Long-term ultraviolet (UV) exposure accelerates the phenomenon of skin photo-aging by activating collagenase and elastase. In this study, we aimed to investigate the effects of a combination of grapefruit and rosemary extracts (cG&Re) on UVB-irradiated damage in HaCaT cells and dorsal mouse skin. In HaCaT cells, cG&Re recovered UVB-reduced cell viability and inhibited protein expression of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated kinases (p-Erk), c-Jun N-terminal kinases (p-JNK), and a class of MAPKs (p-P38). Also, cG&Re suppressed UVB-induced collagen and elastin degradation by decreasing matrix metalloproteinases (MMPs) and nuclear factor kappa light chain enhancer of activated B cells (NF-κB) expression, which is a transcription factor. Similar results were observed in dorsal mouse skin. Taken together, our data indicate that cG&Re prevent UVB-induced skin photo-aging due to collagen/elastin degradation via activation of MAPKs, MMPs, and the NF-κB signaling pathway in vitro and in vivo.

Abstract
Introduction
Materials and Methods
    Preparation of a combination of grapefruit and rosemary extracts (cG&Re)
    Analysis of marker substances by HPLC
    Reagents and antibodies
    Cell culture
    Determination of cell viability
    Cell viability assay in UVB-irradiated HaCaT cells
    UVB-irradiated skin photo-aging animal model
    Western blot analysis
    Statistical analysis
Results
    Quantification of marker substances in cG&Re extract
    Effect of cG&Re on HaCaT cell viability
    Inhibitory effects of cG&Re on UVB-induced MMPs and NF-κB in HaCaT cells
    Suppressive effects of UVB-induced MAPKs on cG&Re in HaCaT cells
    Inhibitory effects of cG&Re on MMPs and NF-κB in UVB-irradiated dorsal mouse skin
    Inhibitory effects of cG&Re on MAPKs in UVB-induced dorsal mouse skin
Discussion
References

• Yeo-Cho Yoon(Natural F&P)
• Hee-Jeong Choi(School of Food Science & Biotechnology, Kyungpook National University)
• Ji-Hyun Park(School of Food Science & Biotechnology, Kyungpook National University)
• Nurud Diniyah(School of Food Science & Biotechnology, Kyungpook National University)
• Hyun-A Shin(Natural F&P)
• Mi-Yeon Kim(Natural F&P) Corresponding author