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Abstract

Lutein a hydroxy carotenoid belonging to xanthophyll group having a hydroxyl group attached to either end of the molecule, making it react more strongly with singlet oxygen than other carotenoids. In the present study, Lutein was modified by appending pyridine moiety for increased antioxidant activity and its ability to inhibit H 2 O 2 induced TGF-β1 expression in peripheral blood mononuclear cells was investigated. Lutein was treated with Isonicotinic acid (Pyridine-4-carboxylic acid) in the presence of DCC and DMF as solvent medium to obtain pyridine appended Lutein (2.28mg/ml). The pyridine appended Lutein was purified using silica gel-G (60-120mesh) column, further by HPLC and fractions were eluted at the rate of 1ml/min using water, acetonitrile, methanol and dichloromethane as mobile phase in the ratio 0.5:9.5:67.5:22.5. A major peak was obtained at 454nm with retention time of 1.60min. In dose dependent study, Pyridine appended Lutein at 0.42µmoles showed a maximum of 91.6% of DPPH radical scavenging activity in comparison to unmodified Lutein (80.76%). Unmodified Lutein showed maximum activity (86.18% at 1.25µmoles) with 2.97 folds higher than Pyridine appended Lutein. TGF-β1 expression in H 2 O 2 (3mM) treated peripheral blood mononuclear cells was inhibited by 83.14% (152.1pg/ ml) and 76.21% (214.62pg/ml) at 0.92µmoles of Pyridine appended Lutein and unmodified Lutein respectively compared to H 2 O 2 treated cells (902.15pg/ml) without test samples. In conclusion, Pyridine appended Lutein showed higher DPPH radical scavenging activity and inhibited H 2 O 2 induced TGF-β1 expression in peripheral blood mononuclear cells at low concentrations than unmodified Lutein.Keywords: DPPH radical, isonicotinic acid, n,n'-dicyclohexylcarbodiimide, n,ndimethyl formamide, lutein, TGF-β1