Hibiscus Suspension Culture Extract Modulates Skin Metabolism and Cellular Pathways in Human Keratinocyte/Fibroblast Co-Cultures: A Proteomic Approach

Hibiscus plant cell cultures were developed to produce a cosmetic ingredient with anti-ageing properties. UHPLC-DAD-MS analysis of Hibiscus plant cell cultures revealed a high content of polyphenols, particularly hydroxycinnamic acid derivatives, including caffeoyl and p-coumaroyl conjugates. The biological activity of a 50/50 mixture of extracts from Hibiscus syriacus and Hibiscus rosa-sinensis cells was investigated in a human keratinocyte/fibroblast co-culture model, which better reproduces the reciprocal epithelial–mesenchymal interactions between epidermal keratinocytes and dermal fibroblasts than monocultures, using quantitative data-independent acquisition (DIA) LC-MS/MS proteomics combined with functional enrichment and protein–protein interaction analyses. A total of 7062 proteins were identified, of which 280 were differentially expressed (107 upregulated and 171 downregulated) following hibiscus treatment. The proteomic profile suggested coordinated molecular reprogramming associated with extracellular matrix remodelling, tissue repair, hydration, and attenuation of inflammatory signalling. Functional enrichment analysis revealed coordinated modulation of extracellular matrix organization, glycosaminoglycan metabolism, lysosomal function, cell communication, and inflammatory signalling. Upregulation of extracellular matrix and adhesion proteins, including lumican, collagen VIII, fibulin-5, syndecans, and glypicans, suggested coordinated extracellular matrix remodelling that may promote skin firmness and elasticity, while the downregulation of inflammatory regulators, including CARD16 and S100 family proteins, suggested attenuation of innate inflammatory responses. Overall, these findings provide mechanistic insights into the biological activity of Hibiscus cell culture extracts and support their potential as cosmetic ingredients promoting skin homeostasis and healthy skin ageing.