Reactive dicarbonyl species (RCS) such as glyoxal (GO) and methylglyoxal (MGO) are common intermediates in protein damage, leading to the formation of advanced glycation end products (AGEs) through nonenzymatic glycation.Catechin, a kind of nature plant extract from tea, has been evaluated for its ability in trapping GO and MGO.However, the trapping ability of catechin in nucleoprotein nonenzymatic glycation is not clear.In present study, histone H1 and MGO was used to establish a vitro protein glycation model.2,4-dinitro phenylhydrazine (DNPH) method is used to determine the content of Schiff base and western blot is used to detect the formation of Nε-carboxymethyllysine (CML).Our data show that MGO can result protein damamge is formed with dose dependence.After 24h incubation, the content of MGO induced Schiff base can be inhibited by catechin with the catechin : MGO molecular ratio was 1:6.Furthermore, catechin can inhibit methylglyoxal induced Schiff base when the catechin : MGO molecular ratio was 1:6 and it has a highest inhibition rate (68%) even than aminoguanidine group.The formation of CML was reduced intensively, when the ratio of catchin and MGO was 1:1, which was closed to the inhibition effect of aminoguanidine (AG).In conclusion, the results of the present study demonstrate that cathin can efficiently inhibit reactive dicarbonyl species induced Schiff Base formation in vitro conditions (100 mM phosphate buffer solution (PBS), pH 7.4, 37 ℃).The formation of AGEs under in vitro conditions can be inhibited by certain concentration (100μM) of catechin.The trapping ability of catechin may be more effctive at the early stage of Non enzymatic glycation.