In vivo and in vitro effects of acute gamma irradiation on usnic acid in the lichen Cladonia sylvatica (L.) Hoffm.

Abstract

The effects of acute gamma radiation on usnic acid in vitro and in vivo were studied with respect to any protective properties this substance may have against radiation damage in Cladonia sylvatica (L.) Hoffm. Attempts were made to determine concentration of usnic acid by gas chromatography but it was found that the substance was not amenable to analysis by the method utilized. Using a ferric chloride colorimetric test for quantity of usnic acid and mass spectroscopy, it was determined that acute irradiation to 106 rad. had no noticeable affect' on usnic acid in vitro. Using the same ferric chloride method, it was found that acute gamma irradiation of C. sylvatica to 106 rad. caused a decrease in concentration of usnic acid present with respect to controls, only if the lichen had been placed back in the field and remained there through a growth season after being irradiated. It was found that lichen samples treated in this manner, irradiated and placed back into the field through 4 winter months, appeared significantly different from the nonirradiated controls in terms of color and texture. However, these lichens did not show a decrease in usnic acid content presumably because they were not in the field during a period which provided proper growth conditions. The results suggested that usnic acid has no protective role against radiation damage in the lichen.