Extraction of Michellamine A (MAA) and B (MAB) was achieved with 25% MeOH-modified CO-2. Selective clean up of the sample with 10% MeOH-modified CO-2 prior to extraction of the target analytes using higher percentages of modifier was demonstrated. Increasing the dynamic extraction time from 30 min to 60 min, using 25% MeOH-modified CO-2, increased extraction efficiency of MAB by 30% compared to conventional liquid-solid extraction (LSE). Also, addition of Myrtanol (0.1%) as an additive to the methanol increased extraction efficiency of MAB by more than 35% compared to LSE. Higher percentages of Myrtanol additive in the primary modifier did not affect the extraction efficiency of MAA or MAB from the leaves.