Phytochemical and chemotaxonomic studies on the rare cliff plant Platycrater arguta (Hydrangeaceae)

Platycrater arguta (family Hydrangeaceae), a monotypic species of the genus, is a rare and endangered cliff plant endemic to East Asia. A preliminary phytochemical investigation on a mass-limited sample of the aerial parts of this plant led to the isolation and characterization of nine compounds including five iridoids (1-5), two flavonoids (6, 7), one coumarin (8), and one lignan (9). The isolation and purification were carried out by various modern chromatographic techniques. Their structures were identified by comparing the observed and reported spectroscopic data and physicochemical properties. The chemotaxonomic significance of the isolated compounds was briefly discussed. Once the right systematic position of P. arguta is solid, the conservation and restoration of this rare cliff plant would be stimulated.