Identification, quantitative determination and isolation of pomolic acid from lavender (Lavandula angustifolia Mill.) wastes

Lavender essential oil production wastes have been investigated as a highly available source of pentacyclic triterpenic acids. Ultrasound assisted extraction was addressed as a simple and scalable procedure for efficient production of enriched extracts from dry plant material with good yields. Flowers and stalks have been processed separately. Analytical studies have been performed basing on both HPLC and qNMR methods. The qNMR analysis proved to be a much more convenient alternative to HPLC and its application resulted in identification, isolation and quantitative determination of substantial amounts of pomolic acid in the obtained extracts, along with widely explored ursolic and oleanolic acids. The ultrasound assisted extraction of lavender flowers with 96% ethanol resulted in a 3.3% yield of triterpenic acids, with a substantial share of pomolic acid that constitutes 1% of the plant material dry weight. Selective extraction of flowers with ethylacetate resulted in an enriched product containing 67.8% of triterpenic acids, including 16.2% of pomolic acid. Quantification of pomolic acid is reported for the first time in this vegetal source. These results demonstrate the relevant potential of lavender wastes as a sustainable raw material for the production of pomolic acid - a highly valued compound of increased nutraceutical and pharmaceutical interest.