Synthesis, characterization, and evaluation of the antioxidant and antibacterial properties of dextran-based heterocyclic Schiff bases.

Polymers are being greatly researched to design biocompatible, cost effective and efficient antibacterial agents. This work explores the impact of derivatization of dextran with the heterocyclic moiety via imine linkages. Introducing a heterocyclic moiety is expected to improve bioactivity of dextran and expand its scope of application. Four imine derivatives of dextran were synthesized to examine the effect of heterocyclic structure on the antibacterial and antioxidant activity. Antibacterial activity was investigated against gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli). Compound 2a, containing a furan ring, exhibited the most potent antibacterial activity, with inhibition zones of 36 mm against E. coli and 24 mm against S. aureus. This was comparable to the standard antibiotic rifampicin which produced inhibition zones of 34 mm and 22 mm against E. coli and S. aureus, respectively. Among the derivatives, compound 2c, featuring an indole ring, exhibited the highest antioxidant activity, with IC values of 29.86 ± 2.28, 34.10 ± 0.39, and 31.60 ± 0.20 μg/mL for DPPH, hydroxyl, and nitric oxide radicals, respectively. The findings showed that heterocyclic moiety and imine linkage enhanced the antibacterial and antioxidant activities of dextran.