MICROBIAL TOXICITY MECHANISM OF COPPER-8-QUINOLINOLATE

Sapstain, an abnormal discoloration in wood caused by microbial growth , can significantly lower the price of a lumber and thus fresh sawn so ftwood lumber of a susceptible species is often treated with a biocide such as pentachlorophenol (PCP) to prevent the development of sapstai n during shipping and prolonged storage. Very recently, chlorophenol-b ased antisapstain agents have been banned in Canada, because of enviro nmental toxicity. The purpose of this study was to elucidate the micro bial toxicity mechanism of the copper salts of 8-quinolinolate (Cu-8-H Q), one of the replacement chemicals for PCP in sapstain control. The results revealed that the biocidal activity of Cu-8-HQ originates from a stable metal (copper) chelate and that the molecular integrity of t he chelate is most critical in the expression of its toxicity potentia l. The chelating power of 8-hydroxyquinoline for trace metals was not found to be directly responsible for the biocidal activity of Cu-8-HQ as suggested in the literature. The anion groups were found to have no significant impact on the biocidal activity of Cu-8-HQ, which has bee n observed with other organometallic compounds. (C) 1994 by John Wiley & Sons, Inc.