Effect of esterification and side-chain alkylation on alteration of translocation characteristics of methamidophos

Abstract

1. The phloem mobility and systemic activity of methamidophos (I); propanedioic acid 1-phosphoramidothionic acid O,S-dimethyl ester, 2-methyl, 3-0monoethyl ester (II); propanedioic acid, 1-phosphoramidothionic acid O,S-dimethyl ester, 2,2-dimethyl, 3-monoethyl ester (III); and butenoic acid, 1-monoethyl ester, 2,3,-E & Z, 3-phosphoramidothionic acid O,S-dimethyl ester (IV) were investigated in soybeans (Glycine max L.) with a bioassay using cabbage looper (Tricoplusia ni Hüber) larvae to determine the impact of side-chain alkylation on the translocation of propanedioic acid 1-phosphoramidothionic acid O,S-dimethyl ester 3-monoethyl ester (V). 2. The ethyl ester of ethanedioic acid, 1-phosphoramidothionic acid OS,-dimethyl ester 2-monoethyl ester (VI) was compared with a bukly ester analogue, the 2-(methyl)butyl ester (VII). 3. Monoethylation of the alpha-carbon of II resulted in enhanced insecticidal and systemic activity, which was interpreted as a steric hindrance to fatty acid oxidation of the propanedioic moiety of III, but not of II and V. 4. Compound IV was an effective insecticide by topical and feeding response, but was not a systemic. 5. A large bulky ester (VII) blocked deesterification and the systemic insecticidal response was lost when compared with VI. 6. This study suggests that the utilization of the malonate semialdehyde-pathway enzymes found in plants but not in insects may be fruitful in the molecular design of new insecticides.

Acute oral toxicity of pesticide combination (acephate 50% and imidacloprid 1.8% as active ingredients) in Sprague-Dawley rats

“…The LD 50 of pesticide combination (acephate 50% and imidacloprid 1.8% as active ingredients) is >2000 mg/kg body weight in Sprague-Dawley female rats as per the OECD Guideline 420 (fixed dose method) [ 17 ]; the pesticide combination (acephate 50% and imidacloprid 1.8% as active ingredients) was classified into category-five as per the GHS. Crisp and Look [ 25 ] reported LD 50 of acephate as 866-945 mg/kg, Worthing and Walker [ 26 ] reported oral LD 50 of acephate in rats as 850 mg/kg, and Kumar [ 14 ] mentioned the median LD of acephate as 2851 mg/kg body weight when tested individually in Wistar rats. Death of one animal of five indicates that the acephate presence may be responsible for lethality at the dose rate of 2000 mg/kg body weight.…”

Phloem Mobility of Xenobiotics. VII. The Design of Phloem Systemic Pesticides

“…These acids lie on the narrow ridge running diagonally from a pK a value of 8 down to a pK a value of ).5 and have 10gKow values approximately equal to (7.0 --pK a ). This subset of weak acids is predicted to be highly phloem mobile because of ion trapping (9) [3] Volume 44, Issue 3 (July-September) 1996 > 14). The relatively low log Kow values of amitrole and oxamyl result in log Cfvalues much higher than that of diuron consistent with experimental observations of modest phloem mobility (2).…”

“…In a previous paper in this series (14), we applied a simple model of the plant vascular system to elucidate factors that enhance the phloem systemicity of chemical hybridizing agents. This model was developed in response to a challenge (20) to reconcile in quantitative terms the weak acid (9) and intermediate permeability hypotheses (30). Since then we have further developed this model to account for the time dependence of phloem transport (18) and have demonstrated the ability of the model to successfully account for the phloem systemicity of most pesticides (10).…”

Χρήση βιοσημάντων των βιοδεικτών coturnix coturnix japonica ( ορτύκι) και onchorhynchus mykiss (πέστροφα) για την αξιολόγηση οικοτοξικολογικών επιπτώσεων του methamidophos

“…ε ιφεξ επίζδξ δεκ παναηδνήεδηε εκδζζιυηδηα ιε ιέβζζηδ δυζδ 7,5 mg/kg bw methamidophos (Burruel et al 2000) ηαζ 28 mg/kg/d acephate . ε ιεθέηεξ ιε acephate ημ LD 50 =866-945 mg/kg, εκχ βζα ημκ εκενβυηενμ ιεηααμθίηδ ημο acephate, ημ methamidophos, ημ LD 50 = 13-30 mg/kg ζε εδθαζηζηά (Crisp and Look, 1982;Singh, 1984;Behera and Bhunya, 1989;Ware, 1989;Pesticide Management Education Program (PMEP), 2008). Γφμ οπμεέζεζξ ελδβμφκ ηδ δζαθμνεηζηή ημλζηυηδηα ηςκ acephate ηαζ methamidophos αθμφ ηα έκημια ηαζ ηα εδθαζηζηά ιπμνμφκ κα ιεηαηνέρμοκ ημ acephate ζε methamidophos (Tucker, 1976b;Kao and Fukuto, 1977).…”