CHINA – A compound commonly found in cinnamon and used in food products may help limit how bacteria spread antibiotic resistance, according to new research published in the journal Engineering.
The study focuses on cinnamic acid, a naturally occurring plant compound that researchers say interferes with the transfer of resistance genes between bacteria without stopping bacterial growth entirely.
Scientists examined the compound in laboratory conditions, simulated gut environments, and animal models to evaluate whether it could reduce the movement of resistance-carrying DNA.
Antibiotic resistance continues to expand globally
Antibiotic resistance has become one of the major public health concerns worldwide. The World Health Organization (WHO) has repeatedly warned that infections once easily treated with antibiotics are becoming harder to manage as bacteria develop ways to survive commonly used medicines.
Recent estimates show that antimicrobial resistance directly causes around 1.14 million deaths each year and contributes to more than 4.7 million deaths globally. Researchers have also warned that annual deaths linked to resistant infections could rise to 10 million by 2050 if resistance continues to spread unchecked.
Data further suggests that one in every six bacterial infections globally now involves resistant bacteria. Between 2018 and 2023, resistance levels increased by roughly 40%, reflecting the speed at which resistant strains continue to emerge.
While mutations contribute to resistance, bacteria also have another mechanism that accelerates the problem. They can exchange genetic material directly through a process known as plasmid conjugation. During this process, small DNA structures called plasmids move from one bacterium to another, carrying resistance genes that can spread across different bacterial species.
Some of these plasmids contain genes such as mcr-1, blaNDM-1, and tet(X4), which are associated with resistance to critical antibiotics used in human medicine.
Researchers have been searching for ways to interrupt this transfer process. However, many compounds previously investigated either showed toxic effects or did not perform consistently in living systems.
How cinnamic acid works
The research team investigated whether cinnamic acid could reduce plasmid transfer while remaining biologically compatible.
Instead of killing bacteria directly, the compound appeared to interfere with the energy systems bacteria rely on to exchange genetic material.
Experiments showed that cinnamic acid reduced the transfer rate of several resistance plasmids in a concentration-dependent manner. Researchers noted that bacterial growth remained largely unaffected within the tested concentrations.
Using fluorescence-labeled plasmid tracking systems, scientists observed reduced plasmid transfer within gut microbial communities under ex vivo conditions. Mouse studies also showed lower conjugation frequencies after oral administration of cinnamic acid, with stronger effects observed at higher doses.
Further analysis suggested that the compound disrupts the tricarboxylic acid cycle, a central metabolic pathway involved in energy production. This disruption weakens the bacterial electron transport chain and lowers proton motive force, ultimately reducing intracellular ATP levels.
ATP acts as an energy source for many cellular activities, including conjugation. By limiting available energy, cinnamic acid appears to make bacterial gene transfer less efficient.
The study also found reduced activity in genes linked to mating pair formation, DNA transfer, and plasmid replication. Researchers additionally observed slight increases in donor cell outer membrane permeability.
Safety findings and gut microbiota impact
Researchers also examined whether cinnamic acid produced harmful biological effects during testing.
According to the study, treated mice maintained stable body weight throughout the experiments, and no visible structural abnormalities were identified in major organs.
The composition and diversity of gut microbiota also remained largely unchanged after treatment, findings the researchers say support the compound’s compatibility in living systems.
Cinnamic acid is already widely present in the human diet through cinnamon and other plant-based foods and is also used as a food additive in some products.