Locomotor-Reducing Activity of Sesquiterpenes Related to Zingiber zerumbet Essential Oil and Hexahydrozerumbone Derivatives

Zerumbone derivatives 1–4 are 11-membered cyclic compounds synthesised from a sesquiterpene zerumbone obtained from the rhizomes of Zingiber zerumbet SMITH (Zingiberaceae). In this study, we investigated the locomotor-reducing effects of hexahydrozerumbone derivatives 1–3 and zerumbol 4, and those of β-caryophyllene 5 and caryophyllene oxide 6, which are present in Z. zerumbet essential oil. The absence of the double bond at C6 weakened the locomotor-reducing effects. β-Caryophyllene 5 and caryophyllene oxide 6 showed locomotor-reducing effects in mice at 4.5×10−3 mg/cage. Moreover, locomotor activity increased significantly at 0.45 mg/cage of caryophyllene oxide 6.