Sixteen crude extracts from six Panamanian plants of the family Bignoniaceae were submitted to rapid TLC tests against DPPH and acetylcholinesterase. Pithecoctenium crucigerum (L.) A.H. Gentry, which showed interesting activity against DPPH, has been studied. The chemical investigation of the methanol extract from the stems afforded the iridoid glycoside theviridoside and three derivatives (6 '-O-cyclopropanoyltheviridoside, 10-O-hydroxybenzoyltheviridoside and 10-O-vanilloyltheviridoside), along with five known phenyl-ethanoid glycosides (verbascoside, isoverbascoside, forsythoside B, jionoside D and leucosceptoside B. These last compounds were all active against DPPH. The structures were determined by means of spectrometric and chemical methods, including 1 and 2D NMR experiments and MS analysis. (c) 2007 Elsevier Ltd. All rights reserved.