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Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
Cinnamon-Derived Compounds Reduce PD-L1 Expression in UV-Exposed Human Skin Cell Line
Chidambaram Ramanathan1, Richard J Bloomer1, Gus Romero2
1Center for Nutraceutical and Dietary Supplement Research, College of Health Sciences, University of Memphis, Memphis, TN 38152, USA.
Medicines (Basel, Switzerland)
|June 25, 2026
Summary
Cinnamon compounds CTD-1 and CTB-1, along with cinnamon extract, protect skin cells from UVAB radiation damage. CTD-1 showed the best results, reducing DNA damage and PD-L1 expression without harming cells.
Area of Science:
- Dermatology
- Photobiology
- Molecular Biology
Background:
- Ultraviolet A and B (UVAB) radiation causes DNA damage and elevates programmed death-ligand 1 (PD-L1) in skin cells, impairing tissue repair and immune function.
- UVAB exposure is a significant environmental factor contributing to skin damage and immune evasion.
Purpose of the Study:
- To evaluate the protective effects of Cinnamtannin B1 (CTB-1), Cinnamtannin D1 (CTD-1), and cinnamon extract against UVAB-induced damage in human keratinocytes (HaCaT cells).
- To assess the impact of these compounds on PD-L1 expression, cell viability, and DNA damage following UVAB exposure.
Main Methods:
- HaCaT cells were exposed to varying doses of UVAB radiation.
- Cells were treated with different concentrations and time points of CTB-1, CTD-1, and cinnamon extract.
- Measurements included PD-L1 expression, cell viability assays, and DNA damage assessment (specifically double-strand breaks).
Main Results:
- Cinnamtannin D1 (CTD-1) significantly reduced UVAB-induced PD-L1 expression and DNA double-strand breaks without affecting cell viability.
- Cinnamtannin B1 (CTB-1) offered protection at certain doses but reduced cell viability at higher concentrations.
- Cinnamon extract showed protective effects at low doses but became cytotoxic at higher concentrations.
Conclusions:
- CTD-1, CTB-1, and cinnamon extract effectively attenuated UVAB-induced cellular damage in HaCaT cells.
- CTD-1 exhibited the most promising protective profile, highlighting its potential therapeutic benefits.
- These cinnamon-derived compounds may serve as candidates for preventing UVAB-induced skin damage and immune dysregulation.
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