Showing papers in "Journal of Agricultural Chemistry and Environment in 2012"

Production of reactive oxygen species by freezing stress and the protective roles of antioxidant enzymes in plants

Abstract: As one of the most severe environmental stresses, freezing stress can determine native flora in nature and severely reduce crop production. Many mechanisms have been proposed to explain the damage induced by freezing-thawing cycle, and oxidative stress caused by uncontrollable production of harmful reactive oxygen species (ROS) are partially contributed to causing the injury. Plants in temperate regions have evolved a unique but effective metabolism of protecting themselves called cold acclimation. Cold-acclimating plants undergo a complex but orchestrated metabolic process to increase cold hardness triggered by exposure to low temperature and shortened photoperiod and achieve the maximum freezing tolerance by a concerted regulation and expression of a number of cold responsive genes. A complicated enzymatic system have been evolved in plants to scavenge the ROS to protect themselves from oxidative stress, therefore, cold-acclimating plants are expected to increase the de novo synthesis of the genes of antioxidant genes. Indeed, many antioxidant genes increase the expression levels in response to low temperature. Furthermore, the higher expression of many antioxidant enzymes are positively correlated to inducing higher tolerance levels against freezing. All the information summarized here can be applied for developing crop and horticultural plants to have more freezing tolerance for higher production with better quality. There have been extensive studies on the activities of antioxidant enzymes and the gene regulation, however, more researches will be required in near future to elucidate the most effective antioxidant enzymes to induce highest freezing tolerance in a crop plant in a transformation process or a breeding program.

In vitro antagonistic potential of Streptomyces sp. AM-S1 against plant and human pathogens

Abstract: In the present investigation, a total number of 132 different actinomycetes strains were isolated from the humus soil samples. Out of 132 isolates, 52 showed inhibitory activity against the fungal pathogen Rhizoctonia solani. Among the antagonists, the isolate designated as AM-S1 exhibited maximum inhibitory activity against the test pathogen R. solani (41 mm). Further, the light microscopic observations of the co-cultures showed severe structural alterations in the mycelia of R. solani near the zone of inhibition. The isolate AM-S1 was identified as Streptomyces sp. by morphological and 16S rDNA sequence analysis. The color of the aerial and substrate mycelia produced by the Streptomyces sp. AM-S1 varied with different media. The isolate Streptomyces sp. AM-S1 also effectively inhibited the growth of various plant and human pathogens. Further works are needed on optimization of this strain’s antagonistic activity, isolation and characterization of the antimicrobial metabolite.

Analysis of apigenin in Blumea balsamifera Linn DC. and its inhibitory activity against aldose reductase in rat lens

Abstract: To investigate the therapeutic potentials of na- tural sources, stepwise polarity fractions of Blumea balsamifera were tested for their ability to inhibit aldose reductase (AR) activity in rat lenses. Of these, the ethyl acetate (EtOAc) fraction exhibited a unique AR inhibitory activity (IC50 value, 0.11 μg/mL). Apigenin was identified from the active EtOAc fraction and exhibited high AR inhibitory activity (IC50 value, 4.03 μM). The content of apigenin was measured in B. balsamifera (0.47 mg/g) by HPLC/UV analysis. Our result suggests that B. balsamifera could be a useful natural source for the development of a novel AR inhibitory agent against diabetic complications.

Biotransformation of endosulfan by the tiger worm, Eisenia fetida

Abstract: This study assesses the role of the earthworm, Eisenia fetida, in the breakdown of endosulfan in a soil environment. Two strains of E. fetida were used in this study to assess the effect of salinity on toxicity and metabolism of endosulfan in these earthworms. One strain of E. fetida (R) was reared in high salinity soil (over 2.0 dS/m of electric conductivity) from Shiwha lake, Korea. A control strain (W) was reared in pig manure compost. Acute toxicity of endosulfan was lower in the R strain when endosulfan was injected. In vitro metabolic studies of endosulfan based on microsomal preparations showed that both strains produced two major metabolites, endosulfan sulfate and endosulfan diol. The production rate of endodulfan sulfate was not significantly different between the strains, while endosulfan diol production was significantly different. In vivo metabolism studies showed only one primary metabolite, endosulfan sulfate, was produced by both strains. HPLC-MS/MS analysis showed annetocin was the indicative protein newly expressed in the R strain in relation to salinity exposure. These findings suggest salinity may induce hydrolyzing enzymes to produce endosulfan diol from endosulfan.

Heavy metal chemistry in soils received long-term application of organic wastes

Abstract: This study was carried out to understand the long-term effect of organic waste treatment on the fate of heavy metals originated from the organic wastes, together with examination of changes in soil properties. For this, the soils received three different organic wastes (municipal sewage sludge, alcohol fermentation processing sludge, pig manure compost) in three different rates (12.5, 25, 50 ton/ha/yr) for 7 years (1994 - 2000) were used. To see the long-term effect, plant growth study and soil examination were conducted twice in 2000 and 2010, respectively. There was no additional treatment of organic wastes for post ten years after ceasing organic waste treatment for seven years. Soil examination conducted in 2010 showed decreases in soil pH, EC, total nitrogen, organic matter, available phosphorus, exchangeable cations and heavy metal contents in all soils received organic wastes compared to the results obtained in 2000. Speciation of heavy metals in soil through sequential extraction showed that organically bound Cu was the dominant species in all treatment and exchangeable Cu was increased in the plots treated with municipal sewage sludge and alcohol fermentation processing sludge. organically bound Ni increased from 25% - 30% to 32% - 45% in 2010 inall treatment while Pb showed increase in carbonate form in all treatments. Zn existed mainly as sulfide and residual forms, showing increases in organically bound form in all treatment during post ten years.

Residue patterns of buprofezin and teflubenzuron in treated peaches

Abstract: The biological half-life and final residue levels of buprofezin and teflubenzuron were examined in peaches over a 14-day cultivation period. The residue levels of buprofezin and teflubenzuron were analyzed by chromatographic method with recovery ranging from 84.0% to 96.6%. The biological half-lives of buprofezin andteflubenzuron were 4.88 and 11.49 days at the standard dose, and 4.40 and 10.86 days at a triple dose, respectively. The initial concentration of buprofezin exceeded the maximum residue limit (MRL) set in Korea, but the concentration decreased to below the MRL within 6 days after application. The initial and persisting concentrations of teflubenzuron were all below the prescribed MRL. The final residue levels of buprofezin and teflubenzuron were 0.17 and 0.10 mg·kg﹣1 following a standard single dose, and 0.20 and 0.23 mg·kg﹣1 following a triple dose, respectively. The final re-sidue levels of buprofezin and teflubenzuron were also compared with the good agricultural practices standards of the United States and Italy.

Determination of phytosterols in Oryza sativa L. cultivars by liquid chromatography atmospheric chemical ionization time-of-flight mass spectrometer (LC-APCI-TOF-MS) coupled with a modified QuEChERS method

Abstract: Development of analytical methods for the determination of phytosterols in whole grains is one of growing interests due to their clinical and nutritional functions in human. In this study, we examined simultaneous determination of β-si tosterol, stigmasterol and campesterol in Korean rice cultivars by liquid chromatography atmospheric chemical ionization time-of-flight mass spectrometer (LC-APCI-TOF-MS). The hulled rice samples were extracted using a modified QuEChERS and analyzed by LC-APCI -TOF-MS. The method was validated by low limit of detection (LOD) and limit of quantification (LOQ) values and high recovery values with low relative standard deviation (RSD). The highest concentration of sitosterol was detected in Hwasung and Undu rice cultivars, exhibiting approximately 195.5 and 191.7 mg/Kg, respectively. Stigmasterol and campesterol were detected at the highest level in Hwasung rice cultivar, giving the concentrations of approximately 70.0 and 53.9 mg/Kg, respectively. Sitosterol was determined to be a main phytosterol detected in the rice samples. Our data demonstrated that LC/APCI-TOF- MS coupled with QuEChERS method can be used as a simple tool for the determination of phytosterols in rice samples.