Quantification of sideroxylonals in Eucalyptus foliage by high-performance liquid chromatography

This paper describes the extraction and quantification of sideroxylonals, a group of formylated phloroglucinol compounds found in the foliage of some eucalypt species. Samples of dry, ground foliage were Soxhlet-extracted with light petroleum spirit:acetone (4:1) and the resultant extract analysed (in the presence of internal standard) by reversed-phase HPLC without further purification. The yield of sideroxylonals was exponential with time and showed an inflection at ca. 4 h of extraction. It is recommended that samples be extracted for 6 h, giving a 92% recovery of the sideroxylonals. The title compounds deteriorate under various conditions, e.g. 10% are lost when foliage is oven-dried at 40 degrees C compared to freeze-drying. Storing samples in mobile phase led to a slow deterioration of sideroxylonals with a 7% loss after 4 days, while 22% of these compounds were lost from dry, ground eucalypt leaf stored at room temperature for 20 months.