Bletilla

Abstract: Three novel bibenzyl derivatives, blestritins A - C (1 - 3), along with 18 known constituents, were isolated from the tubers of Bletilla striata (Orchidaceae), a traditional Chinese medicine used for the treatment of tuberculosis and haemorrhage of the stomach and lungs. Their structures were identified on the basis of spectroscopic analyses. 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.

Abstract: An investigation of a questionable orchid led to the discovery of a new genus and species Thuniopsis cleistogama, endemic to Yunnan province, China. It is characterized by having a subglobose corm, a spike-like (racemose) inflorescence, half opened and spurless flowers, a collar-shaped stigma and subglobose capsules. Based on DNA sequence data from three gene regions (nuclear ribosomal ITS, chloroplast matK and trnL), we investigated its phylogenetic position within the tribe Arethuseae. Phylogenies using maximum likelihood and Bayesian inference support the recognition of Thuniopsis as a distinct genus, and suggest its close relationship to the genera Bletilla, Dilochia, and Thunia. The new genus is circumscribed and a description and illustrations of the new species are provided. The phylogenetic relationships among the genera in Arethuseae are accessed. Moreover, our phylogeny also shed light on the phylogenetic positions of several genera which, to date, remain uncertain.

Abstract: Bletilla-glucomannan, the mucous polysaccharide isolated from Bletilla striata REICHENBACH fil., was found to contain 4.2% of O-acetyl group. The O-acetyl groups were located in position 3 of most of the glucose units. Methylation study provided the evidences that the polysaccharide is mainly composed of β-1→4 linked aldohexopyranose residues having a branched structure with 1→2 branch point at a part of mannose units, and mannose units occupy non-reducing terminal positions in the molecule.