Molecular networking-guided identification of bioactive compounds from Phyla nodiflora green extract protecting keratinocytes against PM-induced oxidative stress via the Nrf2/HO-1 pathway

Ambient particulate matter (PM) is a major air pollutant associated with various skin disorders, including inflammation, atopic dermatitis, and psoriasis [ 1 ] [ 2 ]. Upon PM exposure, excessive reactive oxygen species (ROS) are generated in the skin, leading to oxidative stress, inflammation, and cellular dysfunction [ 3 ]. Phyla nodiflora (PN), a perennial herb in the Verbenaceae family, was selected for investigation due to its documented anti-inflammatory, anti-oxidant, and anti-microbial activities [ 4 ] [ 5 ]. These properties suggest it may offer protective effects against PM-induced skin damage. In this study, we aimed to evaluate the protective effects of PN against PM-induced oxidative damage in human keratinocytes (HaCaT cells). A solvent-free microwave hydrodiffusion and gravity (SF-MHG) extraction method was employed to obtain PN extracts and fractionate them into different polar components. Cell viability (resazurin assay) and intracellular ROS levels (H2DCFDA assay) were used to assess cytoprotective activity. Among the PN fractions, Frs. 4 and 5 significantly reduced ROS levels (>50%) in PM-treated HaCaT cells without cytotoxicity at concentrations below 30 μg/mL. Western blot analysis revealed that PN treatment upregulated Nrf2 and HO-1 expression, suggesting activation of the Nrf2/HO-1 antioxidant pathway. Furthermore, molecular networking based on LC-MS/MS data guided the identification of putative bioactive compounds responsible for the observed activity. Overall, this study highlights Phyla nodiflora as a promising natural resource for protecting the skin against PM-induced oxidative stress through green extraction and bioactivity-guided fractionation. Further investigation of its protective mechanisms is ongoing. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany