A compound of formula (1), particularly where X = O, Y = NR1R2, wherein R1 = R2 = H and Z1 = Z2 = OH, can protect and/or aid the recovery of functionally impaired tissue whose viability is threatened by hypoxia. Typically, the compounds can be used to aid recovery of function of ischaemic tissue during and after open heart surgery. In said formula, X = O or NH, Y = OH, OR?1, NR1R2¿, wherein R?1 and R2¿ are independently H, alkyl, alkenyl (except where applied to OR1), cycloalkyl, aryl, or aralkyl.