Synthesis, characterization and application of chitosan conjugated heterocyclic compounds

Abstract

Derivatives of formyl pyrazole were synthesized by the reaction of acetophenone, 4-methyl acetophenone, 3-acetyl furan, 3-acetyl thiophen and phenyl hydrazine derivatives. The product was treated with Vilsmeier reagent producing different formyl pyrazole derivatives which were characterized by FT-IR, 1HNMR, Elemental analysis and Mass spectroscopy. The formyl pyrazole derivatives were reacted with chitosan to produce chitosan/ pyrazole Schiff base. These Schiff bases were characterized by FT-IR and TGA.The antimicrobial activity of chitosan/ pyrazol Schiff base (CSB) was evaluated against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus), gram negative bacterium (Escherichia coli) and fungus (Aspergillus niger). Results indicated agood inhibitory activity for CSB-14 when tested against B.cereus that gave inhibition zone of 7.5 ± 0.6 (mm), however CSB-18 gave a pronounced inhibitory activity against S. aureus and recorded 25 ± 2.0 (mm). All synthesized derivatives have no inhibitory activity against Gram negative E. coli. CSB-14, and CSB-15 exhibited inhibitory activity against tested A. niger that was used as a fungal model which gave 19 ± 0.9 and 18 ± 1.0 inhibition zone (mm) respectively. Thus, these results showed that, functionalization of chitosan with the hetero-cyclic compounds created biological activities of the synthesized derivatives; hence the synthesized pyrazole derivatives have not recorded any inhibitory activity before its immobilization onto chitosan.

Unravelling the synthetic and therapeutic aspects of five, six and fused heterocycles using Vilsmeier–Haack reagent

“…Further, the intermediate (2) another attack on iminium salt (1) culminating in the formation of intermediate (3). The hydrolysis of the intermediate (3) completes the transformation, resulting in the formation of formyl pyrazole (4) 37 ( Scheme 1 ).…”

“…In 2022, El-Gharably et al 37 synthesized some pyrazole carbaldehydes on treatment of hydrazones with V. H. reagent (DMF-POCl 3 ) in ice-bath for 1 hour and stirred up to 70 °C for 6 to 7 hours, in excellent yield. These formyl pyrazole derivatives were used to prepare Schiff’s bases further and screened for their anti-tumor, anti-fungal activities against Aspergillus niger ( A. niger ) as well as anti-bacterial activities against bacteria Staphylococcus aureus ( S. aureus ), Bacillus cereus ( B. cereus ) and Escherichia coli ( E. coli ).…”

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review

“…This method not only facilitates the introduction of new groups, such as heterocycles, but also enables subsequent alkylation after reduction [78,79]. In a plethora of studies, the attachment of heterocycles such as thiophene, furan, pyrazole, indoles, quinolone, benzothiazole, oxazole, and imidazole-bearing Schiff base CS derivatives (2g; DS: 1.15-56%) was extensively explored in acetic acid as a mild condition [80][81][82][83][84]. Incorporating heteroatoms into CS as Schiff base resulted in a hydrophobic characteristic; nevertheless, the presence of pyrazole and thiophene groups exhibited water solubility for CS [80][81][82][83][84].…”

“…In a plethora of studies, the attachment of heterocycles such as thiophene, furan, pyrazole, indoles, quinolone, benzothiazole, oxazole, and imidazole-bearing Schiff base CS derivatives (2g; DS: 1.15-56%) was extensively explored in acetic acid as a mild condition [80][81][82][83][84]. Incorporating heteroatoms into CS as Schiff base resulted in a hydrophobic characteristic; nevertheless, the presence of pyrazole and thiophene groups exhibited water solubility for CS [80][81][82][83][84]. Additionally, the reduction of Schiff bases with sodium borohydride has been widely employed as an alternative alkylation strategy, leading to the attachment of new functional groups or heterocycles (DS: 36-81%) (2h) [85].…”

Fe3O4/CuO/Chitosan Nanocomposites: An Ultrasound-Assisted Green Approach for Antibacterial and Photocatalytic Properties

“…Furthermore, in previous studies, materials based on Fe 3 O 4, CuO, and CS have been examined to inhibit the growth of various microorganisms, including Staphylococcus aureus, Bacillus subtilis, Escherichia coli , Corynebacterium, Pseudomonas aeruginosa, etc. Taking into consideration the culture conditions and ethical factors, S.…”