Large-Leaved Linden (Tilia platyphyllos Scop.)
1. Identity and Botanical Classification
Tilia platyphyllos Scop., commonly known as the large-leaved lime, broad-leaved lime, or large-leaved linden, is a species of flowering plant in the family Malvaceae (formerly Tiliaceae). The species was formally described by the Italian botanist Giovanni Antonio Scopoli from Carniola, now part of Slovenia. The specific epithet platyphyllos derives from the Greek πλατύφυλλος, meaning "with broad leaves."
The tree is native to central and southern Europe and southwestern Asia, with a smaller range than the small-leaved linden, found in lowlands and lower hills. It can grow up to 30 metres tall; its trunk is straight, the crown wide and well developed, and the bark greyish. The leaves are 5–12 cm long, heart-shaped, somewhat asymmetrical, and serrated along the margin. The flowers hang down and are accompanied by a tongue-shaped modified leaf (bract), with blooms usually developing in groups of 2 to 6 in summer, white or cream-coloured.
Tilia platyphyllos readily hybridises with Tilia cordata, the hybrid being the common lime T. × europaea (syn. T. × vulgaris). The ripe fruits bear 5 longitudinal ribs, a characteristic that distinguishes this species from the small-leaved linden (Tilia cordata Mill.).
In European pharmacopoeial and regulatory contexts, the dried medicinal flower drug is referred to as Tiliae flos (lime flower). Tilia flos (lime flower) consists of the whole dried inflorescence of Tilia cordata Miller, of Tilia platyphyllos Scop., of Tilia × vulgaris Heyne or a mixture of these, according to the European Pharmacopoeia (2008). Herbal linden flower formulas typically call for either Tilia cordata, the small-leaved European linden also known as the winter linden, or Tilia platyphyllos, the large-leaved, early blooming summer linden.
The material of commerce originates mainly from Balkan countries such as Bulgaria, Romania, former Yugoslavia, Turkey, and in part from China.
Common Names and Synonyms
- English: large-leaved linden, large-leaved lime; Spanish: tilo, tilo de hojas grandes, tilo común; Catalan: tell de fulla gran; Basque: ezki hostozabala; Galician: tileiro; Portuguese: tília-de-folhas-grandes.
- Pharmacopoeial name: Tiliae flos (the dried inflorescence).
- Additional synonyms encountered in commerce include Tilia grandifolia, Tiliae folium, Tiliae lignum, lime blossom, lime flower, and European linden.
Common Preparations and Dosage Forms
Linden is a tree of which the dried flower, leaves, and wood are used for medicine. The primary medicinal part is the flower (with its attached bract), but the sapwood, charcoal, and leaves are also used in specific traditions.
- Herbal tea (infusion): A comminuted herbal substance prepared as herbal tea for oral use, typically 1.5 g of the comminuted herbal substance in 150 ml of boiling water.
- Liquid extract and tincture: Single doses of 1.5 g, daily doses of 3–6 g (Czech Pharmacopoeia); 1.5 g in 150 ml of boiling water, 2–4 times daily; liquid extract (1:1 in 25% alcohol) 2–4 ml daily; tincture (1:5 in 45% alcohol) 1–2 ml daily (British Herbal Pharmacopoeia 1976).
- Sapwood decoction: The dried sapwood is consumed as a decoction, used as a drainer of the liver and kidneys, especially in cases of uric acid overload, renal or biliary lithiasis, and digestive spasms.
- Charcoal: Tilia cordata/platyphyllos charcoal has been used orally to treat intestinal disorders and used topically to treat swelling (edema) or infection (such as cellulitis or ulcers) of the lower leg.
2. Traditional and Historical Use
Linden is an herb that comes from various species of Tilia, or lime tree, and has been used in European folk medicine for centuries to treat a wide range of health problems.
Pre-Christian and Ancient Europe
Especially Slavic cultures in the pre-Christian era considered linden as a holy tree ensuring health and happiness. In European tradition there are reports about the beneficial properties of baths with the addition of linden flower; it was believed that such baths allowed the quelling of hysteria. Among the ancient Slavs, linden was considered a talisman against diseases and lightning: its leaves were cut out on log cabins, and the infusion was used for fever. In a 17th-century Russian "Healing" herbal text, linden blossom is mentioned as "a sweat drink that drives away colds."
Medieval and Early Modern Europe
Since the Middle Ages, linden flowers have been considered a diaphoretic agent, as reported by one of the first Polish encyclopaedias (Wóycicki et al., 1864). Also since the Middle Ages, linden flower tea was used to treat and relieve symptoms of the common cold, throat irritation, upper respiratory tract disturbances, and also as a spasmolytic and mild sedative remedy.
German monastic herbalists recommended a decoction for "inflamed breasts," and healers of Galicia gargled it for sore throats. In ancient Gaul, linden was the traditional tree at the centre of a village under which inhabitants used to gather.
Central and Eastern European Traditions
In Poland, the monograph of Tiliae flos was defined in detail in the Polish Pharmacopoeia of 1970, while Inflorescentia Tiliae was known to stimulate secretory and excretory functions — diuretic, gastric fluid, bile flow, transpiration, and skin perspiration. It was used for oral administration as an infusion, as a supportive means in fever states with sore throat and bronchitis, and also in nervousness and states of nervous tension.
In Serbia, the linden flower is used to treat catarrh and for its diuretic, expectorant, and antispasmodic properties, while the leaf is used as a diaphoretic.
Anxiety and Nervous System
Flowers from two linden species (Tilia cordata and Tilia platyphyllos) were historically used to soothe nerves and treat health problems associated with anxiety. These flowers were steeped as a tea to relieve anxiety related to indigestion, irregular heartbeat, and vomiting.
Official Recognition
In Germany, lime flower is approved in the Commission E monographs (Blumenthal et al. 1998), and the tea form is official in the German Standard Licence monographs. Lime flower is also approved by the German Commission E Monograph and the British Herbal Pharmacopoeia (1976), meaning it has been used as a traditional remedy for a long time without safety problems for much more than 30 years. Authentication of plant material is performed according to the monograph in the 9th edition of the European Pharmacopoeia ("Tiliae flos," 2017) using microscopic examination and TLC analysis.
3. Key Constituents and Active Compounds
The main constituents present in the linden flower and responsible for its properties are: flavonoids, mainly quercetin (rutoside) and kaempferol glycosides (tiliroside, astragalin); condensed tannins (mainly procyanidins — dimeric, trimeric, tetrameric, and pentameric compounds); carbohydrates (arabinose, galactose, rhamnose, and also glucose, xylose, galacturonic, and glucuronic acid); saponins; phenolic acids; mucilage (mainly galactomannans); and volatile oil (farnesol, geraniol, eugenol, nerol, α-pinene, limonene, terpenes, citral, citronellol).
Flavonoids
A detailed phytochemical profile of Tilia platyphyllos Scop. inflorescences revealed the presence of flavonoids, mainly quercetin glycosides (rutin, hyperosid, quercitrin, isoquercitrin, quercetin-3,7-di-O-rhamnoside, quercetin-rhamno-xyloside, and quercetin-3-O-gluco-7-O-rhamnoside) and kaempferol glycosides (astragalin, tiliroside, kaempferol-3-O-gluco-7-O-rhamnoside, and kaempferol-3,7-di-O-rhamnoside).
The most pharmacologically prominent flavonoid marker is tiliroside (kaempferol-3-O-β-D-(6″-E-p-coumaroyl)-glucopyranoside). Flavonoids include kaempferol, quercetin, myricetin and their glycosides (mainly tiliroside); volatile oil (0.02% to 0.1%), containing many components including alkanes, phenolic alcohols and esters, and terpenes including citral, citronellal, citronellol, eugenol, limonene, nerol, and α-pinene.
Procyanidins and Tannins
High content of oligomeric and polymeric procyanidins, mainly composed of catechin and epicatechin building blocks such as prodelphinidin C and procyanidin B4, have been identified in T. platyphyllos inflorescences.
Mucilage Polysaccharides
Carbohydrates include mucilage polysaccharides (approximately 3%), with five fractions identified yielding arabinose, galactose, rhamnose, with lesser amounts of glucose, mannose, and xylose; galacturonic and glucuronic acids.
Volatile Oil
The fragrant components of the flowers degrade rapidly under conditions of high moisture. The volatile fraction, though present at only 0.02–0.1%, contributes to the characteristic fragrance and has been attributed a disinfecting effect in traditional use.
Bract Metabolomics
In a dedicated study of the metabolome of Tilia platyphyllos bracts from the appearance of the organ until senescence by LC-ESI-MS and data mining, a set of 504 natural products were detected, 241 of which showed significant seasonal variation. Seven compounds were quantified and 45 were putatively identified; these included flavonoid glycosides, catechins, procyanidins, quinic acid derivatives (including chlorogenic acid), and coumarins.
Novel Alkaloids
Novel piperidine and dihydropyrrole alkaloids from lime flower infusion (Tiliae flos) have been identified, and these have been shown to exert spasmodic activity on murine tracheal smooth muscle. This finding was noted in an addendum to the EMA HMPC assessment report (2021) as new information requiring continued monitoring.
4. Established Mechanisms of Action
Diaphoretic Action
Flavonoids, mainly tiliroside, are attributed to be responsible for diaphoretic (sweat-inducing) action. Active ingredients in linden help promote sweating, which may help treat people with fevers.
Mucilage-Mediated Soothing
Among the constituents in linden flower, mucilage has a protective, antitussive, and soothing effect on the irritation of the throat mucosa and the gastrointestinal tract.
Anti-inflammatory Activity
Quercetin and kaempferol glycosides have anti-inflammatory activity. Isolated flavonoid compounds tested in animal models were found to have anti-inflammatory, antinociceptive, and nephroprotective actions, suggesting these activities may be largely attributed to flavonoid constituents.
Anxiolytic and Sedative Mechanisms
One of the ligands (kaempferol) was identified in benzodiazepine receptor binding studies but had low affinity (Ki = 93 μM) for this receptor and did not produce sedative or anxiolytic effects in mice on its own. On the other hand, a complex fraction — containing yet unidentified constituents but probably of a flavonoid nature — when administered intraperitoneally in mice, had a clear anxiolytic effect in both the elevated plus-maze and hole-board tests, two well-validated pharmacological tests to measure anxiolytic activity.
Natural flavonoids possess a selective and relatively mild affinity for benzodiazepine receptors, but some of them might also produce their tranquilizing activity by acting on serotonergic receptors.
Diuretic Effect
Quercetin derivatives exhibit a weak diuretic effect.
Vascular / Capillary Protection
Rutoside increases the tightness of the capillaries, conferring protection against pathogens.
Antioxidant Activity
Tilia extracts possess the capacity to trap multiple reactive species, including O₂•⁻, HO•, HOCl, H₂O₂, and ¹O₂. These results suggest that free radical scavenging might be a part of the mechanisms underlying the antinociceptive, anxiolytic, and sedative effects previously observed in experimental models and in human use of traditional medicine.
Gut Microbiota Interaction
An ex vivo study found that linden flower extract changed human gut microbiota composition without causing dysbiosis. Both raw extract and its metabolites exhibited inhibition of cytokine production by LPS-stimulated neutrophils, with a reduction of TNF-α production observed. The linden flower extract promoted an increase in the abundance of bacteria responsible for short-chain fatty acid (SCFA) production, and the anti-inflammatory effect was linked to both microbiota composition changes and direct activity of bioavailable metabolites.
5. Scientific Evidence by Area of Use
5.1 Upper Respiratory Tract Infections and Cold Symptoms
Regulatory status: The EMA HMPC Community herbal monograph lists Tiliae flos as traditionally used for the relief of symptoms in the common cold (as a diaphoretic in feverish cold). Tiliae flos is intended for use in adolescents, adults, and elderly. It can also be used for the relief of symptoms of common cold in children between 4 and 12 years of age; however, use in children under 4 years of age for this indication has not been established due to lack of adequate data.
Evidence character: Scientific evidence on linden's effectiveness for these indications is lacking. Approval under the EMA HMPC monograph is based on traditional use rather than controlled clinical trials. The classification is as a "traditional herbal medicinal product," meaning that evidence from at least 30 years of medicinal use (including 15 years within the EU) satisfies the regulatory standard in lieu of clinical trials.
5.2 Anxiolytic and Sedative Effects
Human evidence: There are currently no published randomised controlled trials (RCTs) in humans specifically assessing Tilia platyphyllos for anxiety or insomnia.
Preclinical evidence: Studies from both Latin American (T. tomentosa) and European (T. platyphyllos, T. rubra, and T. argentea) species of Tilia have corroborated anxiolytic and sedative properties of flowers and bracts. In prior studies, significant and dose-dependent antinociceptive and anxiolytic-like activities were demonstrated after administration of hexane, methanol, and aqueous extracts of Tilia inflorescences (10–300 mg/kg), where glycosides of quercetin and kaempferol were characterised as the main active compounds.
Evidence strength: Animal and in vitro only. Clinical translation has not been established in rigorous human studies for this specific species.
5.3 Anticonvulsant Activity
Preclinical evidence: Phytochemical studies have reported that flavonoids — including quercitrin, isoquercitrin, kaempferol, astragalin, hyperoside, tiliroside, quercetin-3,7-O-dirhamnoside, and kaempferol-3,7-O-dirhamnoside — are major components of methanol extracts from the Tilia genus. The presence of flavonoids in the methanol extract suggests that the anticonvulsant properties shown by Tilia could be due to these compounds, which in previous studies have been implicated as responsible anticonvulsants and anxiolytics.
Evidence strength: Preclinical only (rodent models). No human clinical data available.
5.4 Anti-inflammatory and Antinociceptive Effects
Preclinical evidence: Extracts from the flowers, bracts, and inflorescences of T. cordata, T. platyphyllos, T. rubra, and T. tomentosa were evaluated for antioxidant activity, and their ability to mitigate inflammation was assessed through in vitro nitrite assays in LPS-induced RAW264.7 cells. The quercetin and kaempferol glycosides identified in T. platyphyllos have been independently characterised as anti-inflammatory agents in cell and animal models.
Evidence strength: In vitro and animal studies only. No clinical trials specifically for inflammatory conditions have been published.
5.5 Antispasmodic Effects
Extracts from Tiliae flos are used as antispasmodics and expectorants. Novel piperidine and dihydropyrrole alkaloids from lime flower infusion have been shown to exert spasmodic activity on murine tracheal smooth muscle, a finding that complicates the traditional ascription of antispasmodic effects to the plant and remains under evaluation.
Evidence strength: Preclinical; mechanistic evidence is mixed, with some alkaloid fractions showing opposing effects on smooth muscle.
5.6 Gut Microbiota and Anti-inflammatory Metabolic Effects
A study aimed to determine the interaction between human gut microbiota and linden flower extracts, resulting in biotransformation of the extract's constituents and changes in microbiota composition. Linden flower metabolites were obtained by incubation of the extract with human faecal slurries from 5 healthy donors; UHPLC-DAD-MSn analysis determined the composition of raw extract and analysis of microbial metabolites; intestinal microbiota isolation and sequencing were used to determine changes in microbiota composition. After incubation of linden flower extract with human gut microbiota, twenty metabolites were detected and characterised, and three among them were identified. The extract changed human gut microbiota composition. The linden flower extract promoted an increase in the abundance of bacteria responsible for SCFA production; the anti-inflammatory effect was linked to both microbiota composition changes and direct activity of bioavailable metabolites.
Evidence strength: Ex vivo (human faecal slurry model). Preliminary and mechanistic; no clinical trials.
5.7 Cardiovascular Effects
Linden has sedative effects and has been used to treat nervous palpitations and high blood pressure. However, clinical information is limited. No adequately powered RCTs assessing linden or T. platyphyllos specifically for blood pressure or cardiac function have been located in the published literature. Evidence at this level remains largely observational and traditional.
6. Body Systems and Health Areas
- Respiratory system: Today, linden is used in many cough and cold remedies. Traditional and pharmacopoeially recognised use for sore throat, cough, bronchitis, and feverish cold.
- Nervous system: Flowers from T. cordata and T. platyphyllos were historically used to soothe nerves and treat health problems associated with anxiety.
- Cardiovascular system: Linden has been used to treat nervous palpitations and high blood pressure.
- Digestive system: Inflorescentia Tiliae has been known to stimulate secretory and excretory functions including gastric fluid and bile flow. Dried bracts are traditionally consumed in herbal teas as antispasmodic, sedative, digestive, slightly diuretic, expectorant and perspirant remedies.
- Urinary system: Weak diuretic activity is attributed to quercetin derivatives; the sapwood decoction has been used in folk medicine for renal and biliary lithiasis.
- Hepatobiliary system: Tilia cordata/platyphyllos wood is used in some traditions for liver and gallbladder disorders.
- Skin: Linden has also been added as an ingredient in lotions to relieve itchy skin.
- Gut microbiome: Preliminary ex vivo evidence suggests modulation of human gut microbiota diversity and SCFA-producing bacteria.
7. Dosage Forms and Reported Doses
The following dosages are reproduced solely as reported in the cited authoritative sources and regulatory monographs:
- Herbal tea (comminuted dried flower): Single dose 1.5 g; daily dose 3–6 g (Czech Pharmacopoeia 2009); 1.5 g in 150 ml of boiling water, 2–4 times daily (Blumenthal et al. 1998).
- Single/usual daily dose (Hungarian Pharmacopoeia 1970): Single dose 0.5–1 g; usual daily dose 2.5–5 g.
- Liquid extract (1:1 in 25% alcohol): 2–4 ml daily (British Herbal Pharmacopoeia 1976).
- Tincture (1:5 in 45% alcohol): 1–2 ml daily (British Herbal Pharmacopoeia 1976).
- Upper limit (internal use): There are no recent clinical studies to support a specific dosage of linden. No more than 2 to 4 g/day of linden from teas or other preparations for internal use should be consumed.
Therapy for common cold symptoms should start at first signs; if symptoms persist longer than 1 week during use of the medicinal product, a qualified health care practitioner should be consulted.
8. Safety Considerations
8.1 Cardiotoxicity Concern
Although no recent clinical data has been published, the German Commission E monograph concluded that the linden flower is cardiotoxic. References in the German Commission E report that frequent use of linden flower teas has been associated with cardiac damage. However, this signal is contested: statements that overuse of linden can cause heart problems lack scientific merit. Both the German Commission E monograph and the American Herbal Products Association's guide on herbal safety state that linden has no toxic effects. In fact, linden is considered safe for use in children, and there are no known reasons to avoid it during pregnancy and breast-feeding according to those sources. The conflict between these positions reflects the absence of formal clinical toxicology studies and unresolved differences in interpretation of historical case reports.
8.2 Pregnancy and Lactation
In the absence of sufficient data and in accordance with general medical practice, the EMA HMPC recommends not using herbal medicinal products containing Tiliae flos (lime flower) during pregnancy and lactation.
8.3 Allergic and Hypersensitivity Reactions
Reports exist of specific toxicity such as contact urticaria, allergy from certain Tilia fruit oils in rats, seasonal pollinosis, organochlorine pesticide residues in linden-containing beverages, and occupational contact dermatitis with rhinoconjunctivitis from soft wood dust exposure.
8.4 Narcotic Intoxication Claims
There is no documentation supporting the belief that old linden flowers may induce narcotic intoxication.
8.5 Microbial Contamination (Infant Safety)
A concern documented in the literature is that linden flower (Tilia spp.) has been identified as a potential vehicle of Clostridium botulinum spores in the transmission of infant botulism, which has particular relevance to preparations given to infants.
8.6 Adulteration and Quality Control
There is a risk of adulteration with other Tilia species (e.g., Tilia tomentosa) which may have different phytochemical profiles, or with other plant materials. Pharmacopoeial authentication via microscopic and TLC methods is used to address this risk.
8.7 Novel Alkaloid Findings
Novel piperidine and dihydropyrrole alkaloids from lime flower infusion have been shown to exert spasmodic activity on murine tracheal smooth muscle. Tilia extracts also have antioxidant effects. The EMA HMPC addendum (2021) acknowledged these alkaloid findings as new information warranting continued scientific attention, though not triggering an immediate revision of the monograph at the time of reporting.
8.8 Volatile Component Stability
The fragrant components of the flowers degrade rapidly under conditions of high moisture. This has practical implications for storage and the quality of finished preparations.
References
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