Polymeric Quaternary Ammonium Salts Research Articles

Preparation of antibacterial and strong regenerated cellulose film via crosslinking with polymeric quaternary ammonium salt containing epoxy/ZnO

Particulate matter (PM), usually formed as aerosols suspended in atmosphere, is becoming a carrier of viruses and bacteria, accelerating the spread of respiratory diseases. Hence, air filtration devices are widely utilized for removing PM. In this study, a regenerated cellulose (RC) film was prepared with the properties of good mechanical strength, antibacterial, and highly efficient filtration (EF) properties, through cellulose dissolution and further crosslinking with P(AGE-DMDAAC)/ZnO. Results exhibited that the Young’s modulus of the composite membrane was nearly 4.3 GPa. Additionally, the antibacterial performance against Escherichia coli and Staphylococcus aureus, was up to 99.89% and 99.67%, respectively. Meanwhile, RC composite filter exhibited a high PM 2.5 capture efficiency (over 99.91%). This study introduces an interesting approach to produce antibacterial films with the characteristics of notably good mechanical performance and high fine particle EF that can be utilized in a high humidity environment.

Polyacrylamide quaternary ammonium salts based on stable adsorption in soil and its application on the control of soil-borne fungal disease

Currently, soil-borne fungal disease (SBFD) have caused a huge damage in agriculture, and small molecule soil disinfectants have been widely used for the prevention and control of SBFD, which could not only kill the chlamydospore of pathogenic fungi, but also completely destroy the microbial community and its functional diversity in the soil, and is not conducive to subsequent plant planting. Therefore, how to effectively inhibit plant pathogenic fungi while maintaining the general balance of microbial population in the soil to facilitate subsequent plant planting come to be critical problem in the prevention and control of SBFD. In this work, a series of polyacrylamide containing quaternary ammonium salts (PAM-X) were synthesized based on the radical copolymerization of acrylamide (AM) and acrylamide containing different quaternary ammonium salts groups (AMX). Owing to the entanglement between polymer chains and soil, PAM-X could be stably absorbed in the soil, thus effectively delaying the free migration of PAM-X chains in soil, and reducing the probability of being leached from soil, which might be the key to obtain novel polymeric quaternary ammonium salts that have less impact on the environment. Banana Fusarium wilt, also known as “banana cancer”, caused by Fusarium oxysporum f. sp. cubense (Foc), was chosen as a typical soil-borne pathogen disease to verify the rationality of the above thoughts. The results showed PAM-X had well anti-Foc4 activities in soil, and could maintain the general balance of microbial population in the soil, which are almost non-toxic to earthworms in soil and fish, thus provides a new prevention and control method for SBFD.

Fluorine-containing amphiphilic quaternary ammonium salts for the suppression of Banana fusarium wilt

As the pathogen of banana Fusarium wilt, Fusarium oxysporum f. sp. cubense race 4 (Foc4) has the strongest toxicity and pathogenicity due to its long-term viability in soil, but there is still no effective way to control it at present. Based on the activity parameters of polymeric quaternary ammonium salt in our previous work, this paper hopes to enhance the amphiphilicity of polymeric quaternary ammonium salt by introducing a fluoroalkyl group to improve the antifungal property of polymeric quaternary ammonium salt and achieve stable adsorption and long-term inhibition of saprophytic Foc4 conidia in soil. Here, we prepared a series of fluorine-containing ammonium salts with random and block structures by atom transfer radical polymerization (ATRP), and we systematically studied the effects of the introduction of fluoroalkyl groups, the proportion of hydrophobic segments and polymer structure on micelle properties, antifungal properties, adsorption, migration and long-term antifungal properties against Foc4 in soil. Finally, the preferred polymeric quaternary ammonium salts were selected for pot experiments in the prevention and control of banana Fusarium wilt caused by Foc4, and positive experimental results were achieved. In conclusion, we made an exploratory attempt at the practical application of polymeric amphiphilic quaternary ammonium salt in plant disease control.

Antifungal mechanisms of polymeric quaternary ammonium salts against conidia of Fusarium oxysporum f. sp. cubense, race 4

Antifungal mechanisms of polymeric quaternary ammonium salts against conidia of Fusarium oxysporum f. sp. cubense, race 4

Adsorption isotherms of Polyquaternium-10 polymers by activated sludge solids

Polymeric quaternary ammonium salts (polyquaternium-10 polymers, PQ-10) are extensively used as components of hair care products, lotions, and makeup and, therefore, are present in domestic sewage. Adsorption of these polymers by activated sludge was assessed to evaluate their removal by a commonly used wastewater treatment process. Activated sludge solids (ASS) were dosed with PQ-10 polymers with relatively high molecular mass (JR-125 and JR-30 M) and relatively low molecular mass (LR-400 and LR-30 M) and equilibrated for 2 h at 20 ± 2 °C. After equilibration, the vessels with the mixtures were centrifuged and the supernatants were analyzed with a phenol method.The relationships between dosed amounts and equilibrium concentrations in the aqueous phase (dose-response curves) for each tested polymer indicated that at relatively low dosing solution concentrations were negligible (“total adsorption” region of the dose-response curve). Light absorbance of the samples prepared for determination of polymer concentration using a phenol method within this region was close to the absorbance of the blank (0 μg (a.i.)/mL) or below absorbance of the blank, resulting in calculated concentrations apparently below zero. At some level of dosing, a subsequent increase in polymer dosage resulted in a quantifiable increase in solution concentration (“solution concentration rising” region).The relationships between concentrations of the polymers in the aqueous phase and concentrations of adsorbed polymers (adsorption isotherms) were non-linear. The ability of activated sludge solids to bind tested polymers may be characterized by apparent “threshold values” of the loading for each polymer. Below the “threshold value,” solution concentration of the polymer is close to zero and above this value it becomes measurable. “Threshold loading” for all polymers was from 50 to 100 mg (a.i.)/g, far above concentrations of these compounds expected to be present in the sewage.

Activating Room‐Temperature Phosphorescence of Organic Luminophores via External Heavy‐Atom Effect and Rigidity of Ionic Polymer Matrix**

Pure organic room-temperature phosphorescence (RTP) materials have attracted wide attention for their easy preparation, low toxicity, and applications in various fields like bioimaging and anti-counterfeiting. Developing phosphorescent systems with more universality and less difficulty in synthesis has long been the pursuit of materials scientists. By employing a polymeric quaternary ammonium salt with an ionic bonding matrix and heavy atoms, commercial fluorescent dyes are directly endowed with phosphorescence emission. In a single amorphous polymer, the external heavy-atom effect generates excited triplet states and the rigid polymer matrix stabilizes them. This study put forward a new general strategy to design and develop pure organic RTP materials starting from existing library of organic dyes without complicated chemical synthesis.

Activating Room‐Temperature Phosphorescence of Organic Luminophores via External Heavy‐Atom Effect and Rigidity of Ionic Polymer Matrix**

AbstractPure organic room‐temperature phosphorescence (RTP) materials have attracted wide attention for their easy preparation, low toxicity, and applications in various fields like bioimaging and anti‐counterfeiting. Developing phosphorescent systems with more universality and less difficulty in synthesis has long been the pursuit of materials scientists. By employing a polymeric quaternary ammonium salt with an ionic bonding matrix and heavy atoms, commercial fluorescent dyes are directly endowed with phosphorescence emission. In a single amorphous polymer, the external heavy‐atom effect generates excited triplet states and the rigid polymer matrix stabilizes them. This study put forward a new general strategy to design and develop pure organic RTP materials starting from existing library of organic dyes without complicated chemical synthesis.

Facile fabrication of polymeric quaternary ammonium salt hydrogel by radiation for dyes removal from aqueous solution

The effluents containing various dyes from the process industries raise esthetic problems and cause toxic impacts on aquatic and human life. Thus, the dye effluent must be adequately treated before being discharged into water-bodies. A cellulose-derived quaternary ammonium salt was treated by radiation to form hydrogel structure. The radiation dose effects on gel fraction and swelling properties were investigated. The hydrogel structure was characterized by IR and SEM analyses. The Zeta potential values at different pH were all greater than +30 mV, which indicating that the hydrogel possessed enough electrostatic attraction force to anionic ions. The adsorption behaviors of the polymeric quaternary ammonium salts hydrogel (PQH) towards methyl orange (MO), Congo red (CR), and Coomassie brilliant blue (CBB) are discussed. The pseudo-second-order mode well fitted the adsorption kinetics for all three dyes. The increasing order of the initial adsorption rate h0 was MO > CR > CBB. The Langmuir model well described the adsorption isotherms were well described by with the maximum adsorption capacity for MO, CR, and CBB being 628.93, 427.35, and 617.28 mg/g, respectively. HCl was used to regenerate the dye-loaded-hydrogel. The adsorption-desorption test demonstrated the good reusability of this hydrogel. Also, the PQH has selective adsorption of MO from RhB/MO mixing solution.

Intensifying the process of methane gas hydrates crystallization in the presence of surface-activated substances

The crystallization process of gas hydrates during their formation in the presence of surface-active substances (SAS) is studied. The research is conducted in two directions – theoretical and experimental. Experimental data on the crystallization rate of methane gas hydrates formation in the presence of surfactants have been obtained: high-molecular compounds are used on the basis of polymeric quaternary ammonium salts containing side aliphatic radicals of various lengths in the acyl fragment, as well as a number of specific surfactants. The process of methane gas hydrates formation is performed using a laboratory setup of the NPO modification for the gas hydrates creation. To analyse the experimental data, technical and metrological instruments are used: stalagmometric method with automatic photoelectric drop counting, conductometric method, Wheatstone bridge, spectrophotometric titration of amino end-groups, viscometer VPZh-1. It has been substantiated that the crystal formation rate depends on the surfactant concentration. New experimental dependences of the gas hydrates formation on surfactants under thermobaric conditions in the presence of surfactants have been found. It has been revealed that the crystallization process during the methane gas hydrates formation is accelerated in the presence of a surfactant. As a result of their application, the effect of solubilization and catalysis arises with the formation of the so-called “diffusion zone”, the size of which decreases in the presence of surfactants, thereby accelerating the substance transfer to the surface on which crystallization occurs. An increase in the surfactant concentration leads to an increase in the rate of molecular diffusion, and also creates a more intense turbulent diffusion.

Synthesis and antifungal activities of hydrophilic cationic polymers against Rhizoctonia solani

A series of linear hydrophilic cationic polymers with different charge density and molecular weights were synthesized by one-step polymerization process. The effect of the hydrophobicity and molecular weights on the antifungal activity against Rhizoctonia solani (R. solani) and Fusarium oxysporum f. sp. cubense race 4 (Foc4) was assessed. The biotoxicity of the cationic polymers were evaluated based on their median lethal concentration (LC50) for zebrafish and silkworm and median lethal dose (LD50) for Kunming mice. The results indicated that the balance between antifungal activity and biotoxicity could be well tuned by controlling the hydrophobic-hydrophilic balance. The minimum inhibitory concentration (MIC) of PEPB10 and PEPB25 against R. solani were 160 μg/mL and 80 μg/mL, respectively. And the LD50 for Kunming mice of PEPB10 and PEPB25 were more than 5000 mg/kg, which mean that PEPB10 and PEPB25 with high hydrophilicity show low toxicity and better selectivity for R. solani. The cationic polymers can kill the R. solani by damaging their membranes and exchanging the Ca2+ or/and Mg2+ cations of their membranes or cell wall. These results help to understand the antifungal mechanism of low-toxic polymeric quaternary ammonium salts and highlight their potential application as highly selective fungicidal agents for controlling plant diseases.

Biorenewable functional oligomers and polymers – Direct copolymerization of ferulic acid to obtain polymeric UV absorbers and multifunctional materials

Ferulic acid (FA) (3-methoxy-4-hydroxy-cinnamic acid) is obtained from biowaste such as bran of rice, wheat and maize. It possesses tremendous potential for making polymers suited to specialty applications. This manuscript describes the use of FA directly to produce functional polymers useful for making aqueous dispersions, films and other materials with multifunctional characteristics. pH responsive polymers were also prepared for the first time by using off-the-shelf reagents in one step. In the case of pH responsive polymers the absorption maximum (λmax) varied with pH of the medium. The pH responsive polymers were further modified to zwitterioninc polymers and UV absorbing polymeric quaternary ammonium salts. Zwitterionic polymers dispersed well in water. Hydrolytic studies in phosphate buffer indicated that the stability of polymers depended on the chemical structure. The polymers are potentially useful as UV absorbing films and biorenewable multifunctional materials.

Novel Bifunctional Nanofiller (Bioactive\Antimicrobial) for Improving Dental Adhesives Efficacy

Purpose: The objective of this study was to develop novel bio-composite Nanofiller (Quaternary polyethyleneimine\ Hydroxyapatite, QPEI/HAp), which combines the antibacterial activity of polymeric quaternary ammonium salt and the multi-advantages of Hydroxyapatite nanoparticles for improving biological and physico-mechanical properties of Dental Adhesives. Materials and Methods: Hydroxyapatite (HAp) nano rods were produced by hydrothermal process and coated by Polyethyleneimine (PEI) via electrostatic adsorption, followed by two steps polymeric reaction; tertiary amination and quaternization. The resulting powder was characterized using XRD, FTIR and TEM before and after polymer coating, and bioactivity was evaluated after 7 days soaking in simulated body fluid using XRD analysis. An experimental ethanolbased one-bottle adhesive resin was formulated with 0.2, 0.5, 1, 2 and 5% QPEI/HAp nanofiller. The formulated adhesive resins were evaluated for their colloidal stability, antibacterial activity, Ultimate Tensile Strength, and Micro-Shear bond strength to dentin. Results: Powder characterization confirmed successful surface modification of Hydroxyapatite nanoparticles with PEI polymer; the particles presented a high crystallinity with typical chemical groups and mean size around 20 nanometers. XRD analysis revealed nucleation of apatite crystals on the surface of QPEI/HAp nanoparticles after soaking in SBF; confirming their bioactivity. Lower contents of modified nanoparticles showed little or no aggregation tendency and good colloidal stability in the adhesive solution with Zeta potential of 30.6 mV. Antibacterial outcomes of PEI against S. mutans was significantly higher than that of MDPB in Clearfil Protect bond; a commercial adhesive used as control (P<0.05). The addition of 0.2 wt. % modified nano-hydroxyapatite resulted in higher values of Ultimate Tensile and Micro-Shear bond strength than other tested adhesives and commercial Clearfil S3 Bond (all-in-one adhesive); (P<0.05). Conclusion: Incorporation of 0.2 wt. % QPEI-HAp nanoparticles significantly improved the adhesive properties and may be promising multifunctional filler for dental adhesive resin.

Efficient Liquid–Liquid Extraction of Benzene from Its Mixture with Cyclohexane by Utilizing Hyperbranched Polymeric Ammoniums Salts

A novel hyperbranched polymeric quaternary ammonium salt (HPQAS) with benzene rings in the structure (PVBC-TMA) was synthesized by self-condensing vinyl polymerization followed with quaternary amination reaction. Meanwhile, a hyperbranched polyamidoamine (PAMAM) was separately neutralized with different acids to produce the HPQASs without benzene rings. These HPQASs were dissolved in DMSO and used to extract benzene from its mixture with cyclohexane. The liquid–liquid equilibrium (LLE) data indicate that the HPQAS/DMSO mixture showed a higher selectivity coefficient (19.92) than DMSO (<15). PVBC-TMA having benzene rings showed higher extraction performance than the PAMAM salts without benzene rings, especially when the composition of benzene/cyclohexane is close to the azeotrope state. The cation−π and π–π interactions between the ammonium ion and the benzene ring in the HPQAS with benzene in the benzene/cyclohexane mixture were thought to be the mass transfer impetus for extracting benzene from its mixture with cyclohexane by utilizing the HPQASs. This was the first example of applying the hyperbranched polymeric ammonium in the separation of benzene/cyclohexane.

Porous Hybrid Nanoflower Self-Assembled from Polyoxometalate and Polyionene for Efficient Oxidative Desulfurization

A novel and precise ionic self-assembly (ISA) construction strategy for the self-assembly of polymeric quaternary ammonium salts (polyionene) and Anderson-type polyoxometalate (β-Mo8O264–) to form a three-dimensional nanoflower structure was developed successfully and used for oxidative desulfurization (ODS) of fuels for the first time. Furthermore, the morphologies of the self-assembled structures could be precisely regulated by varying the reaction conditions, including the concentrations of the polyionene and temperature. Additionally, nitrogen sorption analysis indicated the porosity with a surface area up to 140 m2 g–1. Remarkably, the nanoflowers showed excellent conversion (98.9%) toward the ODS process with six times of recycling. This could be ascribed to the large amount of active sites dispersed over the relatively high specific area, providing contact with reactants in the ODS process. This facile and innovative fabrication method shed new light on the versatile design and construction of nano...

The study of properties of composite adsorptive materials “silica gel – crystalline hydrate” for heat storage devices

Heat energy storage is one of the most common technical solutions in the conditions of operation of low-potential and renewable energy sources. Adsorption heat energy storage devices based on the composite media “silica gel – salt” are the most effective in these conditions. The technique and technology of sol-gel synthesis of the composite adsorption materials “silica gel – sodium sulfate” and “silica gel – sodium acetate” have been developed. A special feature of this technique is a two-stage process involving the formation of silicon phase nuclei in the interaction of aqueous solutions of silicate glass and sulphuric or acetic acids in the presence of a polymeric quaternary ammonium salt and subsequent coarsening of the particles with the gradual addition of solutions of silicate glass and the corresponding acids. The essence of the technology consists in successive stages of formation and integration of the silicic phase nuclei, hydrolysis of functional OH- groups, filtration and drying of the fine precipitate. A qualitative difference in the adsorption properties of the synthesized composites and the mechanical mixture of salt – silica gel with sorption capacity inferior to them on average by 30% is revealed by differential thermal analysis. The processes of application of the composite adsorption materials “silica gel – sodium sulfate” and “silica gel – sodium acetate” obtained by the sol-gel method have been studied. A qualitative difference in the kinetics of adsorption of water by the composite adsorbents is shown as compared to massive salts. It is established that the amount of heat of adsorption of water vapor by the composite adsorbents of the materials “silica gel – sodium sulfate” and “silica gel – sodium acetate” is approximately 30 % greater than the linear superposition of salt and silica gel.

Anti-Rhizoctonia solani activity by polymeric quaternary ammonium salt and its mechanism of action

Polymeric quaternary ammonium salts (PQASs) exhibit antibacterial action and are less toxic, less stimulatory to the human body and have easier-to-modify functionalities than small molecular antibacterial agents. However, few studies on the structure-activity relationship and toxicity mechanism of PQASs against fungi have been reported. We previously described the synthesis of a novel PQAS, namely, a homopolymer of (2-methacrylamido)propyltetrabenzyldimethylammonium chloride (PQD-BC), and discovered that the polymer exhibits antifungal activities not only against Fusarium oxysporum f. sp. Cubense tropical race 4 (Foc 4), the pathogen of banana wilt, but also against Rhizoctonia solani (R. solani), the pathogen of rice sheath blight (RShB). Furthermore, we studied the mechanism of action of PQD-BC against Foc 4, which is markedly different from R. solani in morphology and life cycle. Therefore, the structure-antifungal activity relationship and toxicity mechanism of PQD-BC against R. solani were extensively studied in this work and compared with those of the low-molecular-weight quaternary ammonium salt benzyldimethyldodecylammonium chloride (BC), and the results play an important role in identifying long-term and low-toxicity fungicides that can suppress the sclerotia of R. solani. The results showed that PQD-BC and BC can destroy the structural integrity and morphology of a cell, such as by loss of the cell wall and plasma membrane integrity, leading to the release of intracellular contents and can induce mitochondrial dysfunction and interference with genomic DNA and inhibit the formation of sclerotia. However, PQD-BC showed a special mechanism for causing the lipid peroxidation of the cell membrane; this mechanism was not observed with BC. The newly elucidated mechanism accounts for differences between polymers and small-molecule compounds and provides a theoretical basis for further application of PQAS against fungi and sclerotia.

PDMS tri-block copolymers bearing quaternary ammonium salts for epidermal antimicrobial agents: Synthesis, surface adsorption and non-skin-penetration

Quaternary ammonium salts are widely used as epidermal and topical antimicrobial agents in medical treatments due to their broad activity, excellent performance and ready availability. However, their epidermal application has revealed many noticeable disadvantages, including short-term functionality, environmental toxicity, rapid antimicrobial resistance and skin penetration. Here, a series of tri-block copolymers grafted with dimethylaminopropyl benzyl chloride and based on a polydimethylsiloxane (PDMS) backbone, referred to as PDMS-b-(PDMS-g-BC)-g-PDMS, were prepared with well-controlled chain length and cationic grafting content. The quaternary ammonium salt-containing polymers were effective antimicrobial agents against epidermal pathogenic microbes, such as E. coli, S. albus and C. albicans. By incorporating hydrophilic and antimicrobial quaternary ammonium salt groups into the hydrophobic PDMS backbones, the amphiphilic tri-block copolymers were water-soluble but capable of assembling onto different surfaces, driven by electrostatic attraction or hydrophobic repulsion, which yielded long-term functionality on the surface. Moreover, the enlarged molecular size prevented penetration though full-thickness rat skins. These findings suggest a promising application of polymeric quaternary ammonium salts with hydrophobic moieties as epidermal antimicrobial agents.

Investigation of the influence of polyelectrolytes hydrodynamic properties on the hydrateformation process

One of the most perspective non-traditional sources of hydrocarbon raw materials and energy is gas hydrates (GH), which stimulates their large-scale study in many laboratories and scientific centers around the world. The interest in the GH is related to the possibility of their industrial application. The use of technologies for storage and transportation of natural gas in the form of GH requires fundamental kinetic studies of the hydration process at atmospheric pressure in the presence of chemical impurities (catalysts, surfactants, etc.). During the research, an increase in the rate of gas hydrates formation was discovered at the expense of activated impurities and composite compounds obtained on their basis, which lead to changes in the hydrochemical and hydrodynamical modes of systems. It was established that the process of GH formation occurs due to the binding of methane macromolecules and other chemical impurities, which contribute to increase the number of moles of gaseous methane, due to the flow of exchange processes between the polymer matrix and water soluble salts, as well as a result of the change in the hydrodynamics of the water system. The purpose of this work is to investigate the effect of polyelectrolytes solutions hydrodynamic properties on the GH formation. We used a number of ionenes based on polymeric quaternary ammonium salts, side aliphatic radicals of different lengths contained in the acyl fragment.

Controllable synthesis and antimicrobial activities of acrylate polymers containing quaternary ammonium salts

A series of acrylate polymers containing quaternary ammonium salts (PDMAEMA-BC) having tunable molecular weights were synthesized via atom transfer radical polymerization (ATRP), and the effect of the degree of polymerization (DP) on the antimicrobial activity against bacteria (Escherichia coli, Staphylococcus albus), pathogenic fungi (Candida albicans) and phytopathogenic fungi (Rhizoctonia solani and Fusarium oxysporum f. sp. cubense race 4) was systematically assessed. The antimicrobial properties against E. coli, S. albus and C. albicans were characterized using the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) or minimum bactericidal concentration (MBC) values, whereas the antimicrobial activities against R. solani and Foc4 were evaluated using the effective concentration (EC50 and EC90), MIC and MFC values. The results indicated that the PDMAEMA-BC homopolymers showed better antimicrobial activities than the corresponding monomer, i.e., the acrylate quaternary ammonium salt monomer (DMAEMA-BC), and the optimal antimicrobial activities were obtained for moderate PDMAEMA-BC chain lengths. These results help to understand the antimicrobial mechanism of polymeric quaternary ammonium salts and highlight their potential application as fungicidal agents for controlling both human and plant diseases.

Polymeric quaternary ammonium salt activity against Fusarium oxysporum f. sp. cubense race 4: Synthesis, structure-activity relationship and mode of action

Polymeric quaternary ammonium salts (PQAS) have been widely used to prevent microbial contamination, but little is known about their activity against phytopathogenic fungi. Our previous report described the synthesis of two novel PQAS, namely a homopolymer of (2-methacrylamido) propyltetrabenzyldimethylammonium chloride (PQD-BC) and dimethylaminopropyl benzyl chloride-grafted polysiloxanes (PDMS-g-BC); we demonstrated their structure-activity relationship against phytopathogenic fungi such as R. solani and Fusarium oxysporum f. sp. cubense tropical race 4 (Foc4). Here, we analyzed the structure-activity relationship and toxicity mechanism of these compounds at the molecular level against Foc4 compared with the low molecular-weight quaternary ammonium salt benzalkonium chloride (BC). The results revealed that PQD-BC and PDMS-g-BC application inhibited the growth of Foc4 in a concentration-dependent manner and that PDMS-g-BC exhibited higher activity than PQD-BC. In addition, these polymers were found to induce cell death in Foc4 by disrupting the cellular structure integrity, such as the loss of the cell wall and plasma membrane integrity and oxidative stress (lipid peroxidation), leading to the release of intracellular contents and inducing mitochondrial dysfunction and interference with genomic DNA. The newly elucidated mechanism provides possible applications in which PQAS can be used against phytopathogenic fungi.