Structure elucidation and an investigation into the in vitro effects of hop acids on human cancer cells

An investigation into the keto-enol relationships in a number of hop acids has been undertaken. These provided samples to enable X-ray analyses of both natural 1 and unnatural humulone 5 to be carried out. Our results suggest that the configuration of humulone 1 may have been incorrectly assigned. An in vitro investigation into the biological activity of hop acids suggests that both humulone 1 and lupulone 2 exhibit significant activity against some human cancer cells. Our results provide evidence to show that they inhibit cell growth, induce caspase dependent apoptosis and inhibit adhesion of some cancer cells to bone tissue. (C) 2009 Published by Elsevier B.V. on behalf of Phytochemical Society of Europe.