Rhoifolin (Apigenin 7-O-Neohesperidoside): A Comprehensive Reference
1. Identity and Chemical Characterization
Names and Synonyms
Rhoifolin, also known as rhoifoloside, is a well-known tri-substituted flavone belonging to the apigenin family. Its full chemical name is apigenin 7-O-neohesperidoside (also called apigenin-7-O-rhamnoglucoside), defined structurally as an apigenin derivative having an alpha-(1→2)-L-rhamnopyranosyl)-beta-D-glucopyranosyl moiety attached to the 7-hydroxy group. The compound is also catalogued under the synonym rhoifoloside. Its empirical formula is C₂₇H₃₀O₁₄, with a CAS registry number of 17306-46-6 and a molecular weight of 578.52 g/mol.
Chemical Classification
Rhoifolin belongs to the class of flavonoids and has been reported to exhibit anti-inflammatory, cytotoxic, antidiabetic, hepatoprotective, and cardioprotective activities. More precisely, it is a flavone glycoside: the aglycone core is apigenin (4′,5,7-trihydroxyflavone), and the sugar moiety attached at the 7-position is neohesperidose — a disaccharide composed of rhamnose and glucose.
Discovery and First Isolation
This molecule was obtained for the first time from the fresh leaves of Rhus succedanea in 1952. The term "Rhoi" in the name is derived from the generic name of the plant Rhus. Rhoifolin was first isolated from Rhus succedanea (Sumac or wax tree), which originates from Asia but is also found in Australia and New Zealand.
Physical Properties
Rhoifolin is a solid at room temperature. Despite its potential therapeutic efficacy, its easy degradation by environmental stress and low water solubility are the main limitations of its application as a drug.
2. Natural Sources and Botanical Distribution
Primary Plant Families
Rhoifolin is a flavonoid found in various plant species, especially within the Rutaceae family, and is considered a dietary component due to its presence in edible plants. This flavone and its glycosides are widely distributed in the plant kingdom, found in many plant families including Apiaceae, Asteraceae, Fabaceae, Lamiaceae, Malvaceae, and Rutaceae.
Key Plant Sources
Rhoifolin has been isolated from Boehmeria nivea (China grass or ramie; leaf), Citrus limon (Canton lemon; leaf), Citrus × aurantium (bigarade or bitter orange; plant), Citrus × paradisi (grapefruit; leaf), Ononis campestris (cammock; shoot), and Sabal serratula (serenoa or sabal fruit; plant). It has also been found in plants such as Paeonia suffruticosa and Buddleja albiflora. Additional botanical sources include Chorisia crispiflora (Malvaceae), from which rhoifolin was isolated and identified by different spectroscopic techniques.
Dietary Sources
Rhoifolin has also been found in several dietary sources such as bitter orange, bergamot, grapefruit, lemon, lupinus, lablab beans, tomatoes, artichoke, bananas, and grapes. It is found in large quantities in several sections and juices of many Citrus species.
Notable Source Plants in Pharmacological Research
Callicarpa nudiflora is a medical herb that widely grows in the southern part of China and has been shown to exert anti-tumor effects. Rhoifolin has been identified as one of its key active constituents. Callicarpa nudiflora is one of the medical herbs in the genus Callicarpa, widely grown in southern China, and is clinically used as an agent for haemostasis, memory improvement, and for treating respiratory tract infections and hepatitis.
3. Traditional and Historical Use
Rhoifolin as an isolated pure compound has no documented history of use in traditional medicine — it is a modern phytochemical isolate, first characterized scientifically in 1952. However, the plants from which it is obtained have extensive traditional use in multiple medical traditions, and rhoifolin is now understood to be one of their bioactive constituents.
Chinese Traditional Medicine
The dried aerial parts of Callicarpa nudiflora are used as traditional Chinese herbal medicine (Luo-hua-zi-zhu), which has been widely used in anti-bacterial and anti-ulcer applications in China. Callicarpa nudiflora has the functions of clearing away heat, detoxification, and dampness; flavonoids, phenylpropanes, terpenoids, volatile oils, phenols and sterols are its main chemical constituents; modern pharmacology shows it has anti-inflammatory, hemostatic, antibacterial, and hepatoprotective effects, and is clinically used to treat tropical bacterial infections, acute infectious hepatitis, and internal and external bleeding.
Citrus Plants in Traditional Medicine
Citrus species, which are rich natural sources of rhoifolin, have deep roots in traditional medicine across Asia, the Mediterranean, and the Americas. Citrus aurantium (bitter orange) and Citrus grandis (pomelo) have been employed in traditional Chinese and Ayurvedic medicine for digestive, anti-inflammatory, and metabolic ailments. Rhoifolin isolated from Citrus grandis leaves was found to be beneficial in metabolic diseases, including type II diabetes, by enhancing adiponectin secretion, tyrosine phosphorylation of insulin receptor-β, and GLUT4 translocation.
Other Ethnobotanical Contexts
Callicarpa nudiflora has been widely used in Li nationality medicine for treating burns and scalds in China. The source plant Rhus succedanea, from which rhoifolin was first isolated, belongs to the sumac family, members of which have been used across Asian and Middle Eastern traditions for their astringent and antimicrobial properties, though rhoifolin specifically was not identified in those traditions as a discrete agent.
4. Active Compounds, Structural Features, and Mechanisms of Action
Structural Basis of Bioactivity
Rhoifolin is a flavonoid glycoside primarily researched for its role in plant biology and its biochemical properties in various experimental models; as a derivative of apigenin linked to a neohesperidose sugar moiety, this compound offers unique insights into the role of flavonoids in plant defense and signaling. The glycosylation at the 7-position is pharmacologically significant. The increase in the degree of glycosylation may decrease the antioxidant abilities of flavonoids, and rhoifolin had moderate enzyme inhibition abilities warranting further investigation.
Relationship to Diosmin
Both rhoifolin and diosmin belong to flavonoids that are widely present in citrus; diosmin is used in the medical field worldwide and as a dietary supplement in the United States; rhoifolin has a similar structure to diosmin and also exhibits antioxidant and anti-inflammatory properties.
Anti-Inflammatory Mechanisms
Proinflammatory cytokines, TNF-α, IL-1β, and IL-6 showed significant downregulation of gene expression following rhoifolin treatment, and the NF-κB pathway showed significant attenuation as evident in the significant reduction in the levels of NF-κB p65 and p-IκB-α. The antioxidant and anti-inflammatory action of rhoifolin is probably mediated by the NF-κB pathway. It has also exhibited potent anti-inflammatory activity at low doses in carrageenan-induced rat paw edema and abolished the prostaglandin E2 level; increasing doses of rhoifolin significantly reduced TNF-α release.
Anticancer Mechanisms
Rhoifolin regulates cell proliferation and apoptosis through the AKT/JNK signaling pathway. Rhoifolin up-regulates the expressions of JNK and p-JNK, down-regulates p-AKT in cancer cells, and up-regulates the expression of caspase-3, suggesting that the AKT/JNK/caspase-3 pathway is involved in rhoifolin-induced apoptosis in pancreatic cancer cells. In breast cancer cell models, rhoifolin was found to suppress Ezrin phosphorylation and its consequent interaction with podocalyxin (PODXL), and showed an obvious inhibitory effect on TGF-β1-induced EMT in MDA-MB-231 cells.
Antidiabetic Mechanisms
This flavone glycoside possesses antidiabetic activity in differentiated 3T3-L1 adipocytes, showing a dose-dependent insulin-mimetic effect (0.001–5 μM) and enhanced tyrosine phosphorylation of insulin receptor-β, adiponectin secretion, and GLUT4 translocation. Rhoifolin produces antioxidant effects as exhibited by DPPH and ABTS⁺ assays, and shows potent alpha-amylase and alpha-glucosidase inhibitory activities.
Hepatoprotective Mechanisms
Rhoifolin has been demonstrated to mitigate ethanol-induced liver injury by impeding NF-κB phosphorylation. In autoimmune liver models, rhoifolin significantly decreased serum biochemical indices (ALT, AST, ALP, and LDH) and regulated related oxidative stress indicators (MDA, SOD, and GSH), reduced hepatic necrosis areas and immune cell infiltration, and inhibited the release of various inflammatory factors (TNF-α, IFN-γ, IL-2, and IL-17).
Antioxidant Mechanisms
Scientific studies have found that rhoifolin contributes to cellular protection mechanisms against oxidative stress in plant cells by scavenging free radicals and upregulating antioxidant pathways. In in vitro tests, however, results revealed weak antioxidant activities for rhoifolin, although the compound demonstrated some promising enzyme inhibitory effects against BChE (4.03 mg GALAE/g) and tyrosinase (7.44 mg KAE/g), but was not active on AChE.
Neuroprotective Mechanisms
Rhoifolin could alleviate anxiety, memory deficits, and brain oxidative stress in scopolamine-treated zebrafish and could regulate the cholinergic function by inhibiting acetylcholinesterase (AChE) activity.
Antiviral Mechanisms
Rhoifolin (apigenin-7-O-rhamnoglucoside) was examined alongside other flavonoids for inhibitory effects on the 3CL-protease of coronavirus; these flavonoids inhibited the enzyme at dose-dependent inhibitory concentrations, and rhoifolin inhibited the CoV-3CL-protease. In addition, rhoifolin was reported to inhibit CVB3 infection, a primary cause of viral myocarditis in humans.
Cardiovascular Mechanisms
Rhoifolin caused a decrease in mean aortic pressure, arterial and pulmonary capillary pressure, and heart rate in the dog in earlier experimental pharmacology work.
5. Scientific Evidence by Area of Use
Important note on evidence quality: As of the current literature, no human clinical trials of rhoifolin as an isolated compound have been published. All evidence reviewed below is derived from in vitro cell studies, animal (in vivo) models, or computational (in silico) studies. This body of evidence is preliminary and cannot be extrapolated directly to human efficacy or safety.
5.1 Oncology / Anticancer Activity
Pancreatic Cancer (In Vitro and Cell-Line)
Rhoifolin inhibited cell migration and invasion, and increased antioxidant capacity in PANC-1 and ASPC-1 pancreatic cancer cell lines; AKT activator (SC79) or JNK inhibitor (SP600125) effectively reversed the anticancer effects of rhoifolin, confirming pathway specificity. This was a mechanistic in vitro study published in Scientific Reports (2022).
Hepatocellular Carcinoma (In Vitro and Xenograft)
The suppressive effect of rhoifolin on HCC cells was assessed via CCK8 assay, apoptosis assay, cell cycle analysis, and a xenograft tumor mouse model; the IC₅₀ values of rhoifolin in HepG2 and HuH7 cells were 373.9 and 288.7 μg/mL at 24 hours and 208.9 and 218.0 μg/mL at 48 hours, respectively.
Breast Cancer (In Vitro)
Treatments with 10 and 40 μM of rhoifolin induced significant inhibitions on cell migration and alterations on the location and organization of actin cytoskeleton in breast cancer cells. Rhoifolin shows anti-motile properties on breast cancer cells due to its potential to downregulate the Podocalyxin-Ezrin interaction during Epithelial Mesenchymal Transition. This was a cell-migration study published in Phytomedicine (2021) and is limited to in vitro methodology.
Cervical and Laryngeal Cancer (In Vitro)
Rhoifolin exhibited potent in vitro cytotoxicity with high selectivity against human epidermoid larynx and human cervical carcinoma cell lines (IC₅₀: 5.9 and 6.2 μg/mL); it also induced a promising effect against hepatocellular and fetal human lung fibroblast cancer cell lines with IC₅₀ values of 22.6, 34.8, and 44.6 μg/mL, respectively.
Evidence Strength: Preclinical only (in vitro and animal models). Recent studies have shown that rhoifolin can induce apoptosis and inhibit cancer cell proliferation, making it a promising candidate for anticancer therapies. No clinical data exist.
5.2 Anti-Inflammatory and Antirheumatic Activity
A study was conducted to identify the effect of rhoifolin on complete Freund's adjuvant (CFA)-induced arthritis in the rat model; treatment with rhoifolin (10 and 20 mg/kg) showed significant improvement in overall health parameters such as paw edema and weight loss; this improvement corroborated findings with gross morphological changes observed in histopathological analysis. Rhoifolin treatment also caused a significant decrease in oxidative stress, evident from changes in intracellular levels of glutathione, glutathione peroxidase, malondialdehyde, and superoxide dismutase in articular cartilage tissue; proinflammatory cytokines TNF-α, IL-1β, and IL-6 showed significant downregulation of gene expression and intracellular protein concentration levels.
A study examining tobacco-smoke-induced lung inflammation found that smoke-induced lung inflammation and oxidative stress was mitigated by rhoifolin treatment; histological examination revealed smoke-related morphological changes in lung tissue; rhoifolin treatment reduced oxidative stress and inflammation, as evidenced by decreased proinflammatory cytokines.
Evidence Strength: Animal studies only; no human trials. Results are consistent across multiple models but require clinical validation.
5.3 Antidiabetic / Metabolic Activity
The anti-diabetic potential of rhoifolin was examined in streptozotocin-induced diabetic rats, where dose-dependent (10 and 20 mg/kg) anti-hyperglycemic, anti-hyperlipidemic, anti-inflammatory, and antioxidant effects were evaluated by measuring fasting blood glucose, serum glucose, serum insulin, HOMA-IR, lipidemic status, inflammatory cytokines, and hepatic antioxidant markers.
A further study in a type 2 diabetes model found that rhoifolin significantly improved body weight and protected against hepatic damage and steatosis; it notably reduced plasma glucose, insulin, HbA1c, and HOMA-IR; serum lipid profiles also improved, with decreases in triglycerides, cholesterol, LDL-c, and free fatty acids, and an increase in HDL-c. Rhoifolin reduced inflammation, demonstrated by lower TNF-α and IL-6 levels and decreased transcription of NF-κB; it also mitigated oxidative stress, evidenced by reduced MDA and increased GSH, SOD, and HO-1 levels. The treatment of rhoifolin improved hepatic glucokinase activity and lowered glucose-6-phosphatase levels; these effects were dose-dependent.
Evidence Strength: Multiple consistent animal studies in streptozotocin and HFD/STZ models. Mechanism explored at molecular level. No human data.
5.4 Hepatoprotective Activity
In a mouse model, adult male mice were pretreated with rhoifolin daily (20 mg/kg and 40 mg/kg, orally) for 7 days before Con A intoxication; results showed that rhoifolin significantly decreased serum biochemical indices (ALT, AST, ALP, and LDH) and regulated related oxidative stress indicators, reduced hepatic necrosis areas and immune cells infiltration, inhibited the release of various inflammatory factors (TNF-α, IFN-γ, IL-2, and IL-17), and improved hepatic tissue apoptosis, thereby alleviating hepatic damage induced by Con A.
Evidence Strength: Animal (mouse) model of autoimmune hepatitis; consistent with parallel metabolic studies. No human clinical trials.
5.5 Neuroprotective / Cognitive Activity
The goal of one study was to investigate the improvement impact of rhoifolin on scopolamine-induced zebrafish anxiety, amnesia, and brain oxidative stress; zebrafish were treated with rhoifolin (1, 3, and 5 μg/L) for nine consecutive days and were subsequently subjected to scopolamine (100 μM) 30 min before behavioral tests (novel tank diving test, Y-maze, and novel object recognition tests). Rhoifolin could alleviate anxiety, memory deficits, and brain oxidative stress in scopolamine-treated zebrafish and could regulate the cholinergic function by inhibiting AChE activity.
A subsequent study found that rhoifolin and baicalin improved spatial memory in Y-maze tasks and recognition memory in the NOR test, and reduced anxiety levels; moreover, these compounds reduced the level of oxidative stress caused by scopolamine administration and increased the activities of catalase and glutathione peroxidase, suggesting an antioxidant profile. A further 2024 publication reported that rhoifolin improved memory and decreased anxiety-like behavior of scopolamine-induced amnesia in zebrafish; additionally, the studied flavonoids reduced AChE activity and brain oxidative stress and upregulated gene expression, collectively contributing to neuroprotective properties.
Evidence Strength: Zebrafish behavioral models only; limited translational relevance to human neurodegenerative disease. No mammalian in vivo studies and no human data.
5.6 Antiviral Activity
Rhoifolin was found to efficiently block the enzymatic activity of SARS-CoV 3CL-protease in computational and in vitro enzyme assays. When rhoifolin and related flavonoids were checked for their inhibitory effect on the 3CL-protease of coronavirus, these flavonoids inhibited the enzyme at dose-dependent inhibitory concentrations; rhoifolin inhibited the CoV-3CL-protease. Rhoifolin was also reported to inhibit CVB3 infection, a primary cause of viral myocarditis in humans.
Evidence Strength: Primarily computational (molecular docking) and in vitro enzyme assay data. Results are hypothesis-generating. No animal-level antiviral studies and no human data on antiviral efficacy have been published for rhoifolin as a standalone agent.
5.7 Antioxidant Activity
The in vitro evaluation of the antioxidative effects of rhoifolin was conducted using multiple assays — DPPH, CUPRAC, ABTS, phosphomolybdenum, and FRAP — and enzyme inhibitory potential was evaluated for AChE, BChE, tyrosinase, amylase, and glucosidase. Results revealed weak antioxidant activities for rhoifolin, although the compound demonstrated some promising enzyme inhibitory effects against BChE (4.03 mg GALAE/g) and tyrosinase (7.44 mg KAE/g), but was not active on AChE; regarding anti-diabetic enzymes, the compound was active on amylase but did not show any inhibition effect on glucosidase.
Evidence Strength: Mixed. In vitro antioxidant activity is described as weak in direct assays, although indirect antioxidant effects (regulation of endogenous antioxidant enzymes such as SOD and GSH) are consistently observed in animal models across multiple organ systems.
6. Body Systems and Health Areas Associated with Rhoifolin
- Oncology: Rhoifolin is widely distributed in the plant kingdom, especially in Citrus species, and exhibits a variety of bioactivities including strong cytotoxic and anticancer effects.
- Liver (Hepatoprotection): Rhoifolin exhibits a diverse range of biological activities, encompassing anticancer, hepatoprotective, antidiabetic, antirheumatic, and antiviral properties.
- Metabolic / Endocrine: Antidiabetic effects demonstrated across multiple preclinical models (see Section 5.3).
- Immune / Inflammatory: NF-κB pathway modulation, cytokine suppression (see Section 5.2).
- Nervous System: AChE inhibition, memory improvement in zebrafish models (see Section 5.5).
- Cardiovascular: Rhoifolin caused a decrease in mean aortic pressure, arterial and pulmonary capillary pressure, and heart rate in the dog.
- Infectious Disease / Antiviral: In vitro inhibition of coronavirus 3CL-protease and CVB3 (see Section 5.6).
- Skin / Pigmentation: Promising enzyme inhibitory effects were demonstrated against tyrosinase (7.44 mg KAE/g), suggesting potential relevance for hyperpigmentation research.
7. Dosage Forms and Reported Dosages
Rhoifolin has not been approved as a pharmaceutical drug or formally standardized as a dietary supplement by any regulatory authority. The following dosages were employed exclusively in preclinical research:
- Rheumatoid arthritis (rat model): Treatment with rhoifolin at 10 and 20 mg/kg showed significant improvement in overall health parameters.
- Autoimmune hepatitis (mouse model): Mice were pretreated with rhoifolin daily at 20 mg/kg and 40 mg/kg orally for 7 days before Con A intoxication.
- Streptozotocin-induced diabetes (rat model): Dose-dependent anti-hyperglycemic effects of rhoifolin were evaluated at 10 and 20 mg/kg.
- Type 2 diabetes model (rat): T2DM was induced in adult male Wistar rats; all experiments were conducted over 8 weeks, with six rat groups administered incremental doses of rhoifolin (10, 20, 40 mg/kg) for the last 4 weeks.
- Neuroprotection (zebrafish model): Zebrafish were treated with rhoifolin at 1, 3, and 5 μg/L for nine consecutive days.
- Breast cancer (in vitro): Treatments with 10 and 40 μM of rhoifolin induced significant inhibitions on cell migration.
- Lung inflammation (rat model): Rhoifolin was administered orally for 21 days before smoke exposure.
No human dosing data are available. Rhoifolin is commercially available as a research-grade analytical standard and as a phytochemical reference substance.
8. Safety Considerations
Acute Toxicity Observations
Studies on acute toxicity of rhoifolin were performed on control animals; graded rhoifolin doses were dissolved in DMSO (1%, v/v) and administered orally at concentrations from 10 to 50 mg/kg; animals were kept on a 10-day observation period during which diet, changes in weight, fluid intake, and psychomotor changes were measured; rhoifolin did not show any toxicity at all the tested doses.
Hepatotoxicity — Lack of Observed Effect
The safety of rhoifolin was confirmed through histochemical experiments (H&E staining) in a subcutaneous tumor transplantation mouse model. In the same HCC study, organ histopathology at therapeutic doses did not indicate hepatotoxic changes, though dose ranges were modest.
Limitations of Bioavailability
Despite the potential therapeutic efficacy of rhoifolin, its easy degradation by environmental stress and low water solubility are the main limitations of its application as a drug. As a glycosylated flavone, its oral bioavailability is expected to differ from that of the aglycone apigenin, as hydrolysis by gut microbiota and intestinal enzymes may partially convert it to apigenin before absorption; however, no dedicated pharmacokinetic study in humans or mammals has been published for rhoifolin in isolation.
Structural Similarity to Diosmin
Both rhoifolin and diosmin belong to flavonoids widely present in citrus; diosmin is used in the medical field worldwide and as a dietary supplement in the United States; rhoifolin has a similar structure to diosmin and also exhibits antioxidant and anti-inflammatory properties. Extrapolation of diosmin's known clinical interactions to rhoifolin is not scientifically validated.
Absence of Human Safety Data
No clinical trials, pharmacovigilance reports, or formal safety assessments of rhoifolin as an isolated or formulated supplement in humans have been published in the peer-reviewed literature as of the time of writing. Any safety conclusions remain speculative beyond the preclinical evidence summarized above. Preclinical studies have demonstrated that rhoifolin exhibits many potent therapeutic activities such as anti-inflammatory, antioxidant, antibacterial, antiviral, anticancer, antidiabetic, hepatoprotective, and antirheumatic properties, but translation to clinical application requires formal toxicological and pharmacokinetic evaluation in humans.
References
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