Polycyclic aromatic hydrocarbons (PAHs) are major toxic organic constituents attached to ambient fine particulate matter (PM2.5) and contribute substantially to PM2.5-associated oxidative stress and respiratory toxicity. This study investigated the protective effects of shallot (Allium ascalonicum) extracts against PAH-induced oxidative stress in human nasal epithelial cells (RPMI 2650). Shallot extracts were prepared using various extraction techniques and assessed for their phytochemical composition and antioxidant capacity. Among the extracts evaluated, the supercritical fluid extract exhibited the highest total flavonoid content and anti-inflammatory property, whereas the ethanolic extract (EtOH) exhibited the highest total phenolic content and antioxidant activity and was therefore selected for subsequent investigations. HPLC analysis of the EtOH extract identified quercetin and gallic acid as major phenolic constituents. Exposure of RPMI-2650 cells to PAHs (0.25 μg/mL) significantly induced intracellular reactive oxygen species (ROS) generation and lipid peroxidation while reducing superoxide dismutase (SOD) activity, indicating oxidative stress induction. Cotreatment with the ethanolic extract (1.25–5 μg/mL) effectively mitigated these effects by reducing ROS generation, suppressing lipid peroxidation, and restoring SOD activity in a dose-dependent manner. These protective effects are attributed to the antioxidant phytochemicals present in shallot, particularly quercetin. Collectively, these findings indicate that shallot extracts attenuate PAH-induced oxidative stress in human nasal epithelial cells.

Ambient fine particulate matter (PM_2.5) is associated with oxidative stress, metabolic dysregulation, and cardiometabolic disease. However, systemic metabolic responses to contrasting real-world ambient air pollution exposure environments remain poorly characterized. In this cross-sectional study, untargeted proton nuclear magnetic resonance (¹H-NMR)-based urinary metabolomics was used to investigate metabolic signatures associated with contrasting ambient air pollution exposure environments in Thailand. Adults residing in Chiang Mai (high-exposure region; n = 51) and Songkhla (low-exposure region; n = 52) were recruited during a period of elevated regional air pollution, with long-term residence serving as a proxy for differential exposure to ambient air pollution environments. Partial least squares-discriminant analysis (PLS-DA) demonstrated separation between exposure groups (R² = 0.873, Q² = 0.447), indicating good model fit but only modest predictive ability. Eight urinary metabolites differed significantly (p < 0.05), implicating pathways related to tryptophan metabolism, nucleotide metabolism, energy metabolism, and host–microbial co-metabolism. L-arginine and L-cystathionine showed lower relative abundance in the high-exposure group, and six metabolites remained significant after Benjamini–Hochberg false discovery rate correction. Following covariate adjustment, L-tryptophan, hippuric acid, xanthine, and 5-hydroxyindoleacetic acid (5-HIAA) remained significantly associated with the high-exposure group. Contrasting ambient air pollution exposure environments, indexed by regional PM_2.5 concentrations, were associated with coordinated urinary metabolic alterations. Because long-term regional residence served as a proxy for individual-level exposure and diet and lifestyle differences between regions were not fully controlled, these findings should be interpreted as associations with contrasting regional exposure environments. Metabolite annotations remain putative and require validation in longitudinal studies with comprehensive pollutant characterization and individual-level exposure assessment.

Background: This study evaluated the effects of aging and subsequent autoclave treatment on the proton nuclear magnetic resonance (¹H NMR) spectral-feature profile and biological activities of lychee pulp extracts. Methods: Dried lychee (DL), aged lychee (AL), and autoclave-treated aged lychee (ATAL) extracts were compared using ¹H NMR spectroscopy, total phenolic content (TPC), total flavonoid content (TFC), antioxidant assays, carbohydrate-hydrolyzing enzyme inhibitory assays, and endothelial cell viability. Results: Sixteen phytochemical spectral features were putatively annotated, and their relative signal intensities differed among the extracts (p < 0.001). Relative to DL, ATAL exhibited higher signal intensities for most features, including taxifolin (8.32-fold) and procyanidin B2 (7.44-fold), whereas epicatechin was particularly prominent in AL (12.31-fold). TPC increased from 0.53 ± 0.07 mg gallic acid equivalents (GAE)/g extract in DL to 8.39 ± 0.19 and 9.07 ± 0.10 mg GAE/g extract in AL and ATAL, respectively. AL and ATAL also showed higher TFC and antioxidant activities than DL. The α-amylase IC₅₀ values were 247.00 ± 45.00, 129.17 ± 8.56, and 126.27 ± 3.90 mg/mL for DL, AL, and ATAL, respectively, while the corresponding α-glucosidase IC₅₀ values were 187.93 ± 8.20, 66.71 ± 6.84, and 50.30 ± 2.72 mg/mL. No significant reduction in endothelial cell viability was detected after multiplicity adjustment. Exploratory principal component analysis (PCA) explained 99.8% of the total variance and revealed distinct processing-associated spectral-feature profiles. Conclusions: Aging followed by autoclave treatment enhanced the phytochemical profile, antioxidant activity, and in vitro carbohydrate-hydrolyzing enzyme inhibition of lychee pulp extracts.