A series of 3, 5-disubstituted indole derivatives was designed, synthesized and evaluated as inhibitors of human nitric oxide synthase (NOS). Various guanidine isosteric groups were explored at the 5-position of the indole ring, while keeping the basic amine side chain such as N-methylpiperidine ring, fixed at the 3-position of the indole ring. Compounds having 2- thiophene amidine and 2-furanyl amidine groups (7, 8, 10 and 12) showed increased ...