THE TOXICITY AND MODE OF ACTION OF DIPHENYLAMINE PESTICIDES

N,N-Diphenylamines and N-substituted N,N-diphenylamines have broad scale of activity as pesticides. Studies were conducted to determine the effects of a series of ring-substituted diphenylamines on mitochondrial oxidative phosphorylation in mice and insects and on the photosynthetic reactions of spinach chloroplasts so as to ascertain and compare the biochemical mechanism of toxic action of these compounds in plants and animals. Ring substituted diphenylamines with acidic NH groups showed all the requisite properties to be classified as uncouplers of oxidative phosphorylation in mouse liver and tobacco hornworm gut mitochondria. They increased state 4 respiration and ATPase activity and decreased the respiratory control index and ADP:O ratio in these mitochondria using glutamate as the substrate. At low concentrations (10 nM) the most active compounds uncoupled photophosphorylation in chloroplasts, while at comparable or somewhat higher concentrations (10-100 nM) they inhibited electron transport in photosystem II. Photosystem I electron transport was resistant to inhibition by these compounds. The uncoupling activity against mitochondrial oxidative phosphorylation or inhibitory effects on photosystem II electron transport of these compounds were positively correlated with the total electron withdrawing effect of the ring substituents particularly as reflected in their pKa values. Although certain diphenylamines such as TTDA (2,4-dinitro-2\u27,4\u27,6\u27-trichloro-6-trifluoromethyldiphenylamine) were among the most potent uncouplers yet reported with clear activity at 1-10 nM, the conversion of the NH bridge to N-methyl resulted in a complete loss of uncoupling activity against oxidative phosphorylation in mouse liver mitochondria and spinach chloroplasts. However, this tertiary diphenylamine like its parent (TTDA), was highly toxic to insects, mites and mammals, causing hypothermia, rapid rigor mortis and brain edema in mice. These compounds appear to act in the same way and this might be attributable to the metabolic release of TTDA in vivo by N-demethylation. In support of this idea, the toxicity of N-methyl TTDA to mice is delayed compared to TTDA and is antagonized by pretreatments with inhibitors of the mixed function oxidase system

Contamination profile of aflatoxin M1 residues in milk supply chain of Sindh, Pakistan

Aflatoxin M1 (AFM1) is a potent carcinogen, teratogen and mutagen found in the milk when lactating animals consume feed contaminated with aflatoxin B1 (AFB1). In the present study, the contamination of AFM1 was evaluated in the milk supply chain of the province of Sindh, Pakistan. For the broader profiling of targeted toxin, enzyme-linked immunosorbent assay (ELISA) was used for the determination of AFM1 in both branded and non-branded milk samples. The results showed that 96.43% of samples (81 out of 84) were contaminated with AFM1 in the range of 0.01–0.76 μg/L. The average contamination level was 0.38 μg/L. The determined values of AFM1 in the collected milk samples were above the standard limit of the European Commission while 70% of the samples exceeded levels established by United States regulations. According to these results, the estimated daily intake of AFM1 for adults was determined as 3.1 ng/kg of body weight per day

Removal of Pesticide Residues from Okra Vegetable through Traditional Processing

The study has been designed to determine the extent of pesticide residues removal from okra through household processing. For this, okra crop was grown on university farm and application of pesticides were carried out at recommended dosage. After 24 hours, the okra was harvested, labeled and brought to the laboratory of Institute of Food Sciences and Technology, Sindh Agriculture University, Tandojam for their analyses and further processing such as washing, detergent washing, sun-drying and cooking, etc. being practiced at various households. Pesticide residues were extracted from okra by solvent partitioning and cleaned by C18 cartridges/activated charcoal by using acetonitrile for elution and then cleaned up residues were analyzed through HPLC-UV. The analysis of data revealed that imidacloprid is highly effective against pests at low dosages and its residues in processed as well as unprocessed okra samples were within MRLs (0.5ppm). Imidacloprid residues 0.31 ppm in unwashed okra was reduced to 0.082 ppm by detergent washing (73% removal). Emamectin benzoate residues were high in unwashed okra (0.51 ppm as against MRLs of 0.2ppm), however, its residues were reduced to MRLs by detergent washing and subsequent processing by frying, thermal dehydration or sun-drying of detergent washed okra

Removal of Pesticide Residues from Okra Vegetable through Traditional Processing

Demand for vegetables in Pakistan is constantly increasing to feed growing population. Pakistan is the second largest producer of okra and in Sindh okra is produced throughout the year. Okra crop is attacked by variety of insect pests and commercial okra production relies heavily on the pesticides belonging to organochlorine, organophosphate, carbamate, pyrethroid and neo-nicotinoid groups for pest control. Moreover, growers do not observe safety interval for okra harvest. Hence the okra sold in Pakistani markets is highly contaminated with pesticide residues. Aim of this research study was to determine the extent of pesticide residue decontamination in okra vegetable through traditional processing. Okra crop was sprayed with bifenthrin, profenofos and endosulfan, and different processing were applied on okra such as washing, detergent washing, sun-drying and cooking, etc. Bifenthrin, profenofos and endosulfan pesticide residues were extracted from okra by solvent partitioning and cleaned up through Florisil column using organic solvents for elusion as described by EPA and FDA procedures. Cleaned up residues were analyzed through GC-µECD. The results revealed that endosulfan levels were reduced to MRL by detergent washing (from 2.01 ppm in unwashed samples to 1.03ppm). Profenofos residues (3.21ppm) were reduced to MRL (2.0ppm) by detergent washing and by combination of plain water washing and frying. Bifenthrin MRL is very low (0.04ppm) and only combination of detergent washing and frying reduced residues from 0.311 ppm to 0.042 ppm