Studies on the constituents of Catalpa species. IX. Iridoids from the fallen leaves of Catalpa ovata G. Don.

Two new iridoids, 6-O-trans-p-coumaroyl-7-deoxyrehmaglutin A (1) and 6-O-cis-p-coumaroyl-7-deoxyrehmaglutin A (2), were isolated from the fallen leaves of Catalpa ovata G. DON. together with six artifact iridoids (3-8). Their structures were established by spectral analysis. In addition, the scavenging effects of the principal compounds isolated from this plant on 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity were examined.