Oxidation processes in mitochondria and different environmental insults contribute to unwarranted accumulation of reactive oxygen species (ROS). These, in turn, rapidly damage intracellular lipids, proteins, and DNA, ultimately causing aging and several human diseases. Cells have developed different and very effective systems to control ROS levels. Among these, removal of excessive amounts is guaranteed by upregulated expression of various antioxidant enzymes, through activation of the NF-E2-Related Factor 2 (NRF2) protein. Here, we show that Mitogen Activated Protein Kinase 15 (MAPK15) controls the transactivating potential of NRF2 and, in turn, the expression of its downstream target genes. Specifically, upon oxidative stress, MAPK15 is necessary to increase NRF2 expression and nuclear translocation, by inducing its activating phosphorylation, ultimately supporting transactivation of cytoprotective antioxidant genes. Lungs are continuously exposed to oxidative damages induced by environmental insults such as air pollutants and cigarette smoke. Interestingly, we demonstrate that MAPK15 is very effective in supporting NRF2-dependent antioxidant transcriptional response to cigarette smoke of epithelial lung cells. Oxidative damage induced by cigarette smoke indeed represents a leading cause of disability and death worldwide by contributing to the pathogenesis of different chronic respiratory diseases and lung cancer. Therefore, the development of novel therapeutic strategies able to modulate cellular responses to oxidative stress would be highly beneficial. Our data contribute to the necessary understanding of the molecular mechanisms behind such responses and identify new potentially actionable targets.

Background/Objectives: Natural products containing hydroxyanthracene derivatives (HADs) such as Cascara (Rhamnus purshiana), Frangula (Rhamnus frangula), Rhubarb (Rheum palmatum), and Senna (Cassia angustifolia) have long been used for their laxative properties, but also raise safety concerns due to reported genotoxic and carcinogenic potential. Most studies have focused on quantifying HADs, whereas the broader secondary metabolite landscape of these herbal drugs remains underexplored. We aimed to generate an untargeted metabolomic fingerprint of these four species and to explore their chemical diversity using AI-based structural classification. Methods: Four commercial botanical raw materials were extracted with 60% methanol and analysed by UPLC–HRMS/MS in positive and negative ion modes. Features were processed in Compound Discoverer and annotated by accurate mass and MS/MS matching against spectral databases, then assigned to structural classes using a graph neural network classifier. Multivariate analyses (PCA, HCA) were used to compare metabolic patterns across species. Results: In total, 93, 83, 83 and 51 metabolites were annotated in cascara, frangula, rhubarb, and senna, respectively, spanning flavonoids, anthraquinones, phenylpropanoids and other classes. Only four flavonoids were shared by all species, indicating marked biochemical divergence. Several putatively species-enriched features were observed, including pavine in cascara and frangula, vicenin-2 in senna, and piceatannol in rhubarb. Senna displayed the most distinct metabolic profile, whereas cascara and frangula clustered closely. Conclusions: This work provides a chemistry-centred metabolomic fingerprint of four HAD-containing herbal drugs using graph-based neural networks for natural product classification, supporting future studies on the pharmacological potential, bioavailability and safety of their metabolites.

Alkaptonuria (AKU) is a rare metabolic disorder caused by homogentisic acid accumulation and characterised by ochronosis, oxidative stress, chronic inflammation, and progressive connective tissue damage. This study aimed to define the circulating proteomic alterations associated with AKU and assess their relationship with nitisinone treatment. Plasma samples from 11 patients with AKU and 6 age- and sex-matched healthy controls were analysed by liquid chromatography coupled to tandem mass spectrometry using label-free quantification. Differentially abundant proteins were identified using thresholds of |log₂FC| ≥ 1 and Benjamini–Hochberg false discovery rate ≤ 0.01, followed by functional enrichment and treatment-stratified analyses. Twenty-two proteins were differentially abundant between AKU patients and controls. Complement components (C1R, C1S, C9, C4BPA, CPN2), fibronectin, clusterin, PGLYRP2, and haemoglobin subunits showed increased abundance, whereas most immunoglobulin chains, kallikrein, apolipoprotein A2, and alpha-1-antitrypsin showed decreased abundance. Functional enrichment highlighted complement activation, B-cell-mediated and humoral immune responses, immunoglobulin-related functions, platelet activation, and erythrocyte gas-exchange pathways. Correlation analysis linked several proteins, particularly CPN2, APOA2, C1R and C1S, to core biochemical parameters of disease activity. Treatment-stratified analysis identified fourteen proteins that remained significantly altered in both treated and untreated patients, forming a treatment-resistant core of the signature, while several complement-, coagulation-, and lipid-related proteins were significant only in one treatment subgroup. These findings define an AKU plasma proteomic signature dominated by complement activation and humoral immune alterations, together with extracellular matrix, erythrocyte-, and coagulation-associated changes. The persistence of most alterations across treatment groups suggests that residual systemic proteomic dysregulation remains despite nitisinone treatment.

Red yeast rice (RYR) food supplements are widely used for cholesterol management due to their monacolin content, particularly monacolin K (MK), which shares the same chemical structure as lovastatin, a compound associated with several side effects. The European Food Safety Authority (EFSA) highlighted uncertainties regarding the compositional variability, characterization of bioactive constituents, and safety of RYR products, concluding that a safe level of monacolin intake could not be established. In this study, twenty-seven commercial semi-processed RYR ingredients for food supplements manufacturing were investigated through a combined chemical and biological approach to characterize their composition and evaluate potential safety concerns. Targeted LC-MS/MS analyses revealed substantial variability in MK, monacolin hydroxy acid (MKA), and dehydromonacolin K (DMK) levels among products. Exploratory qualitative untargeted metabolomics enabled the putative annotation of multiple secondary metabolites, including azaphilones and polyketides, highlighting differences in chemical profiles. Correlation analyses indicated that DMK content was associated with pigment distribution and cytotoxic responses in human hepatocellular carcinoma cells and primary human skeletal muscle cells, whereas MK and MKA showed no significant association with toxicity under the tested conditions. Exploratory proteomic profiling suggested distinct protein-abundance patterns between RYR- and simvastatin-treated cells, providing hypothesis-generating information on functional annotations associated with these patterns. These findings emphasize the importance of comprehensive chemical characterization and quality control strategies considering both monacolins and secondary metabolites to improve the safety assessment of RYR supplements.