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Malondialdehyde (MDA) is the end product of fat peroxidation due to the breakdown of fatty acid chains which are compounds that toxic to cells. Fat peroxidation is caused by body fat bound to free radicals such as hydroxyl radicals, superoxide anion radicals, and hydrogen peroxide, which are compounds or atoms that have unpaired electrons in their outer orbitals so that they are very reactive to cells or surrounding cell components including lipids. As a result of the lipid peroxidation reaction which is continuous which can cause various diseases and accelerate the aging process, because malondialdehyde causes cell damage. The aging process is the weakening of cells and organs as a whole starting from adulthood slowly and progressing quickly after the age of 50 years, marked by the body begins to ache and wrinkled skin. Naturally, the aging process will occur in every human being, but the process is different, some are fast (the process of premature aging) and some are slow (ageless). Although the aging process occurs for several reasons, free radicals such as melondialdehyde also contribute to accelerating the aging process. Efforts to slow down premature aging due to free radicals, namely antioxidants. As an active ingredient, antioxidants are used to protect skin from oxidation damage and prevent premature aging.

The nonenzymatic adduction of malondialdehyde (MDA) to the protein amino groups leads to the formation of malondialdehyde-lysine (MDALys). The degree of unsaturation of biological membranes and the intracellular oxidative conditions are the main factors that modulate MDALys formation. The low concentration of this modification in the different cellular components, found in a wide diversity of tissues and animal species, is indicative of the presence of a complex network of cellular protection mechanisms that avoid its cytotoxic effects. In this review, we will focus on the chemistry of this lipoxidation-derived protein modification, the specificity of MDALys formation in proteins, the methodology used for its detection and quantification, the MDA-lipoxidized proteome, the metabolism of MDA-modified proteins, and the detrimental effects of this protein modification. We also propose that MDALys is an indicator of the rate of aging based on findings which demonstrate that (i) MDALys accumulates in tissues with age, (ii) the lower the concentration of MDALys the greater the longevity of the animal species, and (iii) its concentration is attenuated by anti-aging nutritional and pharmacological interventions ; Research by the authors was supported by the Spanish Ministry of Economy and Competitiveness, Institute of Health Carlos III (FIS grants PI13/00584 and PI14/00328), the Spanish Ministry of Science, Innovation, and Universities (Ministerio de Ciencia, Innovación y Universidades, RTI2018-099200-BI00), and the Generalitat of Catalonia: Agency for Management of University and Research Grants (2017SGR696), and Department of Health (SLT002/16/00250) to RP. This study has been co-financed by FEDER funds from the European Union ("A way to build Europe"). IRBLleida is a CERCA Programme/Generalitat of Catalonia.

We analyzed non-additive effects in resonance assisted hydrogen bonds (RAHBs) in different b-enolones, which are archetypal compounds of these types of interactions. For this purpose, we used (i) potential energy curves to compute the formation energy, DERAHB form , of the RAHBs of interest in different circumstances along with (ii) tools offered by quantum chemical topology, namely, the Quantum Theory of Atoms In Molecules (QTAIM) and the Interacting Quantum Atoms (IQA) electronic energy partition. We established the effect that a given H-bond exerts over DERAHB form associated with another RAHB, determining in this way the cooperativity or the anticooperativity of these interactions. The mesomeric structures and the QTAIM delocalisation indices are consistent with the determined cooperative or anticooperative character of two given RAHBs. The HB cooperativity and anticooperativity studied herein are directly reflected in the IQA interaction energy EOH int , but they are modulated by the surrounding hydrocarbon chain. The IQA decomposition of DEcoop, a measure of the cooperativity between a pair of interacting RAHBs, indicates that the analyzed H-bond cooperative/anticooperative effects are associated with greater/smaller (i) strengthening of the pseudo-bicyclic structure of the compounds of interest and (ii) electron localisations with its corresponding changes in the intra and intermolecular exchange–correlation contributions to DERAHB form . Overall, we expect that this investigation will provide valuable insights into the interplay among hydrogen bonded atoms and the p system in RAHBs contributing in this way to the understanding of the general features of H-bonds. 1 ; DGAPA/UNAM (project PAPIIT IN209715), CONACyT/México (grant 253776, and scholarships 308773 and 381482) and the Spanish government (grant CTQ-2015-65790-P) as well as computer time from DGTIC/UNAM (project SC16-1-IG-99).

AbstractBackgroundPeople who work long hours on the road are intensively exposed to high levels of fine particulate matters (PM2.5) which may lead to oxidative stress mechanisms in the human body that cause deleterious health problems. Malondialdehyde (MDA) is the major metabolite produced during lipid peroxidation metabolism that serves as a reliable biomarker for oxidative stress in cells.ObjectivesTo identify the association between PM2.5exposure and other characteristics with urinary MDA levels among public transport drivers in Jakarta.MethodsA cross-sectional design was implemented by involving 130 public transport drivers of nine trajectories from Kampung Melayu Terminal, Jakarta. The continuous PM2.5data were collected in personal measurement during one round trip of driving. Weight and height measurements were obtained to calculate body mass index (BMI) and structured questionnaires were completed to identify other characteristics. MDA levels were examined from the driver's urine right after driving and evaluated using TBARS analysis.ResultsThe average of PM2.5exposure was 91.56 ± 20.05 μg/m3and MDA levels were 2.23 ± 1.57 nmoL/mL. Drivers with overweight and obese BMI had significantly higher MDA levels (2.66 ± 1.65 nmoL/mL) compared to those with normal and underweight BMI status (1.97 ± 1.47 nmoL/mL). Multiple linear regression analysis demonstrated low PM2.5exposure, normal and underweight BMI status, and a long period of working as drivers were associated with MDA levels (p<0.05). Contrary to the prior study, PM2.5exposure was negatively associated with MDA levels due to most drivers' BMI status being normal and underweight.ConclusionOur study suggests that the drivers who were obese and overweight should lose weight to lower the risk of increased MDA levels. We also suggest the drivers to consider maintaining their vehicle's ventilation system or using personal protection equipment (PPE) to avoid high PM2.5exposure while driving.

AbstractCytokines are physiological seminal components and their abnormal levels, reported in different pathological conditions, negatively influence the sperm function. We analysed the relationship between interleukin (IL)-6 and IL-33 levels and lipid peroxidation (LPO), measured both in semen and sperm lysate, in 44 human semen samples. The semen analysis was performed following the WHO guidelines. Seminal IL-6 and IL-33 concentrations were assessed by ELISA and LPO was evaluated measuring malondialdehyde (MDA) both in seminal plasma and viable spermatozoa. Two small groups of patients with varicocele and infection were extrapolated from the cases analysed and the variables compared with those of a group of control. IL-33 levels were undetectable in all samples and IL-6 levels were positively correlated with both seminal and sperm MDA concentrations (p< 0.01) and negatively with sperm parameters (p< 0.01). Seminal and sperm MDA levels were both negatively correlated with sperm parameters (p< 0.01). IL-6 and semen MDA showed an exponential positive relationship, whereas MDA values measured in viable spermatozoa were low until IL-6 amount reached a concentration of >30 pg/mL, rising consistently. By comparing the variables in the groups, we confirmed that a high IL-6 concentration in the varicocele and infection groups was concomitant with an increase of seminal MDA levels, but also with MDA measured in viable spermatozoa, which represents the novelty of this study. We identified the IL-6 threshold, beyond which sperm MDA concentration rises concomitantly with the increase of IL-6 concentration. Other studies are needed, considering the increasing number of patients with different pathologies affecting male infertility.