Protoporphyrinogen oxidase (PPO) inhibitors have long been considered environmentally friendly herbicides due to their high efficacy and low toxicity. However, we found that a widely used PPO inhibitor butafenacil (BFA) and its transformation products (TPs) possessed exceptionally high toxicity to some marine phytoplankton (96-h EC50 of BFA were 0.71 ± 0.08 μg/L and 1.3 ± 0.06 μg/L for Skeletonema costatum and Chlorella sp., respectively). Bialgal culture experiments revealed that BFA exposure enhanced the competitive advantage of Chlorella sp., triggering a shift in dominance from other microalgae to Chlorella sp., which could alter the community structure and potentially destabilize ecological imbalances in marine environments. The degradation process of BFA in seawater could be accelerated by Phaeodactylum tricornutum, as its half-life decreased from 7.5 to 3.3 days, and 16 (13 new) TPs were identified by solid-phase extraction-liquid chromatography–high-resolution tandem mass spectrometry. Using computational toxicology, TPs with predicted toxicity comparable to parent BFA were isolated by preparative liquid chromatography and subjected to algal toxicity tests. The semiquantitative estimates indicated that the persistent high toxicity to microalgae after BFA degradation was attributable to these toxic TPs on a BFA-equivalent basis, underscoring the necessity to consider the potential environmental risks posed by TPs.
Shuo Liu, Siyuan Jing, Yifan Li et al.· Environmental Science &...· 0 citations
Evaluating the roles of NAA and 6-BA on the G. lemaneiformis showed that both NAA and 6-BA enhanced the relative growth rate, linear growth rate of main and lateral branches, as well as accumulation of phycobiliprotein, soluble polysaccharide and total lipid.
Lizhen Rong, Luke Chu, Mo Zou et al.· Botanica Marina· 0 citations
The blow fly Lucilia sericata is a species of major medical and veterinary importance, functioning both as a causative agent of myiasis and as a beneficial organism in maggot debridement therapy. Increasing resistance to conventional insecticides highlights the need for alternative compounds targeting fundamental physiological processes. In this study, we investigated the insecticidal and physiological effects of 2,6-dimethylphenol (2,6-DMP), a lipophilic phenolic compound, with particular emphasis on its impact on cuticular lipid homeostasis and immune cell integrity. Topical application of 2,6-DMP significantly reduced larval survival and, more prominently, suppressed adult emergence to 5-20% of control levels, indicating disruption of metamorphosis beyond acute toxicity. Dose-response analysis revealed similar median lethal doses (LD50) for larvae and adults (∼1.85-1.95 μg/mg body mass), suggesting comparable susceptibility across developmental stages. Gas chromatography-mass spectrometry demonstrated pronounced, stage-specific remodeling of cuticular free fatty acids (FFAs). In larvae, exposure induced a strong, dose-dependent accumulation of long-chain FFAs, particularly C16:0 and C18:1. In contrast, adults exhibited a biphasic response: sublethal exposure resulted in a >3-fold increase in total FFAs, whereas lethal exposure caused near-complete lipid depletion. Cholesterol was consistently depleted in all treated groups. Principal component analysis confirmed that variation in lipid profiles was driven primarily by changes in total FFA abundance and sterol composition. In parallel, hemocyte analysis revealed clear immunotoxic effects, including reduced granulocyte abundance, impaired aggregation, and progressive morphological disruption in both in vivo and in vitro models. Collectively, these findings demonstrate that disruption of lipid homeostasis contributes to the physiological and immunotoxic effects of 2,6-DMP in L. sericata. Beyond revealing a potential mode of insecticidal action, our findings raise concerns about the potential ecotoxicological impact of 2,6-DMP as an environmental contaminant, particularly with respect to non-target insects, and identify lipid homeostasis as a sensitive mechanistic endpoint for environmental risk assessment.
Corynespora leaf spot, caused by Corynespora cassiicola, is an emerging disease in crops that significantly impacts both yield and quality. Currently, the use of fungicides to control Corynespora leaf spot has led to the development of varying degrees of resistance in the pathogen. Therefore, it is crucial to screen for highly effective fungicides with novel modes of action. This study evaluated the antifungal activity of 1-hydroxyphenazine (1OH-PHZ) against multiple phytopathogenic fungi, with a half-maximal effective concentration (EC50) of 19.23 μg/ml against C. cassiicola hyphae. In vivo assay demonstrated antifungal activity of 67.22 and 45.03% on detached tomato leaves and fruits, respectively, at a dose of 500.0 μg/ml. Microscopic and ultrastructural observations revealed hyphal collapse, surface wrinkling, and indistinct organelle boundaries following treatment. Integrated transcriptomic and metabolomic analyses showed differentially expressed genes and differentially abundant metabolites, primarily affecting amino acid metabolism and biosynthesis pathways. Molecular docking, dynamic simulations, and microscale thermophoresis assays demonstrated that 1OH-PHZ binds to PLP-dependent transferase (PLPDT), exhibiting a binding free energy of -7.2 kcal/mol and a dissociation constant (Kd) value of 1.16 μM. Collectively, these findings suggest that 1OH-PHZ potentially binds to PLPDT, thereby disrupting amino acid metabolism and biosynthesis, which subsequently affects the synthesis and morphological development of the fungal cell wall and cell membrane. Through the combination and screening of highly active fungicidal substances, this study offers mechanistic insights that support the potential development of 1OH-PHZ as a novel agricultural fungicide for managing C. cassiicola infections.
Dongxue Li, Haowen Ni, Yuqi Bin et al.· Phytopathology· 0 citations
Spodoptera frugiperda, known as the fall armyworm (FAW), is a polyphagous pest that causes huge economic losses in different agricultural regions of the world. Its control is challenging due to its widespread resistance to conventional insecticides and Bt events. This study aimed to assess the lethal toxicity and growth-inhibitory effects of eight acetone-derived monoketone curcuminoids (MKCs) on S. frugiperda larvae. MKCs were synthesized by Claisen-Schmidt condensation between acetone and aromatic aldehydes in a basic medium and tested against FAW larvae at a concentration of 250 mg kg-1 (dietary exposure) over 7 days. None of the tested compounds showed a significant lethal toxicity to FAW. However, halogenated MKCs derivatives 4 ((1E,4E)-1,5-bis(4-fluorophenyl)penta-1,4-dien-3-one) and 5 ((1E,4E)-1,5-bis(4-chlorophenyl)penta-1,4-dien-3-one) exhibited sublethal effects, reducing larval weight by 59% and 55%, respectively, compared to the negative control. These results indicated that the halogenation of MKCs may be a promising strategy to be exploited in the search for novel bioactive compounds to manage FAW in agricultural food production systems.
Keywords: Claisen-Schmidt condensation; fall armyworm; halogenated compounds; monoketone curcuminoids
Larissa Costa de Oliveira, Y. R. Robles, Murilo Norberto Pereira et al.· Multi-Science Journal· 0 citations
Trehalose-6-phosphate phosphatase (TPP), a key enzyme in trehalose biosynthesis, represents a promising target for pest and fungal control due to the absence of TPP in higher animals. However, few TPP inhibitors have been reported, and broad-spectrum agents targeting both insects and fungi remain scarce. In this study, 2-cinnamoylbenzimidazole was identified as a dual-targeting inhibitor scaffold against insect and fungal TPPs. Structure-guided optimization by pocket size yielded 5–1 (Ki = 1.3 μM) for insect TPP and 5–3 (Ki = 17.3 μM) for fungal TPP. Molecular docking revealed that 2-cinnamoylbenzimidazole forms hydrogen bonds with conserved active-site residues, while its aryl ring occupies a hydrophobic subsite. Biological assays demonstrated that ingestion of 1 mM 5–1 caused 100% mortality in Plutella xylostella larvae and reduced locomotion in Locusta migratoria, concomitant with marked reductions in hemolymph trehalose and glucose. This work provides a novel TPP inhibitor scaffold, demonstrates a structure-guided optimization strategy, and establishes a foundation for developing multifunctional pesticides.
Xi Jiang, Mingjia Gao, Zhijun Zhang et al.· Journal of Agricultural and...· 0 citations