Synthesis of Glucose–Fipronil Conjugate and Its Phloem Mobility

Abstract

Phloem-mobile insecticides are preferred to achieve economically useful activity. However, only a few phloem-mobile synthetic insecticides are available. One approach to converting nonmobile insecticides into phloem-mobile types is introducing sugar to the parent compound. To test whether the addition of a glucose group to a non-phloem-mobile insecticide enables conversion into phloem-mobile, N-[3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]-1H-pyrazol-5-yl]-1-(β-D-glucopyranosyl)-1H-1,2,3-triazole-4-methanamine (GTF) was prepared through click chemistry. A phloem-mobility test in Ricinus communis L. seedlings confirmed that GTF was mobile in the sieve tubes. Although GTF exhibited lower insecticidal activity against the third-instar larvae of Pzlutella xylostella than fipronil did, it can be reconverted into fipronil in adult plants of castor bean, thereby offsetting the decrease of insecticidal activity. Therefore, the presence of a glucose core confers phloem mobility to fipronil.

Glucose Positions Affect the Phloem Mobility of Glucose–Fipronil Conjugates

“…25 Synthesis and Characterization of GTF Conjugates. The synthetic method of GTF conjugates was proposed by Yang et al 9 To prepare these conjugates via click chemistry, tetraacetylglucosides containing the azide group were synthesized according to the same method mentioned above (Scheme 1). Propargyl was introduced into fipronil according to a previous method by Yang et al 9 as a coupling partner.…”

“…The synthetic method of GTF conjugates was proposed by Yang et al 9 To prepare these conjugates via click chemistry, tetraacetylglucosides containing the azide group were synthesized according to the same method mentioned above (Scheme 1). Propargyl was introduced into fipronil according to a previous method by Yang et al 9 as a coupling partner. In Scheme 2, the CuSO 4 ·5H 2 O/ascorbate click reaction system was explored to prepare the acetyl glucose-containing fipronil conjugates, which were O-deacetylated via the Zempleń procedure to obtain the target products.…”

“…28 The system was adopted to test the phloem mobility of GTF, 2-GTF, 3-GTF, 4-GTF, and 6-GTF. As presented in a previous study, 9 the plasma membrane potential of the conjugates was measured via flow cytometric analysis with DiBAC4(3) as the fluorescent dye indicator. 29 In comparison to the control sample, the relative fluorescence data did not have any remarkable changes during the treatment period ( Figure 1).…”

Fipronil should not be categorized as a “systemic insecticide”: a reply to Gibbons et al. (2015)

“…Of the listed chemicals, fipronil has by far the lowest water solubility and highest logP ow . Nevertheless, Simon-Delso et al (2015) in their review state, B…we address the phenyl-pyrazole fipronil together with neonicotinoids because of similarities in their…phys-icochemical profiles....^Based on its properties, fipronil would not be expected to be a systemic insecticide and consequently is considered to be non-phloem mobile (Yang et al 2011). In fact, Bonmatin et al (2015) acknowledge that fipronil is not systemic B…nonsystemic products, such as fipronil….^Later, Bonmatin et al (2015) discuss field studies employing seeds treated with fipronil or soil-incorporated fipronil products that suggest fipronil is taken up by the root and translocated into the plant.…”

Preparation, Characterization and Intracellular Imaging of 2,4-Dichlorophenoxyacetic Acid Conjugated Gold Nanorods

“…To address this problem, the imaging of the transport process for pesticides in plants was primary. Recently, radioisotopes 2 3 or fluorescence dyes [4][5][6] had been used to track pesticides in cells and plants. However, these approaches were difficultly utilized due to their radioactive risks, unstable fluorescence, 7 8 short half-life, 9 and so on.…”