Anticholinesterase contaminant

Biosensors ai e widely used to the detection of hazardous contaminants in foodstuffs, soil and fresh waters. Due to high sensitivity, simple design, low cost and real-time measurement mode biosensors ai e considered as an alternative to conventional analytical techniques, e.g. GC or HPLC. Although the sensitivity and selectivity of contaminant detection is mainly determined by a biological component, i.e. enzyme or antibodies, the biosensor performance can be efficiently controlled by the optimization of its assembly and working conditions. In this report, the prospects to the improvement of pesticide detection with cholinesterase sensors based on modified screen-printed electrodes are summarized. The following opportunities for the controlled improvement of analytical characteristics of anticholinesterase pesticides ai e discussed ... 

Cell culture based bioassays are used in the agricultural field to screen for harmful contaminants such as mycotoxins. The chick embryo neuron culture system is very sensitive to the anticholinesterase activity of organophosphorus nerve agents, in a manner which parallels toxicities in animals the sensitivity to sarin was around 100 pg . The bioassay was used successfully to detect sarin at low ppm levels spiked into soil. 

Anatoxin-a(s) (Fig. 3.4) was discovered by Mahmood and Carmichael as a metabolite of Anabaena flos-aquae NRC 525-17 [4, 5]. This toxin was implicated in the death of wild animals (ducks, birds, swine) after ingestion of contaminated water. This cyanotoxin is a neurotoxin, but different from anatoxin-a, and this unique alkaloid is an irreversible inhibitor of acetylcholine esterase with a toxicology similar to that of known anticholinesterases such as paraoxon [116-119]. Anatoxin-a(s) provokes salivation (thus the suffix (s)), chromodacryorrhea, fascic-ulation, and urinary incontinence, and death within 7-20 min, on rats treated with 0.25-1.0 mg kg (i.p.) The lethal dose LD50 (mouse, i.p.) is 50 pg kg"" making... 

Figure 8. Inhibition profiles for dilutions of environmental samples contaminated with anticholinesterase compounds. Data points are means, n = 3.

This assay is not intended to yield the identities or exact concentrations of the carbamate and OP insecticides present, but rather the relative anticholinesterase activity. More specifically, this screening assay is intended to flag samples which, from a potential risk perspective, warrant further examination for specific carbamate and organophosphorus insecticide contamination. In this respect, the assay performed exceptionally well using standards in laboratory buffers. Although the assay underestimated the inhibition expected from laboratory standards, the AChE-based assay detected anticholinesterase activity present in all of the environmental samples. 

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