Evaluation of the chemical quality of Sekkoku () in current Japanese commercial crude drugs: constituents of Flickingeria xantholeuca (Rchb. f.) A.D. Hawkes.

In our investigation, most Shihu (; Japanese name, Sekkoku) in current Japanese commercial crude drugs were from Flickingeria xantholeuca (Orchidaceae). As the index compounds, three new ent-pimarane-type diterpenes, flickinxthanthosides A-C (1-3), one known analogue (7), and three new ent-kaurane-type diterpenes, flickinxanthosides D (4) and E (5) and flickinxanthol A (6) were isolated from the stem of F. xantholeuca. The structures of the new compounds were elucidated on the basis of spectroscopic analyses and chemical methods. We attempted to detect these index compounds from the MeOH extracts of other Dendrobium or Flickingeria plants using TLC and LC/MS.