Tannins of Cornaceous Plants. II. Cornusiins D, E and F, New Dimeric and Trimeric Hydrolyzable Tannins from Cornus officinalis

Cornusiin D (3), cornusiin E (4) and cornusiin F (5), new dimeric and trimeric hydrolyzable tannins, were isolated from the fruits of Cornus officinalis (Cornaceae), and their structures were established based on the chemical and spectroscopic data. Unusual chemical shifts of valoneoyl protons and anomeric protons of glucose cores in the proton nuclear magnetic resonance spectra of 3 and 4 were correlated with the stereostructures around the valoneoyl groups. Camptothin A (6) and camptothin B (7), dimeric hydrolyzable tannins previously isolated from Camptotheca acuminata, were also isolated from the fruits of Cornus officinalis.