Indole-3-carbaldehyde Semicarbazone Derivatives: Synthesis, Characterization, and Antibacterial Activities

Abstract

Four indole-3-carbaldehyde semicarbazone derivatives, 2-((5-bromo-1H-indol-3-yl)methylene)hydrazinecarboxamide (1), 2-((5-chloro-1H-indol-3-yl)methylene)hydrazinecarboxamide (2), 2-((5-methoxy-1H-indol-3-yl)methylene)hydrazinecarboxamide (3), and 2-((4-nitro-1H-indol-3-yl)methylene)hydrazinecarboxamide (4) were synthesized and characterized by ESI-MS and spectroscopic (FT-IR, 1H NMR, and 13C NMR) techniques. The two-dimensional NMR (in acetone-d6) spectral data revealed that the molecules 1 and 2 in solution are in the cisE isomeric form. This evidence is supported by DFT calculations at the B3LYP/6-311++G(d,p) level of theory where it was shown that the corresponding most stable conformers of the synthesized compounds have a cisE geometrical configuration, in both the gas and liquid (acetone and DMSO) phases. The in vitro antibacterial activity of compounds 1–4 was determined against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria. Among all the tested semicarbazones, 1 and 2 exhibited similar inhibitory activities against Staphylococcus aureus (MIC = 100 and 150 μg/mL, respectively) and Bacillus subtilis (MIC = 100 and 150 μg/mL, respectively). On the other hand, 3 and 4 were relatively less active against the tested bacterial strains compared with 1, 2, and tetracycline.

Phenylisoxazole-3/5-Carbaldehyde Isonicotinylhydrazone Derivatives: Synthesis, Characterization, and Antitubercular Activity

“…e intense absorption bands of the carbonyl group (CO) were observed in the 1653-1677 cm −1 region [17,21]. ese ](CO) vibrations, found in all the compounds, confirm the presence of the keto tautomer in the solid state, in agreement with the stretching frequencies of the carbonyl group found for other compounds derived from semicarbazones with indole fragments [32]. e strong absorption bands corresponding to the imine C�N group appeared at 1531-1587 cm −1 [17,30].…”

“…Recently, we have reported in vitro antimicrobial studies of indole-3-carbaldehyde semicarbazone derivatives against various Gram-positive and Gram-negative bacteria. e results demonstrated that compounds 2-((5-bromo-1Hindol-3-yl)methylene)hydrazine carboxamide and 2-((5chloro-1H-indol-3-yl) methylene)hydrazine carboxamide were moderately active against Staphylococcus aureus (MIC � 100 and 150 μg/mL, respectively) and Bacillus subtilis (MIC � 100 and 150 μg/mL, respectively) relative to tetracycline (antimicrobial drug) [32]. Continuing with our research on new heterocyclic compounds with potential biological activity, we herein describe the synthesis and spectral characterization of eight new phenylisoxazole isoniazid derivatives.…”

“…e characterization of a novel series of the phenylisoxazole-3/5-carbaldehyde isonicotinylhydrazone derivatives 1-8 was performed by using the 1D NMR ( 1 H-and 13 C-NMR) and 2D ( 1 H-1 H COSY, 1 H-1 H NOESY, 1 H- 13 C HSQC, and 1 H- 13 C HMBC) spectra, recorded in acetone-d 6 / DMSO-d 6 (see Supplementary [11][12][13][14][15]18,19,22,23,26,[28][29][30][31][32][34][35][36][37][38]41,and 42 in Supplementary Materials).…”

Indole/isatin‐containing hybrids as potential antibacterial agents

“…The indole–semicarbazone hybrids 73 (MIC: 100 to >200 μg/ml) showed a weak activity against S. aureus , B. subtilis , E. coli , and P. aeruginosa , and the SAR indicated that the introduction of the electron‐withdrawing group could improve the activity against Gram‐positive bacteria ( S. aureus and B. subtilis ). [ 148,149 ] Among them, two hybrids 73a,b (MIC: 100–150 μg/ml) were active against the Gram‐positive bacteria, but the activity was far inferior to that of tetracycline (MIC: <12.5 μg/ml).…”

Synthesis, Molecular Docking Studies and ADME Prediction of Some New Albendazole Derivatives as α-Glucosidase Inhibitors

“…These derivatives are known to have a broad range of biological properties including antidiabetic activity. [10][11][12][13][14] For instance, pyrazole-phenyl semicarbazone derivatives were reported by Azimi et al as potent α-glucosidase inhibitors IV (Figure 1) with IC 50 values in the range of 65.1-695.0 μM comparing with acarbose (IC 50 = 750.0 μM). 14 More recently, a (E)-2-benzylidene-N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl) hydrazine-1-carboxamide derivative (V) has been reported for its α-glucosidase inhibitory potential 15 (Figure 1).…”