Browsing by Author "Çavuş, M.S."

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Schiff bases based on thio/carbohydrazide: Synthesis, spectroscopic characterization, DFT, antimicrobial, DNA interactions and cytotoxicity studies
(Elsevier B.V., 2024) Çavuş, M.S.; Yakan, H.; Başkan, C.; Muğlu, H.; Babacan, A.A.
New Schiff bases (1–8) have been prepared from numerous aldehydes and thio/carbohydrazide. The chemical structures of these compounds were characterized using IR, 1H NMR, 13C NMR spectroscopic methods, and elemental analysis. Electronic and spectroscopic properties of the compounds were determined by DFT calculations performed at the B3LYP/6–311++G(2d,2p) level of theory and were analyzed comparatively with experimental findings. The relationship between some global reactivity parameters and the nucleophilic-electrophilic attack abilities of the compounds and their antimicrobial and cytotoxic activities was also investigated. The antimicrobial effects of the synthesized compounds on microorganisms were screened using disc diffusion methods. According to the disc diffusion results, compound 8 in particular exhibits a high antibacterial potential against Bacillus cereus (15.66 ± 0.57 mm). The interaction of synthesized compounds with pUC18 plasmid DNA was analyzed by the agarose gel electrophoresis method. The results showed that compounds 6, 7, and 8 interact with plasmid DNA and cause fragmentation of the Form I structure. In addition, in vitro, the cytotoxic activity of compounds on HT-29 (human adenocarcinoma colon) cell lines was investigated by the MTT method. Our study showed that compounds 7 and 8 have cytotoxic effects on HT-29 cell lines. The IC50 value was determined to be 96.93 µM for compound 7 and 91.55 µM for compound 8.
Synthesis, structure elucidation, antioxidant properties, and theoretical calculations of new Schiff bases–isatin derivatives
(Springer Science and Business Media B.V., 2024) Bakır, T.K.; Çavuş, M.S.; Muğlu, H.; Yakan, H.
Isatin-derived Schiff bases are the subject of many studies, finding wide application areas in polymer technology, pharmaceutical industry, and medicine. In this study, a series of new Schiff bases were prepared from monothiocarbohydrazones based on isatins with different substituents (5-F, 5-Br, 5-I, and 5-MeO). The chemical structures of the synthesized compounds were determined using 1H NMR, 13C NMR, FTIR spectroscopic techniques, and elemental analysis. Antioxidant activity determinations of 23 compounds were performed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical quenching method. The highest percent inhibition value at 10 µM concentration was shown by compound number 22, 5-bromoisatin Schiff base containing 3-methoxy-4-hydroxy group. Compound 17, a 5-iodoisatin Schiff base containing 3-methoxy-4-hydroxy group, showed the highest antioxidant activity with an IC50 value of 9.76 ± 0.03 µM. In addition to the theoretical analysis of the compounds, both their spectroscopic and antioxidant properties were investigated. The ground-state geometries and some chemical reactivity parameters of the compounds were calculated using the B3LYP/6-311 + + G(2d,2p) approach. Besides intramolecular interactions, substituent effects, and some QTAIM parameters, the calculations were also performed to study the electronic properties of reactive N/O–H bonds and were used to interpret the experimental results. The effects of the electronic parameters and intramolecular interactions of reactive N/O–H bonds on the antioxidant properties of the compounds were investigated. Additionally, the relationships of DPPH reactions with delocalization indices of N/O-H bonds and the pattern of SET/HAT mechanisms with electronic variables were analyzed. Examination of electron and hydrogen atom transfer mechanisms has shown the dominance of electron transfer, supported by the correlation coefficients between IC50 values and SET reaction energies.