Peroxide Compounds Research Articles

Postharvest internal browning of pineapple fruit originates at the phloem

A typical symptom of postharvest chilling injury (PCI) in pineapple fruit (Ananas comosus (L.) Merr.) is internal browning (IB) near the fruit core. Since vascular bundles (VBs) are localized to this region, it was hypothesized that the VBs might be the site of IB. To test this, the anatomy and histochemistry of VBs during chilling stress in four pineapple cultivars with different levels of sensitivity to PCI were examined. Fruit were stored at 10°C for up to three weeks to stimulate translucency symptoms (TS; the initiation of IB). After three weeks of chilling exposure, the cultivars ‘MD2’ showed 0%, ‘Pattavia’ and ‘Savee’ showed 10–16%, and ‘Trad Sri Thong’ showed 100% TS and IB symptom. Scanning electron microscopy and in situ histochemical staining techniques that detect enzymes and substrates commonly associated with IB initiation were used in parallel. The TS of pineapple fruit coincided with the collapse of the phloem tissue. The VBs in the tissue where IB was initiated (i.e., the flesh adjacent to the core or F/C) had the highest activity of polyphenol oxidase, hydrogen peroxide, and phenolic compounds. The IB-resistant ‘MD2’ genotype had fewer VBs, but a greater proportion of sclerenchyma fibers (P<0.05) than did the susceptible ‘Trad Sri Thong’. Based on these data, the first report of pineapple IB occurrence in the phloem was proposed.

Treatment of an industrial stream containing vinylcyclohexene by the H2O2/UV process.

Petrochemical industries generate wastewaters containing pollutants that can severely impact the biological treatment systems. Some streams from specific production units may contain nonbiodegradable or toxic compounds that impair the performance of the wastewater treatment plant and should be segregated and treated by specific techniques. In this work, the utilization of chemical oxidation (H2O2/UV) was investigated for removing 4-vinylcyclohexene (VCH) from a liquid stream coming from the production of hydroxylated liquid polybutadiene (HLPB). Besides VCH, this stream also contains ethanol, hydrogen peroxide, and many other organic compounds. Experiments were carried out in a small-scale photochemical reactor (0.7L) using a 25-W low-pressure mercury vapor lamp. The photochemical reactor was operated in batch, and the reaction times were comprised between 10 and 60min. Assays were also performed with a synthetic medium containing VCH, H2O2, and ethanol to investigate the removal of these substances in a less complex aqueous matrix. By-products formed in the reaction were identified by gas chromatography and mass spectroscopy (GC-MS). VCH was significantly removed by the oxidation process, in most assays to undetectable levels. Ethanol removal varied from 16 to 23% depending on the reaction conditions. Acetic acid, acetaldehyde, and diols were detected as by-products of the industrial wastewater stream oxidation. A drop on the toxicity of the industrial stream was also observed in assays using the organism Artemia salina.

PENGARUH PAJANAN LOGAM KADMIUM (Cd) TERHADAP KADAR PEROKSIDA (H2O2), KADAR MALODIALDEHID (MDA) DAN KADAR METIL GLIOKSAL (MG) PADA HATI TIKUS PUTIH (Rattus novergicus)

Cadmium and its compounds are used for various industrial interests. However, the accumulation of cadmium in liver will lead to liver damage. This research aims to analyze the effect of the long exposure of cadmium to wards the levels of H2O2, MDA and MG in white-mouse livers. The number of white-mouse livers used in this research were 24 male mouses which were divided into four treatments of cadmium exposure for zero, two, four and six weeks. After the surgeries, the levels of H2O2, MDA and MG of the white-mouse livers were measured using spectrophotometer UV – VIS. The results showed that there were significant differences in the levels of H2O2 between treatment without exposure to Cd and that exposure. The levels of H2O2 increased respectively 3.164 mmol, 11.076 mmol, 16.292 mmol and 31.588 mmol at the weeks of 0, 2, 4, and 6. The results of the Kruskal-Wallis statistical test (p = 0.000; p &lt;0.05), stated that the long exposure of Cd increased significantly the level of H2O2 in the white-mouse livers. The level of MDA of the white-mouse livers also increased consecutively in the week of 0, 2, 4, and 6 as much as 211.5 μM, 230.6 μM, 269.2 μM and 533 μM. The results of the Kruskal-Wallis statistical test (p = 0.000; p &lt;0.05) showed that the Cd exposure could significantly increase the MDA levels in white-mouse livers. This happened because the Cd exposure activated the phagocytic cells to perform respiratory burst resulting in the accumulation of peroxide compounds. The increased Peroxide with Fe metal that existed in the cytoplasm triggered the lipid peroxidation in the membrane producing the MDA compounds. In addition, the results also showed the increased levels of liver MG consecutively in week 0, 2, 4, and 6 as much as 20.039 %, 24.055 %, 27.985 % and 33.87 % . The results of the Kruskal - Wallis statistical test (p = 0.001 ; p &lt; 0.05), showed that the Cd exposure increased significantly the level of MG which was caused by the metal Cd increased the glycation reaction, i.e., the reaction between glucose and proteins to form Amadori product. At the time of the Amadory formation, the formation of 2,3- enediol which was are easily oxidized by the presence of Cd and oxygen to produce MG occurred. It can be concluded that the exposure of heavy metal cadmium (Cd) for 6 weeks may increase the levels of H2O2, MDA and MG

Antioxidant activity of polyphenolic myricetin in vitro cell- free and cell-based systems.

Myricetin (Myc) is one of the most important flavonoids in diet due to its abundance in foods with the highest antioxidant activity. The antioxidant activity of Myc was studied in cell-free and cell-based systems to evaluate the ROS protection efficiency of Myc. The studies were based on the assessment of reducing power of Myc according to ferric ion reduction and intracellular ROS level measurement by assaying the cellular fluorescence intensity using dichlorodihydrofluorescein (DCF) probe as an indicator for ROS in cells. Moreover, the antitoxic capability of Myc was assessed using MTT method. Data indicated that intracellular ROS are highly toxic and applying low concentration of Myc not only inhibited cellular ROS production but also was accompanying with the protection of cells against the highly toxic and the lethal effects of peroxide compounds. Because of strong correlation between cellular ROS and their cell toxic properties, the higher antioxidant potency of Myc in cell medium resulted in effectively blocking intracellular ROS and protecting cell death. This property is achieved by the help of high polar solubility and cell membrane permeability of Myc.

Influence of Nitric Oxide Application on Some Biochemical Aspects, Endogenous Hormones, Minerals and Phenolic Compounds of Vicia faba Plant Grown under Arsenic Stress

Arsenic is a non-essential and toxic heavy metal, which can cause physiological disorder in plants. The present study was undertaken to examine the possible roles of sodium nitroprusside (SNP, a donor of NO) in protection against oxidative damage due to arsenic (As) toxicity in faba bean (Vicia faba L.) plants. In this study, we measured physiochemical parameters (photosynthetic pigments, lipid peroxidation, endogenous hormones, minerals and phenolic contents) in faba bean plants exposed to AS (100, 200 and 400 µM) alone or combined with NO (100 µM). The results showed that application of all concentrations of arsenic (100, 200 and 400 µM) induced decrease on growth parameters, seed yield, photosynthetic pigments, phytohormones, minerals contents (N3−, P3−, K+, Ca2+ and Mg2+) as compared to control plants but increased lipid peroxidation, Na + and total phenolic compounds fraction. Foliar application of 100 µM NO reversed the inhibition induced by As treatment. In addition, arsenic was undetected in harvested seeds at all applied concentrations of arsenic. Therefore, it could be concluded that NO might account for the alleviating effect of As stress on Vicia faba plants.

Characteristics of boar semen preserved at liquid state

ABSTRACTThirty semen ejaculates collected from five Large White Yorkshire boars were preserved in Beltsville thawing solution (BTS) and SAFEcell plus extenders at 16–18°C over a period of seven days. Preserved semen samples were evaluated for sperm motility, plasma membrane integrity and concentration of lipid peroxidation compound malondialdehyde (MDA) every day during storage. Semen samples preserved in the SAFEcell plus extender had significantly more per cent of sperm cells with total motility, progressive forward motility and plasma membrane integrity, significantly low level of MDA concentration than BTS extender from day 1 to day 7 of storage. It can be concluded that the SAFEcell plus extender is better than BTS to preserve boar semen in the liquid state at 16–18°C.

Identification and molecular characterization of peroxiredoxin 6 from Japanese eel (Anguilla japonica) revealing its potent antioxidant properties and putative immune relevancy.

Peroxiredoxins (Prdx) are thiol specific antioxidant enzymes that play a pivotal role in cellular oxidative stress by reducing toxic peroxide compounds into nontoxic products. In this study, we identified and characterized a peroxiredoxin 6 counterpart from Japanese eel (Anguilla japonica) (AjPrdx6) at molecular, transcriptional and protein level. The identified full-length coding sequence of AjPrdx6 (669bp) coded for a polypeptide of 223 aa residues (24.9kDa). Deduced protein of AjPrdx6 showed analogy to characteristic structural features of 1-cysteine peroxiredoxin sub-family. According to the topology of the generated phylogenetic reconstruction AjPrdx6 showed closest evolutionary relationship with Salmo salar. As detected by Quantitative real time PCR (qPCR), AjPrdx6 mRNA was constitutively expressed in all the tissues examined. Upon the immune challenges with Edwardsiella tarda, lipopolysaccharides and polyinosinic:polycytidylic acid, expression of AjPrdx6 mRNA transcripts were significantly induced. The general functional properties of Prdx6 were confirmed using purified recombinant AjPrdx6 protein by deciphering its potent protective effects on cultured vero cells (kidney epithelial cell from an African green monkey) against H2O2-induced oxidative stress and protection against oxidative DNA damage elicited by mixed function oxidative (MFO) system. Altogether, our findings suggest that AjPrdx6 is a potent antioxidant protein in Japanese eels and its putative immune relevancy in pathogen stress mounted by live-bacteria or pathogen associated molecular patterns (PAMPs).

ChemInform Abstract: Photocatalytic Fluoroalkylation Reactions of Organic Compounds

AbstractReview: [118 refs.

A New Laboratory Whitening Method to Evaluate Toothpastes

Purpose: During the conduct of standard tooth brushing studies with toothpaste products it was observed that artificial plaque whitening occurred where there was no toothbrush bristle contact. The purpose of this research was to assess artificial plaque whitening after the application of commercially available whitening toothpastes, without brushing.Methods: Six toothpastes with labeled whitening claims were evaluated. Each toothpaste was placed into a prophylaxis cup, inverted onto the artificial plaque substrate and topped with a 50 g weight. The toothpaste products were evaluated at full strength and after diluting 1:3 with water. A Whitening Index (WI) was determined by visually evaluating the increase in whitening of the plaque using a 0 - 2 scale. Significant differences between the toothpastes were determined using t-tests, assuming unequal variances.Results: Two toothpastes containing hydrogen peroxide had significantly greater WI scores compared to two calcium peroxide-containing toothpastes and two peroxide-free toothpastes (p < 0.001) when tested at full strength or diluted 1:3. The two toothpastes containing calcium peroxide, tested undiluted, exhibited significantly higher whitening means than the peroxide-free whitening toothpastes (p < 0.05).Clinical Significance: It is important for dental health providers to have scientific evidence of efficacy for whitening toothpastes so as to advise patients as to which product will best meet their needs for tooth whitening. A new method has been developed and has been shown to detect significant differences in whitening scores between toothpastes containing different peroxide compounds and peroxide-free products.

ПРОЛОНГИРОВАНИЕ СРОКОВ ХРАНЕНИЯ ПОЛУФАБРИКАТОВ ИЗ МЯСА ПТИЦЫ НА ОСНОВЕ МЕТОДОВ СОНОХИМИИ

Modern consumers are giving preference to prefabricated meat fully prepared for thermal treatment. In its turn production of this type of goods requires optimal technological decisions for safety provision and the required storage life. The paper deals with the effect of ultrasonic exposure on the storage stability of prefabricated meat products. The main study subjects were natural prefabricated broiler chicken meat (“Chicken leg quarter”, “Chicken breast”) and chopped half-finished products in a chilled state like “Nuggets”, obtained according to standard technologies (injected by pickle with antioxidants) and modified technologies (with pickle on the basis of ultrasonic treatment). The dynamics of hydrolytic and oxidizing process behavior in case of ultrasonic treatment in the technology of prefabricated broiler chicken meat is considered. The organoleptic quality control is performed. The relative stability of experimental samples relative to check ones is established. It's shown that the change of physical and chemical indicators (the content of volatile fatty acids, amine nitrogen) happens with a moderate intensity. The positive dynamics is also observed in the reduction of QMAFAnM indicator. In the course of studies on the ultrasound effect on aqueous solutions it's found out that as a result of ultrasonic water treatment reactive oxygen species are formed due to the presence of Fenton's reagent that may result in oxidation of essential substances, primarily fats with the formation of hydroperoxides. During the examination of a lipid fraction of broiler chicken prefabricated meat produced on the basis of ultrasonic exposure, peroxide compounds have not been found, which indicates the optimality of chosen modes of ultrasonic exposure. The selected modes of ultrasonic pickle treatment enabled one to optimally ensure a lethal threshold of sound field characteristics to stop the development of unfavorable microflora in prefabricated meat products, which undoubtedly has a positive effect on their consumer properties.

ІНТЕНСИВНІСТЬ ВІЛЬНОРАДИКАЛЬНИХ ПРОЦЕСІВ У ХРЯЩОВІЙ ТКАНИНІ ЩУРІВ З КОЛАГЕН-ІНДУКОВАНИМ АРТРИТОМ

Products of free radical oxidation and antioxidant enzymes in rats with collagen-induced arthritis were studied. It was established, that under experimental model of arthritis in rat cartilage the content of superoxide anion radical, peroxide and TBA-active compounds and the activity of antiradical enzymes superoxide dismutase and catalase increased.

Antibacterial activity of honey from stingless bees Scaptotrigona bipunctata Lepeletier, 1836 and S. postica Latreille, 1807 (Hymenoptera: Apidae: Meliponinae) against methicillin-resistant Staphylococcus aureus (MRSA)

The antibacterial activity of honey produced by the stingless bees Scaptotrigona postica (H6) and Scaptotrigona bipunctata (H7) was evaluated against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains. Fifty-three MRSA strains in the bacterial collection of the hospital of Londrina State University, three standard MRSA strains and two standard MSSA strains were used. Evaluation of the antibacterial activity of honey samples was determined by agar well diffusion assay, calculation of minimum inhibitory concentrations (MICs), and construction of growth and viability curves. The inhibition zones generated by the honey samples ranged from 20 to 27 mm for H6 and 20 to 24 mm for H7, while MIC values ranged from 0.62 to 1.25% for H6 and 1.25 to 2.5% for H7. According to the growth curves, the growth of all MRSA and MSSA strains was completely inhibited. Honey cytotoxicity was evaluated by dimethylthiazol diphenyl tetrazolium bromide (MTT) assay, and the CC50 values were found to be 13% for H6 and 7.3% for H7, which were significantly higher when compared to the MIC values. The honey of both the stingless bees S. bipunctata and S. postica can thus be utilized as antibacterial substances against MSSA and MRSA strains, and this action is probably due to a synergistic action of different components such as hydrogen peroxide, sugars, and other compounds not identified in this study. The application of natural products is important for the control of MRSA infections. Further studies are warranted to demonstrate that the antimicrobial activity of the honey examined here could be used in clinical applications for the prevention of MRSA infections.

Cytotoxic constituents of Lasiosphaera fenzlii on different cell lines and the synergistic effects with paclitaxel

The fruit body of Lasiosphaera fenzlii was found to show cytotoxicity on cancer cells during a preliminary screening. Repeated column chromatography of the fungal methanol extract resulted in the isolation of six compounds identified as 5α,8α-epidioxy-ergosta-6,22-dien-3β-ol (1), 5α,8α-epidioxy-ergosta-6,9(11),22-trien-3β-ol (2), 5α-ergosta-7,22-dien-3β-ol (3), 5α-ergosta-7,22-dien-3-one (4), ergosta-7,22-dien-3β,5α,6β-triol (5) and 6-dihydroxy-2,3-dihydro-1H-isoindol-1-one (6). The two peroxide compounds, 1 and 2, showed cytotoxic activity and compound 1 was selectively cytotoxic to cancer cells. Furthermore, compound 1 synergised the cytotoxicity of paclitaxel on Hela cells by increasing intracellular accumulation of paclitaxel in cancer cells but not in normal cells.

CrGNAT gene regulates excess copper accumulation and tolerance in Chlamydomonas reinhardtii

Excess copper (Cu) in environment affects the growth and metabolism of plants and green algae. However, the molecular mechanism for regulating plant tolerance to excess Cu is not fully understood. Here, we report a gene CrGNAT enconding an acetyltransferase in Chlamydomonas reinhardtii and identified its role in regulating tolerance to Cu toxicity. Expression of CrGNAT was significantly induced by 75–400μM Cu. The top induction occurred at 100μM. Transgenic algae overexpressing CrGNAT (35S::CrGNAT) in C. reinhardtii showed high tolerance to excess Cu, with improved cell population, chlorophyll accumulation and photosynthesis efficiency, but with low degree of oxidation with regard to reduced hydrogen peroxide, lipid peroxides and non-protein thiol compounds. In contrast, CrGNAT knock-down lines with antisense led to sensitivity to Cu stress. 35S::CrGNAT algae accumulated more Cu and other metals (Zn, Fe, Cu, Mn and Mg) than wild-type, whereas the CrGNAT down-regulated algae (35S::AntiCrGNAT) had moderate levels of Cu and Mn, but no effects on Zn, Fe and Mg accumulation as compared to wild-type. The elevated metal absorption in CrGNAT overexpression algae implies that the metals can be removed from water media. Quantitative RT-PCR analysis revealed that expression of two genes encoding N-lysine histone methyltransferases was repressed in 35S::CrGNAT algae, suggesting that CrGNAT-regulated algal tolerance to Cu toxicity is likely associated with histone methylation and chromatin remodeling. The present work provided an example a basis to develop techniques for environmental restoration of metal-contaminated aquatic ecosystems.

Abstract 4545: Development of a synthetic organic peroxide, RA1, that overcomes p53 and Bcl-2 resistance mechanisms

Abstract Mutations in p53 and elevated expression of Bcl-2 proteins are associated with therapy resistance in many human tumors. A lead compound capable of bypassing these resistance pathways, RA1, was identified from several synthetic peroxides tested at the National Cancer Institute through the In Vitro Cell Line Screening Project. The 1,2-dioxolane scaffold of RA1 differs from that of the peroxide containing anti-malarial agent artemisinin. The lowest concentration of RA1 to cause 50% growth inhibition (GI50) was observed in an ovarian cancer line, IGROV-1 (GI50 435 nM), and the highest in a lung cancer line, NCI-H322M (GI50 42 μM). Eighteen out of the fifty-nine cell lines tested showed a GI50 below 2.5 μM. In cell lines with altered p53 status, RA1 exhibited a potent effect (GI50 for NCI-H522, HOP-92, and HL-60: 1.2 μM, 1.4 μM, and 2.2 μM, respectively). RA1 showed a high selectivity index, inducing &amp;gt;90% cell death at 40 μM in a transformed cancerous cell line (BJ-ELR: LC50 30 μM); while only ∼20% cell death was observed in non-transformed cells of the same origin (BJ-hTERT: LC50 55 μM). Using a B-lymphoblastic cell leukemia line, RS4:11 (LC50 ∼7 μM; wild type p53), as a model system, we investigated the mechanism of action of RA1. No increase in p53 protein expression was observed upon treatment with RA1. Unlike conventional chemotherapy drugs, overexpression of the Bcl-2 protein to prevent mitochondrial outer membrane permeabilization (MOMP) had no effect on RA1's ability to induce cell death. The LC50 of GFP control and Bcl-2 overexpressing cells with RA1 is 7.7 and 7.4 μM, respectively, compared to the control (etoposide: LC50 0.6 μM and &amp;gt;4 μM). No change in cell cycle distribution was observed. No activation of the executioner caspases was seen by Western Blot; however, pretreatment with a caspase-2 inhibitor (z-VDVAD-FMK) prevented cell death. Electron microscopy images showed no morphological features characteristic of apoptosis, necrosis, or autophagy. Ferroptosis, an iron and reactive oxygen species (ROS) dependent form of cell death also lacks these morphological characteristics. While no organic peroxides are known to induce ferroptosis, the use of an iron chelator and Ferrostatin (a lipophillic anti-oxidant known to inhibit ferroptosis) inhibited cell death induced by RA1. Similar to some ferroptosis inducing compounds, a water soluble anti-oxidant had no effect on cell death; however, use of a ROS detection kit indicated oxidative stress is occurring. RA1 demonstrates potential therapeutic activity for the treatment of cancer. It is capable of overcoming two common chemo-resistance pathways: p53 mutation and inhibition of MOMP by modulation of the Bcl-2 family of proteins. RA1 targets cancer cells by a unique mechanism distinct from other peroxide compounds, as well as conventional chemotherapies. Current experimental data suggests RA1 is inducing a form of ferroptotic cell death. Citation Format: Rachel P. Abrams, K. A. Woerpel, William L. Carroll. Development of a synthetic organic peroxide, RA1, that overcomes p53 and Bcl-2 resistance mechanisms. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4545. doi:10.1158/1538-7445.AM2015-4545

Vulcanization of fluoroelastomers using fluorine peroxides

Fluorinated peroxide compounds are used as effective curing and modifying for commercial fluoroelastomers. It is shown that the use of fluorinated peroxide derivatives of poly- and perfluorocaronyl compounds allows development of fluoroelastomer materials with high thermal and chemical resistance.

Total peroxidase and catalase activity of luminous basidiomycetes Armillaria borealis and Neonothopanus nambi in comparison with the level of light emission

The peroxidase and catalase activities in the mycelium of luminous basidiomycetes Armillaria borealis and Neonothopanus nambi in normal conditions and under stress were compared. An increase in the luminescence level was observed under stress, as well as an increase in peroxidase and catalase activities. Moreover, the peroxidase activity in extracts of A. borealis mycelium was found to be almost one and a half orders of magnitude higher, and the catalase activity more than two orders of magnitude higher in comparison with the N. nambi mycelium. It can be suggested that the difference between the brightly luminescent and dimly luminescent mycelium of N. nambi is due to the content of H2O2 or other peroxide compounds.

Reactions of benzo and dibenzo derivatives of five-membered aromatic heterocycles with ozone in the liquid phase

The ozonation reactions of benzo and dibenzo derivatives of pyrrole, furan, and thiophene in acetic acid solution have been studied. Peroxide compounds have been detected as the products. The mechanism of ozone interaction with these hetarenes has been proposed. The kinetics of ozonolytic reactions of benzologues of five-membered aromatic heterocycles (hetarenes) have been investigated. The reaction of ozone with the hetarenes obeys the bimolecular rate law and has the first order in each reactant. The effective rate constants and experimental stoichiometric coefficients for ozone have been found.

Aloe vera long-term saline irrigation increases contents of hydrogen peroxide, lipid peroxidation and phenolic compounds

Salt stress is more and more becoming a serious problem in the world especially if we consider its damaging effect on the plant growth and yield. The cultivation of medicinal plants, such as Aloe vera, might be an alternative for the saline water use and salt-affected soils occupation. Aloe vera, commonly known as aloe, is one of the primary medicinal plants with multipurpose applications going from pharmaceutical to cosmetic aspects with a promising economic return. Aloe plants were cultivated and irrigated, for 14 months, with drinking water (C0) and with two levels of salt (C1 and C2). Changes in growth, hydrogen peroxide (H2O2), lipid peroxidation and phenolic compounds were examined in leaves at harvest. Depressive effects of salt irrigation on the plant growth parameters and a perturbation in inorganic ion contents were found especially with a high level of salt in the irrigation water. The intracellular oxidative stress was evaluated with the H2O2 production. Our results showed that the H2O2 content increased with the accumulation of the toxic ion (Na) in the leaf tissues. In addition, lipid peroxidation, measured by the malondialdehyde (MDA) level, increased as well with salt augmentation in the irrigation water. In response to salt stress, Aloe leaves showed a significant increase in the levels of phenolic compounds too. These results suggest that Aloe can be planted in soils affected by salinity and irrigated with salt water at least at a moderate concentration used in the present study.

Heterogeneous reaction of peroxyacetic acid and hydrogen peroxide on ambient aerosol particles under dry and humid conditions: kinetics, mechanism and implications

Abstract. Hydrogen peroxide (H2O2) and organic peroxides play important roles in the cycle of oxidants and the formation of secondary aerosols in the atmosphere. Recent field observations have suggested that the budget of peroxyacetic acid (PAA, CH3C(O)OOH) is potentially related to the aerosol phase processes, especially to secondary aerosol formation. Here, we present the first laboratory measurements of the uptake coefficient of gaseous PAA and H2O2 onto ambient fine particulate matter (PM2.5) as a function of relative humidity (RH) at 298 K. The results show that the PM2.5, which was collected in an urban area, can take up PAA and H2O2 at the uptake coefficient (γ) of 10−4, and both γPAA and γH2O2 increase with increasing RH. The value of γPAA at 90 % RH is 5.4 ± 1.9 times that at 3 % RH, whereas γH2O2 at 90 % RH is 2.4 ± 0.5 times that at 3 % RH, which suggests that PAA is more sensitive to the RH variation than H2O2 is. Considering the larger Henry's law constant of H2O2 than that of PAA, the smaller RH sensitivity of the H2O2 uptake coefficient suggests that the enhanced uptake of peroxide compounds on PM2.5 under humid conditions is dominated by chemical processes rather than dissolution. Considering that mineral dust is one of the main components of PM2.5 in Beijing, we also determined the uptake coefficients of gaseous PAA and H2O2 on authentic Asian Dust storm (ADS) and Arizona Test Dust (ATD) particles. Compared to ambient PM2.5, ADS shows a similar γ value and RH dependence in its uptake coefficient for PAA and H2O2, while ATD gives a negative dependence on RH. The present study indicates that, in addition to the mineral dust in PM2.5, other components (e.g., soluble inorganic salts) are also important to the uptake of peroxide compounds. When the heterogeneous reaction of PAA on PM2.5 is considered, its atmospheric lifetime is estimated to be 3.0 h on haze days and 7.1 h on non-haze days, values that are in good agreement with the field observations.