Pearl powder is a famous traditional Chinese medicine that has a long history in treating palpitations, insomnia, convulsions, epilepsy, ulcers, and skin lightining. Recently, several studies have demonstrated the effects of pearl extracts on protection of ultraviolet A (UVA) induced irritation on human skin fibroblasts and inhibition of melanin genesis on B16F10 mouse melanoma cells. To further explore the effect we focused on the whitening efficacy of pearl hydrolyzed conchiolin protein (HCP) on human melanoma MNT-1 cells under the irritation of alpha-melanocyte-stimulating hormone (α-MSH) or endothelin 1 (ET-1) to evaluate the intracellular tyrosinase and melanin contents, as well as the expression levels of tyrosinase (TYR), tyrosinase related protein 1 (TRP-1), and dopachrome tautomerase (DCT) genes and related proteins. We found that HCP could decrease the intracellular melanin content by reducing the activity of intracellular tyrosinase and inhibiting the expression of TYR, TRP-1, DCT genes and proteins. At the same time, the effect of HCP on melanosome transfer effect was also investigated in the co-culture system of immortalized human keratinocyte HaCaT cells with MNT-1. The result indicated that HCP could promote the transfer of melanosomes in MNT-1 melanocytes to HaCaT cells, which might accelerate the skin whitening process by quickly transferring and metabolizing melanosomes during keratinocyte differentiation. Further study is needed to explore the mechanism of melanosome transfer with depigmentation.

Gardeniae Fructus (GF), the desiccative mature fruitage of Gardenia jasminoides J. Ellis (G. jasminoides), is a traditional herbal medicine in China with potential value against skin photodamage. However, the phytochemical basis and mechanisms underlying GF’s anti-photodamage effects remain unclear. In this study, the chemical components in GF extract (GFE) were analyzed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS), and iridoids were identified as the main components. The antioxidant, anti-inflammatory, and barrier-repair effects of GFE in UVB-induced photodamage were assessed through in vitro experiments. Additionally, the potential mechanisms of GFE against skin photodamage were predicted using proteomics and network pharmacology. The results showed that GFE significantly increased the levels of total superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) induced by UVB, while decreasing reactive oxygen species (ROS) and malondialdehyde (MDA) contents. GFE also inhibited the secretion of interleukin-6 (IL-6) and interleukin-1β (IL-1β). Additionally, GFE upregulated the expression of filaggrin (FLG), loricrin (LOR), and involucrin (IVL) in 3D epidermal skin models. Proteomic analysis and network pharmacology indicated that the iridoid components identified in GFE ameliorated UVB-induced damage probably by regulating cell cycle-related proteins and signaling pathways, though this requires further experimental confirmation. Overall, the results provide essential evidence to support the development of GFE as a skincare active ingredient.

Gardeniae Fructus (GF), a traditional Chinese medicine rich in iridoids, has demonstrated skin-improving effects. However, its mechanisms for enhancing epidermal barrier function remain unclear. In this study, the iridoids in GF were characterized using UPLC-MS/MS. The improvement in the barrier function by GF was assessed through in vitro experiments and a human efficacy assessment. In addition, the potential targets were predicted through proteomics analysis, molecular docking, and molecular dynamics (MD), and verified in HaCaT cells and three-dimensional epidermal models. Nine iridoids were identified in GF. In vitro, GF effectively promoted cell migration and reduced cell damage and oxidative stress. Proteomics analysis combined with molecular docking and MD simulations predicted that the primary iridoids in GF ameliorate barrier function by binding to the aryl hydrocarbon receptor (AHR) with high affinity and stability. Subsequent validation demonstrated that GF significantly upregulated AHR, filaggrin (FLG), loricrin (LOR), and involucrin (IVL) mRNA and protein expression. A 28-day randomized double-blind human efficacy assessment in subjects with sensitive skin showed that the gel with GF increased stratum corneum hydration, reduced transepidermal water loss (TEWL), and lowered erythema index and lactic acid tingling. These findings suggest that GF enhances the skin barrier via AHR activation-mediated upregulation of barrier proteins, supporting its cosmeceutical potential.