Abstract: 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) in-vitro assay was employed to determine the antioxidant potency of test compounds I to VII [Arg-Thr-Starch (RTStr); Ser-Arg-Lac (SRLac); Asn-Arg-Mannose (NRMs); Arg-Asn-Lac (RNLac); Arg-Thr-Lac (RTLac); His-Asn-Mannose (HNMs); Asn-His-Lac (NHLac)] using ascorbic acid as the standard drug. The percentage scavenging activity of the test drugs were determined at different concentrations and the IC₅₀ value of the test compounds were subsequently compared with that of ascorbic acid. Among the compounds tested, compound II (SRLac) showed highest antioxidant activity with an IC₅₀value of 14.2 mg/ml whereas compounds I (RTS), VII (NHLac) and IV (RNLac) revealed the IC₅₀ value of 14.3 mg/ml, 14.5 mg/ml and 15.7 mg/ml, respectively when compared with ascorbic acid (IC₅₀ = 15.8 mg/ml). All the synthesized glycopeptides were further characterized by TLC, Melting point, IR, NMR and Mass spectral datas. Based on the above results, Ser-Arg-Lac could be considered as a lead compound for the development of new antioxidant drug for prevention of human diseases.

Keywords: 1.1-Diphenyl-2-picryl-hydrazyl, Antioxidant, Glycopeptides, Ascorbic acid, Potency.