Substituted thieno[2,3-d]pyrimidin-4-yl-amines for evaluation of Anti-oxidant Activity SHACHINDRA L. NARGUND 1 , V. MURUGAN 2 , H J HRISHEKESHAVAN 1 and L.V. G.NARGUND 1 1 Nargund college of Pharmacy, BSK 3 rd stage, Bangalore-560085 (India) 2 Dayananda Sagar College of Pharmacy, Shivage Hill, Kumarswamy Layout, Bangalore-560081 (India) (Acceptance Date 28th January, 2016) Abstract A series of novel 4-substituted-thieno[2,3-d]-pyrimidin-4-yl- amines have been synthesized and tested for anti-oxidant activity. The synthesized 11 compounds all have shown anti-oxidant activity that differs in potency. The compounds were subjected to three methods to analyze their anti-oxidant potential a) DPPH (2,2-diphenyl-1- picrylhydrazyl) scavenging method, a) Hydrogen peroxide scavenging method and c) Nitric oxide radical scavenging method. Among the test compounds SLNA2, SLNA3 SLNA4, SLNA7 and SLNA9 have good potential as anti-oxidants. Ultra Scientist Vol. 28(1)B, 1-10 (2016). ISSN 2231-3478(Print) ISSN 2319-8052 (Online) 1. Introduction A constant threat to body comes from chemicals called free radicals. They can damage cells and genetic material. The human body generates free radicals always as inevitable by products of turning food into energy. Some will be in the food we eat and the air we breathe. Some will be generated by sunlight’s action on the skin. Free radical damage can change the nucleotide arrangement in a strand of DNA. It will make circulating low-density lipoprotein (LDL) molecule more likely to get trapped in an artery wall or it can alter a cell’s membrane, changing the transport of different materials. 1 DPPH scavenging assay : DPPH is abbreviation used for 2,2- diphenyl-1-picrylhydrazyl. It is a radical and it traps other free radicals. DPPH has a deep violet colour in solution. It gives a strong absorption at about 520 nm. Antioxidants react with methanolic solution of α, α diphenyl-β- picryl hydrazyl (DPPH) they convert it to α, α diphenyl-β-picryl hydrazine. Then the solution becomes pale yellow or colorless. Change in the absorption at 520 nm indicates the extent of scavenging. 2