Tiliroside

Tiliroside: A Comprehensive Reference Article

1. Identity and Chemical Characterization

1.1 Chemical Names and Synonyms

Tiliroside is chemically designated as kaempferol-3-O-(6′′-p-coumaroyl)-glucoside, a flavonoid glycoside found in rose hips, strawberries, and raspberries. It is a member of the flavonol class of polyphenols. Additional synonyms include astragalin 6″-trans-p-coumarate and Potengriffioside A, and it is registered under CAS number 20316-62-5, with a molecular weight of 594.52. The compound also appears in the literature as tribuloside. The trans (E-configured) isomer is the naturally predominant and biologically active form, commonly referred to as trans-tiliroside; a cis isomer (CAS 163956-16-9) also exists but is far less studied.

The molecular formula of tiliroside is C₃₀H₂₆O₁₃, with an exact mass of 594.525. Structurally, the molecule is built from three components covalently linked: kaempferol (the flavonol aglycone), a β-D-glucopyranose sugar attached at the 3-position of kaempferol, and a p-coumaric acid esterified at the 6″ position of the glucose. This makes tiliroside an acylated flavonol glycoside, specifically a flavonol glycoside ester.

1.2 Biosynthesis and Natural Sources

Tiliroside was first identified in hips of Rosa canina and is commonly found in various parts including fruits, leaves and roots of about 200 plant species coming from 35 different families. Tiliroside was first isolated from Rosa canina, and to date it has been found in 172 species, mostly from the Rosaceae and Malvaceae families. It is most abundant in flowers, followed by leaves, with the lowest concentration in roots and fruits.

According to published literature, tiliroside is present in several plant species belonging to different botanical families, including Araliaceae, Asteraceae, Euphorbiaceae, Lamiaceae, Malvaceae, and Rosaceae. Notable botanical sources confirmed by analytical studies include:

• Rosa canina (dog rose / rose hip): Tiliroside is contained in several dietary plants, such as rose hips, strawberry and raspberry. The seeds of the rose hip pseudofruit are especially rich.
• Tilia spp. (linden / lime tree): Tiliroside, a unique flavonoid identified in Tilia miqueliana Maxim., exhibits diverse biological activities, including anti-oxidation, anti-microbial, anti-inflammatory, anti-diabetic, and hepatoprotective effects. Since the synthesis of tiliroside is expensive, linden trees are a very good source of this compound, particularly given its anti-inflammatory effects and possible wider use in the cosmetic industry.
• Fragaria spp. (strawberry) and Rubus idaeus (raspberry): Defatted strawberry seeds proved to be a convenient source of tiliroside because the matrix of accompanying components is relatively poor, which facilitates separation.
• Potentilla spp. and Agrimonia pilosa: A significant amount of tiliroside was detected in the aerial parts of some Potentilla spp. and in the flowers of Gossypium hirsutum, Rosa rugosa, Althaea rosea, Tilia cordata, and T. platyphyllos.
• Additional species quantified by HPLC include Malva sylvestris, Althaea officinalis, Lavatera thuringiaca, and Lamium album, based on chromatographic separation studies. Tiliroside has been separated and quantified from leaves and inflorescences of Tilia cordata and Tilia platyphyllos, herb of Malva sylvestris, leaves of Althaea rosea, leaves of Lavatera thuringiaca, herb of Potentilla anserina, herb of Lamium purpureum and Lamium album, as well as leaves and roots of Althaea officinalis.

Biosynthetically, first the synthesis of the aglycone (a flavonoid) occurs, which follows the shikimate pathway with cinnamoyl-CoA as a starter unit. Second, there is glucosylation of the aglycone using uridine diphosphosugar (UDPglucose) as the agent for glycosylation. The p-coumaroyl moiety is then esterified onto the 6″ position of the glucose.

1.3 Common Forms and Preparations

Among flavonoid derivatives, tiliroside is a flavonoid contained in several edible plants or specific plant parts (fruits, leaves, or roots). These parts are often widely used as both food and medicines, in the treatment of various ailments and, in some cases, as food supplements. In research and commercial contexts, tiliroside is available in several forms:

• Standardized plant extracts: Rose hip seed extract is the most commercially developed form. The rosehip extract (RHE) used in clinical research contained aqueous ethanol extract from rosehips and excipients, and the standardized tiliroside content was more than 0.1% (w/w).
• Isolated pure compound: Tiliroside can be isolated via chromatographic methods including silica gel, RP-18, and Sephadex LH-20 column chromatography, and is available as a reference standard for research use.
• Linden flower extracts (Tiliae flos): Forty-six various extraction methods have been developed to obtain tiliroside from Tilia L., including ultrasound-assisted extraction, maceration, maceration with stirring, accelerated solvent extraction, and extraction under reflux.

2. Traditional and Historical Use

Tiliroside itself was not known as a discrete compound to traditional healers; rather, it was consumed through the traditional use of the plants in which it is a key constituent. Tiliroside is a flavonoid contained in several edible plants or specific plant parts (fruits, leaves, or roots). These parts are often widely used as both food and medicines, in the treatment of various ailments.

2.1 Rosa canina (Rose Hip) in European and Middle Eastern Traditions

Rose hips have been used as both food and medicine for centuries across European, Asian, and Native American traditions, commonly prepared as jams, jellies, syrups, teas, and more recently as standardized supplements. Rose hip is a good source of different types of micronutrients and phytochemicals such as phenolic acids, tannins and flavonoids. Rose hip has a long history of traditional uses in folk medicine. It has been used for the treatment of several illnesses including ear, nose, and throat problems. In traditional European folk medicine, rose hip has been used as a laxative, diuretic, anti-gout and anti-rheumatism medication.

In Iranian folk medicine, the fruits of Rosa canina were used for treatment of kidney stone, respiratory problems (cough, bronchitis and cold), diarrhea, hypertension, diabetes and jaundice. During World War II, rose hips were widely collected in Britain as a critical source of vitamin C when citrus imports were unavailable.

2.2 Tilia spp. (Linden) in European and East Asian Traditions

Linden flowers (Tiliae flos) have been used for centuries in European herbal medicine, predominantly as teas and infusions for their relaxing and diaphoretic properties. Linden contains flavonoids (especially quercetin and kaempferol), caffeic and other acids, mucilage (about 3%), tannins, volatile oil (0.02–0.1%), and traces of benzodiazepine-like compounds. Folk medicine has employed linden as an antispasmodic. Among the flavonoid glycosides present in linden, tiliroside was the principle flavonol glycoside and showed the most potent activity; astragalin and isoquercitrin also possessed strong hepatoprotective effects against d-galactosamine/lipopolysaccharide-induced liver injury in mice.

2.3 Agrimonia and Potentilla in Chinese and European Traditions

Agrimonia pilosa (hairy agrimony) has a long history of use in Traditional Chinese Medicine (TCM) as a hemostatic, anti-inflammatory, and antiparasitic agent. It is prepared as decoctions and used for gastrointestinal complaints, fever, and wounds. Tiliroside is the major component of Agrimonia pilosa Ledeb ethanol extract. In animal models, in vivo anti-inflammatory activity of the extract was confirmed in xylene-induced ear edema in mice and carrageenan-induced paw edema in rats. Tiliroside, the major component of the extract, was isolated and purified by high-performance liquid chromatography.

Potentilla chinensis (Chinese cinquefoil) is used in TCM in the treatment of diarrhea, dysentery, and febrile conditions. A study was carried out to isolate and identify trans-tiliroside as the principal compound with anti-hyperglycemic, anti-hyperlipidemic and antioxidant effects from Potentilla chinensis. A bioactive compound, trans-tiliroside, was isolated from the ethanol extract of Potentilla chinensis and its administration dose was optimized and patented.

3. Key Constituents, Chemical Context, and Mechanisms of Action

3.1 The Role of the p-Coumaroyl Moiety

Tiliroside has been reported to inhibit neuroinflammation and acute inflammation; notably, all of these effects have been attributed to the antioxidant activity of these compounds. The role of the p-coumaroyl moiety found in these flavonoid glycoside compounds in their antioxidant activity remains an active area of investigation, despite numerous studies towards the structure–activity relationships of flavonoids and flavonols. Comparing tiliroside directly with its deacylated counterpart, astragalin (kaempferol-3-O-glucoside), reveals that the p-coumaroyl ester distinctly enhances certain antioxidant and cytoprotective properties.

3.2 Anti-Inflammatory Mechanisms

Tiliroside exerts its anti-inflammatory effects through a variety of mechanisms, such as the inhibition of inflammatory mediators' cytokines and chemokines, as well as the suppression of nuclear factor-kappa B (NF-κB) signaling pathways. Additionally, it demonstrates potent antioxidant properties, which further contribute to its anti-inflammatory activity by reducing oxidative stress.

At the molecular level, a key study using LPS-activated RAW 264.7 macrophages established that the anti-inflammatory molecular mechanism of tiliroside may involve the downregulation of iNOS and COX-2 protein expression levels, and the inactivation of mitogen-activated protein kinase (MAPK)/JNK, in addition to the MAPK/p38 signaling pathway.

In relation to neuroinflammation, two studies demonstrated that tiliroside decreased cytokine production such as TNF-α and IL-6 in LPS-treated BV2 microglia cells (the resident macrophages of the brain), implying the inhibition effect of tiliroside on inflammatory responses in LPS-treated macrophages.

3.3 Antioxidant Mechanisms (Nrf2/KEAP1 Pathway)

One of the most significant and recurrently documented mechanisms is tiliroside's activation of the Nrf2 (nuclear factor erythroid 2-related factor 2) antioxidant pathway. Tiliroside increased protein levels of Nrf2, HO-1 and NQO1, indicating an activation of the Nrf2 protective mechanisms in microglia. Transfection of BV2 cells with Nrf2 siRNA resulted in the loss of anti-inflammatory activity by tiliroside.

Molecular docking, cellular thermal shift assay, and RNA-seq analysis revealed that tiliroside promoted the activation of NRF2 and the expression of its downstream genes through disruption of the NRF2-KEAP1 protein-protein interaction to inhibit KEAP1-mediated ubiquitination and degradation of NRF2, thereby inhibiting oxidative stress. Tiliroside inhibited NRF2 ubiquitination-mediated degradation, suggesting that it may be an inhibitor of the KEAP1-NRF2 protein-protein interaction (PPI).

3.4 Metabolic and Adiponectin Signaling Mechanisms

Plasma insulin, free fatty acid and triglyceride levels were decreased, and plasma adiponectin levels were increased in mice administered tiliroside. Tiliroside treatment activated AMP-activated protein kinase (AMPK) in both the liver and skeletal muscle and peroxisome proliferator-activated receptor α (PPARα) in the liver.

These findings suggest that tiliroside enhances fatty acid oxidation via the enhancement of adiponectin signaling associated with the activation of both AMP-activated protein kinase and peroxisome proliferator-activated receptor α.

3.5 Enzyme Inhibition and Carbohydrate Metabolism

Tiliroside inhibits pancreatic α-amylase (IC₅₀ = 0.28 mM) in vitro and was found to be a noncompetitive inhibitor of α-amylase with K_i values of 84.2 μM. Tiliroside administration inhibited the increase of plasma glucose levels in an oral glucose tolerance test, but not in an intraperitoneal glucose tolerance test. In human intestinal Caco-2 cells, the addition of tiliroside caused a significant dose-dependent inhibition of glucose uptake.

3.6 Microbial Metabolism of Tiliroside

It has been reported that tiliroside is metabolized into its aglycone form, kaempferol, by intestinal microbiota. In addition, astragalin (kaempferol-3-O-glucoside) and p-coumaric acid have also been identified as microbial metabolites of tiliroside. This metabolic transformation is relevant to interpreting the compound's in vivo bioactivity, as some effects may be attributable to these downstream metabolites rather than tiliroside itself.

4. Scientific Evidence by Area of Use

4.1 Metabolic Health: Obesity and Adiposity

Preclinical evidence: In a study performed on mice, Ninomiya et al. found that extract of the seeds of Rosa canina that was rich in tiliroside, as well as pure tiliroside isolated from Rosa canina, significantly reduced body weight and visceral fat gain after a treatment period of 14 days or less. Ninomiya et al. showed that an 80% aqueous acetone extract of the whole fruit of R. canina significantly suppressed body weight gain and prevented increases in visceral fat in nonobese mice without any changes in diet intake. They also reported that tiliroside upregulated the expression of PPARα messenger RNA in the liver.

In the genetically obese-diabetic KK-A^y mouse model, administration of tiliroside (100 mg/kg body weight/day) for 21 days failed to suppress body weight gain and visceral fat accumulation. Although tiliroside did not affect oxygen consumption, respiratory exchange ratio was significantly decreased in mice treated with tiliroside. This indicates metabolic fuel partitioning toward fat oxidation even in the absence of gross weight loss in that model.

Human/Clinical evidence: One single-blind, placebo-controlled human trial in people whose BMI was between 25 and 30 for 12 weeks found that, in those taking 100 mg rose hip extract containing at least 0.1% of tiliroside, abdominal visceral fat area decreased by 9.23 cm² (versus a 3.24 cm² increase in the placebo group) and bodyweight decreased by 1.4 kg (versus a 0.26 kg decrease in those taking placebo).

A systematic review that aimed to shed light on existing literature on the correlation between intake of rose hip extracts and anti-obesity effects, with a literature search of PubMed and Web of Science, identified nine articles meeting the inclusion criteria, including one in vitro study, seven in vivo animal studies, and one human trial with pre-obese subjects. Eight out of nine articles, including the article on humans, presented significant anti-obesity effects, though some limitations of the studies were found, including in the human trial.

Evidence strength: Preliminary. The mechanistic preclinical data are consistent, but the only available human trial used a whole rose hip extract standardized for tiliroside content rather than isolated tiliroside, was single-blind rather than double-blind by design, and involved a small number of subjects. The contribution of tiliroside specifically — versus other rose hip constituents — to the observed human effects cannot be definitively isolated.

4.2 Metabolic Health: Glycemia and Diabetes

Preclinical evidence: In male ICR mice, the increase in postprandial plasma glucose levels was significantly suppressed in the tiliroside-administered group. Tiliroside treatment also suppressed hyperinsulinemia after starch administration. These findings indicate that the anti-diabetic effects of tiliroside are at least partially mediated through inhibitory effects on carbohydrate digestion and glucose uptake in the gastrointestinal tract.

Plasma insulin, free fatty acid and triglyceride levels were decreased, and plasma adiponectin levels were increased in mice administered tiliroside, suggesting insulin-sensitizing properties mediated through adipokine signaling. A 21-day administration of tiliroside was found to enhance AMPK phosphorylation in the liver and muscle.

Human/Clinical evidence: No published clinical trials have investigated tiliroside as an isolated compound in human diabetic populations. Studies using whole rose hip extract in type 2 diabetic patients exist, but these cannot be attributed specifically to tiliroside content.

Evidence strength: Preclinical only (animal and in vitro). Translational value to humans remains to be established in controlled clinical trials.

4.3 Anti-Inflammatory Effects

In preclinical studies, tiliroside has shown promising results in ameliorating inflammation in conditions like rheumatoid arthritis, inflammatory bowel disease, and atherosclerosis.

Tiliroside and two other flavonoids were analyzed in vitro for their antioxidant properties and in vivo for their anti-inflammatory properties. In vivo, tiliroside significantly inhibited the mouse paw edema induced by phospholipase A and the mouse ear inflammation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA).

Additionally, tiliroside inhibits pro-inflammatory M1 macrophage polarization by blocking the HIF-1α/glycolysis pathway in mouse BMDMs and human THP-1 macrophage cells. In a model of ulcerative colitis, tiliroside administration effectively modulated the balance between pro-inflammatory M1 and anti-inflammatory M2 macrophages.

Evidence strength: Primarily in vitro and animal model-based. No controlled human trials have evaluated tiliroside as an isolated compound for inflammatory conditions.

4.4 Neurological Effects and Neuroprotection

Tiliroside was investigated for its effects on neuroinflammation following activation of BV2 microglia with a combination of lipopolysaccharide (LPS) and gamma interferon (IFNγ). The study also evaluated whether tiliroside could activate the Nrf2/HO-1 antioxidant protective mechanism in BV2 microglia.

Tiliroside increased protein levels of Nrf2, HO-1 and NQO1, indicating an activation of the Nrf2 protective mechanisms in microglia. Transfection of BV2 cells with Nrf2 siRNA resulted in the loss of anti-inflammatory activity by tiliroside. Tiliroside reduced protein levels of acetylated-NF-κB-p65, and increased SIRT1 in LPS/IFNγ-activated BV2 microglia.

Results of neurotoxicity experiments revealed that neuroinflammation-induced toxicity, DNA fragmentation, ROS generation and calcium accumulation in HT22 neurons were significantly reduced by tiliroside treatment.

Overall, a further study established that tiliroside protected BV2 microglia from LPS/IFNγ-induced neuroinflammation and HT22 neuronal toxicity by targeting Nrf2 antioxidant mechanisms. The compound also produced inhibition of NF-κB acetylation through activation of SIRT1, as well as increasing SIRT1 activity in mouse hippocampal neurons.

Evidence strength: In vitro cell-culture data only. No animal or human studies have specifically tested tiliroside for neurological endpoints such as cognitive function or neurodegenerative disease progression.

4.5 Hepatoprotective Effects

In vivo, tiliroside attenuated acetaminophen-induced acute liver injury (AILI) in mice significantly, as evidenced by lower ALT and AST levels. Molecular docking, cellular thermal shift assay, and RNA-seq analysis revealed that tiliroside promoted the activation of NRF2 and the expression of its downstream genes through disruption of the NRF2-KEAP1 protein-protein interaction to inhibit KEAP1-mediated ubiquitination and degradation of NRF2, thereby inhibiting oxidative stress in the livers of AILI mice.

Hepatocyte-specific NRF2 knockout mice exhibited more severe liver injury induced by acetaminophen (APAP), which could not be improved by tiliroside treatment, suggesting that tiliroside's hepatoprotective effects were mediated by NRF2. Similarly, tiliroside has a direct antioxidative stress effect on cultured human hepatocyte THLE-2 cells. Furthermore, the hepatoprotective effects of tiliroside on THLE-2 cells were significantly attenuated by NRF2 deletion.

Evidence strength: Preclinical (mouse in vivo and human cell line in vitro). No human clinical trials exist for tiliroside as a hepatoprotective agent.

4.6 Renoprotective Effects

Mechanistic studies indicated that tiliroside promoted NRF2/GPX4 pathway activation and ferroptosis inhibition, perhaps via the disruption of the NRF2-KEAP1 protein-protein interaction, in a study on acute kidney injury. Ferroptosis — a form of iron-dependent regulated cell death — appears to be a relevant mechanism in acute kidney injury, and tiliroside's ability to activate the NRF2/GPX4 axis positions it as a candidate protective compound in this context.

Evidence strength: Preclinical only (animal models and cell culture). No human data available.

4.7 Hyperuricemia and Gout

Although tiliroside exhibited weak xanthine oxidase (XO) inhibition (IC₅₀ > 100 µM), it significantly suppressed uric acid (UA) production in hepatocytes in a concentration-dependent manner. In hyperuricemic mice, tiliroside (300 mg/kg) lowered plasma and hepatic UA levels by approximately 30% and 55%, respectively (p < 0.05).

Hepatic XO activity was significantly decreased while XO protein expression remained unchanged. Furthermore, mRNA levels of urate transporter 1 (URAT1) were significantly decreased in the kidney of tiliroside-treated hyperuricemic mice. These findings suggest that tiliroside exerts antihyperuricemic effects by suppressing UA production in the liver and modulating renal UA reabsorption.

Of note, kaempferol, a metabolite of tiliroside, exhibited strong XO inhibitory activity (IC₅₀ = 3.9 µM), raising the possibility that some antihyperuricemic activity observed with tiliroside in vivo reflects its metabolic conversion to kaempferol.

Evidence strength: Preclinical only (mouse model and cell culture). No human trials.

4.8 Anticancer Effects

Several in vivo and in vitro studies have indicated tiliroside's anticancer activity against small-cell lung cancer A549 cells, prostate carcinoma PC-3M, breast cancer MCF-7 and T47D, and leukemia cell lines.

In ovarian cancer, tiliroside exerted anti-tumor activities by inducing cell death and inhibiting the invasion and migration of A2780 and OVCAR8 cells. The suppressive effect on ovarian cancer cells was mainly due to the induction of ferroptosis, as demonstrated by the accumulation of ROS, MDA, and Fe²⁺ and a reduction in GPX4 expression.

Tiliroside isolated from Pavonia malacophylla was investigated for its ability to block SARS-CoV-2 viral entry. It was chemically characterized and tested for inhibition of the SARS-CoV-2 Spike receptor-binding domain (RBD)–human ACE2 interaction using a bioluminescent immunoassay. At 10 µM, it inhibited 63% of RBD:ACE2 binding. This finding remains in vitro and exploratory.

Evidence strength: Predominantly in vitro. No clinical oncology data exist for tiliroside as an isolated agent.

4.9 Skin and Dermatological Effects

Tiliroside acts beneficially on skin cells by protecting them from oxidative stress and inflammation, decreasing tyrosinase activity, enhancing the ceramide layer, and thereby preventing moisture loss. These properties suggest potential applications as both a cosmetic and dermatological active ingredient, though the evidence base is preclinical.

Evidence strength: Preclinical (cell culture and in vitro assays). No published human clinical trials.

5. Body Systems and Health Areas Associated with Tiliroside

• Metabolic system: Numerous scientific studies indicate that tiliroside possesses antiobesity and antidiabetic properties.
• Immune and inflammatory system: In preclinical studies, tiliroside has shown promising results in ameliorating inflammation in conditions like rheumatoid arthritis, inflammatory bowel disease, and atherosclerosis.
• Nervous system: Tiliroside possesses a positive impact on the nervous system, primarily demonstrated through anti-neuroinflammatory mechanisms in microglial cell models.
• Hepatic (liver) system: Plant materials containing tiliroside show hepatoprotective activities.
• Renal (kidney) system: Tiliroside has demonstrated renoprotective effects via NRF2/GPX4 activation and anti-ferroptotic mechanisms in acute kidney injury models.
• Cardiovascular system: Plant materials containing tiliroside show antithrombotic and anticoagulant activities.
• Gastrointestinal system: Tiliroside inhibits carbohydrate digestion and intestinal glucose absorption through α-amylase inhibition and transporter-mediated mechanisms in the gut.
• Integumentary (skin) system: Tiliroside acts beneficially on skin cells by protecting them from oxidative stress and inflammation, decreasing tyrosinase activity, enhancing the ceramide layer, and thereby preventing moisture loss.

6. Dosage Forms and Reported Dosages

No standardized clinical dosing regimen for isolated tiliroside has been established. The following dosages are those reported in published studies and should not be interpreted as clinical recommendations:

• Human clinical trial (rose hip extract, standardized to tiliroside): One single-blind, placebo-controlled human trial used 100 mg rose hip extract containing at least 0.1% of tiliroside, taken daily over 12 weeks, in pre-obese subjects (BMI 25–30).
• Animal study (normal mice, anti-obesity): Ninomiya et al. administered 0.1–10 mg/kg of tiliroside to mice for 2 weeks and observed the suppression of body weight gain and decreased amount of visceral fat.
• Animal study (obese-diabetic mice, metabolic effects): In obese-diabetic KK-A^y mice, tiliroside was administered at 100 mg/kg body weight/day for 21 days.
• Animal study (hyperuricemia): In hyperuricemic mice, tiliroside at 300 mg/kg lowered plasma and hepatic UA levels by approximately 30% and 55%, respectively.
• In vitro (cancer cells): Cancer cells were treated with 40, 80, and 160 µM tiliroside in cellular experiments assessing anti-cancer effects.

Since the synthesis of tiliroside is expensive, linden trees are a very good source of this compound. Considering an increasing demand for tiliroside and benefits of the research on this compound, particularly regarding its anti-inflammatory effects and possible wider use in the cosmetic industry, efficient extraction methods are an active area of development.

7. Pharmacokinetics and Bioavailability

Absorption and metabolism of tiliroside and its related compounds kaempferol, kaempferol-3-glucoside and p-coumaric acid were investigated in the small intestinal Caco-2 cell model. Apparent permeation (Papp) was determined as 0.62 × 10⁻⁶ cm/s for tiliroside, compared with 3.1 × 10⁻⁶ cm/s for kaempferol and 22.8 × 10⁻⁶ cm/s for p-coumaric acid. These figures indicate that tiliroside itself has markedly limited passive permeability compared to its metabolites.

Mechanistic study showed that the transportation of tiliroside in the Caco-2 model was transporter-mediated, while transportation of kaempferol was solely by passive diffusion. Efflux transporters, multi-drug-resistance-associated protein-2 (MRP2), were shown to play a role in limiting the uptake of tiliroside.

Metabolites of kaempferol-3-glucoside and p-coumaric acid were not detected in the current Caco-2 model, while tiliroside was metabolised to a limited extent, with two tiliroside mono-glucuronides identified; and kaempferol was metabolised to a higher extent, with three mono-glucuronides and two mono-sulfates identified.

Tiliroside was metabolised and transported across the Caco-2 cell membrane to a limited extent. Transportation could be increased by applying MRP2 inhibitors or co-incubation with kaempferol. It is proposed that tiliroside can be absorbed by humans; future pharmacokinetics studies are warranted in order to determine the usefulness of tiliroside as a bioactive agent.

A complementary study using the Ussing chamber intestinal absorption model found that the ileum had the higher apparent permeability coefficient (Papp) of tiliroside than the duodenum and jejunum, suggesting the best absorption of tiliroside occurs in the ileum. In the presence of the MRP2 inhibitor, the absorption of tiliroside was improved, indicating that MRP2, rather than P-gp or BCRP, affected the absorption of tiliroside and might be responsible for its low bioavailability.

It has been reported that tiliroside is metabolized into its aglycone form, kaempferol, by intestinal microbiota. Astragalin (kaempferol-3-O-glucoside) and p-coumaric acid have also been identified as microbial metabolites of tiliroside. This gut-mediated hydrolysis implies that in vivo bioactivity may partly reflect the combined actions of the parent compound and these downstream metabolites.

8. Safety Considerations

8.1 Available Safety Data

In the human clinical trial of rosehip extract, there were no abnormalities, subjective symptoms, or findings that may indicate clinical problems during the study period. These results suggest that rosehip extract may be a good candidate food material for preventing obesity.

Most natural substances have few adverse effects as most of them come from edible plants or other organisms. The source plants of tiliroside — rose hips, linden flowers, strawberries, and raspberries — are established food-grade materials with long-standing human consumption histories.

Tiliroside-containing plant parts are often widely used as both food and medicines, in the treatment of various ailments, and in some cases, as food supplements. Formal dedicated toxicology studies of isolated tiliroside in humans have not been published in the peer-reviewed literature as of the available search results.

8.2 Bioavailability Constraints as an Implicit Safety Consideration

The low intestinal permeability of native tiliroside (Papp ~0.62 × 10⁻⁶ cm/s) and the active efflux by MRP2 transporters mean that systemic exposure to intact tiliroside following oral ingestion is limited. This constrains both efficacy and systemic toxicity risks from conventional oral doses, though formal safety dose-finding studies have not been reported for isolated tiliroside in humans.

8.3 Potential Transporter Interactions

Efflux transporters, specifically MRP2 (multidrug-resistance-associated protein-2), were shown to play a role in limiting the uptake of tiliroside. Inhibitors of MRP2 (MK571 and rifampicin) and co-incubation with kaempferol (10 µM) increased transfer from the apical to the basolateral side by three to five fold. Although this is established in cell models rather than clinical pharmacokinetic studies, there is a theoretical basis for interactions with drugs that are also MRP2 substrates or inhibitors. Formal drug interaction studies in humans have not been published.

8.4 In Vitro Cytotoxicity Observations

Both tiliroside and trans-tiliroside showed no cytotoxicity in HT-29 cells at concentrations of 0.1–100 μM. Cytotoxic effects on cancer cell lines at higher concentrations (40–160 µM) have been reported in cancer research contexts, but these concentrations are achieved in cell culture rather than physiologically through dietary consumption.

8.5 Evidence Gaps

There are no published randomized controlled trials evaluating the safety of isolated tiliroside in humans at any dose. No maximum tolerated dose, no-observed-adverse-effect level (NOAEL), or formal genotoxicity data for tiliroside in humans have been established in the peer-reviewed literature available at the time of this writing. Evidence of safety for the food plants containing tiliroside (rose hips, linden flowers) is long-standing, but does not translate directly to the safety profile of concentrated or isolated tiliroside supplementation.

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