Uptake and Phloem Transport of Glucose-Fipronil Conjugate in Ricinus communis Involve a Carrier-Mediated Mechanism

Abstract

Some compounds containing glucose are absorbed via the monosaccharide transporters of the plasma membrane. A glucose-fipronil conjugate, 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), has been synthesized in our previous work. GTF exhibits moderate phloem mobility in Ricinus communis. In the current paper, we demonstrate that the uptake of GTF by Ricinus seedling cotyledon discs is partly mediated by an active carrier system (K(m)1 = 0.17 mM; V(max)1 = 2.2 nmol cm(-2) h(-1)). Four compounds [d-glucose, sucrose, phloridzin, and carbonyl cyanide m-chlorophenylhydrazone (CCCP)] were examined for their effect on GTF uptake. Phloridzin as well as CCCP markedly inhibit GTF uptake, and d-glucose weakly competes with it. The phloem transport of GTF in Ricinus seedlings is found to involve an active carrier-mediated mechanism that effectively contributes to the GTF phloem loading. The results prove that adding a glucose core is a reasonable and feasible approach to confer phloem mobility to fipronil by utilizing plant monosaccharide transporters.

Food safety in Thailand 1: it is safe to eat watermelon and durian in Thailand

“…Little is known of the pesticide transport in plants. No direct evidence of transport mechanisms of dimethoate in watermelon but at least active transport system appeared to be one of important transport mechanisms for pesticides in some vegetables and fruits such as soybean, gourd, cucumber and zucchini [34][35][36][37]. In addition, a previous study has shown that the edible part (pulp) of vegetables including cucumber, pumpkin, yam, and sweet potato was less contaminated with an organochlorine pesticide, chlordecone, than the parts that are thrown away, i.e., peels or rinds [38].…”

Synthesis of Rotenone-O-monosaccharide Derivatives and Their Phloem Mobility

“…The Kleier model is widely utilized to predict the phloem mobility of a xenobiotic based on its physicochemical properties (pK a and log K o/w ). 10,27 Most of the tested xenobiotics fit well, except for several xenobiotics whose transport is carrier-mediated. 5,27 Taking the physicochemical properties (pK a and log K o/w ) of tested compounds into consideration (Table 2), compounds 3a−3f, rotenone and dalpanol were predicted to be nonphloem mobile in terms of the Kleier Model ( Figure 6).…”

Glucose Positions Affect the Phloem Mobility of Glucose–Fipronil Conjugates

“…Specific carrier processes were probably involved in the phloem transport, as demonstrated in the phloem transport of GTF in Ricinus seedlings, which involves an active carrier-mediated mechanism that effectively contributes to GTF phloem loading. 16 Among these conjugates, the analysis result showed that linking the fipronil to C-2, C-3, C-4, and C-6 of glucose affected phloem mobility of GTF conjugates. The concentrations of GTF, 2-GTF, 3-GTF, 4-GTF, and 6-GTF in phloem sap were 32.35 ± 1.51, 37.37 ± 1.44, 35.25 ± 1.32, 26.87 ± 1.07, and 35.10 ± 1.19 μM, respectively (Figure 2).…”

“…The parameters were similar to our previously reported method. 16 Physicochemical Properties. The physicochemical properties [molecular weight (MW), ionization constant in aqueous solution (pK a ), octanol/water partitioning coefficient (log K ow ), number of hydrogen bond donors (HBDs), and number of hydrogen bond acceptors (HBAs)] of different positions of glucose conjugates were predicted using ACD LogD suite version 14.0 software ( Table 1).…”