Submitted to: Industrial Crops and Products
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/18/2010
Publication Date: 10/13/2010
Citation: Eller, F.J., Clausen, A., Green, F., Taylor, S.L. 2010. Critical fluid extraction of Juniperus virginiana L. and bioactivity of extracts against subterranean termites and wood-rot fungi. Industrial Crops and Products. 32:481-485. Interpretive Summary: This research determined that extracts of Eastern red cedar (Juniperus virginiana L.) (Cupresseaceae) wood and needles could be impregnated into wood, thus increasing its resistance to both termites and wood-rot fungi. Eastern red cedar is an abundant renewable resource and represents a vast potential source of valuable natural products that may serve as natural biocides. Both the wood and needles from Eastern red cedar were extracted using liquid carbon dioxide or ethanol. Laboratory termite testing indicated that the ethanol extract of needles was lethal to the termites and resulted in no damage to the test wood blocks. The cedarwood oil (CWO) treated wood blocks also exhibited resistance to termite damage. The CWO extracts were significantly more effective against the wood-rot fungus. For wood-rot fungus, the carbon dioxide-derived CWO was equivalent to the uninoculated control. These results demonstrate that cedars could be used as a renewable source of natural wood preservatives while providing a source of income for farmers and ranchers, as well as meet consumer demand for safe products.
Technical Abstract: Eastern red cedar (Juniperus virginiana L.) (Cupresseaceae) is an abundant renewable resource and represents a vast potential source of valuable natural products that may serve as natural biocides. Both the wood and needles from J. virginiana were extracted using liquid carbon dioxide (L-CO2) as well as ethanol (EtOH) and the yields determined. Wood blocks were vacuum impregnated with the extracts and, subsequently, tested for resistance against eastern subterranean termites (Reticulitermes flavipes) and two species of brown-rot fungi (Gloeophyllum trabeum and Postia placenta). Cedarwood oil (CWO) yields were 2.9% and 2.2% using L-CO2 (CWO-CO2) and EtOH (CWO-EtOH), respectively. The yield of juniper leaf oil using EtOH was 1.6%. Laboratory termite testing indicated that the ethanol extract of needles was lethal to the termites and resulted in no damage to the test blocks. The CWO-CO2 and the CWO-EtOH treatments were statistically equivalent and both exhibited significant resistance to termite damage compared to untreated controls. The CWO extracts were significantly more effective against G. trabeum than P. placenta. For G. trabeum, the CO2-derived CWO was statistically equivalent to the uninoculated control. On the other hand, for P. placenta, only the EtOH-derived CWO conferred any significant inhibition. The ethanol extract of the needles did not inhibit either test fungus.