Bioactive A-Type Proanthocyanidins from Cinnamomum cassia
journal contributionposted on 23.09.2011, 00:00 by K. Brian Killday, Matthew H. Davey, Jan A. Glinski, Penggao Duan, Ravikanth Veluri, Gloria Proni, F. Joseph Daugherty, Michael S. Tempesta
Two trimeric proanthocyanidins, cinnamtannin B-1 (1) and cinnamtannin D-1 (2), have been isolated from the bark of Cinnamomum cassia along with the known tetramer parameritannin A-1 (3) and a previously unreported tetramer, named cassiatannin A (4). The structures of 1–4 were elucidated on the basis of 1D and 2D NMR, MS, and CD analyses and compared to the reported data. Proanthocyanidins (1–4) possess significant in vitro inhibitory activity against cyclooxygenase-2 (COX-2) at micromolar concentrations.