Occurrence of the antimicrobials dehydroabietic acid and abietic acid in carton nest of Coptotermes formosanus

Antimicrobial agents present in extracts of carton nest of the Formosan subterranean termite (Coptotermes formosanus) were discovered and identified by a combination of HPLC-MS, GC-MS, TLC, and bioassays. Crude extracts of carton nest material were biologically assayed and demonstrated to inhibit the growth of certain Gram-positive bacteria. Extracts were fractionated using silica gel column chromatography followed by bioautography using thin layer plates. Further fractionation and characterization were completed using HPLC or GC and mass spectroscopy. Authentic compounds were demonstrated to have antimicrobial activity and were also used as standards to determine the authenticity of the extracted compounds. The active components were identified as dehydroabietic acid and abietic acid. These chemicals are natural components of many soft-woods, such as pine and spruce, on which the termites had fed. Equal amounts of these two antimicrobials could be obtained from similar weights of wood. It is speculated that these antimicrobial compounds may provide some protection of the nest from bacterial contamination in the environment.