Chemical composition of Hibiscus tiliaceusL. flowers: A study of extraction methods

The objective of this work was to carry out a comparative study of conventional extraction methods (maceration and Soxhlet) versus sonication in the case of the flowers of Hibiscus tiliaceus, collected at the Santa Catarina swamps (in the south of Brazil), using three solvents with different degrees of polarity. All extracts were analyzed by GC/MSD. For all the extraction procedures used, the initial extraction was performed with hexane with the aim of completely removing non‐polar compounds (mainly hydrocarbons). This procedure will ensure that the compounds of real interest, i. e., those possessing pharmacological properties, can be better characterized. Variation of solvent type is found to have a much greater effect than variation of the extraction method. The total analysis time and the total amount of solvent are clearly reduced on use of the best method, i. e. sonication. The best sonication results were obtained with an extraction time of 160 minutes using methanol as extraction solvent. The solvent used determines the nature of the compounds extracted. Polar compounds are satisfactorily extracted by using highly polar solvents. Among the compounds identified, saturated hydrocarbons from 25 to 33 carbon atoms, esters, and carboxylic acids of high molecular weight, as well as some steroid structures are highlighted.