Shulou(Shulou.com)11/24 Report--

According to CTOnews.com on November 21, paraquat has become a herbicide widely used in the world since it was put on the market in 1962 because of its advantages such as rapid weeding, high efficiency, broad spectrum, low cost and non-toxicity to plant roots. However, another name of paraquat is "pesticide", which is highly toxic to animals and humans, and because there is no effective antidote, the mortality rate of poisoning is 50%.

So far, at least tens of thousands of people around the world have died as a result of suicide or accidental paraquat. Therefore, it is a common goal for academia and industry to develop a safe herbicide comparable to paraquat.

According to the Shanghai Institute of Organic Chemistry of the Chinese Academy of Sciences, Tang Wenjun, a researcher at the Shanghai Institute of Organic Chemistry of the Chinese Academy of Sciences, and Professor Peng Ai of the Tenth people's Hospital affiliated to Tongji University worked together to create a new herbicide diene diamine. It is found that diene diamine has the same herbicidal effect as paraquat, and a series of mouse and cell experiments show that it is safe, and it is expected to become a new green herbicide which is safe and non-toxic instead of paraquat.

It is reported that the herbicidal function of paraquat and its fatal toxicity are due to the electron conduction function of its own chemical structure. Its bipyridine salt structure can not only block the normal function of photosynthetic system I in plants by intercepting electrons, but also lead to the depletion of NADPH and the formation of superoxide free radicals, resulting in cytotoxicity. Therefore, how to achieve "maintain the herbicidal performance of molecules, but eliminate their toxicity" has become a scientific problem.

The team envisions whether it is possible to create a safe and non-toxic herbicide through the strategy of "using a precursor of a non-bipyridine salt structure that has no electron conduction function and is not toxic, but can be transformed into a bipyridine salt structure to produce a herbicidal effect in a herbicidal environment". Based on this assumption, a "reduced state" paraquat precursor-diene diamine, which is easy to prepare and stable, has become the research goal.

▲ figure 1. The research team realized the concise synthesis of diene diamine, determined its structure by X-ray single crystal diffraction, and then used potassium borohydride and water as reaction conditions to realize the large-scale preparation of diene diamine on a scale of 100 grams.

In the process of studying the conversion of diendiamine to paraquat, the research team initially achieved copper-catalyzed oxidation of diene diamine to paraquat in high yield, and was further surprised to find that diene diamine could be converted to paraquat in the presence of air, natural light and water, realizing the original idea of in-situ conversion of diene diamine to paraquat in a herbicidal environment (figure 2). However, it shows considerable stability indoors (without dark room preservation), whether in the form of solid or aqueous solution.

The research team further carried out weed control experiments on three common weeds: Arabidopsis thaliana, Acorus calamus and Bermudagrass. The results showed that diene diamine showed the same herbicidal ability as paraquat, and diene diamine was converted to paraquat under sunlight and air conditions. The team of the Tenth people's Hospital of Shanghai continued to carry out in-depth and systematic safety assessment. The results showed that the toxicity of diene diamine was similar to that of the experimental control group, and the safety was extremely high.

▲ figure 2: identification, preparation and transformation of diendiamine the safe and non-toxic diene diamine found in this study is expected to be developed as a broad-spectrum herbicide instead of paraquat, which may not only help to ensure food security in China and even the world, but also prevent death caused by paraquat poisoning, which has important research significance and social value.

The work was recently published in the top journal Molecular Plant in the field of plant science under the title "Dienediamine: A Safe Herbicide as Paraquat Surrogate".

CTOnews.com attached a link to the paper:

Https://doi.org/10.1016/j.molp.2023.10.018

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