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Unexpected hydroxyl radical production in brewed tea under sunlight
Linjun Qin1,2, Lili Yang1,2, Manabu Shiraiwa3
1State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
PNAS Nexus
|January 26, 2024
Summary
Sunlight exposure unexpectedly creates harmful hydroxyl radicals (•OH) in brewed tea and epigallocatechin gallate (EGCG) solutions. These radicals can cause cell damage, highlighting potential health risks of drinking tea in the sun.
Area of Science:
- Photochemistry
- Food Science
- Environmental Science
Background:
- Tea is a globally popular beverage, with epigallocatechin gallate (EGCG) as its primary active compound.
- The photochemical reactions within brewed tea, particularly under sunlight, remain under-investigated.
- Understanding these reactions is crucial due to the widespread consumption of tea.
Purpose of the Study:
- To investigate the formation of free radicals in brewed tea and EGCG solutions under simulated sunlight.
- To determine the role of sunlight irradiation and metal ions in radical production.
- To assess the in vitro effects of generated radicals on cells and DNA.
Main Methods:
- Exposure of aqueous EGCG solutions and brewed tea to simulated sunlight.
- Detection and characterization of free radicals, specifically hydroxyl radicals (•OH).
- In vitro assays to evaluate the cytotoxic and genotoxic effects of •OH.
Main Results:
- Unexpected production of hydroxyl radicals (•OH) was observed in brewed tea under sunlight.
- Sunlight irradiation was identified as the key factor for •OH formation, irrespective of metal ions.
- The generated •OH exhibited cytotoxicity and induced DNA damage in vitro.
Conclusions:
- Sunlight exposure triggers the formation of reactive hydroxyl radicals in brewed tea.
- The cytotoxic and DNA-damaging potential of these radicals warrants further investigation into health implications.
- This study underscores the importance of considering photochemical reactions in beverage consumption and environmental contexts.
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