Bioactive Compounds Derived from Sargassum wightii Exhibit Antibacterial Activity against Multi-Drug Resistant Acinetobacter baumannii

Abstract

Acinetobacter baumannii (A. baumannii) is a notorious nosocomial pathogen known for its ability to form biofilms, rendering it highly resistant to conventional antibiotics and immune clearance. In this study, the minimum inhibitory concentration (MIC) ranged from 70 µg/mL to 100 µg/mL remarkably, the tested ethanolic extracts inhibited A. baumannii biofilm development in a concentration-dependent manner. Epifluorescence microscopic analysis revealed a significant reduction in treated biofilm formation compared to the control. Additionally, gas chromatography-mass spectrometry (GC-MS) analysis of the ethanol extract of Sargassum wightii (S. wightii) identified 10 major compounds. Molecular docking studies were conducted to explore the interaction of small molecules from S. wightii with the BfmR protein of A. baumannii. The molecular docking of three ligand molecules (CAS No. 002302-12-7, 015120-94-2, and 146397-91-3) with the target BfmR-Ab revealed the lowest binding energies (∆G_bind) of -42.26 and − 50.49 (kcal/mol) for the ligands CAS No. 002302-12-7 and 146397-91-3, respectively, and the lowest Glide score of -4.067 (kcal/mol) for the ligand CAS No. 015120-94-2. These top three hit molecules exhibited the highest affinity as efficient ligands against BfmR of A. baumannii. Nevertheless, S. wightii demonstrated antibiofilm activities against the multidrug-resistant (MDR) pathogen A. baumannii, with bioactive compounds exhibiting promising drug-likeness and pharmacokinetic signatures.