Dihydroxyacetone (DHA), a browning agent, protects photosensitive rats and humans against long ultraviolet radiation (UVA, 320–400 nm) and visible (blue) light. The photoprotective efficacy of DHA and structurally similar compounds was assessed as prevention of edema in the paws of psoralen-sensitized rats, after exposure to blacklight fluorescent lamps. Methylglyoxal produced a yellow-brown color and provided nearly the same protection as DHA, whereas monohydroxyacetone did not color the skin and afforded little or no protection. Glyceraldehyde provided a moderate amount of protection, which was enhanced by prior exposure of the agent to alkaline pH. A solution of 5-hydroxymethyl-furfuraldchyde was yellow and provided minimal protection by staining the skin rather than browning it. We conclude that the ability to produce a brown color in skin is a useful criterion for screening compounds for photoprotective efficacy against UVA radiation.
- Browning agent
ASJC Scopus subject areas