Bioconcentration and Metabolism of the New Herbicide Methiozolin in Ricefish (Oryzias latipes)

Abstract

Methiozolin is a novel herbicide used to control annual bluegrass. It has low vapor pressure and high hydrophobicity, which could result in persistence in water and bioaccumulation. We measured the bioconcentration factors (BCFs) of methiozolin in ricefish (Oryzias latipes). Two radiolabels were used to quantify the parent compound and identify its metabolites. Ricefish were exposed to 2.0 and 20.0 ng/L methiozolin for 28 days in the uptake phase with a 96-h LC50 of 2.2 mg/L­(95% confidence limit: 2.1–2.5 mg/L) and water solubility of 4.2 mg/L after 48 h was observed. On the basis of total radioactivity residues (TRRs), BCFss and BCFk values of 797.0–851.9 and 992.9–1077.4 were observed, respectively, while BCFss values for methiozolin were 251.9–257.5. Several minor metabolites with TRR < 3.4% were detected. Among them, 4-(2,6-difluorobenzyloxy-methyl)-3-hydroxy-3-methyl-1-(3-methylthiophen-2-yl)­butan-1-one, 2,6-difluorobenzyl alcohol, and 4,5-dihydro-5-methyl-3-(3-methylthiophen-2-yl)­isoxazol-5-yl)­methanol were identified. Methiozolin is metabolized into numerous minor metabolites with potentially low bioaccumulation capacity in ricefish. These findings can facilitate risk assessments regarding methiozolin use, particularly its movements and final stages in aquatic environments.

Design, Synthesis, Antifungal Activity, and Molecular Docking Studies of Novel Chiral Isoxazoline-Benzofuran-Sulfonamide Derivatives

“…23,24 In addition, some of the compounds containing chiral isoxazolines, such as the veterinary drug bravecto, have been shown to have antiparasitic activity only in S-configuration, while the Rconfiguration was an inactive structure, as well as the compound methiozolin, which also exhibited herbicidal activity in the S-configuration (Figure 1). 25,26 Furthermore, the advantages of sulfonamide-containing flumctsulam and metosulam were broad spectrum of herbicides, wide range of crops, low dosage, early resistance, good miscibility, safety to crops, and good herbicidal ability (Figure 1). 27−29 However, with the increasing resistance of pathogenic fungi to currently used fungicides, it is urgent to develop chiral pesticide antifungal agents with novel chemical structures to improve the antifugal performance.…”

Survival Rates of Oryzias Celebensis Embryo Reared in Different Media in an Attempt to Provide Embryos for Ecotoxicological Studies

“…Oryzias latipes, the paddy fish, distributed in Japan, Korea, and China, have long been used as model organisms in ecotoxicological studies [28], [29]. Currently, O. melastigma living in seawater is getting attention for use as a model organism in ecotoxicological research [30]- [34].…”