemicals.     

Does returning sites of historic peri‐urban waste disposal to vegetable production pose a risk to human health? – A case study near Manchester,UK

Urban waste disposal occurred on fenland to the west of Manchester, England, between 1900 and 1964. The reclaimed fenland, Chat Moss, is now used for mixed arable farming. A total of 1.92 Mt of waste including privy midden, street sweepings, clinkers and slaughterhouse refuse was incorporated into the moss resulting in a modified topsoil with raised pH and reduced organic matter content compared with the subsoil. Elevated levels of potentially toxic elements (PTEs) are observed in the topsoil beyond the typical depth of atmospheric contamination; Cd and As concentrations exceed soil guideline values (SGVs) at 1.8 and 43 mg/kg, respectively. Sequential extraction indicates that waste‐derived Pb, Zn and Ni remain predominantly in the residual fraction, whereas Cu was mainly organically bound. Arsenic was predominately found in oxide and organic matter fractions with Cd in carbonate, oxide, organic matter and residual fractions. Pot trials indicated limited uptake of PTEs by vegetables grown on the waste‐amended soil, with the exception of Cd uptake by lettuce (0.22 mg/kg FW) and Pb uptake by radish (0.16 mg/kg FW), which exceeded current EU limits of 0.2 and 0.1 mg/kg FW, respectively. Hazard quotients (HQs) identified no risks to adults from consumption of vegetables grown in these soils with the exception of lettuce consumption with a HQ of 1.4. Risks to children were slightly greater with HQs >1 for Cd in lettuce, spinach, carrots and onion, As in lettuce, parsley and onion and for Zn in spinach.     

麦/玉/豆周年套作体系氮素积累分配及转运

【目的】四川盆地特殊的高温寡照气候,使得作物间套作十分广泛。麦/玉/豆体系有利于资源循环高效利用和农业可持续发展。本项目研究了麦/玉/豆周年套作体系中各作物的氮素积累分配和花后氮素转运特征,旨在明确体系各作物的氮素营养吸收特性,为该体系的氮肥合理施用及高产高效提供理论依据。【方法】通过2011、 2012连续两年田间定位试验,研究了小麦/玉米/大豆套作体系在不同氮用量下（小麦设N 0、 60、 120、 180、 240 kg/hm2,分别表示为WN1、 WN2、 WN3、 WN4、 WN5;玉米设N 0、 97.5、 195、 292.5、 390 kg/hm2,分别表示为MN1、 MN2、 MN3、 MN4、 MN5;大豆不施肥,依前作的施氮处理依次记为SN1、 SN2、 SN3、 SN4、 SN5）各作物的氮素积累分配、 花后氮素的转运。【结果】 1）小麦各部位氮积累量都随氮用量增加而增大,籽粒、 茎鞘、 叶片和颖壳穗轴分别占地上部总氮积累量（平均为218.6 kg/hm2）的71.5%、 12.2%、 9.2%和7.1%;小麦花后从营养器官向籽粒转移的氮量及其贡献率随施氮量增加而增大,但转移率在不同氮处理下差异不显著,平均为61.5%;随氮用量增加,籽粒的氮分配比例逐渐减少,而非籽粒部分的氮分配比例则随之增大;小麦籽粒产量随施氮量增加而增大,但WN3~WN5处理间差异不显著。2）玉米各部位氮积累量随氮用量增加而增大,籽粒、 叶片、 茎鞘和苞叶芯分别占地上部总氮积累量（平均为108.1 kg/hm2）的67.2%、 3.9%、 11.8% 和 7.0%;玉米花后从营养器官向籽粒的氮素转移量、 转移率和贡献率均随施氮量的增加呈先增加后降低的变化趋势,都以MN3处理最大;玉米各部位的氮积累比例在叶片、 茎鞘中以MN1处理最大,MN2MN5处理明显降低,在苞叶芯中不同氮处理间无明显变化,在籽粒中表现为施氮处理显著高于不施氮处理,而施氮处理间差异不显著;玉米籽粒产量随施氮量增加而增大,但MN4、 MN5处理间差异不显著。3）大豆收获期茎秆、 荚皮、 籽粒的氮积累量都有随施氮量增加而逐渐增大的趋势,以SN4和SN5两个处理显著高于另外三个处理,而在SN1~SN3、SN4与SN5间无显著性差异;籽粒、 茎秆、 荚皮的氮积累比例在5个处理间无显著变化,平均分别为82.2%、5.2%、12.6%;大豆花后从营养器官向籽粒转移的氮量从SN1SN5处理有先显著降低后又逐渐升高的变化趋势,而氮素转移率和转移氮素的贡献率在各处理之间无显著差异,平均分别为80.8%和26.6%;大豆籽粒产量以SN4和SN5两个处理显著高于另外三个处理,而在SN1~SN3、 SN4与SN5间无显著性差异。【结论】低氮处理显著影响套作小麦、玉米、大豆3种作物的产量及氮素的积累,高氮投入会促使氮素滞留在营养器官中,阻碍其花后向籽粒中转移;体系全年施氮量在255~382.5 kg/hm2为宜,其中小麦120～180 kg/hm2,玉米195～292.5 kg/hm2,大豆不施或依苗情适当追施氮肥。     

Comparative study of health properties and nutritional value of durian, mangosteen, and snake fruit: experiments in vitro and in vivo

In vitro and in vivo studies of the health and nutritional properties of durian (Durio zibethinus Murr.) were compared with snake fruit (Salacca edulis Reinw.) and mangosteen (Garcinia mangostana). Dietary fibers, minerals, and trace metals were comparable. Total polyphenols (mg of GAE/100 g of FW) and flavonoids (85.1+/-6.1) were significantly higher (p<0.05) than in snake fruit (217.1+/-13.2 (mg of CE/100 g of FW)), durian (309.7+/-19.3 and 61.2+/-4.9), and mangosteen (190.3+/-12.1 and 54.1+/-3.8). Antioxidant activity (microM TE/100 g of FW) of durian measured by DPPH and ABTS assays (228.2+/-13.4 and 2016.3+/-81.1) was significantly higher (p<0.05) than in snake fruit (110.4+/-7.9 and 1507.5+/-70.1) and mangosteen (79.1+/-5.9 and 1268.6+/-62.3). HPLC/DAD analysis of durian (microg/100 g of FW) showed that quercetin (1214.23+/-116.7) was present at levels three times that of caffeic acid, and twice as high as p-coumaric and cinnamic acids. The correlation coefficients between the bioactive compounds of fruits and their antioxidant activities were high (R2=0.99). Male Wistar rats (25) were divided into five dietary groups: the control group was fed the basal diet (BD); in addition to BD, the cholesterol (Chol) group was supplemented with 1% of Chol; the diets of the Chol/Durian, Chol/Snake, and Chol/Mangosteen groups were supplemanted with 5% of these fruits, respectively. It was found that diets supplemented with durian, and to a lesser degree with snake fruit and mangosteen, significantly hindered the rise in plasma lipids and the decrease in antioxidant activity. The nutritional values were comparably high. In conclusion, it could be suggested that inclusion of studied tropical fruits, especially durian, in known disease-preventing diets could be beneficial.     

苯并[a]芘污染土壤的丛枝菌根真菌强化植物修复作用研究

研究了种植紫花苜蓿 (MedicagosativaL )在接种和不接种菌根真菌 (GlomuscaledoniumL )情况下对土壤中苯并 [a]芘 (B[a]P)的降解动态。历经 90天的温室盆栽试验表明 ,较高浓度 (10 0mgkg-1)B[a]P能降低菌根真菌对植物根的侵染率。种植紫花苜蓿和接种菌根真菌能促进土壤中可提取态B[a]P的降解 ,在接种情况下 ,有植物时对三种浓度 (1mgkg-1,10mgkg-1,10 0mgkg-1)B[a]P的降解率分别达 86 2 %、86 6 %、5 7 0 % ;而没有植物时B[a]P的降解率为 5 3 5 %、5 3 0 %、33 0 %。不接菌根真菌时的降解率比接菌根真菌的低得多 ,不接种菌根真菌时 ,有植物的B[a]P降解率分别达 75 9%、77 7%、5 3 4 % ;而不种植物的降解率分别为 5 4 9%、5 2 6 %、34 1% ,低、中浓度 (1mgkg-1,10mgkg-1)两处理的降解率明显地高于高浓度处理(p <0 0 5 )。B[a]P添加对土壤中多酚氧化酶活性有较大的影响 ,特别是高浓度B[a]P处理土壤的酶活性明显地低于其它三个处理 ,接种菌根真菌能够提高土壤中的酶活性 ,从而促进了土壤中B[a]P的降解。