Backhousia citriodora F. Muell. (Myrtaceae), a superior source of citral

Leaf from the citral chemical variety of lemon myrtle, Backbousia citriodora, was examined for volatile: constituents by (GC and GC/MS analysis of both steam volatile oils and solvent extracts. Identified constituents present at more than 0.1 per cent on average in the oil we-re found to be myrcene (0.1-0.7%,), 6-methyl-5-hepten-2-one (0.1-2.5%), linalool(0.3-1.0%)), citronellal(0.1-0.9% ), iso-neral (0.6-2.7), iso-geranial.(1.0-4.2%), neral (32.0-40.9%;) and geranial (/46.1-60.7%). I'hysPhsyical constants were found to fall within the ranges of 0.888-0.910 for relative density, 1.4853-1.4909 for refractive index, -1.5 degrees-+0.4 degrees for optical rotation and 0.8-2.3 volumes for solubility in 70% ethanol. Comparison of chemical and physical data with those of other citral-rich commercial oils showed that B. citriodora was richer in citral than both lemongrass (Cymbopogon flexuosus and C.citratus) and Litsea cubeba. Microextraction of fresh leaf with absolute ethanol gave volatile extracts with higher proportions of citral and lower proportions of cogeners iso-neral and iso-geranial than steam distillation suggesting partial double bond migration during the distillation process. No significant variation in citral content was observed between flush growth and mature leaf or between fresh and dried leaf.