Cornsilk (Stigma Maydis): A Comprehensive Reference
1. Identity, Botanical Description, and Common Forms
Cornsilk is derived from the stigma and styles of maize (Zea mays L.), long recognized as a medicinal plant with a variety of uses. The material consists of the long styles and stigmas on the flower pistils — fine, soft, yellowish to green threads of the female flowers. In pharmacognosy, the drug is referred to by the Latin names Stigma maydis or Maydis stigma, and the parent plant belongs to the family Poaceae, and is the third most important cereal crop worldwide.
The flowers of corn are monoecious, with male and female flowers located in different inflorescences on the same stalk; the male flowers (tassel) at the top of the plant produce yellow pollen, while the female flower produces the elongated silky strands. The silks function as the stigma of the female flower, and as the fruit develops, the silk elongates beyond the cob, covering the edible part of the plant.
The proximate composition of corn silk consists of approximately 9.65% moisture, 3.91% ash, 0.29% crude fat, 17.6% crude protein, and 40% crude fiber. The major constituent among carbohydrates is fiber, ranging from 39 to 53%, of which insoluble fiber accounts for the majority (36–52%).
Common Preparations and Forms
Cornsilk is encountered commercially and in traditional practice in several distinct forms:
- Dried herb / tea (infusion or decoction): The most historically common form. The fresh or dried silk is steeped in hot water to produce a tea, or simmered as a decoction.
- Tincture: An alcoholic extract of the fresh or dried material. As early as the 19th century, physicians used different preparations of the stigmata of Zea mays for catarrh of the bladder; those physicians found that preparations made from the fresh article were superior, as the dried material was found by some to be far less effective.
- Capsules / tablets: Encapsulated dried powder or standardized extracts, sold as dietary supplements.
- Aqueous extract / decoction: Used in clinical trials, particularly those investigating hypertension and blood glucose.
- Syrup: A liquid preparation used in some preclinical and clinical studies investigating renal and hepatic applications.
- Poultice: Externally, the fresh (or soaked dried) cornsilk can be applied as a poultice; it has been used for drawing pus from boils and old or infected wounds.
2. Traditional and Historical Use
Origin and Spread of the Plant
Corn (Zea mays Linnaeus), also known as maize, is a member of the family Poaceae. It is indigenous to Mesoamerica and was domesticated in Mexico some 9,000 years ago, then spread throughout the American continents, and is now widely cultivated all over the world. It was introduced into Europe and other continents after Columbus's voyages at the end of the 15th century.
Native American Traditions
Corn silk is an important herb used traditionally by the Chinese and Native Americans to treat many diseases, and is also used as traditional medicine in many parts of the world such as Turkey, the United States, and France. Among Indigenous peoples of the Americas, the medicinal use of cornsilk arose alongside the cultivation of the plant itself. Preparations were used primarily for urinary complaints, kidney ailments, and inflammatory conditions.
Traditional Chinese Medicine (TCM)
In China, corn silk first appeared in the ancient book Southern Yunnan Materia Medica in 1476, and was then recorded in the Lingnan Pharmacopoeia and the Sichuan Journal of Traditional Chinese Medicine. In the Chinese Pharmacopoeia (1997 edition), corn silk was also recommended as a common Chinese herb. In traditional Chinese medicine, corn silk is listed in the "herbs that drain dampness" category. Chinese herbalists consider corn silk to be beneficial for digestion, jaundice, diabetes, and edema, and to promote urination. Based on folk remedies, corn silk has been used as an oral antidiabetic agent in China for decades.
European and Western Herbal Traditions
Historically, corn silk has been used for the treatment of urinary tract disorders, pathological swelling, asthma, dropsy, and hypertension. Traditional medicine in many parts of the world such as China, Turkey, Serbia, United States, and France has used corn silk for the treatment of cystitis, edema, kidney stones, as a diuretic, and for prostate disorders, urinary infections, as well as bedwetting and obesity. In France, it has been used traditionally to stimulate weight loss.
African Ethnomedicine
Corn silk of Zea mays L. (Stigma maydis), family Poaceae, is used in Ibibio ethnomedicine for the treatment of various diseases including CNS disorders.
Traditional Preparations
Across cultures, the primary traditional delivery formats were aqueous: infusions (steep in hot water), decoctions (simmered), and fresh juice. External application as a poultice was also documented. All parts of corn are utilized, including the silks.
3. Key Constituents and Active Compounds
Phytochemistry studies have shown that the main bioactive components in corn silk include flavonoids, polyphenols, phenolic acids, fatty acids, and terpenoids. Detailed phytochemical characterization, employing techniques such as GC–MS and LC–MS, has revealed the following major classes of compounds:
Flavonoids
According to reports in the literature, there are a variety of chemical components in corn silk, covering macromolecular polysaccharides and various micromolecular components like saponins, flavonoids, sterols, amino acids, terpenes, and organic acids. Among the flavonoids, the most pharmacologically studied include maysin (a C-glycosylflavone unique to maize silk), quercetin, apigenin, rutin, and catechin. Jung et al. isolated catechin, a flavonoid from corn silk that was reported to show anticarcinogenic activity. The presence of various compounds like potassium and phytochemicals including the bioactive peptide CSBp5 and maysin, quercetin, rutin, apigenin (flavonoid), protocatechuic acid, and anthocyanin in corn silk exerts an antihypertensive response.
Polyphenols and Phenolic Acids
Corn silk contains substantial quantities of phenolic acids including caffeic acid, p-coumaric acid, and ferulic acid. Using UHPLC-Q-TOF-MS/MS technology, researchers identified 76 compounds in the water extract of corn silk, including caffeic acid and 10 of its derivatives, (E)-p-coumaric acid and 2 of its derivatives, and ferulic acid compounds.
Terpenoids and Volatile Compounds
A total of 36 compounds were identified by GC-MS in the volatile dichloromethane extract of Egyptian corn silk. More than 99% of the volatile compounds were terpenoids; the main constituents were cis-α-terpinol (24.22%), citronellol (16.18%), 6,11-oxidoacor-4-ene (18.06%), trans-pinocamphone (5.86%), eugenol (4.37%), neo-iso-3-thujanol (2.59%), and cis-sabinene hydrate (2.28%).
Sterols and Alkaloids
Corn silk also contains proteins, vitamins, carbohydrates, calcium, magnesium, and sodium salts, fixed and volatile oils, steroids such as sitosterol and stigmasterol, alkaloids, saponins, and tannins.
Polysaccharides
Polysaccharides represent the macromolecular fraction and have been studied for multiple activities including immunomodulatory, hypoglycemic, and kidney-stone-inhibiting effects. PSC2, a heteropolysaccharide from corn silk, decreases blood glucose and serum insulin levels, and improves glucose intolerance in type 2 diabetic mice.
Bioactive Peptides
Researchers applied proteomics and bioinformatics approaches to identify corn silk bioactive peptides (CSBps) that target angiotensin-converting enzyme (ACE) from the boiling water extract of corn silk. The extract significantly reduced systolic blood pressure in spontaneously hypertensive rats and inhibited ACE activity. A novel ACE inhibitory peptide, CSBp5, was identified; it significantly inhibited ACE activity and decreased systolic blood pressure in a dose-dependent manner. Docking analysis showed that CSBp5 occupied the substrate-binding channel of ACE and interacted with it via hydrogen bonds.
Minerals
Corn silk also contains cinnamic derivatives, glucose, rhamnose, and is rich in minerals, including sodium (0.05%), potassium (15%), iron (0.0082%), zinc (0.016%), and chloride (0.25%). The notably high potassium content is considered relevant to its diuretic and antihypertensive properties.
Vitamins
Corn silk contains various vitamins and minerals, including vitamin A, vitamin K, B-group vitamins (B1, B2, B6), vitamin C, flavonoids, inositol, pantothenic acid, saponins, and steroids such as sitosterol and stigmasterol.
4. Established Mechanisms of Action
Diuretic Mechanism
The diuretic action of corn silk is thought to be in part due to the high concentration of potassium salts. In animal experiments, using anesthetized Wistar rats fed water ad libitum, urine flow increased significantly (p < 0.05) by 135% compared to baseline after 90 minutes of intragastric administration of the aqueous corn silk extract. The corn silk–treated group also showed significantly increased sodium excretion during 60-minute (127.5%) and 90-minute (86%) periods, with potassium excretion increasing by 62 and 63% in the same periods, respectively.
Antihypertensive Mechanisms
The mechanism of action of corn silk in reducing hypertension involves biological components including potassium, bioactive peptides like CSBp5, and flavonoids like maysin and quercetin. The main mechanism involved in the antihypertensive property of corn silk is the inhibition of angiotensin-converting enzyme (ACE). ACE inhibitors bind a zinc atom to the active site of ACE, slowing the conversion of angiotensin I to angiotensin II, thus preventing vasoconstriction. The high potassium content observed in the corn silk extract, together with its diuretic and uricosuric properties, suggests that the fall in blood pressure may also result from diuretic activity or direct vasodilatation. Additionally, a comprehensive analysis of microbiota composition suggested that corn silk extract may function as a prebiotic to modulate blood pressure via gut microbial regulation.
Hypoglycemic Mechanisms
The action of corn silk extract on glycaemic metabolism is not via increasing glycogen or inhibiting gluconeogenesis, but through increasing insulin levels as well as recovering injured β-cells. Additionally, corn silk aqueous extract — containing alkaloids, flavonoids, phenols, saponins, tannins, and phytosterols — inhibits α-amylase and α-glucosidase activities, providing an effective strategy to modulate levels of postprandial hyperglycemia via control of starch metabolism.
Anti-inflammatory and Antioxidant Mechanisms
Crude ethanolic extract of corn silk exhibited significant activity as an anti-inflammatory agent for TNF antagonistic activity. The analgesic activity of cornsilk is attributed to the presence of tannins and polyphenolic constituents in Zea mays. Besides maysin, many other factors, such as steroids, flavonoids, volatile oils, and various phenolic compounds, contribute to cornsilk's anti-inflammatory and analgesic properties. Antioxidant activity of cornsilk extract has been evaluated using DPPH scavenging assays; results demonstrated considerable capacity for scavenging free radicals, indicating substantial antioxidant potential.
Lipid Metabolism
Corn silk water extract showed inhibitory effects against adipogenesis and lipids through regulation of CCAAT/enhancer binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) expression.
Gut Microbiota Modulation
In spontaneously hypertensive rats receiving oral corn silk extract for 4 weeks, treatment significantly reduced blood pressure, increased microbial diversity, decreased the Firmicutes/Bacteroidetes ratio, and enriched beneficial genera such as Akkermansia and Lactobacillus. The flavonoid and polyphenol constituents (e.g., apigenin, maysin) have bidirectional microbiota-modulating capacity, acting both as substrates for beneficial microbes and as selective antimicrobial agents to inhibit potential pathogens.
5. Scientific Evidence by Area of Use
5.1 Hypertension
This is the area with the strongest available body of clinical evidence for cornsilk, supported by a systematic review and meta-analysis of randomized controlled trials (RCTs).
A systematic review and meta-analysis found that corn silk, a traditional Chinese medicine, has been found to exert an antihypertensive effect in clinical practice and trials. Five RCTs involving 567 participants were included. Due to the poor quality of methodologies of most trials, limited evidence showed that CST plus antihypertensive drugs might be more effective in lowering blood pressure compared with antihypertensive drugs alone (RR = 1.27; 95% CI: 1.17 to 1.38, P < 0.00001; heterogeneity: P = 0.51, I² = 0%, fixed-effect model).
However, several studies on corn silk tea and its health benefits on hypertension have not reported all-cause mortality and cardiovascular death, and the trials mainly studied the total blood pressure lowering efficacy of corn silk tea plus conventional antihypertensive drugs compared with conventional antihypertensive drugs alone. A meta-analysis of five randomized controlled trials with 286 patients in the corn silk decoction group and 281 subjects in the control group showed significant lowering effects of corn silk decoction plus antihypertensive drugs on blood pressure in patients, when compared with antihypertensive drugs alone.
Although corn silk has been used as an aqueous decoction for antihypertensive healthcare in folk medicine, there are few reported studies on the certification of antihypertensive effects and mechanisms in human subjects or animal models. MartÃn et al. reported that intravenous injection of 1.342 mg/kg boiling dialysate of corn silk decreased diastolic blood pressure by 63.8% ± 33.6% in normotensive anaesthetized dogs. George and Idu reported that oral administration of 260 mg/kg corn silk aqueous extract reduces intraocular pressure in eyes with ocular hypertension and lowers blood pressure in systemic and non-systemic hypertensive subjects.
Evidence strength: Because of its strong bioactive components and low toxicity, corn silk has a bright future as an antihypertensive agent, but large-scale clinical trials should be the focus of future research to verify its safety and efficacy in a variety of populations and to establish the best dosages and long-term effects. The existing meta-analysis is limited by the poor methodological quality of constituent trials and the fact that all were add-on studies (corn silk plus drugs vs. drugs alone), not standalone efficacy evaluations.
5.2 Blood Glucose Regulation / Diabetes
Modern pharmacology has found that corn silk is effective in lowering blood glucose and lipids, which lays the ground for its use in the treatment and prevention of metabolic syndromes.
A notable human clinical study: Newly diagnosed patients with type 2 diabetes mellitus (T2DM) admitted from March 2020 to September 2021 were randomly allocated to either a corn silk intervention group or a control group receiving placebo. A hypoglycemic effect was observed; compared with the control, the glycosylated hemoglobin (HbA1c) and fasting blood glucose of patients in the intervention group significantly decreased after 3 months of treatment (P < .05). Thirty-six patients with T2DM were recruited (18 per group), aged between 30 and 68 years, with an average age of 60.39 ± 12.24 years.
At the preclinical (animal) level: After mice were orally administered corn silk extract, blood glucose and HbA1c were significantly decreased in alloxan-induced hyperglycemic mice (p < 0.05 and p < 0.01, respectively), while insulin secretion was markedly elevated. The alloxan-damaged pancreatic β-cells of the mice were partly recovered gradually after administration of corn silk extract 15 days later.
Corn silk, a traditional Chinese medicine with medicinal and edible properties, has been extensively researched for its anti-diabetes and anti-inflammatory effects. One study investigated the hypoglycemic effect of corn silk extract on type 1 diabetes (T1D) mice by modulating the composition of gut microbiota; the extract had a significant therapeutic effect on STZ-induced T1D by reducing the fasting blood glucose levels and pancreas injury.
The phytochemical components present in corn silk, including flavonoids, phenolics, terpenoids, tannins, sterols, and alkaloids, are phytochemical components with hypoglycemic activity and mechanisms for lowering blood glucose levels.
Evidence strength: There is one small human randomized trial (n=36) showing glycemic benefit, supported by multiple animal and in vitro studies establishing plausible mechanisms. The human evidence base is currently very limited in scale; large, independently replicated RCTs are lacking.
5.3 Urinary Tract Health and Diuresis
Corn silk aqueous extract significantly (p < 0.05) lowered blood pressure in experimental settings, and the diuresis activity of corn silk aqueous extract supports its traditional use as a diuretic agent.
Other uses of corn silk include teas and supplements to treat urinary-related problems. Cornsilk has astringent and demulcent properties that reduce inflammation in the mucous membranes lining the bladder and urethra. It eases sensations of pain, burning, and local irritation accompanying urinary tract infections. It also reduces symptoms such as frequent urination and the sudden urge to urinate.
Evidence strength: The diuretic activity is robustly demonstrated in animal models. Human clinical evidence is limited; the urinary effects are primarily supported by preclinical studies and traditional use. Controlled human trials specifically targeting UTI or urinary frequency are sparse.
5.4 Kidney Stones (Nephrolithiasis)
Research has explored the inhibition of nanocalcium oxalate monohydrate (nano-COM) crystal adhesion and aggregation on the HK-2 cell surface, and the effect of corn silk polysaccharides (CSPs) in this context. The bioactive contents in corn silk including flavonoids, saponins, alkaloids, and phenolic compounds are particularly promising in managing renal disorders such as nephrotoxicity and kidney stones.
Evidence strength: Evidence is primarily in vitro and animal-based. No large-scale human trials evaluating cornsilk as a treatment for nephrolithiasis are available in the peer-reviewed literature.
5.5 Hepatoprotection (Liver Health)
Preclinical and limited clinical studies suggest that corn silk syrup may reduce elevated serum creatinine and urea levels, enhance urine output, and protect against drug- or toxin-induced hepatic damage. Its antioxidant activity contributes to the reduction of oxidative stress and liver and kidney tissue lipid peroxidative damage. In rats given nicotine, corn silk extract has also been shown to have hepatoprotective and hypolipidemic (lipid-lowering) effects, indicating that it may be used to control lipid profiles and liver health.
Evidence strength: Primarily preclinical (animal). Limited clinical data. Further human study is needed before any conclusions can be drawn about liver-protective effects in human subjects.
5.6 Lipid-Lowering Effects
Corn silk water extract showed inhibitory effects against adipogenesis and lipids through regulation of C/EBPα and PPARγ expression. A separate meta-analysis referenced in the literature examined corn silk decoction for blood lipid outcomes in patients with angina pectoris (Shi et al., Phytotherapy Research, 2019), but its detailed results were not fully available in retrieved sources.
Evidence strength: Predominantly animal and in vitro evidence. Some clinical meta-analytic data exists in the context of angina pectoris, but independent large-scale RCTs on cornsilk as a primary lipid-lowering agent are absent.
5.7 Anti-inflammatory and Analgesic Activity
Recent research shows the anti-inflammatory activities of cornsilk extract, which can help relieve pain. Certain biopeptides are involved in the induction of anti-inflammatory action upon administration of cornsilk extract. FK2, a peptide from trypsin hydrolysis of corn silk, inhibits nuclear factor-κB (NF-κB) activation and ameliorates bacterial endotoxin-induced acute systemic inflammation in mice.
Evidence strength: Evidence is predominantly in vitro and animal-based. The inhibition of pro-inflammatory pathways (TNF-α, NF-κB) is mechanistically supported, but human clinical trials are absent.
5.8 Antioxidant Activity
The accumulation of flavonoids and other phenolic compounds in the upper parts of corn silk protects maize DNA from ultraviolet damage, as those parts are exposed to sunlight more than the lower parts. Multiple studies using DPPH, ABTS, and other radical-scavenging assays have confirmed strong antioxidant capacity in various cornsilk extracts. Corn silk antioxidant activity, antimutagenic effects, and some other biological properties have been reported in multiple studies.
Evidence strength: Well-established at the in vitro level. Translation to human clinical benefit has not been demonstrated in controlled trials.
5.9 Anti-fatigue and Antidepressant Activity
Potential antioxidant and healthcare applications of cornsilk as a diuretic agent, in hyperglycemia reduction, as an anti-depressant, and for anti-fatigue use have been claimed in several reports. Pharmacological studies (in vitro and in vivo) have shown remarkable bioactivities including antioxidant effects, hyperglycemia reduction, anti-depressant activity, anti-fatigue effects, and effective diuretic action.
Evidence strength: All evidence for anti-fatigue and antidepressant effects is animal-based. No human data are available.
5.10 Anticonvulsant Activity
Corn silk of Zea mays L. is used in Ibibio ethnomedicine for the treatment of CNS disorders. An ethanol corn silk extract (170–510 mg/kg) was investigated for anticonvulsant activity in mice using pentylenetetrazol and aminophylline-induced convulsion models; the extract was found to significantly (p < 0.005–0.01) offer protection against PTZ- and aminophylline-induced convulsions.
Evidence strength: Animal evidence only. No human clinical data.
6. Body Systems and Health Areas Associated with Cornsilk
- Urinary/Renal System: Diuresis, urinary tract infections, kidney stones, prostatitis, enuresis, nephroprotection.
- Cardiovascular System: Antihypertensive effects via ACE inhibition, diuresis, and vasodilation; lipid-lowering activity.
- Endocrine/Metabolic System: Blood glucose regulation, type 2 diabetes management, insulin secretion support.
- Hepatic System: Hepatoprotection against toxin/drug-induced damage, antifibrotic effects.
- Immune/Inflammatory System: Anti-inflammatory via TNF-α antagonism and NF-κB inhibition; antioxidant activity.
- Central Nervous System: Preliminary anticonvulsant and antidepressant activity (animal data only).
- Gastrointestinal/Microbiome: Prebiotic modulation of gut microbiota; lipid and glucose metabolism modulation.
7. Dosage Forms and Dosages Reported in Studies
The following dosages are reported as they appear in primary or review sources and reflect a range of traditional, clinical, and preclinical contexts:
- Infusion / Tea: For urinary tract infections, 1 cup (200 mL) taken three times a day has been described in traditional use sources.
- Chinese decoction dose (traditional): The Chinese dosage is cited as 15–30 g (approximately ¾ to 1½ oz) of the dried herb.
- Tincture: As a tincture, 3 mL (50 drops) three times a day has been cited for conditions such as cystitis.
- Capsule/Supplement: Typical dosages reported in the supplement context include 400–900 mg per day in capsule form, or 1–2 cups of tea made with fresh or dried corn silk.
- Animal studies (for reference): Research shows the effective hypoglycemic dose in animal models was 1.04 g/kg body weight. The antidiabetic effect was also evaluated at doses of 100–500 mg/kg in streptozotocin-induced rats, which reduced blood glucose, total cholesterol, and triglyceride levels.
- Clinical trial (T2DM): In the clinical randomized study, newly diagnosed patients with T2DM were divided into a corn silk intervention group and a control group; the intervention was administered for 3 months. The exact gram dose administered in that trial was not fully specified in the retrieved text.
- Antihypertensive trials: Intravenous injection of 1.342 mg/kg boiling dialysate of corn silk decreased diastolic blood pressure in normotensive anesthetized dogs in one referenced study; oral human doses in the reviewed RCTs were specified as a "tea" formulation combined with standard antihypertensive drugs.
8. Safety Considerations and Drug Interactions
General Safety Profile
This review highlights the potential of corn silk as a herbal drug for healthcare applications. Pharmacological studies (in vitro and in vivo) have shown its remarkable bioactivities, and some of the studies have confirmed that corn silk is safe and non-toxic. The bioactivities of corn silk were widely reported in the literature, including antioxidant activities, anti-proliferative effects, anti-diabetic activity, diuretic activity, anticoagulant activity, antifungal activity, anti-fatigue, and weight loss activities. Corn silk had a long history of application for therapeutic remedy and was tested as non-toxic.
A subchronic toxicity study in Wistar rats administered corn silk at dietary concentrations of 0.5%, 2.0%, and 8.0% for 90 days forms the basis of preclinical safety data. There is little scientific evidence about its safety; as part of its safety assessment, subchronic toxicity was performed in male and female Wistar rats by dietary administration at concentrations of 0.5%, 2.0%, and 8.0% (w/w) for 90 days.
Cornsilk tea and extracts are generally well-tolerated, with no significant adverse effects reported in the available clinical trials.
Electrolyte Effects
Because of its diuretic effect, corn silk can help lower blood pressure by reducing fluid volume; however, excessive use, especially when paired with other diuretics, can cause electrolyte imbalances including hypokalemia. Corn silk can decrease potassium levels in the blood and can cause skin rashes, itching, and allergies.
Drug Interactions
- Warfarin and anticoagulants: Corn silk contains vitamin K, which is used by the body to help blood clot. Warfarin (Coumadin) is used to slow blood clotting; by helping the blood clot, corn silk might decrease the effectiveness of warfarin. Medscape's interaction database also identifies that cornsilk contains vitamin K, and advises consuming a consistent amount daily when using anticoagulant therapies such as argatroban, bemiparin, antithrombin alfa, and antithrombin III.
- Antihypertensive drugs: Corn silk's interaction with antihypertensive drugs is rated as moderate; large amounts of corn silk appear to decrease blood pressure. Caution is advised due to the potential for an additive hypotensive effect when combined with antihypertensive drugs.
- Diuretic drugs: Corn silk seems to work like "water pills." Corn silk and conventional diuretics might cause the body to get rid of potassium along with water, raising the risk of hypokalemia. Cornsilk increases the effects of loop diuretics such as bumetanide by pharmacodynamic synergism, with an increased risk of hypokalemia (theoretical interaction).
- Antidiabetic drugs: Cornsilk increases the effects of vildagliptin by pharmacodynamic synergism (minor/significance unknown), with a theoretical increased risk of hypoglycemia.
Limitations and Research Gaps
Some studies have confirmed earlier findings, and new research discoveries have proven that corn silk is safe and non-toxic. With the claims in healthcare potential, it is important to carry out clinical evaluations to substantiate these claims and further enhance the confidence in its beneficial therapeutic effects for human consumption. While research is ongoing and supported by some well-conducted RCTs and systematic reviews, particularly focusing on hypertension, it is limited by small sample sizes and regional study populations. Further research is required for toxicity studies and recommended doses for hypertensive patients.
References
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