[Screening of the anti-Malassezia furfur active fraction from Rosa chinensis Jacq. and study on its mechanism against seborrheic dermatitis].

OBJECTIVES: To screen Chinese herbal medicines for optimal inhibitory activity against Malassezia furfur (M. furfur), isolate and identify the most potent antimicrobial fraction, and investigate its underlying mechanism of action.

METHODS: The Chinese herbal extract and its polar fractions exhibiting the strongest inhibitory effect against M. furfur were initially screened from 20 Chinese herbal medicines using the Oxford cup method and broth microdilution assay. A highly active subfraction was subsequently obtained through silica gel column chromatography. The effects of this active subfraction on the growth and cell structural integrity of M. furfur were evaluated by turbidimetry, exogenous sorbitol hypertonic protection assay, extracellular alkaline phosphatase activity assay, propidium iodide fluorescence staining, and crystal violet staining. M. furfur-induced inflammatory models in HaCaT keratinocytes and SZ95 sebocytes were employed. The safety of the active subfraction was assessed by MTT assay for cell viability. Nitric oxide release was measured by Griess test, and the levels of IL-6 and tumor necrosis factorinduced inflammatory models in HaCaT keratinocytes and SZ95 sebocytes were employed. The safety of the active subfraction was assessed by MTT assay for cell viability. Nitric oxide release was measured by Griess test, and the levels of IL (TNF)-α in cell supernatants were determined by ELISA. Lipid synthesis in SZ95 cells was evaluated by Nile red staining. The chemical constituents of the highly active fraction obtained by silica gel column chromatography were analyzed and identified by ultra performance liquid chromatography-mass spectrometry (UPLC-MS). Potential anti-seborrheic dermatitis targets and pathways were predicted through construction of a protein-protein interaction network, Gene Ontology (GO) functional annotation, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis.

RESULTS: Among the extracts of 20 Chinese herbal medicines, the extract of Rosa chinensis Jacq. demonstrated superior inhibitory activity against M. furfur. Its ethyl acetate fraction exhibited the most potent antimicrobial effect, from which subfraction Fr.2 was isolated as the most active component, with an inhibition zone diameter of (25.30±0.49) mm and a minimum inhibitory concentration of 1 mg/mL. Fr.2 effectively inhibited the growth of M. furfur (P<0.05) and disrupted cellular structures, including the cell wall, cell membrane, and biofilm. Within a safe concentration range (25-100 μg/mL), Fr.2 showed no cytotoxicity toward HaCaT and SZ95 cells and dose-dependently reduced the release of inflammatory factors and lipid synthesis in SZ95 cells. A total of 27 constituents were identified from Fr.2 by UPLC-MS, including organic acids, flavonoids (such as myricetin, quercetin, and kaempferol), and alkaloids. The anti-seborrheic dermatitis effect of Fr.2 was associated with the regulation of core targets including TNF, chemokine C-X-C motif ligand 8, prostaglandin G/H synthase 2, signal transducer and activator of transcription 3, and epidermal growth factor receptor. GO analysis indicated that common targets of the drug and disease were primarily involved in neural signal regulation, inflammatory modulation, and membrane structure localization; at the molecular function level, these targets were predominantly associated with protein binding. KEGG pathway analysis further revealed that Fr.2 may exert its therapeutic effect on seborrheic dermatitis by modulating immune-inflammatory pathways, lipid metabolism and vascular function-related pathways, and neural signaling pathways.

CONCLUSIONS: Rosa chinensis Jacq. exerts its antimicrobial effect against M. furfur by disrupting cell wall, cell membrane, and biofilm structures, and also demonstrates anti-seborrheic dermatitis activity, which may be attributed to the inhibition of inflammatory signaling pathways and the reduction of lipid synthesis.