Azobenzene-Avermectin B1a Derivatives for Optical Modulation of Insect Behaviors

Engineering the novel azobenzene-based molecular photoswitches for suppressing bacterial infection through dynamic regulation of biofilm formation

BACKGROUND

Bacterial biofilm is a strong fortress for bacteria to resist harsh external environments, which can enhance their tolerance and exacerbate the drug/pesticide resistance risk. Currently, photopharmacology provides an advanced approach via precise spatiotemporal control for regulating biological activities by light-controlling the molecular configurations, thereby having enormous potential in the development of drug/pesticides.

RESULTS

To further expand the photopharmacology application for discovering new antibiofilm agents, we prepared a series of light-controlled azo-active molecules and explored their photo isomerization, fatigue resistance, and anti-biofilm performance. Furthermore, their mechanisms of inhibiting biofilm formation were systematically investigated. Overall, designed azo-derivative A11 featured excellent anti-Xoo activity with an half-maximal effective concentration (EC50) value of 5.45 μg mL-1, and the EC50 value could be further elevated to 2.19 μg mL-1 after ultraviolet irradiation (converted as cis-configuration). The photo-switching behavior showed that A11 had outstanding anti-fatigue properties. An in-depth analysis of the action mechanism showed that A11 could effectively inhibit biofilm formation and the expression of relevant virulence factors. This performance could be dynamically regulated via loading with private light-switch property.

CONCLUSION

In this work, designed light-controlled azo molecules provide a new model for resisting bacterial infection via dynamic regulation of bacterial biofilm formation. © 2024 Society of Chemical Industry.

Avermectins and Their Derivatives: Recent Advances in Biosynthesis and Application

Avermectins (AVMs) and their derivatives are the most effective and widely used nematicides, insecticides, and acaricides against endo- and ectoparasites of plants, animals, and humans. Demand for avermectins and their highly effective derivatives has increased due to their high cost-effectiveness and wide range of applications as medicines and crop protection products. Due to the unique structures of these compounds and for industrial production purposes, numerous efforts and strategies have been dedicated to enhancing the production of avermectins and creating new analogues in recent years. Here, we have systemically reviewed the recent studies on the biosynthesis and application of avermectins and their derivatives, including avermectin metabolism and its related bioregulation in Streptomyces avermitilis, approaches for enhancing the bioproduction of avermectins, the structure and toxicology of avermectin derivatives, and future prospects, with a focus on the recent advances in biosynthesis and significance of the superior avermectin derivatives.

Knockdown of TcGluCl leads to the premature pupation of Tribolium castaneum larvae possibly by influencing the calcium-mediating hormone homeostasis

The glutamate-gated chloride channels (GluCls) are widely existed in the neural and nonneural tissues of invertebrate. In addition to play important roles in signal transduction, the GluCls also showed multiple physiological functions in insects such as participate in the juvenile hormone synthesis. In the present study, the potential roles of TcGluCl in growth and development of the red flour beetle Tribolium castaneum were explored. Knockdown of TcGluCl showed no effects on the survivability, weight growth, final pupation rate, eclosion and fecundity of T. castaneum, whereas resulted in the significant premature pupation of larvae. Inhibition of TcGluCl expression significantly changed the levels of juvenile hormone and ecdysone as well as the expressions of hormone biosynthetic genes. The increased ecdysone level and decreased juvenile hormone level were observed at the late stage of dsGluCl-treated larvae. Knockdown of TcGluCl significantly reduced the expressions of TcSTIM1 and TcOrai1, which were the primary proteins in store-operated calcium entry (SOCE) mediated Ca2+ influx mechanism. Whilst the L-glutamic acid treatment led to the increased TcOrai1 expression in T. castaneum. These findings suggested that knockdown of TcGluCl increased the ecdysone level and contributed to the premature pupation of larvae, which might be due to the reduced Ca2+ influx caused by the decreased expressions of TcSTIM1 and TcOrai1. These studies provide novel insights on the function of GluCls in insects.

Optical Control of Insect Behavior and Receptors with Azobenzene-Bridged Fipronil and Imidacloprid

Photopharmacology can be implemented in a way of regulating drug activities by light-controlling the molecular configuations. Three photochromic ligands (PCLs) that bind on one or two sites of GABARs and nAChRs were reported here. These multiphoton PCLs, including FIP-AB-FIP, IMI-AB-FIP, and IMI-AB-IMI, are constructed with an azobenzene (AB) bridge that covalently connects two fipronil (FIP) and imidacloprid (IMI) molecules. Interestingly, the three PCLs as well as FIP and IMI showed great insecticidal activities against Aedes albopictus larvae and Aphis craccivora. IMI-AB-FIP in both trans/cis isomers can be reversibly interconverted depending on light, accompanied by insecticidal activity decrease or increase by 1.5-2.3 folds. In addition, IMI-AB-FIP displayed synergistic effects against A. craccivora (LC50, IMI-AB-FIP = 14.84-22.10 μM, LC50, IMI-AB-IMI = 210.52-266.63 μM, LC50, and FIP-AB-FIP = 36.25-51.04 μM), mainly resulting from a conceivable reason for simultaneous targeting on both GABARs and nAChRs. Furthermore, modulations of wiggler-swimming behaviors and cockroach neuron function were conducted and the results indirectly demonstrated the ligand-receptor interactions. In other words, real-time regulations of receptors and insect behaviors can be spatiotemporally achieved by our two-photon PCLs using light.

Dual photo-controlled release system for fipronil and dinotefuran

Development of controlled release system promises a huge impact on the pesticide delivery, which has raised attentions in improving efficacy of pesticides. Herein, the emerging photoremovable protecting group (PRPG), used in spatiotemporal delivery of drug by light, was introduced into agriculture. We obtained three TNB-insecticides and two of them exhibited excellent photophysicochemical properties. Our dual photo-controlled release system displayed more than sixfold insecticidal activity differences upon irradiation with UV light or sunlight. The dual release of DIN-TNB-DIN showed synergistic effect on mosquito larvae and armyworm larvae. Distribution of the fluorescence in body of dead/alive wigglers clearly illustrated the action mode, and visually demonstrated the precise and spatiotemporal delivery of insecticides in the living mosquito larvae. The new developed dual photo-controlled release system might widen the diversity in pesticide delivery, promoting the development in improving pesticide efficacy.