Genifuranal and other derivatives: smoking desert plants

In pre-European Australia, hydrodistillation technology to produce essential oils was not available. Aboriginal people nonetheless employed volatiles in medicinal applications using smoke/steam fumigation modalities. Among species utilized in this manner and examined in this study are 'Eremophila longifolia', 'E. sturtii', 'E. freelingii' ('Scrophulariaceae') and 'Prostanthera striatiflora' ('Lamiaceae'). Simulation of smoke fumigation modalities in the laboratory produced condensates that were examined for antimicrobial activity. Furthermore, the previously described derivative 'genifuranal', produced in abundance in such condensates from 'E. longifolia', was reduced to the corresponding alcohol and the antimicrobial activity determined. All condensates demonstrated significant inhibitory activity against bacterial and fungal organisms, but activity of 'genifuranal' was substantially reduced upon conversion from an aldehyde to an alcohol. Preliminary GCMS analyses of smoke condensates produced in the laboratory suggest that essential oils and novel derivative produced during heating are present during fumigation rituals. In the current study, genifuranal was observed in trace amount in the condensates produced by simulated smoking of 'E. freelingii', and new and as-yet unidentified, smoke derivatives were also observed.