Cynarin: A Comprehensive Reference Article
1. Identity and Chemical Characterization
1.1 Chemical Name, Structure, and Classification
Cynarin is a hydroxycinnamic acid and a biologically active chemical constituent of artichoke (Cynara cardunculus). Chemically, it is an ester formed from quinic acid and two units of caffeic acid. More specifically, cynarin is designated 1,3-O-dicaffeoylquinic acid, and it belongs to the broader class of caffeoylquinic acid derivatives — polyphenolic compounds that are characteristic secondary metabolites of the artichoke plant. Alternative names found in the chemical and pharmacological literature include cynarine, cinarin, cinarine, and 1,5-dicaffeoylquinic acid, though the latter designation reflects a related but distinct isomer. The CAS registry number for cynarin is 30964-13-7.
A significant phytochemical nuance must be noted regarding cynarin's natural occurrence: according to Schütz et al., cynarin (i.e., 1,3-di-caffeoylquinic acid) is not inherently present in artichoke; rather, it is an artifact formed during aqueous extraction through transesterification of 1,5-di-O-caffeoylquinic acid. Notably, 1,5-di-O-caffeoylquinic acid is recognized as the primary caffeoylquinic acid found in artichoke heads and their pomace. This distinction has practical consequences for standardization and research, since the cynarin detected in commercial extracts and studied in the laboratory is largely generated during the drying and extraction process rather than being a pre-formed constituent of the fresh plant tissue.
1.2 Botanical Source
The artichoke (Cynara cardunculus var. scolymus), an Asteraceae family member, is native to the Mediterranean region (North Africa and southern Europe) and is widely used as a source of food and medicine. It belongs to the second-largest family in the plant kingdom comprising more than 2,000 species, namely the Asteraceae family, or Thistle family. Italy holds the world record in the production of this vegetable (approximately 30%), with the areas of greatest production being Sicilia, Sardinia, and Apulia.
Cynarin is considered one of artichoke's main biologically active chemicals. It occurs in the highest concentration in the leaves of the plant, which is why leaf extracts are most commonly employed in herbal medicine. The by-products of the artichoke (stalks, leaves, secondary flowers and outer bracts) as well as the edible part contain large amounts of phenolic compounds, including caffeic acid and cynarin derivatives and flavones (luteolin, apigenin and their glycoside derivatives), which have been associated with beneficial health effects.
While Cynara scolymus (the globe artichoke) is the primary botanical source discussed in the pharmacological literature, cynarin has also been identified in other plants. Cynarin-rich sunflower (Helianthus annuus) sprouts possess both antiglycative and antioxidant activities, indicating that the compound is not exclusive to the artichoke genus.
1.3 Isolation and Discovery
Research into the composition of the artichoke started in the first half of the 20th century. In the early 1950s, cynarin was isolated from the leaves and some years later cynaropicrin was discovered. In the mid-20th century, Italian scientists isolated cynarin, a compound from artichoke leaves, and the major di-caffeoylquinic acid derivative of artichoke, which appeared to replicate many of the holistic effects of the entire artichoke.
1.4 Common Forms and Preparations
Cynarin is encountered in several forms in commerce and research:
- Standardized artichoke leaf extract (ALE): The dominant form in modern phytotherapy. ALE preparations typically standardize to cynarin or total caffeoylquinic acids. Since artichoke total extract is frequently expressed in cynarin content, the amount of cynarin and also of total caffeoyl derivatives expressed as chlorogenic acid are typically determined in each extract tested for choleretic activity.
- Isolated / synthetic cynarin: Synthetic cynarin preparations were used to stimulate the liver and gallbladder and treat elevated cholesterol from the 1950s to the 1980s.
- Dried leaf and herbal tea: Traditional preparations using dried artichoke leaves, in which cynarin is formed from its precursor during the drying process.
- Pharmaceutical ingredient: Cynarin is an ingredient of the drug Sulfad.
The profile of bioactive components in artichoke extract can be influenced by various factors, including the type of artichoke used, growth conditions, and extraction techniques. As a result, the composition of phenolic compounds in artichoke extracts can display variability.
2. Traditional and Historical Use
2.1 Ancient and Classical Antiquity
The knowledge of the health benefits of the artichoke dates back to the 4th century B.C., but its use was not rediscovered until the 16th century. The historical context of artichoke consumption dates back to ancient Greece and Rome, where it was valued not only for its taste but also for its medicinal properties. It has been used for centuries to support liver function and detoxification. Ancient Greeks and Romans valued it for its medicinal properties, particularly for treating digestive issues.
2.2 Medieval to Early Modern Europe
The medicinal properties of artichoke have been known since antiquity, and it was particularly prized in the 16th to 19th centuries. It enjoyed a revival in the 20th century, particularly in France. Around the 19th century in France, artichoke leaf extract became part of folk medicine for indigestion.
2.3 Folk Medicine Systems and Purposes
The therapeutic properties of C. scolymus leaf preparations have been known since ancient times and have been a traditional liver remedy and weight loss aid for centuries. The traditional use of Cynara leaf extract in gastroenterology is mainly based upon its strong antidyspeptic actions that are mediated by its choleretic (increased bile production) activity.
In all herbal medicine systems where it is employed, artichoke is used to increase bile production in the liver, increase the flow of bile from the gallbladder, and to increase the contractive power of the bile duct. These bile actions are beneficial in many digestive, gallbladder, and liver disorders. Artichoke is also often used to mobilize fatty stores in the liver and detoxify it, and as a natural aid to lower cholesterol.
2.4 Formal Recognition and Regulatory History
German Commission E monographs (1978) later validated its traditional use for dyspepsia and stimulating bile flow. State pharmacopeias in Germany and Austria list it under "Artichockenblätter" as a standard remedy.
In the first half of the twentieth century, French scientists began modern research into these traditional medicinal uses of the artichoke plant. Their work suggested that the plant does indeed stimulate the kidney and gallbladder. Midcentury, Italian scientists isolated a compound from artichoke leaf called cynarin, which appeared to duplicate many of the effects of whole artichoke. Synthetic cynarin preparations were used to stimulate the liver and gallbladder and treat elevated cholesterol from the 1950s to the 1980s. Competition from newer pharmaceuticals has since eclipsed the use of cynarin. Artichoke leaf (as opposed to cynarin) continues to be used in many countries.
In the 1970s, European scientists first documented cynarin's ability to lower cholesterol in humans.
3. Phytochemical Context: Key Constituents of Artichoke Alongside Cynarin
Although this article focuses on cynarin, it is essential to understand the compound in the context of the broader phytochemical matrix from which it derives its pharmacological significance. In various pharmacological test systems, artichoke leaf extracts have exhibited hepatoprotective, anticarcinogenic, antioxidative, antibacterial, anti-HIV, bile-expelling, and urinative activities as well as the ability to inhibit cholesterol biosynthesis and LDL oxidation. These broad therapeutic indications cannot be ascribed to a single, but to several active compounds that together generate additive or synergistic pharmacologic effects; these include mono- and dicaffeoylquinic acids and flavonoids.
What is important in explaining the pharmacological activity of artichoke extracts is the presence of a complex of characteristic secondary metabolites: caffeic acid derivatives, including chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid and cynarin; flavonoids, in particular rutin; and sesquiterpene lactones: among others, cynaropicrin, dihydrocynaropicrin, grossheimin and cynaratriol.
The principal phenolic acid co-constituents alongside cynarin include:
- Chlorogenic acid (5-O-caffeoylquinic acid): Chlorogenic acid and its isomers, the cryptochlorogenic, neochlorogenic and pseudochlorogenic acids, have several pharmacological activities, such as a chemopreventive effect in oncological diseases.
- Luteolin and apigenin (flavones): Flavones and their glycosides are responsible for antioxidant and anti-inflammatory activities in the extract.
- Cynaropicrin (sesquiterpene lactone): Cynaropicrin is a derivative of cynarin that also helps give artichoke leaves their bitter taste. It is the subject of ongoing research for its wide range of potential therapeutic benefits, including anti-inflammatory, anti-cancer, anti-hepatitis C virus, antioxidant and antispasmodic properties.
4. Mechanisms of Action
4.1 Choleretic Action (Bile Stimulation)
Cynarin seems to stimulate bile secretion by liver cells and increase the excretion of cholesterol and solid matter in bile. Artichoke contains plant compounds cynarin, chlorogenic acid, caffeoylquinic acid, and scolymoside, which have been demonstrated to increase the flow of bile. This choleretic activity is considered the central mechanism underlying many of the plant's traditional and modern therapeutic applications, including the relief of indigestion and support of hepatobiliary function.
4.2 Inhibition of Cholesterol Biosynthesis (HMG-CoA Reductase)
These properties are thought to operate through a reduction in de novo cholesterol synthesis via the inhibition of HMG CoA reductase, an increase in cholesterol elimination in bile secretions, and an inhibition of LDL oxidation. More specifically, the lipid-lowering mechanisms of these supplements seem to be essentially two: the inhibition of the HMG-CoA reductase enzyme and the sterol regulatory element binding proteins (SREBPs) modulation.
Cynarin is hypocholesterolemic, by virtue of its inhibition of cholesterol biosynthesis and inhibition of LDL cholesterol oxidation. Moreover, it decreases the beta-alpha quotient of lipoprotein and has diuretic effects.
4.3 Antioxidant Activity
Caffeic acid derivatives in general show antioxidant and hepatoprotective effects. At the molecular level, cynarin possesses both antiglycative and antioxidant activities, which grants it a probability for up-regulating Nrf2 expression. In vitro research has confirmed this: cynarin significantly increased the expression level of Nrf-2 and HO-1, suggesting that cynarin might play an antioxidant role by regulating the Nrf2/HO-1 pathway.
4.4 Anti-Inflammatory Pathways
Cynarin inhibits the activation of p38 and nuclear factor kappa B (NF-κB) pathways by inducing the negative regulator mitogen-activated protein kinase phosphatase 3 (MKP-3). In cell-based research, in mesenchymal stem cells from ankylosing spondylitis patients, the expression levels of p-NF-κB, IL-6, IL-1β, and TNF-α were higher and IκB-α, Nrf-2, and HO-1 were lower compared with healthy control cells, and cynarin was shown to modulate these pathways toward a less inflammatory profile.
4.5 Taste Receptor Modulation
Due to its bitter taste, cynarin has been found to cause increased bile flow. Interestingly, it also inhibits specific taste receptors, which results in everything tasting sweeter for a period of time after eating. This is why even water may taste sweet immediately after eating artichokes. This phenomenon is a well-recognized organoleptic property of cynarin, linked to its transient blocking of sour and bitter receptor signals on the tongue.
4.6 Vasorelaxant Effects
Studies carried out ex vivo have demonstrated that artichoke extracts and several of their bioactive compounds display vasorelaxant effects. Currently, these effects seem to be attributed to the potentiation of the endothelial release of NO and to the direct relaxation of the vascular smooth muscle.
5. Scientific Evidence by Area of Use
5.1 Dyslipidemia and Lipid-Lowering Effects
Human/Clinical Evidence
Cynarin and artichoke leaf extract (ALE) have been among the most studied natural compounds for lipid management. A review of the data from 11 clinical studies (conducted between 1936 and 1994) on the lipid-lowering effects of ALEs showed a mean decrease in either total cholesterol or triglycerides of between approximately 5% and 45%, although the robustness of some of these trial designs is unclear.
One key double-blind, placebo-controlled RCT tested ALE in adults with mild to moderate hypercholesterolemia. The objective was to assess the effect of ALE on plasma lipid levels and general well-being in otherwise healthy adults with mild to moderate hypercholesterolemia; 131 adults were screened for total plasma cholesterol in the range 6.0–8.0 mmol/l, with 75 suitable volunteers randomised onto the trial. Volunteers consumed 1,280 mg of a standardised ALE, or matched placebo, daily for 12 weeks. Reductions in total cholesterol and LDL-cholesterol were significant in the active group (18.5% and 22.9%) over placebo (8.6% and 6.3%), respectively.
A meta-analysis of pooled data provides stronger aggregate evidence: meta-analysis of data from 9 trials including 702 subjects suggested a significant decrease in plasma LDL-C (WMD: −14.9 mg/dL; 95% CI: −20.4 to −9.5; p = 0.011).
Evidence Strength
Although several biological mechanisms of action have been suggested, including increased biliary secretion leading to an increased cholesterol elimination and/or inhibition of HMG-CoA reductase activity resulting in a decreased cholesterol biosynthesis, convincing and conclusive human studies investigating the blood cholesterol lowering properties of artichoke or ALE are currently limited. Most trials use ALE as a whole extract, making it difficult to attribute effects specifically to cynarin alone. The evidence from pooled analyses is encouraging but limited by small trial sizes, heterogeneity of preparations, and variable follow-up periods.
5.2 Liver and Hepatobiliary Function
Choleresis (Bile Flow Stimulation)
The choleretic (bile-stimulating) action of the plant has been well documented in a controlled trial involving a small sample of healthy volunteers. After the administration of 1.92 grams of standardized artichoke extract directly into the duodenum, liver bile flow increased significantly. This choleretic effect has led to the popular use of artichoke extract in Europe for the treatment of mild indigestion — particularly following a meal high in fat.
Hepatoprotection and Non-Alcoholic Steatohepatitis (NASH)
Artichoke leaf extracts have long been used in folk medicine, particularly for liver complaints. These therapeutic properties have been often ascribed to the cynarin (1,3-O-dicaffeoylquinic acid) content of these extracts.
A prospective clinical trial examined ALE in NASH patients: in a randomized double-blind clinical trial, 60 consecutive patients suffering NASH were randomly assigned to receive Cynara scolymus extract (as 6 tablets per day consisting of 2,700 mg extract of the herb) as the intervention group or placebo as the control group for two months. Comparing changes in study markers following interventions showed improvement in liver enzymes. The levels of triglycerides and cholesterol were significantly reduced in the group treated with Cynara scolymus when compared to placebo group. However, this study had some potential limitations including small sample size leading to partially low study power as well as ignoring other baseline clinical and pharmacological confounders.
Artichoke leaf extract was one of the few herbal remedies for which the clinical and experimental trials have complemented each other. Both experimental and clinical effects have been verified through extensive biomedical herbal remedy research. Specifically, antioxidant, choleretic, hepatoprotective, bile-enhancing and lipid-lowering effects have been demonstrated, which corresponded with its historical use.
Evidence Strength
In animal studies, liquid extracts of the roots and leaves of artichoke have demonstrated an ability to protect the liver, with possibly even to help liver cells regenerate. In humans, clinical evidence for hepatoprotection remains preliminary — the available RCTs are small, often short in duration, and test the whole extract rather than isolated cynarin. The choleretic effect is the most consistently demonstrated finding across both experimental and clinical settings.
5.3 Functional Dyspepsia and Digestive Health
Human/Clinical Evidence
Artichoke extract administration improved overall symptoms and quality of life at 6 weeks compared to placebo in one double-blind RCT of 247 patients with functional dyspepsia (FD).
A combined supplementation trial using both artichoke and ginger extracts further explored this indication: this was a prospective multicentre, double-blind, randomized, placebo-controlled, parallel-group trial. Two capsules per day were supplied (before lunch and dinner) to 126 FD patients (supplementation/placebo: 65/61). After 14 days of treatment, only the supplementation group showed a significant amelioration (MCA score units, p = 0.017; placebo: p = 0.513).
The traditional use of Cynara leaf extract in gastroenterology is mainly based upon its strong antidyspeptic actions that are mediated by its choleretic (increased bile production) activity.
Evidence Strength
Evidence for functional dyspepsia relief is moderate. Multiple RCTs have been conducted, with consistent directional signals favoring ALE over placebo. However, most trials combine artichoke with other ingredients or use total leaf extract, so the specific contribution of cynarin cannot be isolated. In a 2009 Cochrane systematic review, "Artichoke leaf extract for treating hypercholesterolaemia," the authors concluded that only mild, transient, and infrequent adverse events have been reported for short-term use of ALE, suggesting an acceptable safety profile, though the evidence base for efficacy remains constrained by trial quality and size.
5.4 Antioxidant and Anti-Inflammatory Effects
Antioxidant, choleretic, hepatoprotective, bile-enhancing and lipid-lowering effects have been demonstrated, which corresponded with artichoke's historical use.
Ankylosing spondylitis (AS) is an immune chronic inflammatory disease, resulting in back pain, stiffness, and thoracolumbar kyphotic deformity. Based on the reported anti-inflammatory and antioxidant capacities of cynarin, a study explored its protective role and molecular mechanisms in mesenchymal stem cells (MSCs) from AS. These in vitro and preclinical findings are promising but lack corresponding human clinical trials specifically examining anti-inflammatory outcomes of cynarin administration.
5.5 Cardiovascular Effects
Cynara extracts may also protect against endothelial dysfunction (one of the first stages of atherosclerotic diseases), and they have positive effects on cellular adhesion molecules, a type of endogenous lectin that helps adhere and maintain vascular endothelial cells. Studies carried out ex vivo have demonstrated that artichoke extracts and several of their bioactive compounds display vasorelaxant effects, attributed to the potentiation of the endothelial release of NO and the direct relaxation of the vascular smooth muscle.
Evidence strength in this area is largely preclinical (in vitro and ex vivo), with indirect cardiovascular benefits suggested by the lipid-lowering data from human trials. Dedicated cardiovascular endpoint trials for cynarin or ALE in human subjects have not been published.
5.6 Antimicrobial Activity
A preliminary antimicrobial disk assay of artichoke leaf extracts showed that the n-butanol fraction exhibited the most significant antimicrobial activities against seven bacteria species, four yeasts, and four molds. Eight phenolic compounds were isolated from the n-butanol soluble fraction, and the structures were determined as four caffeoylquinic acid derivatives including chlorogenic acid, cynarin (1,3-O-dicaffeoylquinic acid), and four flavonoids. This research is in vitro only; no human clinical data exist for antimicrobial indications of cynarin.
5.7 Neuroinflammation (Preclinical Only)
Results in animal research showed that treatment with cynarin reduces the level of neuroinflammation and microglial pyroptosis. Moreover, the mice treated with cynarin exhibited lower level of reactive oxygen species (ROS) and cell death, less damage of neurohistology and better locomotor improvement of hindlimbs, and cynarin inhibited the assembly of NLRP3 inflammasome by Nrf2-dependent expression to attenuate microglial pyroptosis and neuroinflammation. This suggested that administration of cynarin is a promising compound for anti-neuroinflammation and anti-pyroptosis after spinal cord injury, and it may be an efficient Nrf2 activator and a NLRP3 inhibitor for microglia in neuropathies. These findings are preclinical only and have not been validated in human studies.
6. Dosage Forms and Reported Doses
Doses reported in the scientific and clinical literature pertain primarily to standardized artichoke leaf extract (ALE), not to isolated cynarin as a single compound, except where synthetic cynarin preparations were used historically:
- 1,280 mg/day ALE for 12 weeks was the dose used in one double-blind, placebo-controlled trial in hypercholesterolemic adults.
- 2,700 mg/day (as 6 tablets per day) of Cynara scolymus extract was used for two months in a double-blind, randomized controlled trial in patients with NASH.
- 1.92 grams of standardized artichoke extract administered directly into the duodenum was used in the controlled trial documenting choleretic effects.
- The suggested dosage for artichoke leaf extract is 1,800 to 1,920 mg/day in 2 or 3 divided doses, as cited in Trease and Evans' Pharmacognosy.
- ALE preparations are dosed between 300–1,200 mg/day in clinical trials.
- Investigational studies have used as little as 500 mg/day; however, this herb is generally considered safe at higher doses, such as 35:1 concentrates dosed at 1,800 mg/day.
- Synthetic cynarin (historical pharmaceutical use): Therapeutic doses of cynarin vary from 5 g to 50 g according to patent literature, though these figures reflect older pharmaceutical preparations and have not been confirmed in modern peer-reviewed RCTs.
7. Safety Considerations and Drug Interactions
7.1 General Tolerability
No serious side effect has been reported, confirming the tolerability and safety of artichoke in the short and medium term. The most frequent adverse event is mild and transient abdominal discomfort. Artichoke heads are generally recognized as safe (GRAS) when used as food. Mild, transient, and infrequent adverse reactions, generally limited to GI complaints such as bloating and flatulence, have been reported.
7.2 Contraindications from Regulatory Monographs
The European Medicines Agency (EMA) Community Herbal Monograph on Cynara scolymus folium specifies the following contraindications: hypersensitivity to the active substance or to plants of the Asteraceae family (Compositae); obstructions of bile ducts, cholangitis, gallstones and any other biliary diseases and hepatitis.
Due to its bile-stimulating (choleretic) effect, artichoke products should not be used by individuals with bile duct obstruction, including those with gallstones, as they could exacerbate symptoms or lead to complications. Avoidance is also advised in intestinal spasm, hepatocellular disease, cholecystitis or hyperbilirubinaemia.
At the recommended amount and according to the German Commission E Monograph, there are no known side effects or drug interactions.
7.3 Allergic Reactions
Contact with artichoke and other plants of the Asteraceae family (daisy, chrysanthemum, marigold, Echinacea, and ragweed) has caused allergic reactions in sensitive individuals; cynaropicrin and other sesquiterpene lactones may be the responsible chemical constituents. Allergic reactions including anaphylaxis, bronchial asthma, and irritant contact dermatitis, as well as a case of hepatotoxicity, have been reported. There have been some reports of contact dermatitis, and allergic reactions after ingestion for some individuals.
7.4 Pregnancy and Lactation
There is insufficient evidence for its safety during pregnancy and lactation. The use in children under 12 years of age is not recommended due to lack of adequate data, per the EMA monograph.
7.5 Drug Interactions
Colchicine: artichoke may increase the serum concentration of colchicine. Monitor therapy. Theoretically, artichoke could cause low blood glucose levels when used in conjunction with antidiabetic medication. Although artichoke has been consumed safely for centuries as a food, standardized supplements and extracts require further investigation to fully characterize their long-term safety and potential interactions with medications.
7.6 Long-Term Safety
Long-term safety data for cynarin as an isolated compound or as standardized extracts are limited. Most clinical trials have been short to medium duration (up to 12 weeks). Standardized supplements and extracts require further investigation to fully characterize their long-term safety and potential interactions with medications.
8. Summary of Evidence Strength
- Choleresis / Bile Flow: Moderate clinical evidence; well-documented in controlled trials and consistent with preclinical data.
- Functional Dyspepsia: Moderate clinical evidence from multiple RCTs; constrained by use of whole extracts and combined formulations rather than cynarin alone.
- Lipid Lowering: Emerging human evidence from RCTs and a meta-analysis; mechanistic plausibility established, but studies remain heterogeneous and mostly short-term.
- Hepatoprotection (NASH, liver enzymes): Preliminary clinical evidence from small RCTs; more robust data needed.
- Antioxidant / Anti-inflammatory: Strong in vitro and preclinical evidence; direct human clinical trial evidence is limited.
- Neuroinflammation / Neuroprotection: Preclinical animal data only; no human trials.
- Antimicrobial: In vitro data only; no clinical evidence.
References
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