What caused the changes in the usage of Atractylodis Macrocephalae Rhizoma from ancient to current times?

Ancient Chinese medicine treatises on Atractylodis Macrocephalae Rhizoma (AMR), the rhizome of Atractylodes macrocephala Koidz, indicated that it possessed an expectorant effect. However, in modern times, it is commonly used as a tocolytic agent. In this study, the components of AMR that are responsible for its expectorant and tocolytic effects were evaluated in order to clarify the differences in its application between ancient and modern times. A decoction of AMR was separated into five fractions, namely, volatile oil (VO), petroleum ether (PE), alcohol eluate from macroporous resin (AE), water eluate from macroporous resin (WE), and polysaccharides (PS), using various separation methods. The expectorant experiment indicated that the VO fraction, which mainly contains atractylone, produced an obvious expectorant effect. The experiment that assessed the irritability of uterine smooth muscle (USM) showed that the PE, which is mainly composed of atractylenolides, and the PS, which is mainly composed of inulin-type polysaccharides, were the active fractions for tocolysis, but the VO fraction had the opposite action. These data suggested that volatile oils are the key components responsible for the usage change of AMR in both ancient and current usage.