In the early 1970s, researchers in Japan and Hawaii noticed that corals produce a UV-absorbing substance, a fringe benefit provided by the symbiotic algae living in their tissue. A decade later, photochemist Walt Dunlap at AIMS identified the substance as a member of a family of compounds found in fungi--the mycosporine-like amino acids (MAA). Test tube studies showed that MAA is a highly efficient sunscreen, absorbing and dissipating UV energy. But MAA is a tricky molecule to work with because it's highly unstable in water. "Stabilizing the molecule and making it insoluble has taken us the best part of 10 years," says Dunlap. Scientists, in collaboration with ICI Australia, experimented with hundreds of versions of the MAA molecule, knocking off water-soluble groups and adding others to reinforce the light-absorbing part of the molecule.

Now the researchers have a financial backer, Sunscreen Technologies Pty. Ltd., which plans to run clinical trials. Dunlap says the coral byproduct is chemically simpler than the aromatic ring molecules on which commercial sunscreens are based, and is less likely to trigger allergic responses. A coral sunscreen should appeal to people looking for "natural" products, adds Gavin Greenoak of the Australian Photobiology Testing Facility in Sydney: "After all, coral has been using it for millennia."