Organic Peroxides Research Articles

Towards the Development of Novel, Point-of-Care Assays for Monitoring Different Forms of Antioxidant Activity: The RoXstaTM System

(1) Background: This study set out to develop a series of simple, novel, rapid methods for assessing different forms of antioxidant activity. (2) Methods: An ABTS platform was used to engineer: (i) an electrochemical post-activation assay to assess free radical scavenging activity; (ii) an electrochemical pre-activation strategy to assesses the suppression of free radical formation; (iii) a horseradish peroxidase-mediated oxidation system to monitor hydrogen peroxide scavenging activity and (iv) a cumene peroxide-hematin system to determine the ability of samples to scavenge the mixture of organic peroxides and peroxyl and alkoxyl radicals generated in the presence of these reagents. Each assay was assessed against a panel of candidate antioxidant compounds to determine their relative activities and specificities. In addition, human semen samples were analyzed to determine how the results of these antioxidant assays correlated with semen quality. (3) Results: All 4 assays revealed dose-dependent antioxidant activity on the part of vitamin C, N-acetyl cysteine, hypotaurine, BSA, melatonin, glutathione, resveratrol and epigallocatechin gallate. The other compounds tested either completely lacked antioxidant activity or were only active in one of the assays. Using unfractionated human semen as an exemplar of biological fluids rich in antioxidants, the outputs from the individual assays were found to reflect different aspects of semen quality. When the data from all 4 assays were combined, accurate predictions were generated reflecting the importance of oxidative stress in defining semen quality as reflected by sperm count, seminal lipid aldehyde content, sperm DNA damage and free radical generation by the sperm mitochondria. (4) Conclusions: The methodologies described in this paper constitute the basis for rapid, point-of-care assessments of oxidative stress.

Deciphering the molecular mechanism of peracetic acid response in Listeria monocytogenes

Peracetic acid (PAA), a strong oxidizing agent, has been widely used as a disinfectant in food processing settings as it does not produce harmful chlorinated by-products. In the present study, the transcriptional response of Listeria monocytogenes to a sub-lethal concentration of PAA (2.5 ppm) was assessed using RNA-sequencing (RNA-seq). Our analysis revealed 12 differentially expressed protein-coding genes, of which nine were upregulated (ohrR, ohrA, rpsN, lmo0637, lmo1973, fur, lmo2492, zurM, and lmo1007), and three were down-regulated (argG, lmo0604, lmo2156) in PAA treated samples compared to the control samples. A non-coding small RNA gene (rli32) was also found to be down-regulated. In detail, the organic peroxide toxicity protection (OhrA-OhrR) system, the metal homeostasis genes fur and zurM, the SbrE-regulated lmo0636-lmo0637 operon and a carbohydrate phosphotransferase system (PTS) operon component were induced under exposure of L. monocytogenes to PAA. Hence, this study identified key elements involved in the primary response of L. monocytogenes to oxidative stress caused by PAA, including the expression of the peroxide detoxification system and fine-tuning the levels of redox-active metals in the cell. The investigation of the molecular mechanism of PAA response in L. monocytogenes is of utmost importance for the food industry, as residual PAA can lead to stress tolerance in pathogens.

Development of a complex antioxidant for stabilization of dressing enriched with omega-3 fatty acids

The solution to the problem of developing a complex antioxidant for the oxidative stabilization of emulsion systems with a high content of ω-3 polyunsaturated fatty acids (PUFAs) is considered. The object of the study is the oxidative stabilization of dressing using a complex antioxidant of plant origin. The ratio of ω-3:ω-6 PUFAs in model samples of the emulsion system was 1:5.46 and 1:2.21. The reasonable range of antioxidant ratios in the complex was substantiated. The ratio of tocopherol extract, garlic and laurel essential oils in the complex antioxidant is 1:1:1, respectively. Over 30 days of storage of the emulsion system model samples stabilized with a complex antioxidant, there is a gradual accumulation of organic acids (from 0.73 % to 0.75 %). The content of primary oxidation products increases for sample No. 2 – from 0.7 to 1.9 mmol ½ O2/kg, for sample No. 3 – from 0.4 to 1.2 mmol ½ O2/kg. The obtained values of physicochemical parameters meet the requirements of regulatory documentation (DSTU 4561). The peculiarity of the obtained results is that the complex antioxidant showed a significant increase in the stability of the emulsion system of high nutritional value, in particular, slowed down the accumulation of organic acids and peroxides. From a practical point of view, the development can effectively stabilize food emulsion systems with a high content of oxidation-labile PUFAs. An applied aspect of the obtained scientific result is the possibility of modeling and developing new formulations of emulsion and individual fat systems with high nutritional value, containing high PUFA concentrations

Antagonistic activities against selected pathogens of a bacteriocin-producing lactic acid bacteria isolated from Balao-balao, a fermented rice-shrimp mixture

Lactic acid bacteria from a fermented rice-shrimp mixture traditionally known in the Philippines as Balao-balao were isolated in the present study. Screening of lactic acidproducing strains revealed that ten isolates showed promising inhibitory activities against test microorganisms namely Staphylococcus aureus BIOTECH 1634, Escherichia coli BIOTECH 1582, Bacillus subtilis BIOTECH 1679 and Vibrio harveyi SEAFDEC 010. Of interest was isolate PL12, a bacteriocin-producing strain which showed the highest inhibitory activity against the pathogens tested. Isolate PL12 was identified as Pediococcus pentosaceus (GenBank accession number MF353992) with 100% similarity by 16S rDNA sequence analyses. Excluding the effects of organic acids and hydrogen peroxide, the cell-free supernatant (CFS) of PL12 isolate exhibited strong antagonistic activities against test pathogens in an agar well diffusion assay. These results confirmed the isolate’s proteinaceous nature and are indicative of typical characteristics of bacteriocins. To further concentrate the proteins present in the CFS, ammonium sulfate precipitation followed by column purification (Sep-Pak C18 cartridge column) was performed. Positive antagonism of PL12 bacteriocin was observed in both Gram-positive and Gram-negative bacteria tested. The highest inhibitory activity was found against E. coli in every purification step. These results suggested that bacteriocin-producing PL12 isolate can be a promising preservative in the food industry and as probiotics in aquaculture since it possesses antagonistic activities against V. harveyi.

Candida albicans pathways that protect against organic peroxides and lipid peroxidation.

Human fungal pathogens must survive diverse reactive oxygen species (ROS) produced by host immune cells that can oxidize a range of cellular molecules including proteins, lipids, and DNA. Formation of lipid radicals can be especially damaging, as it leads to a chain reaction of lipid peroxidation that causes widespread damage to the plasma membrane. Most previous studies on antioxidant pathways in fungal pathogens have been conducted with hydrogen peroxide, so the pathways used to combat organic peroxides and lipid peroxidation are not well understood. The most well-known peroxidase in Candida albicans, catalase, can only act on hydrogen peroxide. We therefore characterized a family of four glutathione peroxidases (GPxs) that were predicted to play an important role in reducing organic peroxides. One of the GPxs, Gpx3 is also known to activate the Cap1 transcription factor that plays the major role in inducing antioxidant genes in response to ROS. Surprisingly, we found that the only measurable role of the GPxs is activation of Cap1 and did not find a significant role for GPxs in the direct detoxification of peroxides. Furthermore, a CAP1 deletion mutant strain was highly sensitive to organic peroxides and oxidized lipids, indicating an important role for antioxidant genes upregulated by Cap1 in protecting cells from organic peroxides. We identified GLR1 (Glutathione reductase), a gene upregulated by Cap1, as important for protecting cells from oxidized lipids, implicating glutathione utilizing enzymes in the protection against lipid peroxidation. Furthermore, an RNA-sequencing study in C. albicans showed upregulation of a diverse set of antioxidant genes and protein damage pathways in response to organic peroxides. Overall, our results identify novel mechanisms by which C. albicans responds to oxidative stress resistance which open new avenues for understanding how fungal pathogens resist ROS in the host.

OH Radical Oxidation of Organosulfates in the Atmospheric Aqueous Phase.

Organosulfates (OS, ROSO3-), ubiquitous constituents of atmospheric particulate matter (PM), influence both the physicochemical and climatic properties of PM. Although the formation pathways of OS have been extensively researched, only a few studies have investigated the atmospheric fate of this class of compounds. Here, to better understand the reactivity and transformation of OS under cloudwater- and aerosol-relevant conditions, we investigate the hydroxyl radical (OH) oxidation bimolecular rate constants (kOS+OHII) and products of five atmospherically relevant OS as a function of pH and ionic strength: methyl sulfate (MeS), ethyl sulfate (EtS), propyl sulfate (PrS), hydroxyacetone sulfate (HaS) and phenyl sulfate (PhS). Our results show that OS are oxidized by OH with kOS+OHII between 108 - 109 M-1 s-1, which corresponds to atmospheric lifetimes of minutes in aqueous aerosol to days in cloudwater. We find that kOS+OHII increases with carbon chain length (MeS < EtS < PrS) and aromaticity (PrS < PhS), but does not depend on solution pH (2, 9). In addition, we find that whereas the OH reactivity of the aliphatic OS studied here decreases by ∼2× with increasing ionic strength (0-15 M), the reactivity of PhS decreases by ∼10×. The oxidation of EtS and PrS produced organic peroxides (ROOH) as first-generation oxidation products, which subsequently photolyzed; the oxidation of PhS resulted in hydroxylated aromatic products. These results highlight the need for inclusion of OS loss pathways in atmospheric models, and suggest caution in using ambient OS concentration measurements alone to estimate their production rates.

Selective and highly sensitive measurement of H2O2 and organic hydroperoxides with PtNP/Poly(Brilliant Green)/SPCE

This research presents a novel electrochemical approach for the selective measurement of hydrogen peroxide and organic hydroperoxides, which is pivotal in many fields. The study details the development of an advanced sensor using a one-pot, one-step synthesis to embed platinum nanoparticles within a 3D-polymeric matrix of poly (brilliant green) on screen-printed carbon electrodes. The modified surfaces were characterized using scanning and transmission electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results obtained by amperometry showed that, at 0.1 V, only H2O2 produced an electrochemical signal, while, at higher potential (0.5 V), all the hydroperoxides tested exhibited an electrochemical signal. Sensitivities obtained for H2O2 by flow injection analysis were 431 ± 3 and 465 ± 4 μC mM−1 at 0.1 and 0.5 V, respectively, with detection limits (S/N = 3) 116 and 30 nM, respectively. For organic hydroperoxides, sensitivities ranged from 22.3 to 32.6 μC mM−1 at 0.5 V, and limits of detection from 1.15 to 5.95 μM. Chemometric analysis indicated the sensor can satisfactorily measure H2O2 in the presence of the organic hydroperoxides herein analysed. The proposed sensor showed excellent properties in terms of repeatability, reproducibility and stability, with minimal interference. The reliability of the sensor was verified by measuring hydroperoxides spiked in aqueous extracts from real air quality monitoring filters. These features highlight the suitability of the sensor for hydroperoxide measurement and underscore its reliability as a practical tool for real-world applications.

Optimizing micropropagation of Miscanthus sinensis ‘Gold Bar’ by shortening the production cycle and reducing acclimation stress through the use of selected growth regulators

Miscanthus, with its decorative qualities and low cultivation requirements in terms of soil fertility and temperature, is the most popular grass in gardens and urban areas. For years, micropropagation has been regarded as an effective method of its production. However, in order to meet the demands of customers and provide adequate quantities of high-quality planting materials, it is necessary to develop more efficient methods of Miscanthus production. The present study evaluated the influence of different media on Miscanthus sinensis (Thunb.) Andersson (silver grass) multiplication as well as assessing the effect of different concentrations of selected cytokinins and auxins on multiplication and rhizogenesis. To shorten the production cycle and reduce costs, ex vitro rooting was combined with acclimatization, and selected growth regulators were used to decrease stress associated with external conditions. Biochemical analyses were conducted at each stage to determine the content of basic organic compounds, hydrogen peroxide (H2O2) and catalase activity. Stomatal function was assessed at the acclimatization stage. The obtained results allowed for the production cycle of plants propagated in tissue culture to be shortened by simultaneous rooting and acclimatization of microcuttings sprayed with abscisic acid (ABA). This regulator has been shown to effectively reduce plant stress associated with acclimatization by reducing H2O2 concentration and increasing assimilation pigment content. Growth regulators reduced the number of stomata that developed on the leaves of silver grass and led to lower stomatal conductance. H2O2 should be considered not only a stress marker but a vital signaling molecule.

Macrocyclic Organic Peroxides: Constructing Medium and Large Cycles with O-O Bonds

Macrocyclic Organic Peroxides: Constructing Medium and Large Cycles with O-O Bonds

Analytical optical methods for measuring organic peroxides and hydroperoxides: An evaluation

Hydrogen peroxide, organic peroxides and hydroperoxides exhibit high reactivity and play a pivotal role in atmospheric chemistry. These compounds are formed during the oxidation of volatile organic compounds in both gaseous and aqueous phases, particularly under low NOx conditions. Their significant contribution to the mass of secondary organic aerosols (SOA) is well-documented, and they are believed to have significant health implications. Several spectrophotometric methods have been employed to measure SOA-bound peroxides in laboratory samples, but systematic comparisons are lacking. In this study, we have assessed the advantages and limitations of these methods, including the traditional and microwave-assisted iodometric methods, the 4-nitrophenyl boronic acid assay (NPBA), and the Fenton reaction-assisted ferrous-xylenol (FOX2) assay. Besides, a comprehensive evaluation of these methodologies was conducted for the first time across a substantial cohort of commercial peroxides and hydroperoxides, employing diverse solvents (namely, water, 1-propanol, acetonitrile, methanol and chloroform) to provide broader insights compared to previous work. Ultimately, the four methods were applied and compared for peroxide determination in laboratory-generated SOA resulting from gas-phase ozonolysis of α-pinene. This study opens new opportunities for future mechanistic investigation into SOA formation and reactivity.

Considerations for the safe handling and processing of unstable materials

AbstractWe evaluate the instability hazards of initiators, monomers, and other unstable materials during storage and handling in individual containers, pallets of containers, and storage and process vessels. We propose a simplistic model to analyze the temperature–time profile of an unstable chemical, given heat transfer from/to the environment, heat generation due to decomposition and other reaction kinetics, and heat generated from auxiliary equipment (e.g., agitators/mixers, pumps, vessel jackets). Lumped capacitance‐based heat transfer and decomposition kinetics are integrated to predict self‐accelerating decomposition temperature (SADT), self‐accelerating polymerization temperature (SAPT), and the temperature profile given exposure conditions (e.g., ambient temperature and additional sources of heat). Case studies related to the storage and processing of unstable liquid monomers (i.e., methyl methacrylate, MMA), and organic peroxides, (i.e., tert‐butyl peroxybenzoate, TBPB), are presented. We also provide recommendations on determining safe storage and processing temperatures and steps to prevent emergency situations and include an overview of thermal analysis and data treatment procedures which might affect chemical process safety recommendations.

Preparation and performance of catalyst for organic peroxide wastewater treatment

To improve the oxidation pretreatment efficiency of wastewater from organic peroxides, a catalyst (CeO2-C catalyst) was developed using the calcination method with ceramic particles as the support. The crystalline structure and elemental composition of the CeO2-C catalyst were characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and X-ray diffraction (XRD). This study explored the effects of CeO2 mass ratio, calcination temperature, and calcination time on the performance of the catalyst. The optimal preparation conditions were established through orthogonal experiments. Additionally, the synergistic effect of the catalyst on the ozone oxidation treatment of peroxide wastewater was investigated. The results indicated that the optimal preparation parameters were a CeO2 mass ratio of 4 %, a calcination temperature of 500 °C, and a duration of 5 h, respectively. After five cycles of reuse, the catalytic activity slightly decreased but remained relatively stable. With an ozone flow rate of 6 L/min, the CeO2-C/ozone catalytic oxidation process achieved a Chemical Oxygen Demand (COD) removal rate of 28.11 % in wastewater, and the B/C (the ratio of BOD concentration to COD concentration) of wastewater improved from 0.093 to 0.152. The calcination method proved effective for preparing the CeO2-C catalyst, which demonstrated significant catalytic performance and held promising application prospects in the oxidation pretreatment of organic peroxide wastewater.

From agricultural waste to value: Integrated chemo and biocatalytic biorefinery processes to produce 2-furoic acid

The integration of biocatalysis in biorefineries can lead to synergies for raw material valorization. Enzymes must perform efficient and selective reactions when using crude effluents (to avoid costly downstream units). Herein, this is showcased with the synthesis of 2-furoic acid, starting from rice husk (agricultural waste), via a sequential organic-acid catalyzed pretreatment – to afford xylose and cellulose and lignin –, followed by the microwave-assisted acidic xylose dehydration to furfural, in situ extraction in ethyl acetate, and the final biocatalytic selective oxidation of furfural to 2-furoic acid (2-FA). To validate the concept, a xylose-rich hydrolysate (∼ 15 g xylose L−1) obtained from rice husk (RH) was used, achieving a furfural yield of 70 % in a biphasic system (water – ethyl acetate). The obtained furfural extracted in the ethyl acetate was subsequently oxidized to 2-furoic acid via an organic peroxide reaction mediated by Candida antarctica lipase B (CALB), with an overall yield of 90 %, and, with a yield of 41.72 % based on the initial xylose in biomass. Notably, 20 mg/mL CALB could tolerate up to 400 mM of furfural under optimum conditions of 40 °C, 48 h. The recyclability of the biocatalyst was investigated, enabling an efficient reuse of four consecutive cycles.

Chemical Bond Energies of Organic Peroxides: From CH3OOCH3 to High-Molecular-Weight Industrially Significant Compounds.

Peroxides are of some importance in a number of industrial areas, as well as in atmospheric and low-temperature combustion chemistries. Although there are some organic peroxides that are powerful explosives, such as hexamethylene triperoxide diamine, their principal use is as initiators in polymerization reactions in the plastics and rubber industries since the O-O bond is easily cleaved to generate two reactive free radicals. This gives rise to concern about safety issues in both the manufacture of and the deployment of these compounds since they are strong oxidizers. A measure of these safety concerns can be achieved by determining the chemical bond energy or bond dissociation energy (BDE) for the following process: R-O-O-R' → RO• + R'O• since those with very weak O-O bonds are most likely to be problematic. We have used the midlevel model chemistry G4 to compute the BDE of a number of organic peroxides ranging from the simplest dialkyl peroxide to diacyl, peroxy ester, and peroxycarbonate peroxides. In addition, we have used much higher levels of theory to benchmark the chemical bond energy of dimethyl peroxide in the expectation that this will anchor all future determinations.

Identification of the organic peroxide scavenging system of Yersinia pseudotuberculosis and its regulation by OxyR.

Oxidative stress caused by reactive oxygen species (ROS) is inevitable for all aerobic microorganisms as ROS are the byproducts of aerobic respiration. For gut pathogens, ROS are an integrated part of colonization resistance which protects the host against bacteria invasion. Alkyl hydroperoxide reductase (AhpR) and organic hydroperoxide resistance (Ohr) proteins are considered as the main enzymes responsible for the degradation of organic peroxides (OPs) in most bacteria. To elucidate how enteric pathogen Yersinia pseudotuberculosis YPIII deals with oxidative stress induced by OPs, we performed transcriptomic analysis and identified the OP scavenging system, which is composed of glutathione peroxidase (Gpx), thiol peroxidase (Tpx), and AhpR. Gpx serves as the main scavenger of OPs, and Tpx assists in the degradation of OPs. Transcriptional factor OxyR regulates Gpx expression, suggesting that OxyR is the regulator mediating the cellular response to OPs. Although AhpR has little influence on OP degradation, its deletion would greatly impair the scavenging ability of OPs in the absence of gpx or tpx. In addition, we found that catalase KatG and KatE are responsive to OPs but do not participate in the removal of OPs.IMPORTANCEIn bacteria, oxidative stress caused by ROS is a continuously occurring cellular response and requires multiple genes to participate in this process. The elimination of OPs is mainly dependent on AhpR and Ohr protein. Here, we carried out transcriptomic analysis to search for enzymes responsible for the removal of organic peroxides in Yersinia pseudotuberculosis. We found that Gpx was the primary OP scavenger in bacteria, which was positively regulated by the oxidative stress regulator OxyR. The OP scavenging system in Y. pseudotuberculosis was composedof Gpx, Tpx, and AhpR. OxyR is the critical global regulator mediating gene expression involved in OPs and H2O2 stress. These findings suggest that Y. pseudotuberculosis has a unique defense system in response to oxidative stress.

Di-tert-butyl Peroxide (DTBP)-Promoted Heterocyclic Ring Construction

Abstract: Di-tert-butyl peroxide (DTBP) is one of the most widely used organic peroxides in a variety of oxidative transformations. The main factors contributing to the increasing use of DTBP are its affordability, minimal environmental impact, great effectiveness, and capacity to substitute scarce or dangerous heavy metal oxidants. We have reviewed critically and succinctly the noteworthy applications of DTBP in heterocyclic ring constructions from 2014 onwards in this decennial update. The main components of this evaluation are the pros and cons of its use, the scope of a synthetic organic transformation, and mechanistic logistics.

Determination of Standard Enthalpies of Formation of Organic Peroxides Using Calibration Dependencies

AbstractIn the present work, the calibration dependencies for the M062X (i=1),B3LYP (i=2), wB97XD (i=3), M08HX (i=4), MN15 (i=5), G3B3 (i=6) and CBS‐QB3 (i=7) and several other modeling approaches are determined using the calculated values of ΔraHo of atomization and literature based values of ΔraHo(X,TAB) of 14 reference peroxides. These calibration dependencies are used for the determination of ΔraHo(X,CORRP)i and ΔfHo(X,CORRP)i of other peroxides. The coordination of values of ΔfHo(X,CORRP)i (i=1–7) by the intersection of their 3σPi intervals is used for the determination of the most consistent values of ΔfHo(X,MEANP). These values of ΔfHo(X,MEANP) are used for the determination of BDE of peroxides. It's demonstrated that the calculated and literature values of BDE are in agreement. Among the considered modeling approaches, the lowest uncertainties (σPi) are determined for the G3B3 (3.1 kJ/mol), CBS‐QB3 (4.1 kJ/mol), and M062X/6‐311++G(d,p) (6.1 kJ/mol) approaches.

Upcycling of recycled polyethylene for rotomolding applications via dicumyl peroxide crosslinking

AbstractPolyethylene (PE), including high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE), makes up a significant part of post‐consumer plastics in municipal solid waste, presenting challenges for traditional recycling methods due to a wide range of melt flow properties and poor interfacial adhesion between the different resin, which often leads to low quality products (downcycling). In this study, a method is proposed to modify the molecular structure of post‐consumer PE (rHDPE and rLDPE) and their blends by using a straightforward organic peroxide crosslinking technique with 1 phr of dicumyl peroxide (DCP). Different rHDPE/rLDPE blend weight ratios (0/100, 20/80, 40/60, 50/50, 60/40, 80/20, and 100/0) were prepared using a combination of co‐rotating twin‐screw extrusion and pulverization. The final parts were produced via rotomolding where both the forming and crosslinking processes occurred concurrently. Subsequently, the materials were characterized in terms of chemical, thermal, and mechanical properties. It was found that the tensile strength (228%), tensile modulus (345%), flexural strength (145%), and flexural modulus (251%) increased by crosslinking the 80% wt. rHDPE (x‐rHDPE). Conversely, the gel content increased by 17%, thermal resistance by 37.2%, and the impact strength by 93% with 80% wt. rLDPE (x‐rLDPE). It can be concluded that a balance between the properties occurs as the addition of DCP improved both the interfacial adhesion and melt properties of rHDPE/rLDPE blends. This innovative approach represents a simple and straightforward method to upcycle mixed plastics (PE) streams, especially for rotomolding applications. It also offers promising avenues for sustainable waste management and material reuse.

Visible-light-induced Synthesis of Organic Peroxides via Decarboxylative Couplings of Carboxylic Acids, Alkenes and tert-Butyl Hydroperoxide

Visible-light-induced Synthesis of Organic Peroxides via Decarboxylative Couplings of Carboxylic Acids, Alkenes and tert-Butyl Hydroperoxide

Effects of NOx and NH3 on the secondary organic aerosol formation from α-pinene photooxidation

Understanding the effects of mixed anthropogenic pollutants on the photooxidation of volatile organic compounds (VOCs) is essential for unraveling the formation pathways of secondary organic aerosols (SOA). Yet, it remains a highly challenging experimental target owing to the complexities in the precise measurement of molecular compositions of products and number/mass concentrations of particles as a function of pollutant concentration in the ambient atmosphere. Here, a series of well-defined chamber experiments were performed to explore the effects of NOx and NH3 on the SOA formation from photooxidation of the most abundant monoterpene, α-pinene. The results indicate that the suppression effect of NO and NO2 on the α-pinene photooxidation shows monotonous and parabolic trends, respectively. The presence of NH3 enhances particle number concentrations during the α-pinene + NOx photooxidation by participating in reactions with organic acids. New compounds, including organic peroxides, esters, organic nitrates, and peroxyacyl nitrates, are observed at molecular weight (MW) = 166, 173, 217, 231, 280, 282, 304, and 410 through threshold photoionization making use of a recently constructed vacuum ultraviolet free electron laser in positive ion mode. The molecular structures and formation paths of these species are speculated, which advance the category of VOC oxidation products. Our study provides significant understanding of the influence of NOx and NH3 on the VOC photooxidation, which can be utilized to establish predictive SOA formation networks and to improve atmospheric models.