Showing papers on "Organomercury Compounds published in 2015"

Plant Uptake of Insecticides, Fungicides, and Fumigants from Soils

Abstract: Soon after the introduction of organic pesticides to control plant diseases and insects several researchers became concerned about the effects of these very useful, but poten tially dangerous agricultural chemicals toward nontarget organisms. One concern was the effect on plan ts. Some of the questions asked were: Are these compounds phytotoxic? Do they enter into plants through roots and leaves? If they enter the plants, are they metabolized or inactivated? If not, do they persist in plants to continue their toxic action against the target species? Are they metabolized to more toxic compounds? Are they potentially harmful to the consumer of the plant? This review will be limited to plant uptake of pesticides from soils. Herbicides and growth regulators will not be considered because Foy, Coats, and Jones (1971) recently extensively reviewed plant absorption of these compounds. Crafts (1961) also reviewed plant sorption of herbicides and growth regulators. The former is most comprehensive and covers plant species, plan t parts, compounds, direction of chemical translocation, and the method used to trace translocation. Various aspects of the literature have been reviewed previously (Marth, 1965; Wheatley, 1965; Newsom, 1967; Caro, 1969; Casida & Lykken, 1969; Edwards, 1970 ; Young, 1971, on chlorinated hydrocarbon insecticides; Spencer, 1965; Finlayson & ~1acCarthy, 1965; ~1etcalf, 1967, on organic phosphate insecticides; Pramer, 1959 and 1961; Brian, 1967, on antibiotics, fungicides, and bactericides; \Varren & Delevault, 1962, on lead; Pimental, 1971, on insecticides, herbicides, and fungicides). Most research on plant absorption of pesticides has been conducted since the early 1960's primarily because gas-liquid chromatography (GLC) development increased analytical sensitivity from 10 to 1,000 times over previous chemical and bioassay techniques (Koblitsky & Chisholm, 1949; Mills, Onley, & Gaither, 1963; Giuffrida, Ives, & Bostwick, 1966). In addition GLC analyses have provided residue identification, whereas previous chemical and bioassay techniques often did not. Certain chemical assays were quite specific and provided sensitivities near 0.1 ppm, though. rrhis is a factor of only about 10 greater than GLC sensitivity in many cases

Inhibition of Zn(II) Binding Type IA Topoisomerases by Organomercury Compounds and Hg(II)

Abstract: Type IA topoisomerase activities are essential for resolving DNA topological barriers via an enzyme-mediated transient single strand DNA break. Accumulation of topoisomerase DNA cleavage product can lead to cell death or genomic rearrangement. Many antibacterial and anticancer drugs act as topoisomerase poison inhibitors that form stabilized ternary complexes with the topoisomerase covalent intermediate, so it is desirable to identify such inhibitors for type IA topoisomerases. Here we report that organomercury compounds were identified during a fluorescence based screening of the NIH diversity set of small molecules for topoisomerase inhibitors that can increase the DNA cleavage product of Yersinia pestis topoisomerase I. Inhibition of relaxation activity and accumulation of DNA cleavage product were confirmed for these organomercury compounds in gel based assays of Escherichia coli topoisomerase I. Hg(II), but not As(III), could also target the cysteines that form the multiple Zn(II) binding tetra-cysteine motifs found in the C-terminal domains of these bacterial topoisomerase I for relaxation activity inhibition. Mycobacterium tuberculosis topoisomerase I activity is not sensitive to Hg(II) or the organomercury compounds due to the absence of the Zn(II) binding cysteines. It is significant that the type IA topoisomerases with Zn(II) binding domains can still cleave DNA when interfered by Hg(II) or organomercury compounds. The Zn(II) binding domains found in human Top3α and Top3β may be potential targets of toxic metals and organometallic complexes, with potential consequence on genomic stability and development.

The Synthesis and Identification Azo dyes Derived from Mercuried Sulfa compounds and used their as Indicator of Acid - Base.

Abstract: Three new organomercury compounds containing azo group were prepared from sulfa compounds. The prepared compounds were synthesized and characterized by FT/IR, elemental analysis (CHN) and 1 H-NMR spectroscopy. According to the results of the titration of strong acid strong base, Azo dyes have multiple uses in volumetric analysis, especially those that have different colors in acidic and basic media.