The invention provides compounds of formula (I) or salts thereof:wherein:A, B, C, D, W, X, Y and Z are as defined in the specification, and at least one of A, B, C, D, W, X, Y and Z is OR1； each R1 being independently H or C(═；O)R2, and at least one R1 group being C(═；O)R2； where each R2 is selected from:CHR3NHR4, where R4 is H and R3 is a group selected from CH3, CH2CH(CH3)2, CH(CH3)CH2CH3, CH2Ph, CH2-3-(1H-indole), CH2CH2SCH3, CH2OH, CHOHCH3, CH2SH, CH2SeH and CH2PhpOH,wherein said R3 group can optionally be substituted by one or more groups selected from halogen, cyano, nitro, ORA or C1-C4 alkyl；or R3 and R4 together with the C and N atoms to which they are attached form a 5-membered heteroalkyl ring, wherein said heteroalkyl ring can optionally be substituted by one or more groups selected from halogen, cyano, nitro, ORA or C1-C3 alkyl,wherein RA is C1-C4 alkyl optionally substituted with one or more halogen, cyano or nitro groups.The compounds are effective pro-drugs for urolithins and they enable the ready delivery of urolithins to the site in the digestive tract where they can be absorbed into the body.
