Hesperetin

Hesperetin: A Comprehensive Reference

1. Identity, Chemical Profile, and Natural Sources

Chemical Identity and Nomenclature

Hesperetin has the systematic chemical name (3′,5,7-trihydroxy-4′-methoxy-flavanone), or (S)-5-hydroxy-2-(3-hydroxy-4-methoxyphenyl)-2,3-dihydro-4H-chromen-4-one. It is the 4′-methoxy derivative of eriodictyol, a flavanone. Chemically, hesperetin is a trihydroxyflavone with three hydroxy groups located at positions 3, 5, and 7, with an additional methoxy substituent at position 4.

Hesperetin belongs to the flavanone subclass of the broader flavonoid family of plant polyphenols. The 7-O-glycoside of hesperetin, hesperidin, is a naturally occurring flavanone glycoside and the main flavonoid in grapefruits, lemons, and sweet oranges. In structural terms, hesperidin is a flavanone glycoside composed of the aglycone hesperetin and the disaccharide rutinose. Hesperetin itself is the aglycone — the non-sugar-bearing — form, and it is what hesperidin is metabolically converted to upon ingestion.

Botanical Sources

Hesperidin and its derivatives are characteristic compounds of citrus fruits (Rutaceae family) such as orange (Citrus sinensis), grapefruit (Citrus paradisi), tangerine (Citrus reticulata), lime (Citrus aurantifolia), and lemon (Citrus limon). Their content in citrus fruits depends on fruit variety, part of the fruit itself, climate, and degree of maturation.

Hesperidin is the predominant flavonoid in citrus fruits, primarily in sweet orange; in young, immature oranges it accounts for up to 14% of the dry weight. Hesperidin mainly exists in the peel of navel orange, where its content can reach 1.4% of the fresh weight of peel. Hesperetin is found in abundance in orange and grape juices (200–590 mg L⁻¹) consumed in the daily diet.

Beyond oranges, hesperidin (as glycoside of hesperetin) is predominant in orange and tangerine, while eriocitrin and hesperidin are the predominant flavonoids found in lemon and lime. The compound is also present in other members of the Rutaceae family, including Zanthoxylum avicennae and Citrus reticulata, which are documented sources in medicinal plant traditions.

Common Supplement Forms and Preparations

Hesperetin is available in several forms as a dietary supplement and food ingredient:

• Hesperidin (glycoside precursor): Hesperetin occurs ubiquitously in citrus fruits as hesperidin (its glycoside form), which acts as a prodrug. Dietary hesperidin gets deglycosylated to hesperetin by intestinal bacteria prior to absorption.
• Free aglycone (hesperetin): Hesperetin as a flavonoid compound possesses advantages such as low toxicity, simple preparation, reasonable cost, and wide availability. It is commercially available as a purified powder from citrus peel extracts.
• Cyclodextrin inclusion complexes: To enhance the bioavailability of hesperetin, various novel formulations have been developed, including nanoparticles, liposomes, and cyclodextrin inclusion complexes. The proprietary inclusion complex of hesperetin-7-O-glucoside with β-CD (HEPT7G/βCD; SunActive® HCD) is a patented formulation prepared via the controlled enzymatic hydrolysis of hesperidin in the presence of β-CD.
• Combined formulations: Hesperidin is often combined with diosmin in supplements designed to support circulation and capillary health.

Due to hesperetin's poor water solubility and low bioavailability, achieving therapeutic concentrations through conventional oral administration presents challenges. This has driven the development of the enhanced-solubility formats described above.

2. Traditional and Historical Use

Traditional Chinese Medicine

Hesperetin is an important bioactive compound in Chinese traditional medicine. As hesperetin exists in nature principally in the form of its glycoside hesperidin, traditional uses centered on preparations of the citrus plant rather than the isolated aglycone. The dried, immature fruit of Citrus aurantium L., known as 'Zhiqiao' in Chinese, has been used to treat cardiovascular diseases in Traditional Chinese Medicine for centuries, and naringenin and hesperetin and their glycosides are present in considerable amounts (about 10–15%) in the herb.

Hesperidin is widely known in Traditional Chinese Medicine alongside naringenin as "Chimpi," wherein the dried peels of citrus have been used medicinally. In TCM, these botanicals are historically utilized for their analgesic, anti-inflammatory, and digestive properties. Hesperetin and naringenin are two flavonoids that are widely applied in Traditional Chinese Medicine and are mostly found in citrus fruits.

Ayurvedic and European Folk Medicine

Citrus peels, which are rich in hesperidin, have been used for centuries in Ayurveda, Traditional Chinese Medicine, and European herbalism to aid digestion, reduce phlegm, improve circulation, and support immune health. In European folk medicine, citrus peel infusions were historically used to treat poor digestion, sluggish circulation, and colds, often as part of bitter aperitifs or digestive tonics.

Although hesperetin itself is a modern pharmacological isolate, its precursor — hesperidin — has a long-standing presence in traditional and folk medicine. The specific isolation and characterization of hesperetin as a distinct compound belongs to the 20th century.

The "Vitamin P" Era: 20th-Century Scientific History

In 1936, citrus flavonoids were reported to decrease capillary fragility and improve blood flow and were actually labeled "Vitamin P" (Rusznyak and Szent-Györgyi, 1936). Vitamin P was postulated by Szent-Györgyi as a regulator of vascular permeability, isolated in crystalline form as a flavone glucoside from lemon juice and named "citrin" to indicate its chemistry. Szent-Györgyi recounted having a hunch that the action in patients bleeding from subcutaneous hemorrhage may have been due to the flavones present as an impurity in an early ascorbic acid preparation, and that treating similar cases with flavones gave excellent results. He was not sure these were vitamins, so tentatively called them "vitamin P."

The substance formerly known as 'citrin' is now known to be a mixture of the rhamnoglucosides of eriodictyol (a tetrahydroxyflavone) and methyl eriodictyol (hesperetin). Szent-Györgyi later carried out further studies of citrus fruits, identifying vitamin P (a complex compound of flavonoids) and postulating its use in strengthening capillaries; however, a deficiency disease linked to the lack of vitamin P has never been identified. Although flavonoid preparations such as hesperidin and rutin are used in medicine, they do not appear to have justified the high hopes which followed the work of Szent-Györgyi in 1935 on the 'citrin' of paprika and lemon peel.

Scientific interest in citrus flavonoids intensified in the 20th century as researchers explored their roles in capillary strength and vitamin C synergy. The development of standardized extracts and bioactive isolates like hesperetin has since allowed more precise application in cardiovascular, metabolic, and neurological research.

3. Pharmacokinetics and Bioavailability

Absorption and Metabolism

Studies suggest that hesperidin ingested orally in humans or animals is absorbed in the form of aglycone (hesperetin) after the removal of rutinose by bacterial enzymes in the intestine, followed by conversion to glucuronidated and sulfated metabolites that can be detected in blood or urine. In more specific terms, the glucoside form (hesperetin-7-O-glucoside) is rapidly hydrolyzed by brush border enzymes without any contribution from pancreatic, stomach, or other secreted enzymes, or from bacterial enzymes, with only ~3% of the dose recovered intact in the perfusate, indicating high absorption. The rutinoside form (hesperidin) behaves differently: very little hydrolysis or absorption of hesperetin-7-O-rutinoside (hesperidin) was observed, with ~80% recovered in the perfusate, and no hesperetin metabolites detected in blood.

The poor absorption of hesperidin forces a large portion of the glycoside to the ileum and colon, where bacterial β-glucosidases capable of cleaving the flavonoid glycosides are abundantly present and impact bioavailability. Because of the action of intestinal microflora, significant absorption of hesperetin occurs after hesperidin is gradually hydrolyzed in the terminal ileum and colon.

Pharmacokinetic analysis in humans showed that hesperetin was rapidly absorbed and its plasma concentration was observed 20 minutes after dosing, reaching a peak at approximately 4.0 hours. Oral administration of the flavanone aglycone hesperetin leads to rapid absorption as its conjugated forms; however, the cumulative urinary recovery data indicated low bioavailability for the flavanone aglycone, owing to extensive first-pass metabolism partly by cleavage of the C-ring by intestinal bacteria, leading to degradation products such as phenolic acids.

Water-dispersible hesperetin was absorbed rapidly in humans, with maximum plasma concentration (Cmax) being 10.2 ± 1.2 μM, and the time to reach Cmax was within 1 hour when 150 mg of this preparation was orally administered. LC-MS analyses of the plasma at Cmax demonstrated that hesperetin accumulated in plasma as hesperetin 7-O-β-D-glucuronide (Hp7GA), hesperetin 3′-O-β-D-glucuronide (Hp3′GA), and hesperetin sulfate exclusively.

Hesperetin appears in plasma 3 hours after ingestion in the form of glucuronides (87%) and sulfoglucuronides. The extensive metabolism of hesperetin within intestinal cells, coupled with the subsequent transport of hesperetin conjugates back into the gut lumen by apical ATP-Binding Cassette (ABC) transporters like ABCG2, ultimately reduces hesperetin's bioavailability.

Inter-individual Variability and Gut Microbiota

The intake of hesperidin-rich sources, mostly found in orange juice, can decrease cardiometabolic risk, potentially linked to the gut microbial phase-II hesperetin derivatives. However, the low hesperidin solubility hampers its bioavailability and microbial metabolism, yielding a high inter-individual variability (high vs. low-producers) that prevents consistent health-related evidence. High interindividual variability in response to hesperidin-based acute and chronic interventions can be partly attributed to differences in gut microbiota.

Bioavailability Enhancement Strategies

In a human pharmacokinetic study, bioavailability of the hesperetin-7-O-glucoside/β-cyclodextrin inclusion complex (HEPT7G/βCD) was 12.1-fold higher compared with α-monoglucosyl hesperidin in Sprague-Dawley rats, and 104-fold higher compared with hesperidin in humans. In healthy human subjects, an acute single dose of the HEPT7G/βCD inclusion complex significantly enhanced plasma hesperetin metabolites concentration and displayed an improved pharmacokinetic profile compared to an identical dose of hesperetin from hesperidin. The Tmax was nearly 10-fold faster after subjects consumed the HEPT7G/βCD inclusion complex.

4. Key Constituents and Mechanisms of Action

Antioxidant Mechanisms

Hesperetin (Hst) is a flavonoid from citrus species with numerous biological properties, particularly antioxidant and anti-inflammatory. New findings showed that the antioxidant activity of hesperetin was not only limited to its radical scavenging activity, but it also augmented the antioxidant cellular defenses via the ERK/Nrf2 signaling pathway. Hesperetin and hesperidin provide antioxidant benefits via enhanced activity and production of cellular antioxidant enzymes such as superoxide dismutase (SOD), heme oxygenase-1 (HO-1), and catalase, and elevation of the predominant cellular antioxidant glutathione.

Anti-Inflammatory Mechanisms

Various in vitro and in vivo studies have been conducted to evaluate hesperetin at reducing inflammatory targets including NF-κB, iNOS, and COX-2, and the markers of chronic inflammation. RT-PCR showed that hesperetin upregulated Nrf2 mRNA expression, which is involved in the transcription of several antioxidant genes. In addition, hesperetin modulated the expression of genes associated with NF-κB signaling, including RELA, NF-κB1, NF-κB2, and NF-κBIA.

After spinal cord injury in animal models, hesperetin treatment effectively reduced the expression of inflammatory factors, including IL-1β, TNF-α, and NF-κB, demonstrating anti-inflammatory effects. Since oxidative damage and chronic inflammation are critical to the progression of dementia and neuronal loss, research has investigated the molecular mechanisms of hesperetin's antioxidant and anti-inflammatory effects, exploring the modulation of oxidative stress through the Nrf2/Keap1 signaling pathway, as well as hesperetin's modulatory effect on the inflammatory process through the regulation of NF-κB and PD-1/PD-L1 signaling pathways.

Metabolic and Lipid Mechanisms

Naringenin and hesperetin influence adiponectin expression, which plays an important role in glucose and lipid metabolism with antiatherogenic and anti-inflammatory properties. Treatment with hesperetin enhanced adiponectin transcription in differentiated 3T3-L1 cells. In vitro studies have revealed that hesperidin/hesperetin stimulates the production of nitric oxide (NO) in endothelial cells, inhibits the secretion of endothelin-1, and inhibits platelet activity by inhibiting the activities of specific phospholipases and cyclooxygenase-1.

Neuroprotective Mechanisms

As interest is growing in the use of dietary flavonoids to combat oxidative stress-mediated neurodegeneration in CNS-associated pathophysiological processes, including Alzheimer's disease and Parkinson's disease, there is growing concern regarding hesperetin's entry into the CNS and penetration through the blood–brain barrier. In preclinical work, accumulated amyloid-β induces abnormal ROS production, disturbing the endogenous antioxidant genes Nrf2 and HO-1, and the elevated ROS may promote the induction of the innate immune response by inducing TLR4 and the phosphorylation of NF-κB, leading to activation of apoptotic and inflammatory signaling. Hesperetin addresses these pathways.

The findings from cellular studies indicate that hesperetin may be a potential candidate for neurodegenerative disease therapy by upregulating Nrf2 expression and subsequent transcription of antioxidant genes, and also by reducing neuroinflammation through modulation of NF-κB signaling, which could slow the onset and progression of Alzheimer's disease.

Bone and Osteogenic Mechanisms

Several studies showed that hesperetin was capable of promoting osteogenic differentiation of both human and rat mesenchymal stem cells via Erk/Smad/BMP pathways. Hesperetin can attenuate RANKL-induced osteoclastogenesis by regulating Irf-3-mediated activation of Jnk, c-Jun, and NFATc-1 in osteoclasts. Flavonoids and their metabolites regulate the phosphoinositide 3-kinase (PI3K), Akt, mitogen-activated protein kinase (MAP kinase), and Wnt/β-catenin signaling pathways. Inhibition or stimulation of these pathways can modulate cellular functions including bone formation and regeneration processes.

5. Scientific Evidence by Area of Use

5.1 Cardiovascular Health

Preclinical studies have shown promising effects of hesperetin on cardiovascular diseases, and clinical studies have supported its promissory effects as a cardioprotective agent.

Lipid profile (clinical evidence — moderate): A systematic review and meta-analysis of nine clinical studies involving 2,414 subjects found that hesperidin significantly reduced LDL (IV: −0.55 [−0.94 to −0.16] at 95% CI, p = 0.005, I² = 70%), total cholesterol (TC) (IV: −0.61 [−0.82 to −0.41] at 95% CI, p < 0.00001, I² = 69%), and triglycerides (TG) (IV: −0.21 [−0.40 to −0.02] at 95% CI, p = 0.03, I² = 12%).

A second meta-analysis of RCTs with data up to August 2022 confirmed several of these effects: hesperidin supplementation had a significant effect on reducing serum triglyceride (TG), total cholesterol (TC), low-density cholesterol (LDL), tumor necrosis factor-alpha (TNF-α), and systolic blood pressure (SBP), whereas weight was increased. However, an updated meta-analysis found divergent results on some endpoints: hesperidin supplementation could significantly improve TC, LDL cholesterol, fasting blood glucose, quantitative insulin-sensitivity check index (QUICKI), CRP, VCAM-1, and ICAM-1; however, no beneficial effect was found in HDL cholesterol, TG, SBP, DBP, insulin, HOMA-IR, body weight, BMI, or waist circumference.

Important limitations: The intervention periods of included studies were very short (3–12 weeks), making it impossible to assess long-term effects. Despite the studies being designed as RCTs, most were classified as unclear on risk-of-bias assessment, implying that more research may significantly impact confidence in the estimated effects. Results from RCTs examining the effect of hesperidin supplementation on the constellation of CVD risk factors are inconclusive due to high variability between human trials.

Endothelial function and blood flow (preliminary human evidence): In a study where participants consumed 300 mg/day of HCD (hesperetin-7-glucoside-β-cyclodextrin inclusion complex) for 12 weeks, there was a notable improvement in endothelial dysfunction. No significant adverse clinical events were reported during this period. In a randomized, double-blind, crossover, placebo-controlled study, a significant dose-dependent increase in skin cutaneous blood flow following relatively small doses of HEPT7G/βCD inclusion complex ingestion was confirmed, which led to a relatively effective recovery of peripheral skin temperature. The doses tested were 150 mg and 300 mg, containing 19.5 mg and 39 mg of HEPT7G respectively.

5.2 Neurological and Neurodegenerative Conditions

Hesperetin, a flavanone class of citrus flavonoid, is a derivative of hesperidin found in citrus fruits such as oranges, grapes, and lemons. It has been extensively reported that hesperetin exerts neuroprotective effects in experimental models of neurodegenerative diseases; all such studies compiled in a systematic review were conducted in in vivo and in vitro models of neurodegeneration. No large human clinical trials for neurodegeneration have been identified in the published literature to date.

In TCM, these botanicals are historically utilized for their analgesic, anti-inflammatory, and digestive properties, but their potential in influencing neurodegenerative processes is receiving growing scrutiny. Systematic reviews have retrieved peer-reviewed preclinical and clinical trial research on hesperetin and naringenin in multiple mechanisms connected with Alzheimer's disease.

In cellular models of Alzheimer's disease, hesperetin may be a potential candidate for neurodegenerative diseases therapy by upregulating Nrf2 expression and subsequent transcription of antioxidant genes, and by reducing neuroinflammation through the modulation of the NF-κB signaling pathway, which could slow the onset and progression of AD. These findings are so far from preclinical research and should not be interpreted as evidence of clinical efficacy.

5.3 Metabolic Health and Diabetes

Preclinical studies have shown promising effects of hesperetin on carbohydrate dysregulation. Hesperetin and its metabolites have been reported to ameliorate insulin resistance and endothelial dysfunction, among other biological activities. However, clinical evidence is limited.

An updated meta-analysis found evidence of effects of hesperidin on fasting blood glucose (WMD: −0.15 mg/dL; 95% CI: −0.29, −0.02 mg/dL) and on quantitative insulin-sensitivity check index (WMD 0.06, 95% CI 0.01 to 0.10). These effect sizes are modest, and current findings demonstrate that hesperidin might be advantageous in improving numerous cardiovascular risk factors in humans, such as blood lipid concentrations, blood glucose control, and management of inflammatory indicators. However, other meta-analyses have found no significant effects on blood glucose, and the evidence remains inconsistent across studies.

In experimental models of diabetic retinopathy, hesperetin reduced the level of mRNA expression for TNF-α (4.9-fold), IL-1β (4.15-fold), IL-6 (4.6-fold), and NF-κB (5.2-fold), as well as protein level, accompanied by induction of autophagy proteins beclin 1 and LC3-II, affording evidence that hesperetin is effective in alleviating the pathology of diabetic retinopathy via suppressing the inflammatory burden and inducing autophagy. These are animal findings and require clinical replication.

5.4 Bone and Skeletal Health

Hesperetin and its metabolites have been reported to have biological activities influencing bone strength and osteoblast differentiation. Hesperetin, a glycoside flavonoid from the flavanone family derived from citrus fruit, has been demonstrated to exert immune-regulatory, anti-tumor, and anti-inflammatory effects. Several studies showed that it was capable of promoting osteogenic differentiation of both human and rat mesenchymal stem cells via Erk/Smad/BMP pathways.

Clinical evidence is very limited. A 2-year, double-blind, placebo-controlled, two-arm, parallel-group clinical trial was designed to investigate the effect of hesperidin in preventing bone loss in postmenopausal women, with the primary outcome measure being change in bone mineral density (BMD). Hesperetin may be a potential candidate for promoting bone regeneration given its therapeutic efficiency and low cost, but robust clinical results from completed long-term trials in humans remain to be published.

5.5 Antioxidant and Anti-Inflammatory Activity

Citrus-derived flavonoids have a variety of health-promoting properties, including anti-inflammatory, anticancer, antioxidant, and metal-chelating properties, all of which contribute substantially to the prevention of a wide array of diseases. Both hesperidin and hesperetin are well known as potent natural antioxidants effective in reducing oxidative stress. These properties are documented primarily in cellular and animal studies. The clinical translation of antioxidant effects, such as reduction of oxidative DNA damage and lipid peroxidation, has been tested in some small RCTs.

Meta-analysis data indicate hesperidin reduces CRP (WMD: −0.56 mg/L; 95% CI: −1.11, −0.01 mg/L), intercellular adhesion molecule 1 (ICAM-1) (WMD: −13.60 ng/mL; 95% CI: −23.72, −3.48 ng/mL), and vascular cell adhesion molecule 1 (VCAM-1) (WMD: −15.60 ng/mL; 95% CI: −30.13, −1.06 ng/mL) in humans.

5.6 Anticancer Research

Preclinical studies have shown promising effects of hesperetin on cancer. Hesperidin (and its aglycone hesperetin), bioactive flavonoids found in orange peel and other citrus plants, have shown effective anti-cancer effects against various cancer cell lines and are non-toxic to normal cells in preclinical work. Hesperetin exhibits anticarcinogenic effects. There are currently no published large-scale human clinical trials demonstrating anticancer efficacy for hesperetin specifically. All such evidence remains at the in vitro or animal model stage.

6. Body Systems and Health Areas of Association

• Cardiovascular system: Cardioprotective effects; lipid lowering; ameliorating endothelial dysfunction.
• Central nervous system: Neuroprotective effects in experimental models of Alzheimer's and Parkinson's disease.
• Metabolic system: Ameliorating insulin resistance.
• Musculoskeletal system: Influencing bone strength and osteoblast differentiation.
• Immune and inflammatory pathways: Reducing inflammatory targets including NF-κB, iNOS, and COX-2.
• Vascular/microcirculation: Citrus flavonoids including hesperetin decrease capillary fragility and are employed in cases of hypertension and radiation injuries.
• Endocrine/adipose: Influence on adiponectin expression, which plays a role in glucose and lipid metabolism.

7. Dosage Forms and Dosages Reported in Studies

No universal recommended dietary allowance (RDA) or adequate intake has been established for hesperetin by any major regulatory body. The following dosages appear in the cited research literature:

• Water-dispersible hesperetin was administered at a single dose of 150 mg orally in a human pharmacokinetic study, achieving a Cmax of 10.2 ± 1.2 μM within 1 hour.
• In a randomized, double-blind, crossover, placebo-controlled human vasodilation study, doses of 150 mg and 300 mg of HEPT7G/βCD inclusion complex were tested, containing 19.5 mg and 39 mg of HEPT7G respectively.
• In a study where participants consumed 300 mg/day of HCD (hesperetin-7-glucoside-β-cyclodextrin inclusion complex) for 12 weeks, a notable improvement in endothelial dysfunction was observed, with no significant adverse clinical events reported.
• Intervention periods in the clinical RCTs included in meta-analyses were very short, ranging from 3 to 12 weeks.

The clinical literature on hesperidin (the glycoside precursor to hesperetin) has used a wider range of doses in RCTs, most commonly in the range of 500–1000 mg/day of hesperidin. However, because hesperidin is not hesperetin, dosages should not be conflated without accounting for the conversion efficiency that is governed by individual gut microbiota and metabolic capacity.

8. Safety Considerations and Drug Interactions

General Safety Profile

Hesperetin as a flavonoid compound possesses advantages such as low toxicity, simple preparation, reasonable cost, and wide availability. No signs of toxicity have been observed with the normal intake of hesperidin or related compounds. In the human HEPT7G/βCD crossover pharmacokinetic study, no adverse effects were reported, and no clinically significant changes were noticed in blood biochemical markers.

The potential toxicity of hesperetin glucosides is not fully established. An initial assessment of the safety of hesperetin-7-glucoside-β-cyclodextrin inclusion complex (HPTGCD) as a functional food ingredient was undertaken to assess toxicity and mutagenic potential. These results provided initial evidence of the safety of HPTGCD. Formal long-term human safety data for isolated hesperetin in supplement doses remain limited.

CYP Enzyme Interactions

An in vitro study examined the effects of hesperetin on CYP2C9-mediated drug metabolism using kinetic analysis and molecular docking simulations. The conversion of diclofenac to 4′-hydroxydiclofenac by human liver microsomes was used as a model assay. Kinetic analyses showed that hesperetin was a reversible, dead-end inhibitor of 4′-hydroxydiclofenac formation, with a mean Ki (inhibitor dissociation constant) value of 21.50 ± 3.62 μM.

In human liver microsomes, hesperetin inhibited the CYP2C9-mediated conversion of diclofenac to 4′-hydroxydiclofenac. CYP2C9 is responsible for the biotransformation of drugs with a narrow therapeutic index. This indicates that the concomitant administration of hesperetin with diclofenac may result in enhanced bioavailability of diclofenac due to the inhibition of CYP2C9 by hesperetin.

In another study, hesperetin inhibited the CYP3A4-mediated metabolism of felodipine in rats, thereby increasing its systemic exposure and suggesting the role of hesperetin as a CYP3A4 inhibitor. The intestinal absorption of metoprolol was increased by 1.16-, 1.46-, and 1.6-fold when pre-treated with hesperetin at concentrations of 25, 50, and 100 μg/mL, establishing that P-gp suppression by hesperetin improved the intestinal absorption of metoprolol.

These interaction findings are predominantly derived from in vitro microsomal assays and animal studies. Their direct clinical relevance for supplement users taking standard oral doses has not been established in human pharmacokinetic interaction trials, but they raise a plausible signal for caution with drugs metabolized by CYP2C9 and CYP3A4.

Variability in Response

The low solubility of hesperidin hampers its bioavailability and microbial metabolism, yielding a high inter-individual variability (high vs. low-producers) that prevents consistent health-related evidence. This means that therapeutic responses may vary substantially between individuals depending on gut microbiome composition, and that clinical evidence based on group averages may not reliably predict individual outcomes.

References

• Agrawal PK, Agrawal C, Blunden G. Pharmacological Significance of Hesperidin and Hesperetin, Two Citrus Flavonoids, as Promising Antiviral Compounds for Prophylaxis Against and Combating COVID-19. Natural Product Communications. 2021.
• Klimek-Szczykutowicz M, et al. Hesperidin: A Review on Extraction Methods, Stability and Biological Activities. Nutrients. 2022;14(12):2387. PMC9227685.
• Parhiz H, et al. Antioxidant and anti-inflammatory properties of the citrus flavonoids hesperidin and hesperetin: an updated review. Phytotherapy Research. 2015;29:323–331.
• Hajialyani M, et al. Antioxidant and Anti-Inflammatory Effects of Citrus Flavonoid Hesperetin: Special Focus on Neurological Disorders. Antioxidants. 2020. PMC7402130.
• Hesperetin — ScienceDirect Topics Overview.
• Zhang Y, et al. Hesperidin: a citrus plant component, plays a role in the central nervous system. PMC11564962. 2024.
• Li X, et al. Traditional wisdom to modern science: Hesperetin and naringenin as emerging TCM-based treatments for Alzheimer's disease. ScienceDirect. 2025.
• Hurst RD, et al. Naringenin and hesperetin, two flavonoids derived from Citrus aurantium up-regulate transcription of adiponectin. PubMed. 2008.
• Ávila-Gálvez MÁ, et al. New Insights into the Metabolism of the Flavanones Eriocitrin and Hesperidin: A Comparative Human Pharmacokinetic Study. Antioxidants. 2021. PMC8000041.
• Kanaze FI, et al. Pharmacokinetics of the citrus flavanone aglycones hesperetin and naringenin after single oral administration in human subjects. European Journal of Clinical Nutrition. 2007. PubMed 17047689.
• Yamamoto M, et al. Bioavailability of orally administered water-dispersible hesperetin and its effect on peripheral vasodilatation in human subjects. Food & Function. 2012.
• Almeida AF, et al. Gastrointestinal absorption and metabolism of hesperetin-7-O-rutinoside and hesperetin-7-O-glucoside in healthy humans. Molecular Nutrition & Food Research. 2015. PubMed 26018925.
• Poletti A, et al. In Vivo pharmacokinetics of hesperidin are affected by treatment with glucosidase-like BglA protein isolated from yeasts. PMC2782632.
• Nomura Y, et al. Improved bioavailability of hesperetin 7-O-glucoside inclusion complex with β-cyclodextrin in Sprague-Dawley rats and healthy humans. Journal of Functional Foods. 2023.
• Heidari M, et al. Effect of hesperidin on blood pressure and lipid profile: A systematic review and meta-analysis of randomized controlled trials. Phytotherapy Research. 2024. PubMed 38462779.
• Cao Y, et al. The effects of hesperidin supplementation on cardiovascular risk factors in adults: a systematic review and dose–response meta-analysis. Frontiers in Nutrition. 2023. PMC10369082.
• Fan H, et al. Effects of Citrus Flavanone Hesperidin Extracts or Purified Hesperidin Consumption on Risk Factors for Cardiovascular Disease: Evidence From an Updated Meta-analysis of RCTs. Current Developments in Nutrition. 2024. PMC11399677.
• Robles-Vera I, et al. Effect of Hesperidin on Cardiovascular Disease Risk Factors: The Role of Intestinal Microbiota. Nutrients. 2020;12(5):1488.
• Leyva-Soto A, et al. Effects of hesperidin consumption on cardiovascular risk biomarkers: a systematic review. Nutrition Reviews. 2019;77(12):845.
• Evans J, et al. Involvement of Nrf2 Activation and NF-kB Pathway Inhibition in the Antioxidant and Anti-Inflammatory Effects of Hesperetin in Activated BV-2 Microglial Cells. Brain Sciences. 2023. PMC10452655.
• Takahashi T, et al. Flavonoids Diosmetin and Hesperetin are Potent Inhibitors of Cytochrome P450 2C9-mediated Drug Metabolism in vitro. Journal of Functional Foods. 2015.
• Pillai P, et al. Effect of hesperetin on the pharmacokinetics of metoprolol succinate in rats. Future Journal of Pharmaceutical Sciences. 2023.
• Miyake M, et al. Mutagenic, Acute, and Subchronic Toxicity Studies of the Hesperetin-7-Glucoside-β-Cyclodextrin Inclusion Complex. PubMed 36280476. 2022.
• Ortiz-Ortiz A, et al. Therapeutic Effects of Citrus Flavonoids Neohesperidin, Hesperidin and Its Aglycone, Hesperetin on Bone Health. Nutrients. 2022. PMC9138288.
• Zeng X, et al. Hesperetin Prevents Bone Resorption by Inhibiting RANKL-Induced Osteoclastogenesis. Frontiers in Pharmacology. 2018. PMC6142014.
• Nomura Y, et al. Hesperetin-7-O-glucoside/β-cyclodextrin Inclusion Complex Induces Acute Vasodilator Effect: A Randomized, Double-Blind, Crossover, Placebo-Controlled Study. Nutrients. 2023. PMC10489958.
• Miyake M, et al. Safety evaluation of excessive intake of Hesperetin-7-Glucoside-β-Cyclodextrin Inclusion Complex in Healthy Japanese Subjects. Functional Foods in Health and Disease. 2024.
• Abdel-Ghaffar A, et al. Computational and Experimental Approaches Exploring the Role of Hesperetin in Improving Autophagy in Rat Diabetic Retinopathy. PMC10968489. 2024.
• ClinicalTrials.gov: Effects of Hesperidin on Bone Mineral Density and Bone Metabolism of Postmenopausal Women. NCT00330096.
• Ortega-Aguilar AL, et al. Hesperetin's health potential: moving from preclinical to clinical evidence and bioavailability issues. Critical Reviews in Food Science and Nutrition. 2022;62(16).
• Song B, et al. Comprehensive review of Hesperetin: Advancements in pharmacokinetics, pharmacological effects, and novel formulations. PubMed 39255908. 2024.
• Guthrie N, Carroll KK. Citrus Flavonoids: A Review of Past Biological Activity Against Disease. Springer Nature. 1998.
• Science History Institute. Albert Szent-Györgyi. Scientific Biography.
• Garg A, et al. Chemistry and pharmacology of the citrus bioflavonoid hesperidin. Phytotherapy Research. 2001;15(8):655–669.