Synthesis of Schiff bases based on Chitosan, thermal stability and evaluation of antimicrobial and antitumor activities.

A Schiff base of Chitosan was prepared by condensing of the Chitosan (CS) with six aromatic aldehydes and confirmed by FT-IR, NMR, XRD, TGA, and DSC. XRD results showed the disappeared of peaks at 2θ = 10° for CS and appeared one peaks at around 2θ of 23° for Schiff bases, while TGA was demonstrated that the thermal stability of CS has improved after the modification with the corresponding aldehyde. Also, DSC shows endothermal peak of CS at 100 °C due to the loss of water and second thermal event related to the decomposition of amine units with an exothermic peak at 295 °C, while Schiff bases shows endothermal peak around 70-95 °C which is related to the loss of water for all samples and the second exothermic peak around 260-280 °C is related to the decomposition of the amine group in the polymer units. The antimicrobial activities of Schiff bases were tested against + ve/ - ve Gram bacteria, and fungi, while antitumor activities were evaluated against cell lines, MCF-7, HCT-116, and HepG-2. The result shows that Schiff bases exhibited higher antimicrobial activity than Amoxycillin and Tetracycline, while Schiff bases indicated the absence of cytotoxic activity when compared to the Colchicine.