Preparation of novel derivatives of pyridothiazine-1,1-dioxide and their CNS and antioxidant properties.

Starting from isothiazolopyridine-1,1-dioxide (1), corresponding derivatives of 3-aryl-4-hydroxypyrido[3,2-e]-1,2-thiazine-1,1-dioxide (6) possessing the 3-[4-(substituted-phenyl)piperazinyl]propyl or 3-(4-substituted-piperidinyl)propyl side chain by the nitrogen atom of the thiazine ring were prepared. Under pharmacological central nervous system (CNS) screening in animal models (mice), all of the six pyridothiazines 6 tested exhibited analgesic action as the predominant profile of their activity ('writhing' test 12.5-50 mg/kg). Moreover, the radical scavenging activity against peroxyl radicals of the representative pyridothiazines 6 was evaluated in vitro in water environment and some of them proved to be moderate antioxidants.