Abstract
Objective: This study aims to explore a practical, protection–deprotection-free protocol for synthesizing naturally occurring hydroxycinnamic acids and their analogues, followed by comparative antibacterial screening, cytotoxicity evaluation, SAR interpretation, and molecular docking analysis. Materials and methods: In this study, we have developed an efficient and scalable procedure for the synthesis of hydroxylated cinnamic acids and their analogues via Knoevenagel condensation reactions, eliminating the need for protection–deprotection strategies and affording high yields. Structural elucidation of all the synthesised compounds was carried out using NMR spectroscopy and Mass spectrometry. Synthesised compounds were screened for antibacterial activity in both Gram-negative strains, Klebsiella aerogenes (ATCC 13,048), Acinetobacter baumannii (ATCC 15,308), and Gram-positive E. faecalis (MVBP-18) and Staphylococcus aureus (MVBP 22) strains. An in silico molecular modelling study was performed using AutoDock Vina (version 1.2.5). The synthesised compounds were docked against K. aerogenes, A. baumannii, E. faecalis., and S. aureus to determine their binding affinity and interaction profile. Results: The efficient strategy resulted in a practical and protection-deprotection-free protocol for synthesizing naturally occurring hydroxycinnamic acids and analogues, followed by comparative antibacterial screening, cytotoxicity evaluation, SAR interpretation, and molecular docking analysis. Amongst compounds tested and SAR studies observed, 2‑methoxy cinnamic acid and ferulic acid were found to be best against both Gram-negative and Gram-positive strains. The key findings suggest that methoxy substitution and its positional orientation may contribute to antibacterial activity; however, additional analogues and quantitative MIC/MBC data are needed to confirm this SAR trend. An in silico molecular modelling study identified key functional groups responsible for effective binding compared to the standard drug. Conclusion: A series of structurally diverse cinnamic acid derivatives was successfully synthesised using an optimised Knoevenagel condensation reaction. Among the investigated derivatives, methoxy substitution in cinnamic acid emerged as a key structural feature. The group of molecules with methoxy substitution was found to be the most promising derivatives. Further, ortho substitution was found to be more favourable for activity against multidrug-resistant strains. In addition, in silico modelling suggests that 2‑methoxy cinnamic acid provides comparable interactions with the standard across most proteins, including the key amino acid interactions of the targeted proteins. These features provide valuable insights for the development of potential drug leads against multidrug-resistant strains.