The present invention relates to compounds of formula (I) wherein: Ar1 or Ar2 is an optionally substituted indole, and the other group is an optionally substituted aromatic or heteroaromatic group, suitably an optionally substituted bicyclic heteroaromatic group, preferably an optionally substituted indole, X is O or S, R is H, OH, NH2, C1-6alkyl, hydroxyC1-6alkyl, aminoC1-6alkyl, and R1 is H, C1-6alkyl, fluoro substituted C1-6alkyl, phenyl, benzyl, carboC1-6alkoxy, carbobensyloxy, carbohydroxy, carbamoyl, or methyl(N-C1-6alkylcarbamoyl) and salts and solvates thereof and solvates of such salts, and the use of such compounds in medical therapies.