Aseries of barbatic and diffractaic acid analogues has been synthesized and evaluated as inhibitors of leukotriene B4 (LTB4) biosynthesis and as antiproliferative agents. The 4-O- demethyl barbatic and diffractaic acid derivatives were among the most active compounds in both assays. In particular, ethyl 4-O-demethylbarbatate was the most potent LTB4 biosynthesis inhibitor of this series, with an IC50 value in the submicromolar range. ...