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The present study was aimed at synthesizing isatin-5-sulphonamide derivatives are prepared by chlorosulphonation of isatin to prepare isatin-5-sulphonic acid chloride and it is subjected to reaction with different amines or anilines to form respective sulphonamide derivatives. The new compounds were characterized based on spectral (FT-IR, NMR and Mass) analysis. All the test compounds showed CNS depression while studying the gross behavioral changes. All the test compounds exhibited reduction in locomotor activity. Compound IIIf (R = p-toluidino) showed more reduction in the locomotor activity among all the test compounds. Compounds IIId, IIIc, IIIb, IIIa were next in the order of reduction of locomotor activity. The compounds were evaluated for anticonvulsant activity against maximum electric shock induced and Pentylenetetrazol (PTZ) induced seizures in mice using phenytoin as a standard.

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CHAPTER-2: AIMS AND OBJECTIVES OF THE PRESENT WORK:
It is evident from literature that the presence of the indole nucleus found to have various pharmacological activities like antimicrobial, anti-convulsant, MAO inhibitory, anticancer and psychotropic activities. It is interesting to note from the literature that the important isatin moiety is yet to be explored both synthetically and biologically in conjunction with the molecular moieties of several other biologically prominent heterocyclic systems, inspite of the extensive work reported so far on isatins.
Therefore, keeping this in view as the main objective, the present project has been aimed at achieving the following:
- To synthesize the Isatin derivatives as depicted in Scheme-I.
- To purify the new isatin derivatives by crystallization and chromatographic technique.
- To characterize the new compounds by physical and spectral data (IR, 1H NMR and Mass)
- To screen the compounds for CNS activity by standard protocol available in literature
- To study the SAR of the compounds.
PLAN OF WORK:
In the present investigation, involving reactions of isatin with a view to synthesize some biologically active compounds, it has been felt worthwhile to study chlorosulphonation of isatin to form Isatin-5-sulphonic acid chloride and it is subjected to reaction with different amines or anilines to form respective sulphonamide derivatives, as such a reaction is not reported so far and also to evaluate the products biologically. The synthesis of title compounds could be achieved by the Scheme I.

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Gangarapu Kiran, M.Pharm, (Ph.D) is Assistant Professor of Kakatiya Institute of Pharmaceutical Sciences, Pembarthy, Warangal. He has an experience of about 7 years in teaching medicinal chemistry and performing research work in synthetic medicinal chemistry and pharmaceutical analysis. He submitted his Ph.D from Jawaharlal Nehru Technological University Hyderabad. He has published about 30 research papers in national and international journals. His research activities are collaborated with various research organizations like Rega Institute for Medical Research, Belgium; Graduate School of Medical Science Kanazawa University, Japan and National Cancer Institute, USA.

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