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As the festive season fills our homes with the comforting aromas of cinnamon, clove, and thyme, these beloved Christmas spices bring more than just a cosy feel - they also have notable antimicrobial effects. Herbal beverage extracts produced from these traditional ingredients have been shown to inhibit pathogenic microbes, offering a potential solution to the current antimicrobial resistance pandemic. In this literature review, we will explore how these seasonal herbs blend centuries of tradition with modern health benefits.
Herbalism has evolved significantly over centuries, with some modern remedies being widely used around the world. Plant-derived products, including essential oils, extracts and herbal teas are a promising alternative treatment due to their therapeutic effects and rich content of natural compounds such as flavonoids and alkaloids. The rise of antibiotic resistance has caused scientists to delve into alternative antimicrobial treatments; extracts and herbals have been a promising avenue for exploration and have shown promise in overcoming resistance mechanisms. Among different plants used in herbal teas are cinnamon, clove and thyme, all of which exhibit antimicrobial properties. Due to the presence of eugenol, clove essential oil can disrupt bacterial cell membranes, whilst thyme essential oil contains carvacrol and thymol, both of which interfere with bacterial cell respiration and protein synthesis. Cinnamaldehyde, the flavonoid that gives cinnamon its aroma, is thought to exert its antimicrobial effect by increasing bacterial cell membrane permeability, causing leakage of cell contents. There is limited research into their combinational effect with existing antibiotics as well as their sole effect.
Seukep et al. explored the antibacterial activities and combinatorial effects of cinnamon, clove and thyme extracts by determining minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) against a panel of 14 multi-drug-resistant (MDR) strains. The bacterial panel consisted of Staphylococcus aureus, Escherichia coli, Salmonella spp., Shigella spp. and Pseudomonas aeruginosa; broth microdilution was used to determine MICs and MBCs. The extracts on their own exhibited a range of MICs depending on bacteria and solvent with MIC values ranging between 13 to 1024 μg/mL. Nevertheless, all extracts showed inhibitory effects on bacterial growth with clove extract showing the highest potency; most MICs fell between 13 and 256 μg/mL. When clove extract was combined with antibiotics, the MICs of tetracycline, erythromycin and ciprofloxacin were significantly reduced, and the effect was more synergistic than additive. These results suggest that clove extract is a promising antimicrobial when used in conjunction with certain antibiotics and shows great antibacterial promise against pathogenic strains such as S. aureus, S. typhimurium and S. flexneri. However, there was a high MBC/MIC ratio of > 4 for clove against most bacterial strains, suggesting there may be concerns regarding administering enough of the product to eliminate 99% bacteria. Despite this, this study provides evidence for the antimicrobial efficacy of cinnamon, clove and thyme extracts against MDR pathogens, both alone and in combination with conventional antibiotics.
Advances in research will hopefully impede the progression of antimicrobial resistance, whether this be research into new remedies or enhancements of those already on the market. Synergistic agents are promising and preferred as we can utilise traditional antibiotics without resistance mechanisms hindering their action, especially if we have remedies such as herbal extracts that can aid their effect.
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Reference
- Seukep AJ, Ojong OCG, Mbuntcha HG, Matieta VY, Zeuko’o EM, Kouam AF, et al. In Vitro Antibacterial Potential of Herbal Beverage Extracts From Cinnamon, Clove, and Thyme and Their Interactive Antimicrobial Profile With Selected Antibiotics Against Drug‐Resistant Clinical Pathogens. Ullah R, editor. Journal of Tropical Medicine. 2025 Jan;2025(1).
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