PYROLIGNEOUS ACIDS FROM CARBONISATION OF WOOD AND BAMBOO: THEIR COMPONENTS AND ANTIFUNGAL ACTIVITY

Abstract

Pyroligneous acids, i.e. by-products from the manufacture of charcoal by carbonisation of Eucalyptus camaldulensis, Leucaena leucocephala, Azadirachta indica, Hevea brasiliensis (rubberwood) and Dendrocalamus asper (bamboo) along with two commercial products were studied. Characterisations of their compositions were performed qualitatively by gas chromatography–mass spectroscopy and quantitatively by gas chromatography with flame ionisation detector. Twenty-three components were identified, of which acetic acid was the major component, followed by 2-methoxy-4-propylphenol and 2-methylphenol. Antifungal activity and efficacy of pyroligneous acids as wood preservatives were conducted using Petri dish bioassay and soil block test respectively against two white rot fungi (Trametes versicolor and Rigidoporopsis amylospora), a brown rot fungus (Gloeophyllum trabeum) and a sapstain fungus (Botryodiplodia theobromae). All pyroligneous acids exhibited antifungal activity (growth inhibition, minimum inhibitory concentration and minimum fungicidal concentration) especially those from bamboo and rubberwood, which had higher total phenolic concentrations. Soil block experiments for 12 weeks showed that pyroligneous acids from bamboo and rubberwood were more effective as wood preservatives.