Phenolic fractions from Trifolium pallidum and Trifolium scabrum aerial parts in human plasma protect against changes induced by hyperhomocysteinemia in vitro.

Elevated concentration of homocysteine (Hcy) in human plasma, defined as hyperhomocysteinemia has been correlated with some diseases, such as cardiovascular, neurodegenerative, and kidney disorders. Homocysteine occurs in human plasma in several forms, including the most reactive form of Hcy - its cyclic thioester - homocysteine thiolactone (HTL), which represents up to 0.29% of plasma total Hcy. It is suggested that Hcy and HTL may also act as oxidants, but various polyphenolic antioxidants are able to inhibit the oxidative damage induced by Hcy or HTL. The aim of our present study was to investigate in vitro oxidative changes in human plasma induced by the model of hyperhomocysteinemia in the presence of the phenolic fractions from selected clovers (Trifolium pallidum and Trifolium scabrum aerial parts). Hyperhomocysteinemia was stimulated by a reduced form of Hcy (final dose 100 μM) or HTL (final dose 1 μM). The aim of our study was also to explain the effect of the phenolic fractions on the coagulation activity of human plasma treated with Hcy and its thiolactone. Tested phenolic fractions significantly inhibited the oxidative stress (measured by the total antioxidant level - TAS) in plasma treated with Hcy or HTL. The phenolic fractions from T. pallidum and T. scabrum also caused a distinct reduction of plasma lipid peroxidation (measured by the level of thiobarbituric acid reactive substance) induced by the model of hyperhomocysteinemia. Moreover, tested fractions modulated the coagulation properties of plasma treated with homocysteine and its thiolactone. It seems that antioxidative activities of the phenolic fractions from T. pallidum and T. scabrum aerial parts may be responsible for their medicinal properties during hyperhomocysteinemia.