The new iridoid glycosides, 4-deoxykanoko side A and 4'-deoxykanokoside C, were isolated from the methanolic root extract of Centranthus long florus ssp. longiflorus. They were accompanied by the three known iridoid glycosides, kanokoside A, kanokoside C and valerosidatum, and two known phenylpropanoid glycosides, coniferin and isoconiferinoside. The structures were elucidated mainly by spectroscopic methods. The presence of 4-deoxy glucose as a part of plant glycosides is rather unusual. Cytotoxic effects of the isolated compounds were also investigated. (C) 2002 Elsevier Science Ltd. All rights reserved.