The extraction yields obtained from different extraction methods were analyzed with two-way ANOVA and Bonferroni post hoc analysis. Among the 11 experimental groups, Rhizoma Imperatae produced the highest yields (P = 0.001) regardless of extraction methods, followed by Cortex Magnoliae Officinalis (Figure 1 ). These two dry herbs were processed through comminution producing fine powder prior to extraction. The reduced particle size decreases the internal mass resistance for compounds to traverse through the plant matrix and increases the specific surface area for extraction. The extraction yields obtained from boiling were higher than those from other extraction methods.