Concentrations Of Profenofos Research Articles

Cytotoxicity and Genotoxicity Induced by the Pesticide Profenofos on Cultured Human Peripheral Blood Lymphocytes

Profenofos is a broad-spectrum organophosphate insecticide and acaricide used widely for agricultural and household purposes. The aim of this investigation was to determine its toxicity profile in vitro, using lymphocytes from peripheral blood samples of healthy human donors. We found the IC50 of profenofos to be 3.5 μM as measured by Trypan blue dye exclusion method. Chromosomal analyses of the metaphase plates of the samples treated with sublethal concentrations of profenofos revealed satellite associations and chromatid breaks and gaps, indicating its effect on chromosomes. The results were further supported by comet assay, where single-strand breaks in DNA were observed as comet tail lengths. The results were statistically significant (p < 0.01, ANOVA). Hence, it may be proposed that in vitro assays like the comet assay and chromosomal aberrations test, which indicate genetic damage, could be used to study the effect of organophosphorus pesticide poisoning in humans.

Profenofos toxicity to the eastern rainbow fish (Melanotaenia duboulayi)

AbstractThe 96‐h median lethal concentration for profenofos in the Australian eastern rainbow fish (Melanotaenia duboulayi) was 0.9 mg/L, corresponding with an 83% reduction in acetylcholinesterase (AChE) activity in fish head. This is an order of magnitude less sensitive than the figure reported for crucian carp (Carassius carassius). Higher lethal body burdens were found in rainbow fish exposed to high concentrations of profenofos but the inhibition of AChE activity in these fish was less than in those killed by longer, normally sublethal, exposures. During sublethal exposure to 10 μg/L for 10 d, the fish accumulated profenofos residues of 5.3 mg/kg associated with a 70% reduction in AChE activity in fish head. Decreases in food intake, food conversion efficiency, and growth were observed at 10 d and significant loss of weight was noted at 21 d. These were associated with markedly increased swimming activity and response to light. A clear relationship existed between the depression of AChE activity and observed behavioral responses, such as swimming activity and food intake.

Target-Site Insensitivity as the Mechanism of Resistance to Oregano phosphorus, Carbamate, and Cyclodiene Insecticides in Tobacco Bud worm Adults

Mechanisms of resistance to oregano phosphorus, carbamate, and cyclodicne insecticides were investigated in adult tobacco bud worms, Heliothis virescens (F.). Comparative studies on profenofos toxicity with or without synergists failed to demonstrate that enhanced metabolism was a major mechanism of resistance to this insecticide. Percentage of survival of several partially resistant tobacco bud worm populations at diagnostic concentrations of profenofos and methomyl was highly correlated, suggesting the same mechanism confers resistance to these insecticides. Differences between resistant and susceptible tobacco bud worms in inhibition of acetylcholinesterase by tetrachlorvinfos (7-fold), methomyl (7.6-fold), and carbaryl (4-fold) indicated that target-site insensitivity was a major mechanism of resistance to oregano phosphorus and carbamate insecticides. The high correlation of survival of field tobacco bud worm populations exposed to diagnostic concentrations of endosulfan and dieldrin suggested that the same mechanism (target-site) conferred resistance to both insecticides. Measurements of penetration of radiolabeled profenofos indicated that a decrease in insecticide uptake may be an additional resistance factor in the tobacco bud worm. Because target-site resistance to insecticides is expressed in both larvae and adults, monitoring for resistance in adults is appropriate with these insecticides.

Detoxification of diflubenzuron and teflubenzuron in the larvae of the beet armyworm ( Spodoptera exigua) (lepidoptera: Noctuidae)

The predominant pathway for diflubenzuron and teflubenzuron detoxification in fifth instar larvae of Spodoptera exigua was studied. The insect showed a high tolerance against diflubenzuron and teflubenzuron, and a relatively high susceptibility to chlorfluazuron and hexaflumuron. According to LC 50 values, chlorfluazuron (0.093 mg/liter) and hexaflumuron (0.053 mg/liter) were considerably more potent than diflubenzuron (15.79 mg/liter) and teflubenzuron (7.30 mg/liter). Profenofos and diethyl maleate synergized both diflubenzuron and teflubenzuron, indicating that the major route of detoxification in S. exigua was through hydrolysis and conjugation. Limited synergism by piperonyl butoxide indicated that mixed function oxidase enzymes play a minor role in benzoylphenylurea (BPU) detoxification. A metabolic study in function of time was carried out. A large part of the less potent benzoylphenylureas was rapidly excreted. An excretion of 67% of diflubenzuron and teflubenzuron was detected 12 hr after intake. The remaining part of diflubenzuron was mostly hydrolyzed to 4-chlorophenylurea and 4-chloroaniline (62% of the metabolites) confirming the conclusions of the synergism study. In addition to hydrolysis, conjugation plays an important role in the detoxification of teflubenzuron (45% of the metabolism). The in vivo metabolism of diflubenzuron and teflubenzuron could be reduced by 50 and 30%, respectively, using sublethal concentration of profenofos and by 35 and 40%, respectively, using diethyl maleate.

Properties and toxicological significance of diflubenzuron hydrolase activity in Spodoptera littoralis larvae

Optimal assay conditions for gut diflubenzuron (DFB) hydrolase(s) of the Egyptian cotton leaf worm Spodoptera littoralis larvae are 0.9 mg protein of the postmitochondrial supernatant fraction incubated for 2 hr at 37°C with 0.5 nmol [ 14C]DFB (uniformally labeled on the aniline ring) in 0.4 ml of 0.05 M glycine-NaOH buffer (pH 9.0). The radiolabeled metabolites are separated and quantitatively evaluated using a TLC procedure. DFB hydrolase activity is a major factor for DFB detoxification in S. littoralis larvae. This conclusion is based on the ability of the larval gut enzyme to hydrolyze DFB to 4-chloroaniline (4-CA) and 4-chlorophenylurea (4-CPU), 4-CA being a major metabolite with a level of about 10% and 4-CPU a minor one with a level of about 1% of the total recovery. A relatively high level of radiolabeled polar metabolites is observed at the origin of the TLC plate; these metabolites are considered to be conjugated materials. DFB hydrolysis is totally inhibited in vitro at a concentration of 10 −5 M of profenofos or DEF, which are both considered typical esterase inhibitors. Over 90% inhibition of DFB hydrolase activity in vivo is obtained when larvae are fed with castor bean leaves treated with 2.4 × 10 −4% profenofos. Addition of sublethal concentrations of profenofos to dietary DFB resulted in a considerably higher toxicity of the latter.