Compounds of formula (I) and pharmaceutically acceptable salts, solvates and hydrolysable esters thereof wherein X is O or S; X is O or S; X is S or O; R and R are independently H, methyl, or halogen; R and R are independently H or C1-3 alkyl or R and R may, together with the carbon atom to which they are bonded, form a 3-5 membered cycloalkyl ring; R and R are independently H, C1-3 alkyl, or allyl; each R is independently halogen, C1-6 straight or branched alkyl, or CF3; and y is 0, 1, 2, 3, 4 or 5 act as hPPAR alpha agonists.