From MS/MS library implementation to molecular networks: Exploring oxylipin diversity with NEO-MSMS.

Oxylipins, small polar molecules derived from the peroxidation of polyunsaturated fatty acids (PUFAs), serve as biomarkers for many diseases and play crucial roles in human physiology and inflammation. Despite their significance, many non-enzymatic oxygenated metabolites of PUFAs (NEO-PUFAs) remain poorly reported, resulting in a lack of public datasets of experimental data and limiting their dereplication in further studies. To overcome this limitation, we constructed a high-resolution tandem mass spectrometry (MS/MS) dataset comprising pure NEO-PUFAs (both commercial and self-synthesized) and in vitro free radical-induced oxidation of diverse PUFAs. By employing molecular networking techniques with this dataset and the existent ones in public repositories, we successfully mapped a wide range of NEO-PUFAs, expanding the strategies for annotating oxylipins, and NEO-PUFAs and offering a novel workflow for profiling these molecules in biological samples.

Analysis of Fractional Cerebral Oxygen Extraction in Preterm Infants during the Kangaroo Care.

INTRODUCTION: We aimed to investigate the cerebral fractional tissue oxygen extraction (FtOE) during kangaroo care (KC) in premature infants and compare cardiorespiratory stability and hypoxic or bradycardic events between KC and incubator care. METHODS: A single-center prospective observational study was carried out at the NICU of a level 3 perinatal center. Preterm infants <32 weeks gestational age were subjected to KC. Patients were subjected to continuous monitoring of regional cerebral oxygen saturation (rScO2), peripheral oxygen saturation (SpO2), and heart rate (HR) during KC, before KC (pre-KC), and after KC (post-KC). The monitoring data were stored and exported to MATLAB for synchronization and signal analysis including the calculation of the FtOE and events analysis (i.e., desaturations and bradycardias counts and anormal values). Furthermore, the event counts and the mean SpO2, HR, rScO2, and FtOE were compared between studied periods employing the Wilcoxon rank-sum test and the Friedman test, respectively. RESULTS: A total of forty-three KC sessions with their corresponding pre-KC and post-KC segments were analyzed. The distributions of the SpO2, HR, rScO2, and FtOE showed different patterns according to the respiratory support, but not differences between the studied periods were detected. Accordingly, no significant differences in monitoring events were evidenced. However, cerebral metabolic demand (FtOE) was significantly lower during KC compared with post-KC (p = 0.019). CONCLUSION: Premature infants remain clinically stable during KC. Moreover, cerebral oxygenation is significantly higher and cerebral tissular oxygen extraction is significantly lower during KC compared with incubator care in post-KC. No differences in HR and SpO2 were shown. This novel data analysis methodology could be expanded to other clinical situations.

Hypoxemia events in preterm neonates are associated with urine oxidative biomarkers.

BACKGROUND: Intermittent hypoxemia (IH) events are common in preterm neonates and are associated with adverse outcomes. Animal IH models can induce oxidative stress. We hypothesized that an association exists between IH and elevated peroxidation products in preterm neonates. METHODS: Time in hypoxemia, frequency of IH, and duration of IH events were assessed from a prospective cohort of 170 neonates (<31 weeks gestation). Urine was collected at 1 week and 1 month. Samples were analyzed for lipid, protein, and DNA oxidation biomarkers. RESULTS: At 1 week, adjusted multiple quantile regression showed positive associations between several hypoxemia parameters with various individual quantiles of isofurans, neurofurans, dihomo-isoprostanes, dihomo-isofurans, and ortho-tyrosine and a negative correlation with dihomo-isoprostanes and meta-tyrosine. At 1 month, positive associations were found between several hypoxemia parameters with quantiles of isoprostanes, dihomo-isoprostanes and dihomo-isofurans and a negative correlation with isoprostanes, isofurans, neuroprostanes, and meta-tyrosine. CONCLUSIONS: Preterm neonates experience oxidative damage to lipids, proteins, and DNA that can be analyzed from urine samples. Our single-center data suggest that specific markers of oxidative stress may be related to IH exposure. Future studies are needed to better understand mechanisms and relationships to morbidities of prematurity. IMPACT: Hypoxemia events are frequent in preterm infants and are associated with poor outcomes. The mechanisms by which hypoxemia events result in adverse neural and respiratory outcomes may include oxidative stress to lipids, proteins, and DNA. This study begins to explore associations between hypoxemia parameters and products of oxidative stress in preterm infants. Oxidative stress biomarkers may assist in identifying high-risk neonates.

Plasma serotonergic biomarkers are associated with hypoxemia events in preterm neonates.

BACKGROUND: Hypoxemia is a physiological manifestation of immature respiratory control in preterm neonates, which is likely impacted by neurotransmitter imbalances. We investigated relationships between plasma levels of the neurotransmitter serotonin (5-HT), metabolites of tryptophan (TRP), and parameters of hypoxemia in preterm neonates. METHODS: TRP, 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and kynurenic acid (KA) were analyzed in platelet-poor plasma at ~1 week and ~1 month of life from a prospective cohort of 168 preterm neonates <31 weeks gestational age (GA). Frequency of intermittent hypoxemia (IH) events and percent time hypoxemic (<80%) were analyzed in a 6 h window after the blood draw. RESULTS: At 1 week, infants with detectable plasma 5-HT had fewer IH events (OR (95% CI) = 0.52 (0.29, 0.31)) and less percent time <80% (OR (95% CI) = 0.54 (0.31, 0.95)) compared to infants with undetectable 5-HT. A similar relationship occurred at 1 month. At 1 week, infants with higher KA showed greater percent time <80% (OR (95% CI) = 1.90 (1.03, 3.50)). TRP, 5-HIAA or KA were not associated with IH frequency at either postnatal age. IH frequency and percent time <80% were positively associated with GA < 29 weeks. CONCLUSIONS: Circulating neuromodulators 5-HT and KA might represent biomarkers of immature respiratory control contributing to hypoxemia in preterm neonates. IMPACT: Hypoxemia events are frequent in preterm infants and are associated with poor outcomes. Mechanisms driving hypoxemia such as immature respiratory control may include central and peripheral imbalances in modulatory neurotransmitters. This study found associations between the plasma neuromodulators serotonin and kynurenic acid and parameters of hypoxemia in preterm neonates. Imbalances in plasma biomarkers affecting respiratory control may help identify neonates at risk of short- and long-term adverse outcomes.

High Concentration of Protein Oxidation Biomarker O-Tyr/Phe Predicts Better Outcome in Childhood Bacterial Meningitis.

Neuronal damage in bacterial meningitis (BM) partly stems from the host´s inflammatory response and induced oxidative stress (OS). We studied the association of cerebrospinal fluid (CSF) biomarkers indicating oxidative damage to proteins with course of illness and outcome in childhood BM in Angola. Ortho-tyrosine/phenylalanine (o-Tyr/Phe), 3-chlorotyrosine/para-tyrosine (3Cl-Tyr/p-Tyr), and 3-nitrotyrosine/para-tyrosine (3NO2-Tyr/p-Tyr) concentration ratios were measured in 79 BM admission CSF samples, employing liquid chromatography coupled to tandem mass spectrometry. Besides death, disease outcomes were registered on Day 7 of treatment and one month after discharge (control visit). The outcome was graded according to the modified Glasgow Outcome Scale (GOS), which considers neurological and audiological sequelae. Children with a o-Tyr/Phe ratio below the median were more likely to present focal convulsions and secondary fever during recovery and suboptimal outcome (GOS < 5) on Day 7 and at control visit (odds ratio (OR) 2.85; 95% CI 1.14-7.14 and OR 5.23; 95% CI 1.66-16.52, respectively). Their most common sequela was ataxia on Day 7 and at control visit (OR 8.55; 95% CI 2.27-32.22 and OR 5.83; 95% CI 1.12-30.4, respectively). The association of a higher admission CSF o-Tyr/Phe ratio with a better course and outcome for pediatric BM points to a beneficial effect of OS.

Early molecular markers of ventilator-associated pneumonia in bronchoalveolar lavage in preterm infants.

INTRODUCTION: Ventilator-associated pneumonia (VAP) constitutes a serious nosocomial infection. Our aim was to evaluate the reliability of cytokines and oxidative stress/inflammation biomarkers in bronchoalveolar lavage fluid (BALF) and tracheal aspirates (TA) as early biomarkers of VAP in preterm infants. METHODS: Two cohorts were enrolled, one to select candidates and the other for validation. In both, we included preterms with suspected VAP, according to BALF culture, they were classified into confirmed VAP and no VAP. Concentration of 16 cytokines and 8 oxidative stress/inflammation biomarkers in BALF and TA was determined in all patients. RESULTS: In the first batch, IL-17A and TNF-α in BALF, and in the second one IL-10, IL-6, and TNF-α in BALF were significantly higher in VAP patients. BALF TNF-α AUC in both cohorts was 0.86 (sensitivity 0.83, specificity 0.88). No cytokine was shown to be predictive of VAP in TA. A statistically significant increase in the VAP group was found for glutathione sulfonamide (GSA) in BALF and TA. CONCLUSIONS: TNF-α in BALF and GSA in BALF and TA were associated with VAP in preterm newborns; thus, they could be used as early biomarkers of VAP. Further studies with an increased number of patients are needed to confirm these results. IMPACT: We found that TNF-α BALF and GSA in both BALF and TA are capable of discriminating preterm infants with VAP from those with pulmonary pathology without infection. This is the first study in preterm infants aiming to evaluate the reliability of cytokines and oxidative stress/inflammation biomarkers in BALF and TA as early diagnostic markers of VAP. We have validated these results in two independent cohorts of patients. Previously studies have focused on full-term neonates and toddlers and determined biomarkers mostly in TA, but none was exclusively conducted in preterm infants.

Impact of Kangaroo Care on Premature Infants' Oxygenation: Systematic Review.

INTRODUCTION: Kangaroo care (KC) is defined by the World Health Organization as a method of care consisting in putting premature infants or newborns in skin-to-skin contact with their parents. KC is an effective method of promoting health and well-being of infants and their families. Physiological stability during KC has been widely analyzed, however with controversial results. METHODS: A systematic review was conducted. Electronic databases searched included MEDLINE, Embase, CINAHL, and Scopus. Two authors independently reviewed and extracted information using a data extraction form. The methodological quality of the observational studies was assessed using "STROBE" and the "Cochrane Collaboration tool" for randomized controlled trials. The physiological monitoring parameters included were heart rate (HR), arterial oxygen saturation (SpO2), regional cerebral oxygen saturation (rScO2), and fractional oxygen extraction (FtOE). RESULTS: A total of 345 articles were identified. First, 302 articles were excluded by title and then 34 articles after full-text analysis. Finally, a total of 25 studies were included. Physiological parameters monitored (HR, SpO2, rScO2, and FtOE) showed no significant changes at different study periods: pre-KC, during KC, and post-KC. CONCLUSIONS: We conclude that stable preterm infants receiving or not respiratory support show no significant differences in HR, SpO2, FtOE during KC compared to routine incubator care. rScO2 remains stable during KC with slight upward trend. Further studies with a higher level of methodological quality are needed to confirm these findings.

High Oxygen Does Not Increase Reperfusion Injury Assessed with Lipid Peroxidation Biomarkers after Cardiac Arrest: A Post Hoc Analysis of the COMACARE Trial.

The products of polyunsaturated fatty acid peroxidation are considered reliable biomarkers of oxidative injury in vivo. We investigated ischemia-reperfusion-related oxidative injury by determining the levels of lipid peroxidation biomarkers (isoprostane, isofuran, neuroprostane, and neurofuran) after cardiac arrest and tested the associations between the biomarkers and different arterial oxygen tensions (PaO2). We utilized blood samples collected during the COMACARE trial (NCT02698917). In the trial, 123 patients resuscitated from out-of-hospital cardiac arrest were treated with a 10-15 kPa or 20-25 kPa PaO2 target during the initial 36 h in the intensive care unit. We measured the biomarker levels at admission, and 24, 48, and 72 h thereafter. We compared biomarker levels in the intervention groups and in groups that differed in oxygen exposure prior to randomization. Blood samples for biomarker determination were available for 112 patients. All four biomarker levels peaked at 24 h; the increase appeared greater in younger patients and in patients without bystander-initiated life support. No association between the lipid peroxidation biomarkers and oxygen exposure either before or after randomization was found. Increases in the biomarker levels during the first 24 h in intensive care suggest continuing oxidative stress, but the clinical relevance of this remains unresolved.

Do Levels of Lipid Peroxidation Biomarkers Reflect the Degree of Brain Injury in Newborns?

The pathogenesis and progression of hypoxic-ischemic encephalopathy (HIE), a major cause of severe neurological disability and mortality in the perinatal period, are shaped by the interplay of multiple processes, including inflammation, oxidative stress, and excitotoxicity. We conducted a longitudinal study to determine biomarkers of oxidative stress and inflammation in noninvasive urine samples of newborns with moderate/severe HIE (N = 51), employing liquid chromatography-mass spectrometry. We noted that levels of several biomarkers of oxidative stress increased over time, demonstrating the ongoing propagation of oxidative injury. Prostaglandins, in contrast, showed a decreasing trend in their concentration profiles over time, which probably reflects their mediation in pathogenic mechanisms, including the inflammatory response. Statistically significant differences in the levels of oxidative stress of neonates with distinct brain lesion patterns, as detected with magnetic resonance imaging (MRI), were observed, revealing an increase of lipid peroxidation biomarkers in newborns with cerebral lesions (MRI score of 1 compared with scores of 0 and 2). Moreover, a gender-dependent study showed no statistically significant differences in biomarker concentrations between male and female infants. Our observation leads to the hypothesis that monitoring of noninvasive lipid peroxidation biomarkers could aid in diagnosis and prediction of long-term outcomes as a complementary tool to standard exploration. Antioxid. Redox Signal. 35, 1467-1475.

Oxidative stress biomarkers in the preterm infant.

Oxidative stress (OS) plays a key role in the pathophysiology of preterm infants. Accurate assessment of OS remains an analytical challenge that has been partially addressed during the last few decades. A plethora of approaches have been developed to assess preterm biofluids to demonstrate a link postnatally with preterm OS, giving rise to a set of widely employed biomarkers. However, the vast number of different analytic methods and lack of standardization hampers reliable comparison of OS-related biomarkers. In this chapter, we discuss approaches for the study of OS in prematurity with respect to methodologic considerations, the metabolic source of different biomarkers and their role in clinical studies.

The Relationship between Oxidative Stress, Intermittent Hypoxemia, and Hospital Duration in Moderate Preterm Infants.

INTRODUCTION: Lipid peroxidation products are present following oxidation of polyunsaturated fatty acids in the eye, brain, and various cell membranes. Elevated levels of lipid peroxidation products and increased intermittent hypoxemia (IH) events have been associated with adverse outcomes in extremely preterm infants. The moderate preterm newborn has a still-developing oxidant defense system and immature respiratory control, but little is known about lipid peroxidation levels and IH in this larger and more common preterm population. OBJECTIVE: To determine the association between oxidative stress and IH in moderate preterm infants. METHOD: Oxygen saturation was continuously monitored in 51 moderate preterm infants (i.e., 31 + 0/7 to 33 + 6/7 weeks' gestation). Urine samples were collected at the end of the first and second weeks of life. Samples were analyzed for total lipid peroxidation products (neurofurans, isofurans, neuroprostanes, isoprostanes, and di-homo-isofurans). RESULT: At week 1, there was a correlation between increased IH frequency and neurofurans (p < 0.04) and di-homo-isofurans (p < 0.003). At week 2, there was no correlation between IH and lipid peroxidation markers. Ele-vations in neurofurans, isofurans, neuroprostanes, and di-homo-isofurans in the first and/or second week of life were associated with a longer stay in hospital. CONCLUSION: Elevations in lipid peroxidation biomarkers in moderate preterm infants during their first weeks of life are associated with a higher frequency of IH and prolonged hospitalization.

Effect of a Marathon on Skin Temperature Response After a Cold-Stress Test and Its Relationship With Perceptive, Performance, and Oxidative-Stress Biomarkers.

CONTEXT: Although skin-temperature assessment has received much attention in recent years as a possible internal-load measurement, scientific evidence is scarce. PURPOSE: To analyze baseline skin temperature and its rewarming through means of a cold-stress test before and after performing a marathon and to study the association between skin temperature and internal/external-load measurements. METHODS: A total of 16 runners were measured 48 and 24 h before and 24 and 48 h after completing a marathon. The measurements on each day of testing included urine biomarkers of oxidative stress, pain and fatigue perception, skin temperature (at baseline and after a cold-stress test), and jump performance. RESULTS: Reduced jump performance (P < .01 and effect size [ES] = 0.5) and higher fatigue and pain perception were observed 24 h after the marathon (P < .01 and ES > 0.8). Although no differences in baseline skin temperature were observed between the 4 measuring days, posterior legs presented lower constant (P < .01 and ES = 1.4) and higher slope (P = .04 and ES = 1.1) parameters in the algorithmic equations fitted for skin-temperature recovery after the cold-stress test 24 h after the marathon than on the day before the marathon. Regressions showed that skin-temperature parameters could be predicted by the ratio of ortho-tyrosine isomer to phenylalanine (oxidative stress biomarker) and body fat composition, among others. CONCLUSIONS: Although baseline skin temperature was not altered 24 or 48 h after a marathon, the application of cold stress after the marathon would appear to be a good method for providing information on vasoconstriction and a runner's state of stress.

Metabolic Phenotypes of Hypoxic-Ischemic Encephalopathy with Normal vs. Pathologic Magnetic Resonance Imaging Outcomes.

Hypoxic-Ischemic Encephalopathy (HIE) is one of the most relevant contributors to neurological disability in term infants. We hypothesized that clinical outcomes of newborns with (HIE) can be associated with changes at plasma metabolic level enabling the detection of brain injury. Plasma samples of a cohort of 55 asphyxiated infants who evolved to moderate/severe HIE were collected between birth and completion of therapeutic hypothermia (TH). Samples were analyzed employing a quantitative gas chromatography-mass spectrometry method for the determination of lactate and pyruvate and an untargeted liquid chromatography-time-of-flight mass spectrometry method for metabolic fingerprinting. Brain injury was assessed employing magnetic resonance imaging (MRI). A critical assessment of the usefulness of lactate, pyruvate, and pyruvate/lactate for outcome prediction was carried out. Besides, metabolic fingerprinting identified a dynamic perturbation of eleven metabolic pathways, including amino acid and purine metabolism, and the steroid hormone biosynthesis, in newborns with pathologic MRI outcomes. Although data suggest the usefulness of lactate and pyruvate monitoring during 72 h for discerning outcomes, only the steroid hormone biosynthesis pathway was significantly altered in early plasma samples (i.e., before the initiation of TH). This study highlights pathways that might potentially be targeted for biomarker discovery or adjuvant therapies to be combined with TH.

Small molecule biomarkers for neonatal hypoxic ischemic encephalopathy.

Hypoxic Ischemic Encephalopathy (HIE) is one of the most deleterious conditions in the perinatal period and the access to small molecule biomarkers aiding accurate diagnosis and disease staging, progress monitoring, and early outcome prognosis could provide relevant advances towards the development of personalized therapies. The emergence of metabolomics, the "omics" technology enabling the holistic study of small molecules, for biomarker discovery employing different analytical platforms, animal models and study populations has drastically increased the number and diversity of small molecules proposed as candidate biomarkers. However, the use of very few compounds has been implemented in clinical guidelines and authorized medical devices. In this work we review different approaches employed for discovering HIE-related small molecule biomarkers. Their role in associated biochemical disease mechanisms as well as the way towards their translation into the clinical practice are discussed.

Correction: Nitric oxide and preterm resuscitation: some words of caution.

A correction to this paper has been published and can be accessed via a link at the top of the paper.

Protein Oxidation Biomarkers and Myeloperoxidase Activation in Cerebrospinal Fluid in Childhood Bacterial Meningitis.

The immunological response in bacterial meningitis (BM) causes the formation of reactive oxygen and nitrogen species (ROS, RNS) and activates myeloperoxidase (MPO), an inflammatory enzyme. Thus, structural oxidative and nitrosative damage to proteins and DNA occurs. We aimed to asses these events in the cerebrospinal fluid (CSF) of pediatric BM patients. Phenylalanine (Phe), para-tyrosine (p-Tyr), nucleoside 2'-deoxiguanosine (2dG), and biomarkers of ROS/RNS-induced protein and DNA oxidation: ortho-tyrosine (o-Tyr), 3-chlorotyrosine (3Cl-Tyr), 3-nitrotyrosine (3NO2-Tyr) and 8-oxo-2'-deoxyguanosine (8OHdG), concentrations were measured by liquid chromatography coupled to tandem mass spectrometry in the initial CSF of 79 children with BM and 10 without BM. All biomarkers, normalized with their corresponding precursors, showed higher median concentrations (p < 0.0001) in BM compared with controls, except 8OHdG/2dG. The ratios o-Tyr/Phe, 3Cl-Tyr/p-Tyr and 3NO2-Tyr/p-Tyr were 570, 20 and 4.5 times as high, respectively. A significantly higher 3Cl-Tyr/p-Tyr ratio was found in BM caused by Streptococcus pneumoniae, than by Haemophilus influenzae type b, or Neisseria meningitidis (p = 0.002 for both). In conclusion, biomarkers indicating oxidative damage to proteins distinguished BM patients from non-BM, most clearly the o-Tyr/Phe ratio. The high 3Cl-Tyr/p-Tyr ratio in pneumococcal meningitis suggests robust inflammation because 3Cl-Tyr is a marker of MPO activation and, indirectly, of inflammation.

Does Pasteurized Donor Human Milk Efficiently Protect Preterm Infants Against Oxidative Stress?

Pasteurized donor human milk (DHM) is the preferred alternative for infant nutrition when own mother's milk (OMM) is unavailable. Whether DHM is an efficient means for protecting preterm infants from oxidative stress remains unknown. We quantified a panel of oxidative stress biomarkers in urine samples from preterm infants (≤32 weeks of gestation and a birth weight ≤1500 g) receiving ≥80% of feeding volume as either DHM or OMM. The noninvasive in vivo assessment of oxidative stress showed no statistically significant difference between both groups at the time when full enteral nutrition (150 mL/kg body weight) was achieved and until hospital discharge. In addition, the changes of urinary biomarker levels with time were assessed. This is the first longitudinal study on oxidative stress levels in preterm infants fed with DHM in comparison with OMM. There is no statistically significant difference in urinary oxidative stress levels of preterm infants from both groups indicating that despite the effects of pasteurization, DHM is a valid alternative when OMM is not available. Based on the results, we raise the hypothesis that pasteurized DHM protects preterm infants from oxidative stress as good as OMM, and consequently, its use could prevent oxidative stress-related diseases. Antioxid. Redox Signal. 31, 791-799.

Topiramate plus Cooling for Hypoxic-Ischemic Encephalopathy: A Randomized, Controlled, Multicenter, Double-Blinded Trial.

BACKGROUND AND OBJECTIVES: Therapeutic interventions to improve the efficacy of whole-body cooling for hypoxic-ischemic encephalopathy (HIE) are desirable. Topiramate has been effective in reducing brain damage in experimental studies. However, in the clinical setting information is limited to a small number of feasibility trials. We launched a randomized controlled double-blinded topiramate/placebo multicenter trial with the primary objective being to reduce the antiepileptic activity in cooled neonates with HIE and assess if brain damage would be reduced as a consequence. STUDY DESIGN: Neonates were randomly assigned to topiramate or placebo at the initiation of hypothermia. Topiramate was administered via a nasogastric tube. Brain electric activity was continuously monitored. Topiramate pharmacokinetics, energy-related and Krebs' cycle intermediates, and lipid peroxidation biomarkers were determined using liquid chromatography-mass spectrometry and MRI for assessing brain damage. RESULTS: Out of 180 eligible patients 110 were randomized, 57 (51.8%) to topiramate and 53 (48.2%) to placebo. No differences in the perinatal or postnatal variables were found. The topiramate group exhibited less seizure burden in the first 24 h of hypothermia (topiramate, n = 14 [25.9%] vs. placebo, n = 22 [42%]); needed less additional medication, and had lower mortality (topiramate, n = 5 [9.2%] vs. placebo, n = 10 [19.2%]); however, these results did not achieve statistical significance. Topiramate achieved a therapeutic range in 37.5 and 75.5% of the patients at 24 and 48 h, respectively. A significant association between serum topiramate levels and seizure activity (p < 0.016) was established. No differences for oxidative stress, energy-related metabolites, or MRI were found. CONCLUSIONS: Topiramate reduced seizures in patients achieving therapeutic levels in the first hours after treatment initiation; however, they represented only a part of the study population. Our results warrant further studies with higher loading and maintenance dosing of topiramate.

Adrenic acid non-enzymatic peroxidation products in biofluids of moderate preterm infants.

Oxidative stress plays an essential role in processes of signaling and damage to biomolecules during early perinatal life. Isoprostanoids and isofuranoids from the free radical-catalyzed peroxidation of polyunsaturated fatty acids (PUFAs) are widely recognized as reliable biomarkers of oxidative stress. However, their quantification is not straightforward due to high structural similarity of the compounds formed. In this work, a semiquantitative method for the analysis of adrenic acid (AdA, C22:4 n-6) non-enzymatic peroxidation products (i.e. dihomo-isoprostanes and dihomo-isofurans) was developed. The proposed ultra-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) method was applied to the analysis of blood plasma and urine from preterm infants providing information about AdA peroxidation.