Isolation, analytical quantification and seasonal variation of labdanolic acid from the Portuguese-grown Cistus ladaniferus

An original analytical protocol for the quantification of labdanolic acid (LA) present in the crude oil of Cistus ladaniferus plant was successfully developed during this investigation. The application of the new method, based on the HPLC technique with UV detection at 240 nm, involves prior derivatization of LA with benzyl bromide to the corresponding benzyl ester. By using the implemented analytical method, a seasonal and regional distribution of LA during a broad period of time was completed. Extracts of C. ladaniferus from three different locations in Portugal, harvested during the same season and also during different seasons within the same harvest location were analysed. From this study, it was shown that regional influences are more important for the production of LA by the plant than seasonal variations. Lastly, a series of molecular imprinted polymers (MIPs) and their corresponding non-imprinted polymers (NIPs) were synthesised using supercritical carbon dioxide and applied on the LA purification from the acidic crude oil of C. ladaniferus. From all the tested polymers, the 2-(dimethylamino)ethyl methacrylate non-imprinted polymer (DMAEMA-NIP) revealed the most preeminent result on the LA purification. After passing twice the acidic crude containing 15% of LA in the DMAEMA-NIP, 34% of LA was recovered due to the selective retention of non-desired compounds by the polymer.