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Summary and ConclusionSummary and ConclusionPart-I of this thesis deals with “Synthesis, Pharmacological Evaluation and QSAR ofsome pyrimidylmethylsulfinylbenzimidazoles as potential reversible Proton PumpInhibitors (PPIs)”.A careful study of the literature on the currently used PPI’s especially of the PMSB typesindicates some important drawbacks associated with their usage. An investigation into themechanism of action of these PPI’s can throw some light on the probable reasons forthese drawbacks. These molecules rearrange in the strongly acidic environment of theparietal cells. Covalent binding of the rearranged inhibitor to the H + /K + -ATPase results ininactivation of proton pump. In the covalent binding, a disulfide linkage of the drug isformed with the active site of the cystine-rich H + /K + -ATPase (Proton Pump). One ofthese sites has been identified as cystine-813 (and probably cystine-822) of H + /K + -ATPase.Therefore, it was realized to develop better analogs of the existing PPI’s in which theformation of this disulfide intermediate can be avoided, so as to attain reversible protonpump inhibition & thus overcome the drawbacks of the currently available PPI’s.One of the options that has not been tried is the 3-aza analog of pyridine i.e. pyrimidine,(which is it’s logical bioisoster) in the PMSB nucleus. Thus, one can envisage that thissystem though can bind to the proton pump; the binding may not as strong as the PMSBpyridine system and may be even loose and reversible. Therefore, a series of pyrimidineanalogues of the existing drug PMSB skeleton was planned to be synthesized andevaluated for the proposed work.Thus, a series of 2-(1H-benzimidazol-2-ylsulfinyl)-3H-pyrimidin-4-ones and 2-(5-methoxy-1H-benzimidazol-2-ylsulfinyl)-3H-pyrimidin-4-ones was planned to besynthesized, characterized and evaluated for antiulcer activity, using a suitable animalmodel.In all 35 derivatives have been synthesized in this part which are characterized by spectraldata. These derivatives were evaluated preliminary for anti-secretary and antiulcer488