[Peroxides as plant constituents. 8. Guaianolide-peroxides from yarrow,Achillea millefolium L., a soluble component causing yarrow dermatitis].

From the ether extract of the blossoms of yarrow, Achillea millefolium L., two guaianolides (1, 2) with a peroxide bridged cyclopentane ring and an alpha-methylene-gamma-butyrolactone structure have been isolated. For these compounds the names alpha-peroxyachifolid (1) and beta-peroxyisoachifolid (2) are proposed. 1 is responsible for the allergic contact dermatitis caused by yarrow.