The genus Sideritis, a member of the mint family Lamiaceae, comprises dozens of species distributed across the Mediterranean basin, and Turkey is one of the richest centers of diversity for the group. Locally, the dried flowering aerial parts of these plants are steeped as a soothing infusion, often called mountain tea or dağ çayı, and traditionally used to ease digestive complaints, calm colds, and support general wellbeing. Earlier pharmacological work on the genus has documented anti-inflammatory, antioxidant, antimicrobial, and antispasmodic properties, which has fueled growing scientific and commercial interest in these plants. Yet many Anatolian species remain poorly characterized, and distinguishing between closely related taxa can be surprisingly difficult, both for botanists and for the herbal trade that depends on correctly identified raw material.

That identification problem is precisely where the new study makes its most practical contribution. The researchers set out to determine whether specific secondary metabolites, particularly the phenylethanoid glycoside martynoside, could serve as discriminative chemotaxonomic markers, chemical fingerprints that reliably distinguish one species from another. Chemotaxonomy, the use of chemical profiles to classify and authenticate organisms, has become an increasingly valuable tool as global demand for herbal products rises and adulteration or mislabeling of medicinal plants becomes a genuine concern. For endemic species with limited geographic ranges, such as the two Anatolian Sideritis taxa examined here, robust chemical markers could help protect both consumer safety and biodiversity.

To build those fingerprints, the team deployed a two-pronged analytical strategy. First, they characterized the essential oil compositions of both plants using gas chromatography with flame ionization detection and gas chromatography coupled to mass spectrometry, the gold-standard techniques for resolving and identifying volatile compounds. Second, they mapped the non-volatile phenolic constituents using liquid chromatography tandem mass spectrometry, or LC-MS/MS, which allows researchers to detect and tentatively identify polar compounds such as flavonoids and phenylpropanoid glycosides with high sensitivity. The biological potential of the extracts was then evaluated through a battery of standardized antioxidant and antimicrobial assays, allowing the researchers to correlate the chemical findings with measurable functional activity rather than relying on chemistry alone.

The essential oil results revealed two strikingly different volatile worlds. Sideritis syriaca subsp. nusairiensis produced a hydrocarbon-dominated profile, with its most abundant constituents being hexahydrofarnesyl acetone at 11.7 percent, hexadecanoic acid at 11.6 percent, and the long-chain alkane nonacosane at 10.9 percent. This composition translates into the waxy, fatty olfactory notes often associated with cuticle lipids and long-chain molecules. Sideritis argyrea, by contrast, displayed a terpene-rich profile dominated by monoterpenes and sesquiterpenes: beta-pinene at a remarkable 35.5 percent, alpha-pinene at 24.3 percent, and the sesquiterpenoid epi-cubebol at 13.0 percent. Anyone who has walked through a pine forest will recognize the significance of that pinene content, because these compounds are responsible for the fresh, resinous, pine-like aroma that characterizes many coniferous landscapes.

These chemical differences were not merely academic curiosities. The researchers noted that the volatile profiles correlated directly with the olfactory characteristics of the two plants, explaining why the two mountain teas would smell and taste noticeably different despite their close relationship. The waxy and fatty notes of Sideritis syriaca subsp. nusairiensis stand in sharp contrast to the crisp, fresh pine character of Sideritis argyrea. For the herbal tea industry, where aroma is a key driver of consumer preference and product identity, such distinctions carry real economic weight. They also provide a practical means of authentication: a supplier or regulator could, in principle, verify the botanical identity of a batch of dried mountain tea simply by analyzing its volatile profile.

The phenolic analysis added another layer of differentiation. LC-MS/MS identified a higher prevalence of methylated and acylated flavonoid and phenylpropanoid derivatives in Sideritis argyrea compared with its counterpart. Methylation and acylation are biochemical modifications that alter the solubility, stability, and biological behavior of plant phenolics, and their prevalence in one species but not the other reinforces the idea that these two taxa have followed genuinely divergent metabolic paths. Phenylethanoid glycosides such as verbascoside and martynoside, compounds well documented in the Lamiaceae family and studied for their antioxidant and anti-inflammatory properties, form part of this phenolic repertoire and underpin the study’s chemotaxonomic argument.

When the team turned to biological testing, the functional differences between the two species became even more apparent. Sideritis argyrea exhibited more pronounced antioxidant activity, achieving an IC50 value of 0.18 milligrams per milliliter in the standardized assays, and it demonstrated a broader antifungal spectrum, with particularly notable activity against Candida species. The IC50 value, the concentration required to neutralize half of the free radicals in the test system, serves as a widely used benchmark of antioxidant potency, and lower values indicate stronger activity. Candida species are yeasts that include common human pathogens, and the rise of antifungal resistance has made the search for new antifungal compounds from natural sources an urgent priority in medical mycology.

The superior performance of Sideritis argyrea in both antioxidant and antifungal assays aligns neatly with its chemical profile. Terpene-rich essential oils, particularly those abundant in pinenes, are well known for antimicrobial properties, and the elevated levels of modified flavonoids and phenylpropanoids likely contribute additional radical-scavenging capacity. The authors conclude that Sideritis argyrea possesses genuine potential as a source of natural bioactive substances with medicinal interest. At the same time, they are careful to frame their findings within the scope of the investigated populations, a scientifically responsible caveat given that essential oil composition in plants can vary with geography, altitude, harvest time, and environmental conditions.

Beyond the laboratory findings, the study carries broader implications for conservation and commerce. Both taxa are endemic to Anatolia, meaning they grow nowhere else on Earth, and endemic plants with medicinal reputations are often vulnerable to overharvesting as demand grows. Reliable chemotaxonomic markers give researchers and regulators the tools to authenticate plant material, trace supply chains, and support sustainable cultivation initiatives, much as DNA barcoding has been proposed for related Sideritis species destined for industrial cultivation. For now, the message from the Turkish team is clear: the two mountain teas of Anatolia are not interchangeable. One smells of pine and fights microbes with terpene firepower, while the other carries a waxy, fatty signature and a different phenolic arsenal. As interest in functional foods and plant-based therapeutics continues to surge worldwide, studies like this one remind us that the fine chemical details separating closely related plants can determine everything from the flavor in the cup to the future of a species on a mountainside.

Subject of Research: Comparative phytochemistry and biological activities of two endemic Anatolian Sideritis mountain tea species

Article Title: Comparative phytochemical analysis and biological activities of two Anatolian Mountain Teas: Sideritis syriaca subsp. nusairiensis and Sideritis argyrea

Article References: Saltan, N., Iscan, G., Kose, Y. B., Goger, F., & Demirci, B. (2026). Comparative phytochemical analysis and biological activities of two Anatolian Mountain Teas: Sideritis syriaca subsp. nusairiensis and Sideritis argyrea. Plant Biosystems, 160(4), Article 223. https://doi.org/10.1007/s44473-026-00231-4

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00231-4

Keywords: Sideritis, mountain tea, chemotaxonomy, essential oil, GC-MS, LC-MS/MS, antioxidant, antifungal, phenolic compounds, beta-pinene, Anatolia, endemic plants