Ingredients"Vicenin" is the collective name for a group of naturally occurring flavonoid C-glycosides whose aglycone (sugar-free) core is apigenin (4′,5,7-trihydroxyflavone). The vicenins are distinguished from the large majority of flavonoid glycosides by the nature of their sugar linkage: the sugars are attached directly to the aromatic carbon atoms of the apigenin backbone via stable carbon-carbon (C–C) bonds, making them C-glycosyl flavones rather than the more common O-glycosyl flavones. Vicenin-2 is a naturally occurring C-glycosylated flavone, also referred to as apigenin-6,8-di-C-glucoside due to the two glucose units attached via carbon-carbon bonds to the apigenin backbone. This C–C glycosidic linkage has a critical pharmacological consequence: it is relatively stable and resistant to enzymatic hydrolysis, in contrast to O-glycosylated flavones.
Three principal vicenin analogues are characterised in the scientific literature:
Vicenin-2 is by far the most extensively researched member of the group and is the primary subject of the pharmacological literature. Unless otherwise noted, "vicenin" in the scientific literature typically refers to vicenin-2, and this article emphasises it accordingly while noting data specific to other congeners where they exist.
The vicenins are widely distributed across the plant kingdom, occurring in taxonomically diverse species. Vicenin-3 (and other vicenins) are distributed across taxonomically diverse medicinal plants, predominantly in the families Fabaceae, Orchidaceae, Asteraceae, and Lamiaceae. Key documented botanical sources include:
Vicenin-2 is also identified in the leaves of Lychnophora ericoides, which is utilised in Brazilian folk medicine for treating inflammation, pain, and wounds.
Research has identified a plausible ecological role for vicenin-2 in certain plant species. Mass spectrometric imaging revealed that vicenin-2, unlike other flavonoids, was produced at the top of the leaves; the combination of localization and UV absorption properties of vicenin-2 suggests that it could act as a UV light barrier to protect the plants, since plants are sessile organisms that have to protect themselves from harsh external conditions such as intense sunlight.
In research and nutraceutical contexts, vicenin compounds appear in several forms:
The most extensively documented traditional context for vicenin-bearing plants is the Ayurvedic system of medicine. Ocimum sanctum L. (also known as Ocimum tenuiflorum, Tulsi) has been used for thousands of years in Ayurveda for its diverse healing properties. Revered as the "Queen of herbs," Tulsi is known for its religious and spiritual sanctity as well as its important role in the traditional Ayurvedic and Unani systems of holistic health and herbal medicine. It is mentioned by Charaka in the Charaka Samhita, an Ayurvedic text. Tulsi is known to be an adaptogen, aiding the body in adapting to stress by harmonising various bodily systems; revered in Ayurveda as the "Elixir of Life," it is believed to enhance lifespan and foster longevity.
Tulsi preparations were traditionally made as decoctions, fresh juice, herbal teas, and as powdered leaf, and used for a broad range of applications including respiratory complaints (cough, asthma, bronchitis), fevers, digestive disorders, stress, wounds, and infections. Vicenin-2 is a bioactive flavonoid present in Ocimum sanctum, commonly known as tulsi or holy basil, a herb widely used for centuries in Ayurvedic medicine.
Fenugreek (Trigonella foenum-graecum), another vicenin source, has centuries of documented use in Ayurveda as well as in ancient Egyptian, Greek, and Roman medicine, primarily for digestive complaints, diabetes-like conditions, and as a galactagogue (milk promoter). The seeds were consumed whole, as a paste, or as a decoction.
Vicenin-2 has been identified as an anti-inflammatory compound in the leaves of Lychnophora ericoides, which is utilised in Brazilian folk medicine for treating inflammation, pain, and wounds. Plants of the genus Lychnophora (collectively called "arnica do campo" or "Brazilian arnica") are used in the Cerrado region of central Brazil, where they have been prepared as macerates and poultices for topical application to musculoskeletal pain, wounds, and bruises for generations.
Artemisia capillaris (Yīn Chén Hāo in Chinese medicine) is a plant used in Traditional Chinese Medicine (TCM) for centuries, principally as a hepatoprotective and choleretic agent for liver and gallbladder conditions, jaundice, and fever. Vicenin-2 was isolated from this traditionally used medicinal plant Artemisia capillaris. Perilla frutescens is similarly used in Chinese and Japanese traditional medicine (Shiso in Japan) for digestive complaints, nausea, coughs, and allergic conditions, and is a food plant with a long culinary history across East Asia.
Urtica circularis, another confirmed vicenin-2 source, has been used in Argentine folk medicine. Decoctions are consumed or applied as wound cleansers, with flavonoid-rich fractions (including vicenin-3 in related species) linked to antioxidant and anti-inflammatory actions.
All vicenins share the flavone aglycone apigenin (4′,5,7-trihydroxyflavone) as their scaffold. They differ in the number and positional arrangement of their sugar substituents at C-6 and/or C-8:
The C-glycosidic bond confers structural stability. Flavonoid C-glycosides have been reported to have significant antioxidant, anticancer, hepatoprotective, anti-inflammatory, antidiabetes, antiviral, antibacterial, and antifungal activities. In most cases, C-glycosyl flavonoids showed higher antioxidant and antidiabetes potential than their corresponding O-glycosyl flavonoids and aglycones.
Structurally, the two glucose units in vicenin-2 add significant aqueous polarity and bulk to the apigenin core, which contributes to its water solubility and influences how it interacts with membrane-bound and cytosolic biological targets. This structural arrangement contributes to its solubility and interaction with biological targets; under acidic or enzymatic conditions, vicenin compounds can hydrolyse to release their sugar moieties, which can affect biological activity.
Multiple biochemical mechanisms have been identified in preclinical experiments for vicenin-2 specifically:
The hypoglycaemic and hypolipidaemic effects of flavonoid C-glycosides on type 2 diabetes could be due to inhibition of AGEs and digestive enzymes, stimulation of glycogen storage, and activation of insulin signalling, though there is still a lack of in vivo data on the biological benefits of flavonoid C-glycosides.
Important methodological note: The overwhelming majority of studies on vicenin compounds are in vitro (cell culture) or in vivo (animal model) experiments. No published, peer-reviewed, randomised controlled clinical trials (RCTs) in human participants evaluating isolated vicenin compounds as primary interventions have been identified in the current literature. The evidence characterisation below reflects this limitation explicitly for each area.
Radioprotection — protecting biological tissues from damage caused by ionising radiation — is among the most extensively investigated areas for vicenin/orientin from Ocimum sanctum.
Animal and cell-based evidence: Two flavonoids, orientin and vicenin, isolated from the leaves of the Indian plant Ocimum sanctum were tested for their radioprotective effect in mice; both compounds provided protection against death from gastrointestinal syndrome as well as bone marrow syndrome when injected intraperitoneally before whole-body exposure to 11 Gy gamma radiation. The optimum drug dose for protection was 50 µg/kg body weight. Vicenin was slightly better than orientin in increasing survival at 30 days; protection by vicenin also lasted longer.
In a comparative study of radioprotection by Ocimum flavonoids and synthetic aminothiol protectors in mice, adult Swiss mice were injected intraperitoneally with 50 µg/kg body weight of orientin or vicenin and exposed to whole body irradiation of 2 Gy gamma radiation 30 minutes later; pretreatment with all protective compounds resulted in significant reduction in percentage of aberrant metaphases, with vicenin producing the maximum reduction in percentage of aberrant cells.
Studies have shown that Ocimum sanctum Linn. and its water-soluble flavonoids, orientin and vicenin, protect experimental animals against radiation-induced sickness and mortality at nontoxic concentrations. Studies with tumour-bearing mice have also shown that both Tulsi extract and its flavonoids selectively protect the normal tissues against the tumoricidal effects of radiation.
Evidence strength: Preclinical (animal and cell-culture) only. The radioprotective data is consistent across multiple rodent studies, but no human clinical trials have been conducted on isolated vicenin for this purpose. The relevance of the specific intraperitoneal dosing used in mouse studies to any human oral application remains untested.
Prostate cancer (in vitro and in vivo, preclinical): A study determined the efficacy of vicenin-2 (VCN-2), an active constituent of Ocimum sanctum, as a single agent and in combination with docetaxel in prostate carcinoma; VCN-2 effectively induced anti-proliferative, anti-angiogenic and pro-apoptotic effects in prostate cancer cells (PC-3, DU-145 and LNCaP) irrespective of their androgen responsiveness or p53 status. VCN-2 reached a level of 2.6 ± 0.3 µmol/l in serum after oral administration in mice, reflecting that VCN-2 is orally absorbed. In combination with docetaxel, VCN-2 synergistically inhibited the growth of prostate tumours in vivo.
Colorectal cancer (in vitro): A study analysed the anti-proliferative effect of vicenin-2 on human colon cancer cells via Wnt/β-catenin signalling inhibition; MTT assay assessed cell viability at different concentrations and time points, and vicenin-2 at 50 µM (IC₅₀) decreased phosphorylated glycogen synthase kinase-3β, cyclin D1, and non-p-β-catenin expressions in HT-29 cells.
Oral/buccal carcinoma (animal model): A study investigated the possible impact of vicenin-2 on 7,12-dimethylbenz[a]anthracene (DMBA)-induced oral carcinogenesis in hamsters; buccal carcinoma was induced by DMBA application three times a week for 14 weeks, with 100% tumour incidence observed in induced animals. Vicenin-2 at 30 mg/kg treated hamsters showed averted tumour incidence, improved antioxidant status, and inhibited lipid peroxidation; vicenin-2 inhibited the immunohistochemical expression of PCNA, Cyclin-D1, and Bcl-2, significantly restored apoptotic Bax levels, and prevented lesion formation in the oral epithelium; treatment also halted production of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α.
Hepatocellular carcinoma (animal model): Studies have investigated vicenin-2's effect on diethylnitrosamine (DEN)-induced liver carcinoma in experimental rats, with findings related to oxidative stress attenuation and increased apoptotic protein expression (referenced in the Journal of Environmental Pathology, Toxicology and Oncology, 2020).
Cytotoxicity data (in vitro): Among tested compounds from Dypsis pembana, vicenin-II was the most cytotoxic against the HepG-2 cell line with an IC₅₀ value of 14.38 µg/mL; molecular docking demonstrated that vicenin-II exhibited superior enzyme-binding affinities to studied vital targets. Biological and computational findings revealed that vicenin-II and isovitexin are possible lead structures as inhibitors of human topoisomerase IIα and cyclin-dependent kinase 2 enzymes.
Evidence strength: Entirely preclinical (cell lines and animal models). No human cancer treatment or prevention trials exist. The in vitro IC₅₀ values and tumour regression data in rodents and hamsters are hypothesis-generating only.
Vascular inflammation (in vitro and in vivo): Vicenin-2 and the structurally related flavonoid scolymoside, both found in Cyclopia subternata (honeybush), were examined for effects on inflammatory responses by monitoring their effects on LPS-mediated vascular inflammatory responses; anti-inflammatory activities were determined by measuring permeability, monocyte adhesion and migration, and activation of pro-inflammatory proteins in LPS-activated HUVECs and mice; post-treatment of each compound inhibited LPS-induced barrier disruption, expression of CAMs, and adhesion/transendothelial migration of human neutrophils to human endothelial cells. Vicenin-2 and scolymoside possess anti-inflammatory functions by inhibiting hyperpermeability, expression of CAMs, and adhesion and migration of leukocytes.
Macrophage model (in vitro): The U-937 macrophage model was used to study the anti-inflammatory effects of Lychnophora ericoides, primarily focusing on vicenin-2; macrophage stimulation with lipopolysaccharide (LPS) generated a controlled immune response measured by production of TNF-α and prostaglandin E-2 (PGE-2); vicenin-2 was found to have a dose-dependent effect on PGE-2 without variation in the expression of cyclooxygenase COX-2; TNF-α production was not affected by vicenin-2 in this study.
Evidence strength: Cell culture and animal model data are consistent with anti-inflammatory effects via multiple mechanisms. No human clinical trials exist.
Enzyme inhibition (in vitro, biochemical assays): The anti-diabetic potential of vicenin-2 was evaluated via α-glucosidase, PTP1B, rat lens aldose reductase (RLAR), and AGE formation inhibitory assays; vicenin-2 strongly inhibited α-glucosidase, PTP1B, and RLAR; additionally, vicenin-2 inhibited formation of both fluorescent AGE and nonfluorescent AGE, as well as fructosamine levels in glucose-fructose-induced bovine serum albumin (BSA) glycation.
Vicenin-2 was found to be a potent inhibitor of glycation-induced formation of amyloid cross-β structures in BSA; together, these results suggest vicenin-2 might be a useful lead for development of multiple target-oriented therapeutic modalities for the treatment of diabetes and diabetes-associated complications.
The hypoglycaemic and hypolipidaemic effects of flavonoid C-glycosides on type 2 diabetes could be due to inhibition of AGEs and digestive enzymes, stimulation of glycogen storage, and activation of insulin signalling.
Evidence strength: In vitro enzyme assays and biochemical models only. No human glucose-lowering trials have been conducted with isolated vicenin compounds.
Animal model (diabetic wound): A preclinical study investigated topical application of vicenin-2 in a hydrocolloid film formulation on diabetic wounds in Sprague Dawley rats. VCN-2 reduced pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), mediators (iNOS and COX-2), and nitric oxide (NO) via the NF-κB pathway; data suggest the VCN-2 film facilitated healing in hyperglycaemic conditions by releasing growth factors such as VEGF and TGF-β to enhance cell proliferation, migration, and wound contraction; topical treatment with VCN-2 hydrocolloid films effectively enhanced wound healing in hyperglycaemic conditions.
Evidence strength: Single animal model preclinical study. No human wound healing trials identified.
Research on vicenin-2's gastrointestinal effects is particularly notable because it is one of the few areas where a human pilot study has been reported, albeit with Perilla frutescens extract (in which vicenin-2 is the putative active constituent) rather than isolated vicenin-2.
Mechanistic data: The prokinetic effect of vicenin-2 improves gastrointestinal motility by increasing the frequency of contractions in the small intestine, without changing their rhythm, leading to relief from gastrointestinal symptoms such as abdominal discomfort, bloating, constipation, and other symptoms linked to functional dyspepsia or irritable bowel syndrome.
Human pilot study (Perilla extract): In vitro and ex vivo studies clearly showed that the proprietary Perilla frutescens extract combines prokinetic, antispasmodic, and anti-inflammatory effects; the study was designed to develop a health claim substantiated food ingredient and thus comply with EFSA requirements. A published human pilot study assessed the Perilla extract (with vicenin-2 as a key constituent) in subjects with gastrointestinal discomfort, though the direct contribution of vicenin-2 as an isolated compound versus other extract constituents cannot be established from this design (PMC4038823).
Evidence strength: Mechanism identified in preclinical electrophysiological models. The human data are pilot-level and attributable to the whole plant extract, not purified vicenin-2 alone. Regulatory submissions (e.g., to EFSA) have been based on the whole standardised extract.
Antihepatotoxic studies of sixteen flavonoid-glycosides, including vicenin-2, were tested in hepatocytes induced by CCl₄ and GalN; the results indicated that most of them had significant inhibitory effects in both tested models.
The beneficial effects of vicenin-2 including anti-oxidant, anti-hepatotoxic, trypanocidal, antispasmodic, improvement of functional gastrointestinal discomfort, and anti-nociceptive effects have been reported in multiple investigations.
Evidence strength: In vitro hepatocyte protection models and some animal (rat) data. No human liver-function clinical trials with isolated vicenin have been identified.
In Desmodium styracifolium, vicenin-3 contributes to ACE inhibition (IC₅₀ = 46.91 µM), supporting traditional use for cardiovascular and renal conditions; this activity is linked to its ability to chelate zinc ions in the ACE active site. Vicenin-2 is also an orally active ACE inhibitor with an IC₅₀ of 43.83 µM.
Evidence strength: Biochemical (enzyme assay) data only. No in vivo cardiovascular efficacy studies or human blood pressure trials with isolated vicenin have been published.
All dosages below are as specifically reported in the cited research; they are not clinical recommendations and have not been established in human trials for isolated vicenin compounds unless otherwise stated.
The optimum drug dose for radioprotection (intraperitoneal injection in mice) was 50 µg/kg body weight; no acute toxicity was observed at doses as high as 100 mg/kg body weight of either compound (orientin or vicenin). In a comparative radioprotection study, adult Swiss mice were injected intraperitoneally with 50 µg/kg body weight of vicenin 30 minutes before whole-body irradiation.
Vicenin-2 at 30 mg/kg (body weight) was the dose used in the DMBA-induced buccal pouch carcinoma hamster study.
Vicenin-2 at a concentration of 50 µM (IC₅₀) was the concentration at which it decreased phosphorylated glycogen synthase kinase-3β, cyclin D1, and non-p-β-catenin expressions in HT-29 human colon cancer cells.
A pharmacokinetic study investigated vicenin-1 following a single 60 mg/kg oral dose in rats. The pharmacokinetic results showed Cmax of 7.039 µg/mL and Tmax of 2 hours after oral administration of vicenin-1; tissue distribution showed the highest concentration in the liver followed by the lung; approximately 24.2% of the administered dose was excreted via urinary excretion.
Studies provided evidence that almost 40% of the original dosage of vicenin-2 was quickly absorbed in the small intestine. In prostate cancer mouse studies, VCN-2 reached a level of 2.6 ± 0.3 µmol/l in serum after oral administration in mice, reflecting that VCN-2 is orally absorbed.
First-pass metabolism, poor solubility, and the presence of the reducing sugar moiety in vicenin-1 may decrease its bioavailability.
The most formal toxicological evaluation published for any vicenin compound is a mouse study for vicenin-1 isolated from fenugreek, conducted according to OECD guidelines. The objective was to determine in vivo acute and subacute (28-day repeated dose) oral toxicity of vicenin-1 isolated from fenugreek seed; vicenin-1 (93%) was isolated from a hydroalcoholic extract and characterised using HPLC, TLC, ¹H NMR and ¹³C NMR; acute oral toxicity and subacute toxicity studies were carried out according to OECD 425 and OECD 407 guidelines in Swiss albino mice.
In the acute oral toxicity study, vicenin-1 showed 10% mortality when administered at 5,000 mg/kg; however, when administered for 28 days at doses of 37.5, 75, or 150 mg/kg it did not show any mortality; vicenin-1 at 75 mg/kg did not show observational, behavioural, biochemical or histopathological toxic effects; there were minor alterations in body weight, haematology, and histopathology of mice administered vicenin-1 at 150 mg/kg, but these changes were within normal laboratory ranges; the highest concentration of vicenin-1 was found in liver (3.46%) followed by lung (0.65%).
Vicenin-1 showed a median lethal dose (LD₅₀) of 4,837.5 mg/kg with a no-observed-adverse-effect level (NOAEL) at 75 mg/kg and lowest-observed-adverse-effect level (LOAEL) at 150 mg/kg for both sexes of mice during acute and sub-acute toxicity studies.
The water-soluble flavonoids orientin and vicenin from Ocimum sanctum protect experimental animals against radiation-induced sickness and mortality at nontoxic concentrations. The optimum radioprotective dose (50 µg/kg, intraperitoneal) in animal studies is far below the doses at which toxicity was observed.
Vicenin-1 accumulated in the liver, lung, kidney, and small intestine. These distribution data are from rodent studies and their relevance to human pharmacokinetics is uncertain.
It has been well documented that flavonoids often have poor bioavailability due to their pre-systemic metabolism. For vicenin compounds specifically, first-pass metabolism, poor solubility, and the presence of the reducing sugar moiety may decrease bioavailability.
No published human clinical trials have systematically evaluated the safety of isolated vicenin-1, vicenin-2, or vicenin-3 as standalone supplements. No peer-reviewed data exist on drug-herb interactions for purified vicenin preparations in humans. The available enzyme-inhibitory data (e.g., ACE inhibition, α-glucosidase inhibition, cholinesterase inhibition) identify theoretical interaction concerns — for example, potential additive effects with antihypertensive drugs, antidiabetic agents, or cholinomimetics — but these have not been studied in human subjects. The formal toxicological evidence base consists of preclinical OECD-compliant mouse studies for vicenin-1 only.
The C-glycosidic bond is pharmacologically relevant to safety as well as efficacy: vicenin-2 is relatively stable and resistant to enzymatic hydrolysis, mainly due to C-glycosylation, compared to O-glycosylated flavones. This stability may mean vicenin compounds reach the colon relatively intact, where they may be metabolised by gut microbiota, though the nature and extent of this colonic biotransformation in humans has not been fully characterised for vicenin.
As of the current literature, vicenin compounds — particularly vicenin-2 — have a well-characterised phytochemical identity and a growing body of preclinical (in vitro and animal) pharmacological data demonstrating antioxidant, anti-inflammatory, antidiabetic, hepatoprotective, anticancer, radioprotective, and gastrointestinal motility-modulating activities. The mechanisms of action for several of these effects have been delineated at the molecular level. However, the evidence base is almost entirely preclinical; human clinical trials evaluating isolated vicenin compounds are absent from the published literature. The one area with human-level data is the gastrointestinal application using standardised Perilla frutescens extract (of which vicenin-2 is a constituent), and even there the contribution of vicenin-2 specifically cannot be isolated from other extract components. Bioavailability remains a potential obstacle, and formal human safety data for supplemental doses are lacking.
Health conditions that Vicenin may help support.
Body systems that Vicenin may help support.
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