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Synthesis and Anti-inflammatory Activity of Novel 2-(Substituted Alkyl or Aryl Pyridynyl) Benzimidazole Derivatives
* 1 , 2 , 2 , 3
1  Department of Pharmaceutical Chemistry, KGRD College of Pharmacy, Karjat, (MS) 410101
2  Medicinal Chemistry Division, Shital Laddha Research Soceity, Umarkhed, DistYeotmal (MS) 445206
3  Department of Pharmaceutical Chemistry, Ideal College of Pharmacy and Research, Adarsh Vidya Nagari, Via Kalyan Rly. Station, Malang Road, At-Bhal, Post: Dwarli, Dist: Thane (MS) 421301

Abstract: Benzimidazole derivatives belong to a crucial structural design that is seen in many pharmaceutically and biologically interesting molecules. Benzimidazoles have shown potential for application in a variety of pharmacological targets. They have been intensively used in medicinal chemistry as drugs such as antihistaminic, antimalarial action, antiprotozoal activity, antibacterial activity, antiulcerative, antihelmentic, antipsychotic etc. The preparation and investigation of nitrogen heterocycles is one of our main projects. We have already developed some procedures to gain access to diverse structures of benzimidazoles. It has been reported that 2-(Substituted pyridynyl) benzimidazole possess anti-inflammatory activity. At the same time alkyl or aryl substitution at second position of benzimidazole is not yet reported, which may possess same activity as that of benzimidazole substituted with pyridynyl. The series of new 2-(Substituted alkyl and aryl pyridynyl) benzimidazole derivatives have been prepared. In this case, corresponding eight orthophenylenediamine (opd) derivatives were prepared and these results prompted us to extend this methodology for similar synthesis of benzimidazole derivatives. Compounds 1 (5-Ethoxy, 1H-Benzimidazole), 7 (2-(5-Ethoxy-1H-benzoimidazol-2-yl)-Ethanol) and 8 (2-(5-Ethoxy-1H-benzoimidazol-2-yl)-Methanol) were exclusively isolated and characterized with other five derivatives. It was thought that preparing such derivatives as 2-substituted benzimidazoles would probably result in compounds of having high biological activity like anti-inflammatory with low toxicity toward many diseases and hence tested for their possible anti-inflammatory activity. Carrageenan induced rat paw edema is the most widely used, primary test to screen inflammation which measures the ability of the compounds to reduce local edema induced in the rat paw by carrageenan. Hence anti-inflammatory activity was evaluated by using carrageenan induced rat paw edema method. Most of the obtained compounds exhibit anti-inflammatory activity, especially compound Compounds 1 (5-Ethoxy, 1H-Benzimidazole), 7 (2-(5-Ethoxy-1H-benzoimidazol-2-yl)-Ethanol) and 8 (2-(5-Ethoxy-1H-benzoimidazol-2-yl)-Methanol) showed significant activity when compared with that of standard drug ibuprofen.
Keywords: anti-inflammatory activity, carrageenan induced rat paw edema, substituted benzimidazoles, 2-(substituted pyridynyl) benzimidazole