Isovitexin: A Comprehensive Encyclopedic Reference
1. Identity and Chemical Characterization
Names and Synonyms
Isovitexin (also known as homovitexin or saponaretin) is a flavonoid, specifically the apigenin-6-C-glucoside. Additional synonyms documented in the chemical literature include 6-glucosylapigenin, 6-C-glucosylapigenin, and 6-C-glucosyl-apigenin. The prefix "iso" does not imply an isoflavonoid structure (i.e., it does not refer to the position of the B-ring on the C-ring), but rather indicates the position of the glucoside on the flavone backbone, in comparison to vitexin.
Structural Classification
Among flavonoids, apigenin (4′,5,7-trihydroxyflavone) is a typical natural flavonoid. Vitexin and isovitexin are C-glycosylated derivatives of apigenin, with glucose units attached at different positions — C-8 in vitexin and C-6 in isovitexin. Isovitexin, the 6-C-glucoside isomer of vitexin, shares the same molecular formula (C21H20O10) and molecular weight (432.38 g/mol), but differs in glycosylation position. Both compounds contain seven hydroxyl groups, and their polyhydroxylated structures contribute significantly to their biological activity.
The C-glycosidic bond — in which the glucose unit is directly attached to a carbon atom of the flavone ring rather than through an oxygen atom — is a structurally distinguishing feature. Based on structural differences, almost all flavonoids in natural foods are presented as either flavonoid O-glycosides or flavonoid C-glycosides. In most cases, C-glycosyl flavonoids showed higher antioxidant and antidiabetes potential than their corresponding O-glycosyl flavonoids and aglycones.
In plants such as Lemna minor, vitexin was found converting to isovitexin rather than the reverse direction, demonstrating that a biosynthetic route to isovitexin is via vitexin.
CAS Registration and Registry
Isovitexin is registered under CAS number 38953-85-4 and is listed in the NIH National Center for Advancing Translational Sciences (NCATS) Inxight Drugs database. It is classified as apigenin-6-C-glucoside, an isomer of vitexin, found in plants such as pigeon pea, Passiflora, bamboo, mimosa, wheat leaves, and the rice hull of Oryza sativa, among others.
2. Natural Sources and Botanical Distribution
Primary Plant Sources
Isovitexin is widely distributed across the plant kingdom. As a mono-C-glycosylflavone, it is found in various natural sources, including certain insects, honey, fungi, and a wide range of plants such as pigeon pea, mung bean, mosses, Passiflora species, bamboo, mimosa, and wheat leaves, as well as in numerous fruits, flowers, roots, and leaves.
Isovitexin (apigenin-6-C-glucoside) exists in plants containing vitexin, such as pigeon peas, passion flowers, bamboo, mimosa, and wheat leaves, and has been screened as a bioactive ingredient. Isovitexin has been found in passion flower, cannabis, oat, and the açaí palm. Buckwheat contained the highest concentration among the sources tested.
Additional plant sources documented in the peer-reviewed literature include:
- Fagopyrum esculentum (common buckwheat): Orientin, vitexin, isoorientin, and isovitexin have been isolated from buckwheat grain and hulls, while buckwheat seeds also contain isovitexin.
- Oryza sativa (rice): The glycosylflavonoid isovitexin, extracted from rice hulls of Oryza sativa, possesses various biological activities, including anti-inflammatory and antioxidant activities.
- Celtis sinensis (Chinese hackberry): Isovitexin is the most abundant flavonoid in the leaf of Celtis sinensis and is a widely found natural carbon glycoside flavonoid.
- Passiflora incarnata (passionflower): Constituents of the Passiflora genus include flavonoids, mainly C-glycosides of apigenin and luteolin, such as vitexin, isovitexin, orientin, iso-orientin and their 2″-β-D-glucosides.
- Bamboo leaves (Phyllostachys spp.): Bamboo leaves from Phyllostachys spp., prevalent in temperate Asian regions, contain vitexin alongside related glycosides like orientin and isovitexin, isolated in yields up to 15 mg from ethanol extracts.
- Cannabis sativa: Vitexin and isovitexin can be found in plants such as millet, oak, fenugreek, linseed, buckwheat, flax, and cannabis.
- Euterpe oleracea (açaí palm): Also confirmed as a source alongside passion flower and other plants.
Forms and Preparations in Commerce
Isovitexin occurs naturally in whole plant material and is consumed as part of ordinary foods (buckwheat, oats, rice) as well as in herbal preparations. In research and pharmaceutical contexts, it is isolated as a pure reference standard of typically ≥98% purity using high-performance liquid chromatography (HPLC). Traditionally, dried aerial parts are gathered during the fruiting season, and a dry hydroalcoholic extract is made. Isovitexin is also found in standardized passionflower extracts, where the British Pharmacopoeia drug is required to contain not less than 1.5% total flavonoids calculated as vitexin. Emerging delivery systems under investigation include microencapsulation, nanoparticles, and liposomal formulations to address bioavailability limitations (see Pharmacokinetics section).
3. Traditional and Historical Use
Isovitexin has not been isolated and studied as a standalone compound in traditional medicine; rather, it is a phytochemical constituent of several plants with long-standing ethnobotanical use. Its history is therefore inseparable from the traditions surrounding its primary botanical sources.
Passionflower (Passiflora spp.)
In the countries of origin (North, Central and South America), passionflower has been used empirically as an antispasmodic and sedative. Popular as a sedative in the early 20th century, passionflower even appeared in the US National Formulary (a predecessor of the modern American pharmacopoeia) until 1936. European regulatory recognition of its traditional use followed: the European Medicines Agency's Committee on Herbal Medicinal Products (HMPC) lists its traditional use as relief of mild stress symptoms and as a sleep aid, while ESCOP approved it for tension, restlessness, excitability, and sleep disorders, and Commission E approved it for nervous restlessness.
Passionflower contains flavonoids, notably vitexin, isovitexin, apigenin, and quercetin, and these C-glycosylated flavonoids are considered to contribute to the plant's pharmacological activity alongside alkaloids.
Traditional Chinese Medicine and Asian Traditions
Vitexin and isovitexin are active components in many plants used in traditional Chinese medicines to soothe pain and inflammation and support brain function. Plants rich in these flavonoids, including bamboo leaves and Celtis sinensis, have featured in Chinese pharmacopoeia traditions. There is a folk tradition from the Maolan karst forest that if someone contacted poison ivy inadvertently, treatment involved putting the leaf of Celtis sinensis Pers. into the mouth — and isovitexin is the most abundant flavonoid in the leaf of Celtis sinensis.
Buckwheat in Asian and European Foodways
The major bioactive compounds in buckwheat are flavonoids (i.e., rutin, quercetin, orientin, isoorientin, vitexin, and isovitexin), fatty acids, polysaccharides, proteins, and amino acids, iminosugars, dietary fiber, and other nutrients. Buckwheat possesses high nutritional value due to these bioactive compounds. Buckwheat has been cultivated in China, Japan, Korea, and Europe for centuries, used both as a food grain and in folk medicinal preparations for circulatory health.
4. Key Constituents, Chemical Properties, and Mechanisms of Action
Chemical Structure and Radical-Scavenging Properties
Vitexin and isovitexin both have seven hydroxyls which may contribute to their bioactivities, especially the o-di-hydroxyl structure in the A ring, which has been proven to contribute to effective radical scavenging in flavonoids. The C-glycoside bond confers resistance to enzymatic hydrolysis, making isovitexin more metabolically stable than equivalent O-glycosides. Vitexin has been proven capable of donating electrons and acts as a good radical scavenger. It has better antioxidant activity than apigenin, since the presence of C-glucoside causes a reduction in bond dissociation enthalpy compared to the aglycone apigenin.
Anti-Inflammatory Pathways
Isovitexin may offer a protective role against LPS-induced acute lung injury (ALI) by inhibiting MAPK and NF-κB and activating HO-1/Nrf2 pathways. These pathways are central mediators of the inflammatory response: NF-κB controls the transcription of pro-inflammatory cytokines, MAPK cascades regulate cellular stress responses, while HO-1 (heme oxygenase-1) and Nrf2 (nuclear factor erythroid 2–related factor 2) constitute a cytoprotective antioxidant axis.
Isovitexin attenuates the LPS-induced phosphorylation of all three MAPKs, reduces NF-κB activation, and promotes M2 polarization in macrophages. Vitexin and isovitexin showed anti-inflammatory activity through modulation of the MAPK signaling pathway and inhibited the secretion of COX-2, IL-1β, IL-6, MCP-1, and TNF-α.
Antioxidant Mechanisms
Flavonoid C-glycosides such as isovitexin have been reported to have significant antioxidant activity, anticancer and antitumor activity, hepatoprotective activity, anti-inflammatory activity, antidiabetes activity, antiviral activity, antibacterial and antifungal activity, and other biological effects. In most cases, C-glycosyl flavonoids showed higher antioxidant and antidiabetes potential than their corresponding O-glycosyl flavonoids and aglycones.
Anticancer Mechanisms
Isovitexin helps to stimulate apoptotic cell death and autophagy of various cancer cells through the upstream regulation of Bax, PARP, p-JNK, and MAPK and the downstream regulation of the caspases Bcl-2 and ERK1/2. Both in vitro and in vivo studies have validated the anticancer potential of these compounds, primarily through the induction of apoptosis and autophagy.
Neuroprotective Mechanisms
Isovitexin (IVX) suppresses M1 microglial polarization and promotes M2 microglial polarization in LPS-activated BV-2 cells and mouse primary microglia, and this regulation improved sickness behavior in LPS-treated mice in vivo. The in vivo results are supported by in vitro results showing that IVX promotes microglial polarization into the M2 phenotype to exert a neuroprotective effect in LPS-caused neuroinflammation. This shift from pro-inflammatory M1 to anti-inflammatory M2 microglia is mediated via the CaMKKβ/AMPK-PGC-1α signaling axis.
Antidiabetic Mechanisms
The hypoglycemic and hypolipidemic effects of flavonoid C-glycosides on type 2 diabetes may be due to the inhibition of advanced glycation end-products (AGEs) and digestive enzymes, stimulation of glycogen storage, and activation of insulin signaling. Administered orally, vitexin and isovitexin significantly reduced postprandial blood glucose both in sucrose-loaded normoglycemic mice and sucrose-induced diabetic rats, demonstrating a potential role in diabetes management.
5. Scientific Evidence by Area of Use
5.1 Inflammation and Acute Lung Injury
Evidence level: Preclinical (in vitro and animal models); no human clinical trials identified.
A study published in International Journal of Biological Sciences evaluated the protective effects of isovitexin in RAW 264.7 macrophage cells exposed to LPS and in an LPS-induced ALI mouse model. Isovitexin effectively protected against LPS-induced damage, oxidative stress, and inflammation in vitro and in vivo. Isovitexin treatment effectively increased Nrf2 and HO-1 expression in lung tissues, and may therefore offer a protective role against LPS-induced ALI by inhibiting MAPK and NF-κB and activating HO-1/Nrf2 pathways.
A separate study investigated isovitexin's role in contact hypersensitivity using a mouse model of allergic contact dermatitis. Isovitexin dose-dependently upregulated apoptosis and suppressed the cytokines TNF-α, IFN-γ, IL-2 and IL-17A. This result was consistent with animal experiments, indicating that isovitexin exerts an immunomodulatory effect when facing an inflammatory challenge.
All anti-inflammatory evidence for isovitexin as a standalone compound is preclinical. No randomized controlled trials or other human clinical studies specifically examining isovitexin for inflammatory conditions have been identified in the peer-reviewed literature.
5.2 Cancer
Evidence level: Preclinical (in vitro and animal models); no human clinical trials identified.
Two natural flavonoids, apigenin and isovitexin, have been shown to act synergistically with conventional chemotherapeutic drugs by sensitizing cancer stem cells (CSCs), ultimately leading to improved therapeutic efficacy. A thorough review of the included literature supports a strong association between anti-CSC activity and treatment with apigenin or isovitexin.
A study published in Biomedicine & Pharmacotherapy investigated isovitexin in combination with cisplatin in non-small cell lung cancer (NSCLC). The study investigated the synergistic effects of isovitexin and cisplatin in NSCLC A549 and H1975 cells. The results showed that the combined treatment markedly inhibited proliferation and induced apoptosis of both NSCLC cell lines. Using a mouse model of A549 xenograft, isovitexin potentiated the inhibition of cisplatin on tumor growth, but reduced cisplatin-induced hepatotoxicity and nephrotoxicity in mice.
Work on hepatocellular carcinoma has also been documented. A 2020 publication in Cancer Management and Research reported that modulation of MnSOD and FoxM1 is involved in invasion and epithelial-mesenchymal transition (EMT) suppression by isovitexin in hepatocellular carcinoma cells. Isovitexin has been documented to alleviate inflammation, liver injury, and diabetes.
The mechanistic breadth of isovitexin's anticancer activity is notable but all current evidence is preclinical. Extrapolation to human cancer therapy is not supported by clinical trial data at this time.
5.3 Neuroprotection and Neurodegenerative Disease
Evidence level: Preclinical (in vitro and animal models); one retracted publication noted.
Isovitexin (IVX) is a natural bioactive constituent present in various medicinal plants, and it has been shown from an assortment of studies to exert potential antioxidant, anti-inflammatory, and neuroprotective effects as well as to ameliorate neurobehavioural and psychiatric disorders (e.g., memory-enhancing, anxiolytic effects).
A 2019 study published in Frontiers in Immunology demonstrated that isovitexin could shift microglia from M1 to M2 by the CaMKKβ/AMPK signaling pathway. This mechanistic study used BV-2 microglial cells and a mouse model of LPS-induced neuroinflammation.
A study examining an Alzheimer's disease model found that isovitexin administered to a streptozotocin (STZ)-induced AD mouse model produced neuroprotective and cognitive effects via a miR-107 signaling mechanism. However, it should be noted that a retraction of the paper titled "Isovitexin modulates autophagy in Alzheimer's disease via miR-107 signalling" was published in Translational Neuroscience in November 2022, which affects the evidentiary weight of that specific finding. The broader mechanistic literature on isovitexin and neuroinflammation, however, remains published and peer-reviewed.
Growing scientific interest in vitexin and isovitexin stems from their multitarget pharmacological effects and their potential health benefits against several diseases, including Alzheimer's disease, neurological or psychiatric diseases, ischemic injury, inflammation, diabetes mellitus, cancer, and oxidative stress-related conditions.
5.4 Diabetes and Metabolic Disorders
Evidence level: Preclinical (in vitro, animal); very limited human data through passionflower combination products.
Isovitexin has been documented to alleviate diabetes in preclinical models. The antidiabetic mechanisms attributed to isovitexin and related C-glycosylflavones include inhibition of α-glucosidase (an enzyme critical for carbohydrate digestion), suppression of AGE formation, and activation of insulin signaling cascades. An in vitro anti-diabetic activity assay showed that the inhibitory rate of vitexin against human sodium-dependent glucose co-transporter 2 (SGLT2) was 3 times higher than that of isovitexin, suggesting that despite structural similarities, isovitexin may have quantitatively different potency at specific targets.
The hypoglycemic and hypolipidemic effects of flavonoid C-glycosides on type 2 diabetes could be due to the inhibition of AGEs and digestive enzymes, stimulation of glycogen storage, and activation of insulin signaling. No human clinical trials specifically testing isolated isovitexin for diabetes management have been identified.
5.5 Cardiovascular and Hepatoprotective Effects
Evidence level: Preclinical; some limited clinical data for passionflower combination products (not isolate).
Isovitexin and vitexin have demonstrated antioxidant, anti-inflammatory, anticancer, neuroprotective, and cardioprotective properties. Additionally, they have demonstrated lipid-lowering effects, regulation of glucose metabolism, and hepatoprotective activity.
Preliminary clinical research shows that taking a combination of passionflower and hawthorn flower extracts orally three times a day for six weeks increases six-minute walk distance compared with placebo in people with mild heart failure. This finding pertains to a multi-ingredient botanical combination and cannot be attributed solely to isovitexin.
5.6 Sedation, Anxiolytic, and Sleep Effects
Evidence level: Preclinical for isolated isovitexin; moderate clinical evidence for passionflower herb (containing isovitexin as a key constituent).
Isovitexin is one of the principal flavonoids in Passiflora incarnata, a plant with regulatory recognition for anxiolytic and sedative use. Isovitexin and vitexin have shown an ability to attenuate withdrawal symptoms in morphine-dependent animals, indicating an action on GABA receptors. The full passionflower extract is recognized by the ESCOP, Commission E, and EMA/HMPC for use in nervous restlessness and sleep disorders. Whether isovitexin is independently responsible for these effects — as opposed to other constituents such as chrysin or the β-carboline alkaloids — has not been conclusively determined.
5.7 Antinociceptive (Pain-Reducing) Effects
Evidence level: Preclinical.
Work with Brazilian medicinal plants of the genus Echinodorus identified isovitexin as both a marker compound and a bioactive constituent contributing to antinociceptive activity in animal models. Vitexin has received increased attention due to its wide range of pharmacological effects, including anti-nociceptive activity, and parallel properties have been attributed to isovitexin in related research. No human analgesic trials have been published for isolated isovitexin.
5.8 Antimicrobial and Antiviral Effects
Evidence level: In vitro only.
Vitexin has a variety of pharmacological effects, including antiviral and antibacterial effects. Isovitexin shares these classifications in the broader flavonoid C-glycoside literature, but specific antimicrobial studies on isovitexin as an isolated compound in human-relevant settings have not been identified. The evidence base is limited to in vitro studies against specific pathogens and does not support conclusions about clinical efficacy.
6. Body Systems and Health Areas Associated with Isovitexin
These compounds exhibit therapeutic potential across multiple biological systems, including the immune, nervous, respiratory, cardiovascular, and endocrine systems, through antioxidant, anti-inflammatory, anticancer, antibacterial, and neuroprotective mechanisms. The specific body systems for which peer-reviewed preclinical evidence exists are:
- Nervous system: Neuroprotection, microglial polarization, cognitive function modulation, anxiolytic activity (preclinical).
- Immune system: Anti-inflammatory signaling through NF-κB, MAPK, and Nrf2/HO-1 pathway modulation; macrophage and T-cell regulation (preclinical).
- Respiratory system: Protection against LPS-induced acute lung injury; reduction of pulmonary inflammation (preclinical).
- Cardiovascular system: Cardioprotective and lipid-lowering properties (preclinical; limited combination-product clinical data).
- Hepatic system: Hepatoprotective activity; potential attenuation of liver fibrosis and injury (preclinical).
- Endocrine/Metabolic system: Glucose metabolism regulation, antidiabetic activity (preclinical).
- Musculoskeletal system: An in vitro study identified isovitexin as depressing osteoarthritis progression via the Nrf2/NF-κB pathway.
- Oncology: Anti-proliferative and pro-apoptotic activity in multiple cancer cell lines and xenograft models (preclinical).
7. Pharmacokinetics and Bioavailability
Vitexin and isovitexin are natural flavone C-glucosides that have numerous benefits for human health. However, their low oral bioavailability and poor gastrointestinal absorption dramatically restrict their potential medicinal uses.
Vitexin and isovitexin are poorly absorbed in the gastrointestinal tract. They directly reach the colon, where they are hydrolysed by the gut microflora through deglycosylation and ring-opening of the heterocyclic C ring. It is likely that vitexin and isovitexin are degraded into small-molecule phenols and various aromatic acids such as phloretic acid.
The first-pass effect is predominantly intestinal. The first-pass effects of vitexin are almost intestinal (approximately 94%) and less gastric (30%) and hepatic (5%), which contribute to its low bioavailability. Similar profiles are expected for isovitexin given its analogous structure.
Pharmacokinetic parameters for isovitexin specifically have been reported in animal studies. After oral administration of 29.3 mg/kg in rats, the Cmax, tmax, t1/2, AUC0→t, AUC0→∞, MRT0→t, and MRT0→∞ were 76.0 ± 25.1 mg/l, 0.305 ± 0.07 h, 10.0 ± 6.03 h, 290.5 ± 84.4 mg·h/l, 320.5 ± 92.4 mg·h/l, 6.78 ± 1.04 h, and 12.1 ± 6.37 h, respectively.
The highest level of intravenously administered isovitexin was examined in the kidney, liver, and lung, with the lowest level found in the brain.
Researchers have explored several strategies to improve bioavailability. Microencapsulation with biodegradable polymers is a promising strategy for improving stability, bioavailability, and biocompatibility. Microspheres have been prepared using alginate as the core matrix and a chitosan outer layer. In one delivery system, the oral bioavailability of vitexin increased by 5.6-fold compared to free vitexin. Liposomal encapsulation using the thin-film hydration method provides an effective strategy for treating liver cirrhosis by enhancing the bioavailability and therapeutic effectiveness of vitexin through oral delivery. These technologies are in experimental stages and have not been evaluated in human clinical trials.
8. Dosage Forms and Doses Reported in Research
No established human clinical dose for isolated isovitexin has been determined. The following doses appear in the peer-reviewed preclinical literature:
- Oral administration in rats: 29.3 mg/kg (used for pharmacokinetic profiling).
- High-dose vitexin in mice: 10 mg/kg, administered intraperitoneally over a seven-day period (used to assess safety).
- Microsphere formulations tested with 1.17% low-viscosity alginate, showing a loading ratio of 22.45% and encapsulation efficiency of 68.92% for vitexin–isovitexin combined preparations.
In the context of passionflower herbal preparations containing isovitexin as a key constituent, standardized extracts used in European clinical research have been prepared from dried aerial parts. The European Pharmacopoeia and British Pharmacopoeia specify minimum flavonoid content standards for passionflower drug preparations, but do not specify an isovitexin-specific dose.
Limited knowledge on side-effects and the metabolism process, as well as complicated pharmacological actions and molecular mechanisms, means the majority of current research is still pre-clinical. Reviews provide a comprehensive summary of the pharmacological actions and mechanisms of vitexin and isovitexin, as well as a brief overview of their pharmacokinetic studies, to provide a reference for further clinical applications.
9. Safety Considerations and Drug Interactions
General Safety Profile
Vitexin and isovitexin are dietary flavonoids widely distributed in food and medicinal plants and have attracted increasing attention owing to their diverse pharmacological activities and favorable safety profiles.
Preclinical toxicological studies have found no significant cytotoxicity at pharmacologically relevant doses. In terms of liver and gastric mucosal injury, the long-term repeated use of high-dose vitexin (10 mg/kg, i.p.) was shown to be safe. Vitexin did not cause significant toxic reactions, even at high doses in in vivo experiments. By extrapolation, similar safety has been attributed to isovitexin, though direct long-term toxicology studies on isovitexin specifically are limited.
Bioavailability-Related Safety Considerations
Due to the pharmacokinetic characteristics of vitexin and isovitexin, routes of administration and drug combinations should be chosen properly. The poor oral bioavailability of isovitexin means that the effective tissue concentration may be substantially lower than the administered dose, complicating both efficacy assessments and dose-finding for potential clinical use.
Context of Passionflower Safety
Since isovitexin is most commonly consumed as part of passionflower preparations, the safety data for passionflower are relevant. Passionflower has regulatory recognition in Europe for its use as a traditional herbal medicinal product, indicating a recognized safety profile at customary doses. The Commission E, ESCOP, and EMA HMPC monographs support its use without listing serious adverse events at typical doses. Due to sedative properties, because of its anxiolytic and sedative properties, passionflower is recommended to relieve states of tension, agitation, irritability, and nervousness, caution is warranted with concurrent central nervous system depressants.
Drug Interactions
No specific drug interaction studies on isolated isovitexin in humans have been identified. The potential for interactions exists based on isovitexin's effects on cytochrome P450 enzymes and drug-metabolizing pathways, extrapolated from the broader flavonoid class. Isovitexin's demonstrated modulation of multiple signaling pathways — including NF-κB, MAPK, and AMPK — raises theoretical interaction concerns with drugs that share these targets. The pharmacological mechanisms, clinical efficacy, and potential synergistic effects of isovitexin with other therapeutic agents remain unclear, and systematic drug interaction studies have not been published. In the context of combination with chemotherapy, the preclinical evidence of synergy with cisplatin is promising but not clinically validated.
Overall Evidentiary Status
Limited knowledge on side-effects and metabolism process, as well as complicated pharmacological actions and molecular mechanisms, means the majority of current research is still pre-clinical. The pharmacological mechanisms, clinical efficacy, and potential synergistic effects of vitexin and isovitexin with other therapeutic agents remain unclear. Further systematic research is needed to clarify molecular targets and optimize their therapeutic applications. As of the available literature through mid-2025, no pivotal human clinical trials have been published that evaluate isovitexin as an isolated compound for any indication.
References
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