PARIS, Jan. 11 (UPI) -- Egyptian women in ancient times may have worn thick eyeliner to guard against bacterial infection, French scientists said.
Scientists at the University of Pierre and Marie Curie tested lead-based substances found in eye makeup from the time of the pharaohs. The makeup had been preserved at the Louvre museum in Paris.
When cultured on human skin cells, the lead-based substances, which contained the mineral laurionite, boosted production of nitric oxide by as much as 240 percent, the scientists wrote in this week's issue of the journal Analytic Chemistry.
Nitric oxide is a signaling agent that strengthens the immune system to fight disease, researcher Christian Amatore and his colleagues wrote of their study. Bacterial eye infections are common in people living around tropical marshes, such as those of the river Nile, Amatore said.
The findings show why ancient Egyptians could have believed the makeup had magical properties, the researchers said.