In the present study, fractions and residues from three Cornus mas fruit categories (well matured fruits; half-ripe fruits; sterilized pulp) were analyzed by LC-DAD-MS and were evaluated for their in vitro antioxidant potential, their ability to inhibit the aldose/aldehyde reductase enzyme and their anti-inflammatory activities. Qualitative analysis showed the presence of phenolics, iridoids and flavonoids. Results revealed that the compound content of the pulp differs from that of the fruits and this may have occurred during the processing and the storage of the pulp. The diethyl ether and ethyl acetate fractions of the fruits were strong inhibitors of aldose reductase enzyme, while the ethyl acetate fraction of the pulp displayed the highest antioxidant activity. In conclusion, due to the rich phenolic, iridoid and flavonoid content of Cornus mas fruits, their strong antioxidant activity and their inhibitory potential to aldose/aldehyde reductase enzyme, the fruit consumption could be considered a promising way for lowering the incidence of long-term complications of diabetes mellitus