The gaseous molecule nitric oxide (NO) is a highly reactive molecule that is synthesized by a variety of biological tissues and it modulates a large variety of physiological functions including vascular tone, intestinal motility, platelet aggregation, proliferation, apoptosis, and neurotransmission. Its physiological effects are attributed to a very small, freely diffusible, and potentially highly reactive radical. NO regulation, signal transduction, and cytotoxicity is strictly dependent upon its chemical reactivity with oxygen and metals rather than specific structural instructions with physiological targets. The S-Nitrosothiols are the biological metabolites of nitric oxide. They represent a more stable metabolite of nitric oxide that can either be stored, or transported in the form of Snitrosothiols (e.g. S-Nitrosocysteine in the body). Various hybrid copounds of S-Nitrosothiols such as SNitrosomercaptobenzothiazole and S-Nitrosomercaptobenzimidazole have been synthesized in the laboratory. The structure of the synthesised compounds was confirmed through the interpretation of spectral data. Prepared compunds were then evaluated for the smooth muscle relaxant activity on rat tracheal chain. The paired t-test value for SNAP (S-Nitroso-Acetylpenicillamine) as standard and SNMBT was found to be 0.878 from t-distribution table, p = 0.3 for degree of freedom, F = 5 the value of t is between 0.559. The calculated value of t is greater than this which indicated that significant level is more than 98%.
