Synthesis and Biological Evaluation of Three New Chitosan Schiff Base Derivatives

Abstract

Recently, chemical modifications of chitosan (CS) have attracted the attention of scientific researchers due to its wide range of applications. In this research, chitin (CH) was extracted from the scales of Cyprinus carpio fish and converted to CS by three chemical steps: (i) demineralization, (ii) deprotonation, and (iii) deacetylation. The degree (measured as a percentage) of deacetylation (DD %) was calculated utilizing the acid–base titration method. The structure of CS was characterized by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). Three new CS Schiff bases (CSSBs) (CS-P1, CS-P2, and CS-P3) were synthesized via coupling of CS with 2-chloroquinoline-3-carbaldehyde, quinazoline-6-carbaldehyde, and oxazole-4-carbaldehyde, respectively. The newly prepared derivatives were verified, structurally, by nuclear magnetic resonance (1H and 13C NMR) and FT-IR spectroscopy. Antimicrobial activity was evaluated for the prepared compounds against both “Gram-negative” and “Gram-positive” bacteria, namely, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Streptococcus mutans, in addition to two kinds of fungi, Candida albicans and Aspergillus fumigates. Cytotoxicity of the synthesized CSSBs was evaluated via a MTT screening test. The results indicated a critical activity increase of the synthesized compound rather than CS generally tested bacteria and fungi and the absence of cytotoxic activity. These findings suggested that these new CSSBs are novel biomaterial candidates with enhanced antibacterial and nontoxic characteristics for applications in areas of both biology and medicine.

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“…XRD pattern of complex 2 (Figure 4a) is different from 1, and there are 7 sharp and broad peaks at 2θ = 27.5, 31.8, 45.9, 56.8, 66.5, and 75.4, due to the good crystalinity and different structure of 2 than 1. However, the XRD pattern of the CuO nanoparticles prepared by decomposition of 2 (Figure 4b) is a little similar to that of CuO nanoparticles prepared from 1 [20][21][22][23][24][25][26][27]30].…”

“…After calcination of complexes at 600 °C, vibrations related to organic bonds are expected to be eliminated and have only the vibration related to the oxygen metal ion. In the FT-IR spectra of the as-prepared CuO particles (Figure 2), there is one peak at 523 cm -1 in the FT-IR spectra of the CuO particles prepared from 1, while there are two peaks at 582 and 532 cm -1 in the FT-IR spectra of the CuO nanoparticles prepared from 2, assigned to the stretching vibration of Cu II -O bond in monoclinic CuO nanoparticles [14,[23][24][25][26][27]. Copper(II) oxide has three structures such as monoclinic, tetragonal, and cubic phases.…”

“…The antibacterial properties were tested against different pathogenic bacteria such as E. coli, P. aeruginosa, S. aureus and B. cereus [21][22][23]. To estimate the antibacterial activity of the compounds, good diffusion assay was performed.…”

Synthesis of Schiff bases: A Glimpse on recent literature

“…[8][9][10][11] Schiff bases containing numerous donor atoms -such as N, O, S, and others have a wide range of biological functions and they are of particular interest owing to the diversity of ways they may link to metal ions, with their stability, and biological implications. [12][13][14] Typical procedures comprise workings from Babu 15,16 , Nadia, 17 Xie, 18 Yahaya, 19 Kargar, 20 Nedime, 21 Tahere, 22 Mighani 23 etc.…”

Synthesis and Characterization of Aminophosphonate Containing Chitosan Polymer Derivatives: Investigations of Cytotoxic Activity and in Silico Study of SARS-CoV-19

“…These factors certainly must be taken into account in an analysis of its antiviral activity [ 9 ]. Chitin has a chemical structure of a characteristic supplementary biopolymer found in the exoskeletons of roaches and crustaceans [ 10 ], but chitosan is frequently obtained by the deacetylation of chitin [ 11 ]. CS has a few receptive NH 2 groups that offer additional chemical alteration for the expansion of derivatives that are cost-effective [ 12 ].…”