A novel diynoic acid, evectic acid (21-furan-heneicosa-5,7-diynoic acid), has been isolated from the roots of Polyalthia evecta. Its structure was elucidated by spectroscopic methods. The H-1 and C-13 NMR spectra were assigned by combined application of COSY, HMQC, DEFT, HMBC and NOESY experiments. (C) 1997 Elsevier Science Ltd.