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