SYNTHESIS, SPECTRAL CHARACTERIZATION AND PHARMACEUTICAL IMPORTANCE OF NOVEL 4H-1, 4-BENZOTHIAZINES, AND THEIR SULFONE ANALOGUES

In recent years, synthesis and biological evaluation of novel 4H-1, 4-benzothiazines and their sulfone analogues have gained momentum due to their medicinal and industrial importance. The present article describes the synthesis of new 4H-1, 4-benzothiazines via condensation and oxidative cyclization of substituted 2-aminobenzenethiols with compounds containing active methylene groups. It is believed that the reaction proceeds via intermediary of the enaminoketone system. The sulfone derivatives were synthesized by oxidation of 4H-1, 4-benzothiazines using 30% hydrogen peroxide in glacial acetic acid. The structures of the compounds have been confirmed by spectral and chemical analysis.The synthesized compounds were screened for antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^●+) radical cation decolorization assay. The in vitro antibacterial activity was tested against S. aureus, B. subtilis (Gram positive) and E. coli, Pseudomonas aeruginosa (Gram negative) microorganisms using paper disc  diffusion method using nutrient agar medium and the antifungal activity of synthesized compounds was tested on fungal strains: A. niger, C. albicans using disc diffusion method.