The skin, as the outermost layer of the body, serves as a crucial barrier against environmental insults, including solar ultraviolet (UV) radiation. While UV exposure is essential for vitamin D synthesis, excessive exposure, particularly to UVB (290-320 nm), is a primary cause of acute skin damage and contributes significantly to photoaging. Prolonged UVB irradiation leads to the generation of excessive reactive oxygen species (ROS), overwhelming the skin’s antioxidant defense system and resulting in oxidative stress. This oxidative stress triggers inflammation and impairs the epidermal barrier function. Consequently, there is a growing interest in identifying natural products with photoprotective properties for use in functional foods and medicinal or cosmetic applications. Gardeniae Fructus (GF), the dried mature fruit of Gardenia jasminoides J. Ellis, is a traditional herbal medicine in China known for various beneficial activities, including anti-inflammatory and antioxidant effects, and has been used in cosmetics for its soothing properties. Although previous studies have suggested GF’s potential to protect cells from UV irradiation, the specific mechanisms underlying these anti-photodamage effects remain largely unclear. This study aimed to investigate the protective effect of Gardeniae Fructus extract (GFE) on UVB-damaged HaCaT cells (a human keratinocyte cell line) and elucidate the potential mechanisms involved.
Methods
Gardeniae Fructus extract (GFE) was prepared by water extraction, decolorization, purification with macroporous resin, and lyophilization. The chemical components of GFE were analyzed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS), identifying iridoids as the main constituents. In vitro experiments were conducted using HaCaT cells exposed to UVB radiation to assess the antioxidant and anti-inflammatory effects of GFE. Additionally, 3D epidermal skin models were used to evaluate GFE’s impact on barrier repair following UVB irradiation. Proteomic analysis and network pharmacology approaches were employed to predict the potential molecular targets and pathways involved in GFE’s anti-photodamage effects.
Key Findings
•Chemical Composition: UPLC-MS/MS analysis identified ten iridoids as the main components in GFE, including genipin 1-gentiobioside, geniposidic acid, and geniposide.
•Antioxidant Effects: GFE treatment significantly increased the levels of antioxidant enzymes total superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in UVB-irradiated HaCaT cells. Concurrently, GFE decreased the production of reactive oxygen species (ROS) and the levels of malondialdehyde (MDA), a marker of lipid peroxidation.
•Anti-inflammatory Effects: UVB irradiation increased the secretion of pro-inflammatory cytokines interleukin-6 (IL-6) and interleukin-1β (IL-1β) in HaCaT cells, whereas treatment with GFE inhibited the secretion of both IL-6 and IL-1β.
•Barrier Repair: UVB exposure downregulated the expression of key skin barrier proteins filaggrin (FLG), loricrin (LOR), and involucrin (IVL) in 3D epidermal models. GFE treatment restored the barrier function by upregulating the expression of FLG, IVL, and LOR.
•Proteomic Analysis: Proteomic analysis revealed that UVB irradiation interfered with cell cycle-related proteins in HaCaT cells, particularly activating the G2/M checkpoint. GFE treatment mitigated UVB-induced photodamage by influencing the cell cycle and significantly downregulating the G2/M checkpoint.
•Network Pharmacology: Network pharmacology analysis identified 24 potential target genes shared between GFE’s iridoids and photodamage pathways. Key targets with high centrality in the protein-protein interaction (PPI) network included IL1B, MMP9, TP53, BCL2, and SIRT1. Geniposide, the most abundant iridoid in GFE, was associated with the most targets.
•Molecular Docking: Molecular docking studies showed a favorable binding affinity between geniposide and TP53 (p53), with a binding energy of -6.0 kcal/mol, suggesting a potential interaction in regulating photodamage.
This study provides significant evidence for the photoprotective effects of Gardeniae Fructus extract (GFE) against UVB-induced skin damage. The novelty of this research lies in its comprehensive approach, combining in vitro pharmacological experiments with proteomics and network pharmacology to elucidate the underlying mechanisms. The findings reveal that GFE, rich in iridoids, effectively combats UVB-induced oxidative stress, inflammation, and epidermal barrier dysfunction. Furthermore, the study highlights the potential of GFE’s components, particularly geniposide, in ameliorating UVB damage by regulating cell cycle-related proteins and interacting with key targets such as p53. These results strongly support the potential of GFE as a valuable active ingredient for the development of skincare products aimed at preventing and repairing skin photodamage and photoaging. Future research should focus on further in vivo validation of these findings and exploring the specific contributions of individual iridoids within GFE to its overall photoprotective efficacy.
Link to the study: https://www.mdpi.com/2079-9284/12/2/72
