Novel Bibenzyl Derivatives from the Tubers of Bletilla striata

Introduction. – Bletilla striata (Thunb.) Reichb. f. (Orchidaceae) is mainly distributed in East Asia, and its tubers are used as a Chinese traditional medicine for the treatment of tuberculosis and haemorrhage of the stomach or lung [1]. Previous phytochemical studies on Bletilla species have led to the isolation of phenanthrene derivatives [2 – 11], bibenzyls [2] [4], flavonoids and phenolic compounds [5], and cyanidin glycosides [12]. As part of our ongoing chemical study on Bletilla striata, three novel bibenzyl derivatives, blestritins A –C (1 – 3), were isolated from the tubers of B. striata, together with 18 known constituents. We report herein the isolation and structural elucidation of these compounds.