The research team, led by B. S. Bandusekara of the University of Colombo Institute for Agro-Technology and Rural Sciences and colleagues at the University of Peradeniya, focused on six wild Cinnamomum species native to Sri Lanka: C. capparu-coronde, C. citriodorum, C. dubium, C. litseifolium, C. ovalifolium, and C. sinharajaense. Most of these species are classified as vulnerable or endangered on the national Red List, and several, such as C. sinharajaense and C. ovalifolium, survive only in geographically restricted habitats. Alongside the wild species, the team analyzed cultivated C. verum varieties, including the commercial cultivars Sri gemunu and Sri wijaya, as well as wild-growing C. verum populations, a comparison that had never been made before.

Samples were collected from at least two distinct agroecological zones for each species, spanning both domesticated research plots and natural forest habitats such as the Sinharaja forest. To ensure comparability, the researchers harvested bark and leaves from uniform, pest-free branches of standard circumference, air-dried them under controlled conditions, and ground them into fine powder. The team then deployed two complementary analytical techniques. High-performance liquid chromatography, or HPLC, quantified six key bioactive compounds in bark and leaf methanol extracts, including cinnamaldehyde, eugenol, coumarin, cinnamyl alcohol, cinnamyl acetate, and coumaric acid. Gas chromatography-mass spectrometry, or GCMS, mapped the volatile oil profiles of the leaves, while hydrodistillation in a Clevenger-type apparatus determined the leaf oil yield.

One of the most striking results concerns coumarin, a compound that has become a regulatory headache for the cinnamon industry. Coumarin, which occurs naturally at high levels in cassia cinnamon, is considered potentially harmful to the liver at elevated doses, and the European Union has set strict limits on its content in foods. In this study, none of the Sri Lankan species, whether wild or cultivated, showed detectable levels of coumarin or coumaric acid. Given the very low limit of detection of the method, the authors conclude that Sri Lankan Cinnamomum species comfortably comply with international daily intake recommendations, reinforcing the reputation of true cinnamon as the safer, premium alternative to cassia. Because the samples came from widely differing environments, the researchers suggest that the absence of coumarin is likely governed more by genetics than by growing conditions.

The two compounds that drive cinnamon’s commercial value, cinnamaldehyde in the bark and eugenol in the leaves, told a more complicated and fascinating story. Across the genus, bark-cinnamaldehyde ranged from 0.09 to 18.31 milligrams per gram and leaf-eugenol from 0.32 to 38.13 milligrams per gram. As expected, the elite cultivated varieties Sri gemunu and Sri wijaya topped the rankings. But the wild species were far from disappointing. Cinnamomum capparu-coronde delivered the second-highest bark-cinnamaldehyde content, with remarkably consistent values of 8.34 and 8.18 milligrams per gram at its two collection sites, Delpitiya and Matara. Even more dramatic was C. sinharajaense: trees grown in a domesticated plot in Matara produced a leaf oil yield of 1.53 percent, leaf-eugenol of 30.38 milligrams per gram, and bark-cinnamaldehyde of 8.20 milligrams per gram, all far exceeding the same species growing wild in Sinharaja forest, where the corresponding values were 0.32 percent, 4.99, and 1.67 milligrams per gram.

That last comparison carries real weight for the future of cinnamon breeding. The domesticated C. sinharajaense not only outperformed its wild counterpart by several fold but also beat wild-growing C. verum samples from Bibila and Norwood, which produced only 2.13 to 4.20 milligrams per gram of bark-cinnamaldehyde, and came close to matching cultivated varieties. Combined with earlier genetic work showing that C. sinharajaense from Matara has the lowest sequence divergence from the Sri gemunu cultivar, the chemical data suggest this wild species is the closest known relative of cultivated cinnamon and a prime candidate for incorporation into breeding programs aimed at disease resistance, pest tolerance, and climate resilience.

The GCMS analysis revealed an extraordinary diversity of leaf volatile oil profiles. In total, the study identified more than fifty different biochemical compounds across the genus, twenty of which are considered economically important. Each species carried a distinctive chemical signature. Cinnamomum sinharajaense and C. verum produced leaf oils dominated by eugenol, with relative abundances above 90 percent in several samples, confirming their close chemical kinship. Cinnamomum citriodorum stood out for its citronellal and citronellol, the compounds behind its characteristic citronella aroma, reaching 42.16 and 26.55 percent in the Matara sample. Cinnamomum litseifolium from Delpitiya was overwhelmingly rich in methyl eugenol at 61.02 percent, while C. ovalifolium was dominated by naphthalene. Cinnamomum dubium proved the most chemically complex of all, with 39 volatile compounds detected across its range, including alpha-phellandrene, beta-santalol, and terpineol in varying proportions.

Crucially, the variation did not stop at species boundaries. Within single species, the number of compounds, their relative abundances, and the identity of the dominant constituents shifted dramatically between locations. Cinnamomum capparu-coronde, for example, produced benzyl benzoate as its leading compound at 28.92 percent in Delpitiya, but bicyclogermacrene at 19.77 percent in Matara, with eugenol, alpha-copaene, and gamma-muurolene also fluctuating between sites. Cinnamomum dubium yielded 35 compounds in Matara but only 19 in Sinharaja, with economically valuable compounds such as eucalyptol and beta-santalol far more abundant in the Sinharaja sample. The authors attribute this intraspecies mosaicism to a combination of genetic diversity and environmental forcing: temperature influences enzymatic activity and metabolic flux, rainfall shapes the overall chemical budget, and leaves, being directly exposed to light, heat, and water stress, vary more than the protected bark. Statistically, both leaf-eugenol and bark-cinnamaldehyde correlated positively with mean annual temperature and leaf oil yield, while total compound diversity declined with increasing rainfall.

A cluster analysis integrating the HPLC concentrations, volatile profiles, and oil yields grouped the species into two main branches at 57.4 percent similarity. The cultivated C. verum clustered tightly with both C. sinharajaense samples, so closely that Sri gemunu sat nearer to the wild species than to wild C. verum itself, a pattern driven by their shared wealth of eugenol and cinnamaldehyde. The remaining species formed a second cluster from which C. ovalifolium separated at 71.6 percent similarity, underscoring its chemical distinctiveness. For the researchers, this biochemical map is more than an academic exercise. It provides species-specific chemical fingerprints that can guide identification, quality control, and conservation prioritization, and it demonstrates that wild cinnamon trees respond to domestication with striking plasticity.

The broader implications reach from the rainforest to the pharmacy shelf and the spice rack. Wild Cinnamomum species in Sri Lanka are threatened by habitat loss and remain underutilized, yet they harbor unique phytochemical profiles with potential applications in pharmaceuticals, cosmetics, and food. The study’s authors argue that both in-situ protection of natural populations and ex-situ cultivation in new environments are essential, noting that moving species such as C. sinharajaense, C. citriodorum, and C. capparu-coronde into managed plots could actually enhance their biochemical value. They also acknowledge limitations, including modest sample sizes and the absence of metabolomic and genomic tools, and call for genome-wide association studies to uncover the genetic architecture underlying metabolite biosynthesis. For now, the message is clear: the wild relatives of the world’s favorite spice are not botanical relics but dynamic, chemically rich resources whose diversity may prove indispensable as climate change and rising demand test the resilience of global cinnamon production.

Subject of Research: Intraspecies phytochemical diversity of wild and cultivated Cinnamomum species in Sri Lanka

Article Title: Intraspecies diversity of the bioactive compounds of wild and cultivated Cinnamomum species in Sri Lanka

Article References: Bandusekara, B. S., Pushpakumara, D. K. N. G., Bandaranayake, P. C. G., Ranil, R. H. G., Wimalasiri, K. M. S., & Ranawaka, R. A. A. K. (2025). Intraspecies diversity of the bioactive compounds of wild and cultivated Cinnamomum species in Sri Lanka. BMC Agriculture, 1(1), Article 5. https://doi.org/10.1186/s44399-025-00004-y

Image Credits: AI Generated

DOI: 10.1186/s44399-025-00004-y

Keywords: cinnamon, Cinnamomum verum, Sri Lanka, phytochemical diversity, cinnamaldehyde, eugenol, coumarin, essential oils, HPLC, GCMS, plant conservation, crop wild relatives

The research team, led by Ahmed Abass Fadel and Khalid H. Alobaidi of Al-Nahrain University in Baghdad together with Jameel R. Al-Obaidi of Universiti Pendidikan Sultan Idris in Malaysia, screened 100 midstream urine samples from patients with symptomatic urinary tract infections at three Baghdad hospitals. Two E. coli isolates fulfilled the formal criteria for carbapenem resistance, showing minimum inhibitory concentrations of ertapenem of at least 8 mg/L, imipenem of at least 16 mg/L and meropenem of 8 mg/L, and they were additionally resistant to 15 of the 19 antimicrobial agents tested by the VITEK 2 automated system. The authors stress that the low recovery rate of only two CRE isolates reflects the actual prevalence of carbapenem resistance in their cohort rather than deliberate selection, and they frame their findings explicitly as proof-of-concept evidence.

The synthesis route was deliberately simple and environmentally benign. Dried cinnamon bark purchased from local markets in Baghdad was authenticated by the College of Agriculture at Al-Qasim Green University, ground into powder, and extracted in distilled water for 24 hours at room temperature. Anhydrous ferric chloride was then dissolved in the freshly prepared extract and stirred in darkness for 45 minutes, with the phytochemicals in the extract acting simultaneously as bioreductants, converting ferric iron into iron oxide, and as capping agents that adsorb onto the particle surface and stabilise the growing nanoparticles. The researchers recovered the precipitate by centrifugation, washed it with ethanol, and dried it at approximately 40 degrees Celsius before comprehensive physicochemical characterisation.

Characterisation data converged on the formation of an iron oxide nanoparticle preparation carrying a substantial organic corona. Ultraviolet-visible spectroscopy showed that the extract’s absorption maximum at 300 nanometres shifted to 290 nanometres in the nanoparticle preparation, a blue shift consistent with a change in the coordination environment of ferric iron during particle formation. Fourier-transform infrared spectroscopy revealed the diagnostic iron-oxygen stretching vibration at 621.08 per centimetre, alongside retained bands attributed to the phenolic hydroxyl, aliphatic carbon-hydrogen, carbonyl and carbon-carbon double bond functionalities of trans-cinnamaldehyde and related phytochemicals, confirming that the plant-derived molecules remained on the particle surface. Field-emission scanning electron microscopy showed dense, semi-spherical aggregates with an illustrative mean diameter of 65.63 nanometres, while atomic force microscopy, which the authors regard as the more statistically robust measurement because it sized 905 particles, yielded a mean diameter of 49.23 nanometres.

Energy-dispersive X-ray spectroscopy quantified the elemental composition as 61.01 percent carbon, 23.43 percent oxygen, 9.15 percent chlorine and 6.41 percent iron. The high carbon fraction reflects the abundance of the phytochemical capping layer, and the co-presence of iron and oxygen signals, together with the infrared evidence, supports iron oxide formation. However, X-ray powder diffraction showed a broad amorphous hump centred near 15 to 25 degrees two-theta with no discrete Bragg peaks, indicating that the room-temperature biogenic synthesis produced a predominantly amorphous or poorly crystalline material rather than a well-defined crystalline hematite phase. The authors accordingly use the designation iron oxide nanoparticles as a working label, note that the residual chlorine most plausibly represents trapped chloride within the organic corona, and identify calcination with confirmatory diffraction, together with X-ray photoelectron or Moessbauer spectroscopy, as priorities for unambiguous phase identification in future work.

The antibacterial results were striking. The crude cinnamon extract alone required a concentration of 25 milligrams per millilitre to inhibit the carbapenem-resistant UPEC culture, whereas the nanoparticle preparation achieved a minimum inhibitory concentration of 0.19 milligrams per millilitre, a 131.6-fold improvement in potency. The authors attribute this enhancement to three concurrent and synergistic mechanisms: Fenton-type hydroxyl radical generation by the iron oxide core, in which ferric iron is reduced to ferrous iron that reacts with hydrogen peroxide to produce highly reactive hydroxyl radicals capable of simultaneously attacking nucleic acids, membrane lipids and proteins; electrostatic interaction between the charged nanoparticle surface and the anionic lipopolysaccharide of the Gram-negative outer membrane, which promotes localisation of reactive oxygen generation at the cell surface; and the intrinsic antibacterial activity of the retained cinnamaldehyde- and eugenol-rich capping layer, which disrupts bacterial membranes and inhibits amino acid decarboxylases. Crucially, none of these mechanisms depends on the molecular machinery of carbapenem resistance, which typically involves carbapenemase enzymes that hydrolyse the beta-lactam ring, loss of porin channels such as OmpC, and active efflux via pumps such as AcrAB-TolC.

Anti-biofilm activity, measured with a crystal violet microplate assay over 24 hours, was potent and concentration-dependent. For the first isolate, blank-corrected biofilm inhibition reached 93.4 percent at 50 milligrams per millilitre and 73.7 percent at 12.5 milligrams per millilitre, with statistical significance confirmed by one-way analysis of variance with Tukey’s post-hoc test across three biological replicates. Near-complete suppression was observed for the second isolate at the highest concentration, although the researchers interpret that particular result cautiously because the blank absorbance was elevated at that dose. Biofilm formation is central to the clinical persistence of UPEC, particularly in catheter-associated infections, because the curli and cellulose matrix shields bacteria from antibiotics and immune clearance and creates conditions favourable for the horizontal transfer of resistance plasmids, including those carrying carbapenemase genes.

Perhaps the most novel dimension of the study is the transcriptional analysis. When the isolates were exposed to a sub-lethal concentration of the nanoparticles, half of the minimum inhibitory concentration, quantitative reverse-transcription PCR with the 16S rRNA gene as the reference showed strong suppression of two key virulence genes. Expression of csgD, the master regulator of curli and cellulose biosynthesis, fell by 93.8 percent in the first isolate and 89.1 percent in the second, a mean reduction of 91.5 percent. Expression of fimH, which encodes the adhesin at the tip of type 1 fimbriae that binds mannosylated uroplakin receptors on bladder cells and initiates the invasion-persistence cycle underlying recurrent infection, was reduced by 98.3 percent in the first isolate, roughly a 59-fold suppression, and by 80.7 percent in the second, a mean of 89.5 percent. The transcriptional suppression of csgD is mechanistically coherent with the observed anti-biofilm phenotype, since silencing this regulator dismantles the genetic programme for extracellular matrix assembly. The authors propose three non-exclusive explanations: sub-lethal reactive oxygen species may activate global stress regulators such as OxyR and SoxRS that divert transcriptional resources away from virulence; nanoparticle perturbation of intracellular iron homeostasis could dysregulate the ferric uptake regulator, which controls roughly 90 genes in E. coli including virulence loci; or direct nanoparticle-DNA interaction may impede transcription factor binding at the target promoters. None of these hypotheses was directly tested, and the team identifies RNA sequencing, regulator activity assays and intracellular iron quantification as needed follow-up experiments.

The authors are notably candid about the limitations of their work. The virulence gene data derive from only two treated biological replicates, below the conventional threshold of three for inferential statistics, so the fold-change values are presented as strong preliminary evidence requiring independent confirmation. Only two clinical isolates were available for testing, and species identification relied solely on the VITEK 2 system at a 92 percent identification probability without orthogonal molecular confirmation. No reference antibiotic comparator was included in the minimum inhibitory concentration assays, no reactive oxygen species detection or scavenger-rescue experiment was performed, and no dynamic light scattering, zeta potential, cytotoxicity, biocompatibility or in vivo efficacy data were generated. The researchers emphasise that therapeutic potential remains prospective rather than demonstrated, and that validation across a larger, phylogenetically diverse panel of CRE UPEC isolates, formal toxicity assessment and bladder colonisation models constitute essential next steps. Nevertheless, the combination of a 131.6-fold potency gain over the crude extract, 93.4 percent anti-biofilm activity and profound transcriptional silencing of the two pivotal UPEC virulence genes, in pathogens resistant to every carbapenem tested, marks this cinnamon-derived nanoparticle platform as a compelling in vitro candidate in the search for alternatives to conventional antibiotics against critical-priority resistance threats.

Subject of Research: Green-synthesised iron oxide nanoparticles as antibacterial and anti-virulence agents against carbapenem-resistant uropathogenic Escherichia coli

Article Title: In Vitro antibacterial, anti-biofilm, and virulence-modulating activity of Cinnamomum verum–mediated iron oxide nanoparticles against carbapenem-resistant uropathogenic Escherichia coli

Article References: Fadel, A. A., Alobaidi, K. H., & Al-Obaidi, J. R. (2026). In Vitro antibacterial, anti-biofilm, and virulence-modulating activity of Cinnamomum verum–mediated iron oxide nanoparticles against carbapenem-resistant uropathogenic Escherichia coli. International Microbiology. https://doi.org/10.1007/s10123-026-00876-3

Image Credits: AI Generated

DOI: 10.1007/s10123-026-00876-3

Keywords: iron oxide nanoparticles, green synthesis, Cinnamomum verum, carbapenem-resistant Enterobacteriaceae, uropathogenic Escherichia coli, biofilm, csgD, fimH, anti-virulence, urinary tract infection, reactive oxygen species, nanomedicine