Optimization of Soxhlet Extraction of Herba Leonuri Using Factorial Design of Experiment

Soxhlet extraction technique is employed for the extraction and separation of chemical constituents in the medicinal plant, Herba Leonuri. The main goal of this analytical study was focused on extracted compounds and extraction conditions themselves. Soxhlet extractions were performed at three extraction time (6h, 9h and 12h) and with two solvents (n-hexane and methanol). A general full factorial design with two factors (extraction time and types of extractor solvents) was implemented. The Soxhlet extraction method presented a good yield of components in extract. The study shows that methanol extracted almost double yield than n-hexane. The highest yield obtained with methanol was 14.18%; while the highest yield obtained by n-hexane was 7.25%.The results also indicated that, for methanol extraction, the mass yield percent extracted increased with increasing length of extraction period (up to 14.18%); for n-hexane extraction, the mass yield percent extracted was not consistent with increasing length of extraction period. The extracted oil extracted was analyzed by GC-MS. The compounds identified were vitamin E, palmitic acid and syringol. General characteristics of the Herba leonuri oils obtained by different conditions were further compared, showing that the composition of the Herba leonuri oil extracted by different conditions is mostly similar, whereas relative concentration of the identified compounds is apparently different. This study can be considered as the first information on the chemical compound of Herba leonuri.