A topical gel might protect against pesticide damage to humans

A group of researchers in India has developed a topical skin gel they hope farmers and landscape workers can use to minimize the neurotoxic effects of organophosphate pesticides (Sci. Adv.2018, DOI: 10.1126/sciadv.aau1780). The gel, called polyoxime, contains a nucleophilic pyridine-2-aldoxime on a chitosan base and works by cleaving the phosphate or thiophosphate group off of pesticides like methyl parathion (MPT) before they absorb into the skin and irreversibly inhibit an enzyme called acetylcholine esterase. The goal, says lead researcher Praveen K. Vemula of the Institute for Stem Cell Biology & Regenerative Medicine, was to create a heat- and cold-stable compound that worked catalytically and would be inexpensive to produce. Initial tests in rats showed that after treatment with the gel, exposing the animals to MPT did not lead to the same decline in active acetylcholine esterase that they saw in either the sham group (gel with no active ingredient) or the untreated group. Acetylcholine esterase, an enzyme involved in the breakdown of a neurotransmitter important for motor function, is the target of many organophosphates, and its off-target activity in humans is of concern because it can lead to nerve damage and paralysis. The team expects to begin human studies in 2019.