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.

Novel fused chromenes (4,7–11) and pyrimidines (12–16) were designed, synthesized, and evaluated for their mammary gland breast cancer (MCF-7), human colon cancer (HCT-116), and liver cancer (HepG-2) activities. The structural identity of the synthesized compounds was established according to their spectroscopic analysis, such as FT-IR, NMR, and mass spectroscopy. The preliminary results of the bioassay disclosed that some of the target compounds were proven to have a significant antiproliferative effect against the three cell lines, as compared to Doxorubicin, Vinblastine, and Colchicine, used as reference drugs. Particularly, compounds 7 and 14 exerted promising anticancer activity towards all cell lines and were chosen for further studies, such as cell cycle analysis, cell apoptosis, caspase 3/7 activity, DNA fragmentation, cell invasion, and migration. We found that these potent cytotoxic compounds induced cell cycle arrest at the S and G2/M phases, prompting apoptosis. Furthermore, these compounds significantly inhibit the invasion and migration of the different tested cancer cells. The structure-activity relationship (SAR) survey highlights that the antitumor activity of the desired compounds was affected by the hydrophobic or hydrophilic nature of the substituent at different positions.