From glyphosate-based herbicide, organic extract, purified organic extract to pure glyphosate: comparative toxicity to cholinesterase enzyme

Abstract

Glyphosate is an organophosphate herbicide widely used in agriculture and has been classified as a probable carcinogen by the International Agency for Research on Cancer (IARC). Roundup Original Mais (ROM) is a glyphosate-based herbicide that contains glyphosate along with other ingredients, and its effects on human health are still a matter of controversy. This study aimed to compare the toxicity of ROM, gradual purified organic extract until pure glyphosate, on serum cholinesterase. Petroleum ether organic extracts of ROM were obtained through procedure A, in which ROM was solubilized in water followed by acetone purification, and procedure B, in which procedure A was submitted to alkalization with 1 M NaOH at pH=11 aiming for purification. Enzymatic activities of ROM, organic extracts obtained from procedures A and B, pure glyphosate, neostigmine (an anticholinesterase agent as positive control), and serum alone (negative control) were detected using a commercial kit for cholinesterase determination, in triplicate. The results showed that all substances, except the pure glyphosate standard, significantly inhibited the enzyme, with the inhibition being: ROM>neostigmine>Procedure A>Procedure B. ROM was found to be potentially more toxic than pure glyphosate due to the presence of impurities. We showed the gradual toxicity loss with the purification process of ROM, the form by which workers are exposed. The use of serum cholinesterase for toxicity evaluation can provide valuable information on the toxicity of glyphosate-based herbicides. Further studies are needed to investigate the specific impurities present in ROM and their toxic potential on health.