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Phototoxicity of melatonin
Y O Kim1, H J Chung, S T Chung
1Department of Toxicology, National Institute of Toxicological Research, KFDA, Seoul, Korea.
Archives of Pharmacal Research
|May 7, 1999
Summary
Melatonin (MLT) exposed to UVA light undergoes molecular changes, forming new photoproducts. Studies predict moderate phototoxicity for MLT due to these UVA-induced alterations.
Area of Science:
- Photochemistry
- Dermatology
- Biochemistry
Background:
- Melatonin (MLT), N-acetyl-5-methoxytryptamine, is primarily secreted by the pineal gland.
- Understanding MLT's behavior under UV irradiation is crucial for assessing its safety and potential applications.
Purpose of the Study:
- To investigate the effects of UVA irradiation on the molecular structure of Melatonin (MLT).
- To evaluate the phototoxicity of MLT using in vitro and in vivo models.
Main Methods:
- Spectroscopic analysis (UV, IR, 1H-NMR) of irradiated and non-irradiated MLT.
- In vitro phototoxicity assays (MTS assay, yeast growth inhibition).
- In vivo phototoxicity assessment on guinea pig skin and histopathological examination.
Main Results:
- UVA irradiation altered MLT's UV absorption and 1H-NMR spectra, indicating molecular structure modification.
- The IC50 ratio (UV-/UV+) for MLT was 10, suggesting reduced inhibitory concentration after UV exposure.
- Histopathological examination of irradiated guinea pig skin revealed epidermal and dermal lesions, indicating moderate phototoxicity.
Conclusions:
- UVA irradiation transforms MLT into unidentified photoproducts.
- Melatonin (MLT) exhibits moderate phototoxicity upon UVA exposure, necessitating further investigation into its photostability and safety profile.