242p2p522p1 62416 107 122 121 2 2 121 1251 6A compound of formula (I) wherein X is O C O or S; Y is N or CH; R and R are each independently H (CH)COOH (CH)CON(R) or (CH)COOC alkyI; or R and R together form a 6 membered phenyl ring fused to the five membered ring; each R is independently selected from H halo (e.g. fluoro or chloro) Caryl Carylalkyl Calkenyl; OCalkyl OC aikenyl or a C alkyl group; each R is H or C alkyl; each p is 0 to 3; n is 1 to 4; or a salt ester solvate N oxide or prodrug thereof e.g. a salt thereof.