Starting from theophylline (1,3-dimethylxanthine) new thiazolidin-4-one derivatives 7a_1–7, 7b_1–7 have been synthesized as potential antidiabetic drugs. The structure of the new derivatives was confirmed using spectral methods (FT-IR, ¹H-NMR, ¹³C-NMR). The in vitro antioxidant potential of the synthesized compounds was evaluated according to the ferric reducing power, the total antioxidant activity and the DPPH and ABTS radical scavenging assays. Reactive oxygen species (ROS) and free radicals are considered to be implicated in a variety of pathological events, such as diabetes mellitus and its micro- and macrovascular complications. The results of chemical modulation of the thiazolidin-4-one intermediaries 6a, 6b through condensation with several aromatic aldehydes is the improvement of the antioxidant effect. All benzylidenethiazolidin-4-one derivatives 7a_1–7, 7b_1–7 are more active than their parent thiazolidin-4-ones. The most active compounds are the ones obtained by reaction of condensation with 4-hydroxybenzaldehyde (compounds 7a₅, 7a₆), 4-dimethylaminobenzaldehyde (compounds 7a₆, 7b₆) and 2-nitrobenzaldehyde (compounds 7a₇, 7b₇).

New series of N-(arylidene)hydrazinoacetyl sulfonamides 4a_1–6, 4b_1–6 and N-(4-aryl-3-chloro-2-oxoazetidin-1-yl)aminoacetyl sulfonamides 5a_1–6, 5b_1–6 were synthesized. The structures of the new derivatives was confirmed using spectral methods (FT-IR, ¹H-NMR, ¹³C-NMR). The antibacterial activities of these compounds against Gram positive (Staphyloccoccus aureus ATCC 6583, Staphyloccoccus epidermidis ATCC 12228, Enterococcus faecalis ATCC 25912) and Gram negative (Klebsiella pneumoniae CIP 53153, Proteus vulgaris CIP 104989, Citrobacter freundii CIP 5732, Enterobacter cloacae CIP 103475, Escherichia coli ATCC 25922, Pseudomonas aeruginosa CIP 82118) bacterial strains were evaluated using the broth micro-dilution method. Compound 4a₂ displayed the highest antibacterial activity, especially against Staphyloccoccus epidermidis, Enterococcus faecalis and Pseudomonas aeruginosa. The antioxidant potential of the synthesized compounds was also investigated according to ferric reducing power, total antioxidant activity and DPPH radical scavenging assays. All tested compounds showed excellent antioxidant activity in comparison with sulfadiazine and sulfisoxazole which were used as parent sulfonamides. Moreover, some of them showed an antioxidant activity comparable with that of ascorbic acid. In general, the compounds designed based on a sulfadiazine skeleton (compounds 4a_1–6, 5a_1–6) are more active than those obtained from sulfisoxazole (compounds 4b_1–6, 5b_1–6), and the N-(arylidene)hydrazinoacetyl sulfonamide derivatives 4a_1–6, 4b_1–6 are more active than their azetidionone analogues 5a_1–6, 5b_1–6.