Combined antibacterial effects of turmeric and cinnamon ethanolic extracts with ampicillin against resistant-microbial strains: in vitro and molecular docking approaches

Abstract

Antimicrobial resistance refers to the phenomenon in which microorganisms cease to respond to antibiotic therapy. Plants are known to possess antimicrobial effects. The inhibitory effects of turmeric and cinnamon were tested using the disc diffusion method on S. aureus and E. coli, respectively, while molecular docking analyses were carried out using the GOLD docking software and Biovia Discovery Studio 2016. S. aureus exhibited sensitivity to turmeric extract alone and a combination of turmeric and ampicillin, while demonstrating moderate sensitivity to ampicillin alone. Similarly, E. coli exhibited moderate sensitivity to both cinnamon extract and ampicillin but demonstrated higher sensitivity to the combination of cinnamon extract and ampicillin. Furthermore, molecular docking studies of curcumin, bisdemethoxycurcumin, demethoxycurcumin, tetrahydrocurcumin, zingiberene, curcumenol, and curcumol in turmeric extract with Sortase-A (SrtA) indicated binding efficiencies, evidenced by fitness scores of 65.72, 63.46, 62.37, 61.80, 49.19, 41.26, and 37.47, respectively. In the same manner, molecular docking investigations of eugenol, cinnamyl acetate, linalool, β-caryophyllene, and cinnamaldehyde in cinnamon extract with extended-spectrum β-lactamase (ESBL) indicated better binding efficiencies, evidenced by fitness scores of 40.64, 39.62, 38.03, 36.86, and 35.25, respectively. Inhibitory effects of turmeric and cinnamon extracts combined with ampicillin were effective against S. aureus and E. coli resistant strains. The combination of antibiotics with plant-based products may represent a promising strategy for future therapies targeting infections caused by bacteria that have developed resistance to some standard antibiotics.