Nonenantioselective environmental behavior of a chiral antiviral pesticide dufulin in aerobic soils

Evaluation of Chiral Pesticide Chlorbufam at the Enantiomeric Level: Absolute Configuration, Separation, Herbicidal Activity, and Degradation in Soil

Chlorbufam is a photosynthesis inhibitor chiral herbicide with a pair of enantiomers, which is rarely a concern. In this work, the optically pure enantiomers of chlorbufam were first synthesized and characterized, and the enantioselective herbicidal activity and mechanism were studied. Chlorbufam enantiomers showed significant differences in bioactivity against Echinochloa crus-galli and Abutilon theophrasti, and R-(+)-chlorbufam was identified as the most active against the targeted organisms with higher bioactivity of 3.95 and 1.71 times than S-(-)-chlorbufam. Chlorbufam enantiomers exerted herbicidal activity by inhibiting photosynthesis according to the results of the determination of photosynthetic pigment contents and molecular docking. Additionally, a novel HPLC-MS/MS method was successfully developed and validated for the detection of chlorbufam enantiomers and further applied for the enantioselective degradation study in soil. As a result, chlorbufam was satisfactory enantioseparated with a resolution of 2.37 on a Chiralpak IH column using the mobile phase of acetonitrile and water (60:40, v/v). Good linearity for chlorbufam enantiomers was obtained with correlation coefficients ≥0.9990, and the recovery ranged from 74.1 to 119% with relative standard deviations ≤10.9% at three spiked levels. The degradation behaviors of chlorbufam enantiomers were significantly different, and S-(-)-chlorbufam was preferentially degraded. The findings encouraged the application of enantiopure R-(+)-chlorbufam herbicide to reduce dosage rates, decrease environmental risks, and protect human health.

Effects of charged polystyrene microplastics on the bioavailability of dufulin in tomato plant

Microplastics (MPs) and pesticides commonly exist in the environment, yet the interactions between them and their subsequent impacts on plants remain poorly understood. Thus, this study aimed to investigate the impacts of differently charged polystyrene (PS) MPs, including PS-COO-, PS and PS-NH3+ MPs, on the fate of 14C-labelled new antiviral pesticide Dufulin (DFL) in a hydroponic tomato system. The results showed that MPs greatly reduced the growth of tomato plants, with suppression of 18.4-30.2%. Compared to the control group, PS-COO-, PS and PS-NH3+ MPs also reduced the bioaccumulation of DFL in whole tomato plants by 40.3%, 34.5%, and 26.1%, respectively. Furthermore, MPs influenced the translocation of DFL in plant tissues, and the values decreased at the rates of 38.7%, 26.5% and 15.7% for PS-COO-, PS and PS-NH3+, respectively. Interestingly, compared to the control group, PS-COO- exhibited a profound inhibitory effect on DFL concentrations in tomatoes, potentially resulting in a lower dietary risk in the hydroponic tomato system. This may be due to the strong adsorption between PS-COO- and DFL, and PS-COO- may also inhibit the growth of tomato plants. Overall, our study could provide valuable insights into the risk assessment of DFL in the presence of MPs in plant systems.