Chem. Pharm. Bull., 47(7),1049-1050, July 1999

Communications to the Editor

Apocynins A-D: New Phenylpropanoid-substituted Flavan-3-ols Isolated from Leaves of Apocynum venetum(Luobuma-Ye)

Wenzhe FAN, Yasuhiro TEZUKA, Quanbo XIONG, Masao HATTORI, Tsuneo NAMBA and Shigetoshi KADOTA^*

Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.

Four new phenylpropanoid-substituted flavan-3-ols called apocynins A-D (1-4) have been isolated from the leaves of Apocynum venetum (Apocynaceae), together with two known phenylpropanoid-substituted flavan-3-ols, catechin-[8,7-e]-4 a-(3,4-dihydroxyphenyl)-dihydro-2(3H)-pyranone (5) and cinchonain Ia (6), and four known flavan-3-ols, (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, and (+)-gallocatechin. Their structures were elucidated on the basis of spectral analysis, including 2D NMR and CD spectra. They showed hepatoprotective activity against D-galactosamine (D-GalN)/tumor necrosis factor-a(TNF-a)-induced cell death in primary cultured mouse hepatocytes.

Key words apocynin; Apocynum venetum; phenylpropanoid-substituted flavan-3-ol; Luobuma-Ye; hepatoprotective activity; Apocynaceae