Hydrolysis, Photolysis, and Biotoxicity Assessment of a Novel Biopesticide, Guvermectin

Abstract

Guvermectin is a biopesticide isolated from the secondary metabolites of Streptomyces sp. NEAU6, an endogenous actinomyces of a Chinese medicine named Paris polyphylla. However, the environmental degradation behavior and biotoxicity of guvermectin are still unclear, which may affect its rational application. Therefore, the degradation of guvermectin in water at different pH values (pH 4, pH 6, pH 7, and pH 9) and with or without light was investigated in the laboratory. The results showed that guvermectin could be degraded in pH 4 solution, and the presence of light irradiation enhanced the degradation process with a DT50 of 2.95 and 12 days for photolysis and hydrolysis, respectively. However, guvermectin was fairly stable in other conditions. Three products transformed from guvermectin degradation were identified by UPLC-QTOF/MS. Biotoxicity assessment was performed on Danio rerio and Daphnia magna Straus by ECOSAR prediction and in vivo biological tests. The test data showed that guvermectin and its transformation products exhibited low toxicities to D. rerio and D. magna Straus (LC50/EC50 > 100 mg a.i./L), and the transformation products had lower toxicity than their parent substance. The results provided a reference for elucidating the potential risk of guvermectin to nontarget organisms and promoting its rational use.

Design, One-Step Highly Selective Synthesis and Enhancing Insecticidal Activity and Photo-Self-Degradation of Phenylpyrazole Esterified Derivatives as GABA and nACh Receptor Inhibitors

“…Under photocatalysis, the parent compound acts synergistically with its various photoproducts to increase toxicity and thus enhance biological activity, the exact mechanism of which needs to be further investigated. Clarifying the photolytic behavior of pesticides is important to promote rational application of pesticides and accurate environmental risk assessment. , …”

“…Clarifying the photolytic behavior of pesticides is important to promote rational application of pesticides and accurate environmental risk assessment. 58,59 According to the structure−activity relationship principle, structural modifications were made to the most typical phenylpyrazole insecticide, fipronil, and phenylpyrazole ester derivatives acting on GABA and nACh receptors were designed. In this study, a new solvothermal method was employed, and through an improved Pinner reaction, a series of phenylpyrazole ester derivatives with fused ester bonds (PE 1 −PE 10 ) and PH were successfully synthesized.…”

Development and Application of the Novel Plant Growth Regulator Guvermectin: A Perspective

“…25 While GV remains stable in ultrapure water, it readily undergoes hydrolysis under acidic conditions (pH 4.0), with degradation further accelerated by exposure to light. 26 The products of GV degradation differ between soil and water environments. In a laboratory setting, the GV degradation products in soil include hypoxanthine, inosine, an adenosine analogue, and small molecules.…”

“…A study of four representative agricultural soils (black, red, cinnamon, and fluvoaquic soil) found that GV displays a degradation half-life (DT 50 ) ranging from 0.95 to 10.10 days . While GV remains stable in ultrapure water, it readily undergoes hydrolysis under acidic conditions (pH 4.0), with degradation further accelerated by exposure to light . The products of GV degradation differ between soil and water environments.…”

Uptake and Biotransformation of Guvermectin in Three Crops after In Vivo and In Vitro Exposure

“…Guvermectin (Figure S1) was a novel nucleoside-like biopesticide and registered as a plant growth regulator using seed soaking of rice in China in 2021. − Guvermectin exhibited an excellent effect on increasing the rice yield and improved tolerance for abiotic stress. It has low toxicities to aquatic organism, bee, and quail, , In neutral and alkaline buffer solutions, guvermectin was fairly stable, but it was unstable in an acid solution and transformed into adenine. In soils, guvermectin was converted into hypoxanthine catalyzing by nucleoside phosphorylase of microbes. , The biotransformation of guvermectin in plants has not yet been reported.…”