A privileged molecular framework: Bifunctional benzoxazines from renewable chrysin for antimicrobial, low toxicity, molecular docking studies for sustainable multifaceted applications

Two series of bifunctional benzoxazines were synthesized using renewable chrysin as a precursor, incorporating both synthetic and bio-based amine sources. The synthesized benzoxazine monomers were structurally validated through Fourier transform infrared (FTIR), ¹H-nuclear magnetic resonance (NMR) and high resolution mass (HRMS) spectral analyses. The lowest polymerization temperature of 193 °C was observed in CH-pga and CH-ffa. The bio-based benzoxazines possessed lower polymerization temperature than synthetic amine substituted benzoxazines. In contrary, the thermal stability of the synthetic amine substituted polybenzoxazines was found to be greater than that of bio-based polybenzoxazines. Poly(CH-pga) showed highest thermal stability with a char yield of 39 % at 850 °C exhibiting highest theoretically calculated limiting oxygen index (LOI) and heat resistance index (HRI) values. CH-oda possessed highest antimicrobial activity of 55 % and 90 % bacterial growth inhibition against S.aureus and E.coli respectively. CH-oda showed least toxicity towards L929 cell line showing highest IC50 value of 171 µg/mL when compared to rest of the monomers. Poly(CH-oda) exhibited highest water contact angle of 143° and corrosion inhibition efficiency of 99.89 % which was further validated by density functional theory (DFT) studies. From the molecular docking, CH-a showed the best docking score and binding affinity to the epidermal growth factor receptor (eGFR) ascertaining the presence of higher anticancer activity. Also, the absorption, distribution, metabolism, excretion and toxicity (ADMET) parameters have been satisfied by all the benzoxazines showing drug likeliness. Therefore, from the current study experimental data suggests that bio-based benzoxazines possess better hydrophobicity, anticorrosion property, antimicrobial activity and low toxicity when compared to synthetic amine based benzoxazines. Whereas, both the series of benzoxazines exhibit good anticancer and drug likeliness property as per docking studies.