A xanthanolide diol and a dimeric xanthanolide from Xanthium species

Extracts of the aerial parts of Xanthium strumarium and fruit of X. pungens afforded a new xanthanolide diol derivative, 11 alpha,13-dihydroxyxanthati n and a new dimeric xanthanolide sesquiterpene lactone, pungiolide C, in ad dition to some known compounds. The structures of the new compounds were de termined by spectroscopic methods particularly high resolution H-1-, C-13-N MR and 2D H-1-H-1 and H-1-C-13 COSY NMR analysis.