Tannins occurring in the toxic Brazilian plant Thiloa glaucocarpa.

Four tannins were isolated from dried leaves of Thiloa glaucocarpa, which is one of the plants causing poisoning of cattle in Brazil. These four tannins were determined from spectrometric and chemical evidence to be the ellagic C-glucosyl tannins vescalagin, castalagin, stachyurin and casuarinin. The main components, vescalagin and castalagin, are also known as constituents of oak (Quercus spp.), the toxicity of which for cattle is supposed to be due to tannins. Suggestions concerning the resemblance of the symptoms of poisoning by Thiloa glaucocarpa and by oak are supported by the presence of the constituents in both plants.