# Forsythin (Phillyrin, from Forsythia suspensa)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/forsythin-phillyrin-from-forsythia-suspensa
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-03
**Evidence Score:** 1 / 10
**Category:** Compound
**Also Known As:** Phillyrin, Forsythia suspensa lignan, Lianqiao lignan, Phillygenin glycoside, 连翘苷 (Liánqiào gān)

## Overview

Forsythin (also called phillyrin) is a lignan glycoside that exerts [anti-inflammatory](/ingredients/condition/inflammation), [antiviral](/ingredients/condition/immune-support), and anti-obesity effects primarily through inhibition of cyclic AMP phosphodiesterase 4 (PDE4) and modulation of TLR4/MyD88/NF-κB signaling pathways. Preclinical studies demonstrate antiviral and anti-inflammatory activity in cell and animal models, though no human clinical trials have yet established effective doses, safety thresholds, or confirmed efficacy in humans.

## Health Benefits

- **[Antiviral](/ingredients/condition/immune-support) Activity**: Forsythin and co-occurring phenylethanoid glycosides from Forsythia suspensa have demonstrated inhibitory effects against multiple viruses in preclinical models, likely through disruption of viral replication machinery and enhancement of host innate immune signaling via NF-κB and interferon pathways.
- **Anti-Inflammatory Effects**: Forsythin modulates the TLR4/MyD88/NF-κB signaling axis, reducing downstream production of [pro-inflammatory cytokine](/ingredients/condition/inflammation)s such as TNF-α, IL-1β, and IL-6 in macrophage and animal models of inflammation.
- **Anti-Obesity Potential**: As a selective inhibitor of cyclic AMP phosphodiesterase 4 (PDE4), forsythin elevates intracellular cAMP levels, which promotes lipolysis and suppresses adipogenesis, suggesting a mechanistic basis for anti-obesity activity observed in preclinical studies.
- **[Hepatoprotective](/ingredients/condition/detox) Properties**: Forsythin and related Forsythia lignans have shown liver-protective effects in rodent models of chemically induced hepatotoxicity, likely through antioxidant pathway activation including Nrf2/HO-1 upregulation and reduction of oxidative stress markers.
- **[Antioxidant Activity](/ingredients/condition/antioxidant)**: Via activation of the Nrf2/HO-1 signaling pathway, forsythin promotes upregulation of endogenous antioxidant enzymes, reducing cellular oxidative damage in preclinical neuronal and hepatic cell models.
- **Potential Anticancer Activity**: Co-occurring compounds in Forsythia suspensa fruit extracts, including forsythiasides A, E, and I, have inhibited B16-F10 melanoma cell viability and prolonged survival in murine tumor models, while triterpenoids from ethanol extracts suppressed proliferation of gastric cancer cell lines MKN-45, BGC-823, and SGC-9701.
- **[Neuroprotective Effect](/ingredients/condition/cognitive)s**: Preclinical evidence suggests forsythin and associated phenylethanoid glycosides reduce neuroinflammation and oxidative stress in CNS models, with proposed mechanisms involving cytokine suppression and antioxidant enzyme induction, though human data are absent.

## Mechanism of Action

Forsythin exerts its primary pharmacological effects as a competitive inhibitor of cyclic AMP phosphodiesterase 4 (PDE4), preventing the degradation of intracellular cAMP and thereby amplifying downstream protein kinase A (PKA) signaling; this mechanism underlies its proposed anti-obesity and anti-inflammatory actions. At the immunological level, forsythin and co-occurring phenylethanoid glycosides in Forsythia suspensa suppress the TLR4/MyD88/NF-κB signaling cascade, reducing nuclear translocation of NF-κB and transcription of [pro-inflammatory cytokine](/ingredients/condition/inflammation)s including TNF-α, IL-1β, and IL-6. Antioxidant effects are mediated through activation of the Nrf2/Keap1 pathway, leading to HO-1 upregulation and enhanced cellular defense against [reactive oxygen species](/ingredients/condition/antioxidant). In cancer cell models, related Forsythia lignans and phenylethanoid glycosides (notably forsythoside B) have been shown to block NF-κB activation and upregulate the cyclin-dependent kinase inhibitor p21, resulting in inhibition of the cyclin E/CDK2 complex and G1-phase cell cycle arrest.

## Clinical Summary

No human randomized controlled trials have been published specifically investigating forsythin (phillyrin) as an isolated compound for any clinical endpoint. The broader Forsythia suspensa fruit extract has a long history of use in Traditional Chinese Medicine formulations (such as Lianhua Qingwen) that have been studied in small clinical trials for respiratory infections, but compound-specific effects attributable to forsythin cannot be extracted from these multi-ingredient studies. Pharmacopeia standardization requires immature Forsythia fruits to contain ≥0.3% phillyrin (forsythin) and ≥2.0% forsythoside A, reflecting regulatory recognition of these markers, but not clinical dose-efficacy data. Given the complete absence of isolated human clinical trial data, confidence in efficacy claims for forsythin across any indication remains very low, and all benefits should be considered hypothesis-generating from preclinical work only.

## Nutritional Profile

Forsythin is a pure phytochemical compound (a lignan glycoside, molecular formula C₂₇H₃₄O₁₁, molecular weight 534.55 g/mol) rather than a whole food, and thus does not possess a conventional macronutrient or micronutrient profile. In the context of Forsythia suspensa fruit, the whole dried fruit contains lignans (including forsythin/phillyrin at ≥0.3% in immature fruit), phenylethanoid glycosides (forsythoside A as the dominant compound at ≥2.0% in immature fruit), flavonoids including rutin and quercetin, triterpenoids, phytosterols, and volatile essential oils. Bioavailability of forsythin as a glycoside is subject to intestinal hydrolysis to its aglycone phillygenin, which may exhibit different absorption kinetics; no formal human pharmacokinetic studies have characterized absolute bioavailability, Cmax, Tmax, or half-life for forsythin in humans. The compound's lipophilicity (moderate logP) suggests potential for passive intestinal absorption, but first-pass hepatic [metabolism](/ingredients/condition/weight-management) and interactions with intestinal microbiota likely influence systemic exposure significantly.

## Dosage & Preparation

- **Traditional TCM Decoction (Forsythiae Fructus)**: Dried immature or mature fruits boiled in water; typical traditional dose is 6–15 g of dried fruit per decoction, taken as tea 2–3 times daily, though this delivers a complex mixture of compounds, not isolated forsythin.
- **Standardized Fruit Extract**: Commercial research extracts are standardized to ≥0.3% phillyrin (forsythin) for immature fruit and ≥0.09% for mature fruit per Chinese Pharmacopeia standards; no clinically validated supplemental dose for isolated forsythin has been established.
- **Ethanolic/Methanolic Extracts (Research Grade)**: Laboratory isolation uses methanol or ethanol fractionation followed by column chromatography; these are not commercially available as standardized consumer supplements.
- **Combination TCM Formulas**: Forsythia suspensa fruits appear in classical formulas such as Yin Qiao San and Lianhua Qingwen capsules at doses of 300–1500 mg extract per formula serving, but again, forsythin-specific dosing is not delineated.
- **Timing and Notes**: No clinical data exist to support specific timing recommendations; traditional use is typically administered during acute illness phases in TCM practice, and prolonged unsupervised use is not supported by safety data.

## Safety & Drug Interactions

The safety profile of isolated forsythin in humans is essentially uncharacterized, as no clinical trials or formal toxicology studies in humans have been published; traditional use of Forsythia suspensa fruit in TCM at decoction doses of 6–15 g/day has a long empirical history without widely reported severe adverse events, but this cannot be directly extrapolated to concentrated or isolated forsythin supplementation. Pharmacological data from preclinical studies indicate that Forsythia suspensa constituents regulate cytochrome P450 enzyme activity, suggesting potential pharmacokinetic drug interactions with CYP2C9-, CYP3A4-, and CYP1A2-metabolized medications including warfarin, statins, and certain antivirals, though specific interaction magnitudes in humans are not established. Forsythin and Forsythia extracts are not recommended during pregnancy or lactation due to complete absence of safety data in these populations, and the compound's [immunomodulatory](/ingredients/condition/immune-support) properties theoretically warrant caution in individuals on immunosuppressive therapies. No maximum safe dose has been established for isolated forsythin, and consumers should be advised that standardized supplement products are not approved by regulatory agencies such as the FDA or EMA for any therapeutic indication.

## Scientific Research

The evidence base for forsythin specifically consists almost entirely of in vitro cell culture studies and rodent animal models, with no published randomized controlled trials or human pharmacokinetic studies identified as of the current literature review. Preclinical studies have demonstrated that forsythiasides A, E, and I inhibit B16-F10 melanoma cell viability and extend survival in murine tumor models, and forsythoside B has been shown to suppress cervical cancer cell proliferation through [NF-κB](/ingredients/condition/inflammation) blockade and p21 upregulation in cell-line experiments. Anti-proliferative activity against gastric cancer cell lines (MKN-45, BGC-823, SGC-9701) has been reported from ethanol extracts of Forsythia suspensa fruits in preclinical assays, though compound-specific attribution to forsythin versus co-occurring actives is not always clearly delineated. Overall, the evidence is preliminary and mechanistically suggestive, but the absence of human trials, standardized bioavailability data, or dose-response characterization in humans significantly limits any clinical conclusions.

## Historical & Cultural Context

Forsythia suspensa fruits, known as Lianqiao (连翘) in Chinese, have been used in Traditional Chinese Medicine for over 2000 years and are listed in the Shennong Bencao Jing, the foundational Chinese materia medica compiled around the first century CE. The fruits are classified in TCM as a heat-clearing and toxin-resolving herb (清热解毒药), traditionally indicated for febrile diseases, acute infectious conditions, erysipelas, lymphadenitis, carbuncles, and urinary tract infections. Immature green fruits (青翘) are preferred for their higher bioactive content and stronger anti-infective properties, while mature fruits (老翘) are used for milder presentations; both forms are prepared as decoctions, often combined with Lonicera japonica flowers (金银花) in the classical Yin Qiao San formula. The compound's isolation and characterization as phillyrin/forsythin emerged from twentieth-century phytochemical investigations, linking specific molecular constituents to the ethnopharmacological actions long described in classical texts.

## Synergistic Combinations

In classical TCM formulation, forsythin-containing Forsythia suspensa fruit is consistently paired with Lonicera japonica (honeysuckle) flowers in formulas such as Yin Qiao San, with the combination believed to produce synergistic heat-clearing and [antiviral](/ingredients/condition/immune-support) effects through complementary phenylethanoid glycoside and flavonoid contributions acting on overlapping NF-κB and [antioxidant](/ingredients/condition/antioxidant) pathways. Preclinical evidence from multi-compound Forsythia extracts suggests that forsythin (phillyrin) and forsythoside A may act additively or synergistically on inflammatory signaling, as standardized extracts containing both compounds consistently outperform single-compound preparations in animal inflammation models. Quercetin, a co-occurring flavonoid in Forsythia suspensa, may enhance forsythin's antiviral and [anti-inflammatory](/ingredients/condition/inflammation) effects through complementary inhibition of viral protease activity and independent suppression of NF-κB nuclear translocation, though direct co-administration studies confirming synergy in humans do not yet exist.

## Frequently Asked Questions

### What is forsythin and where does it come from?

Forsythin, also called phillyrin, is a lignan glycoside (molecular weight 534.55 g/mol) isolated from the dried fruits of Forsythia suspensa, a shrub native to China used in Traditional Chinese Medicine for over 2000 years. Immature Forsythia fruits contain the highest concentrations, with Chinese Pharmacopeia standards requiring ≥0.3% phillyrin content, alongside ≥2.0% of the co-occurring phenylethanoid glycoside forsythoside A. It is one of the principal bioactive markers used to standardize Forsythia fruit extracts for research and quality control purposes.

### What does forsythin do in the body?

Forsythin acts primarily as an inhibitor of cyclic AMP phosphodiesterase 4 (PDE4), an enzyme that breaks down the second messenger cAMP; by blocking PDE4, forsythin elevates intracellular cAMP and activates downstream protein kinase A signaling, which contributes to anti-inflammatory and potential anti-obesity effects. It also modulates the TLR4/MyD88/NF-κB inflammatory signaling cascade and activates the Nrf2/HO-1 antioxidant pathway, as demonstrated in cell culture and rodent models. All mechanistic data currently derive from preclinical studies, and whether these pathways are meaningfully engaged at achievable human doses remains unknown.

### Is forsythin clinically proven to work in humans?

No human clinical trials have been published specifically investigating forsythin (phillyrin) as an isolated compound for any health condition, making it impossible to confirm clinical efficacy, safe dosing, or pharmacokinetics in people. Available evidence is limited to in vitro cell experiments and animal models demonstrating anti-inflammatory, antiviral, and anti-proliferative effects, which are hypothesis-generating but not sufficient to establish clinical benefit. Broader Forsythia suspensa formulas have been included in some small TCM clinical trials, but compound-specific conclusions about forsythin cannot be drawn from these multi-ingredient studies.

### What is the recommended dose of forsythin?

No clinically validated or regulatory-approved dose has been established for isolated forsythin supplementation in humans, as the compound has not been studied in human pharmacokinetic or efficacy trials. Traditional TCM practice uses 6–15 g of dried Forsythia suspensa fruit per decoction daily during acute illness, but this delivers a complex mixture of compounds at variable forsythin concentrations rather than a defined forsythin dose. Until human dose-finding studies are conducted, any specific supplemental dose recommendation for forsythin would be speculative and unsupported by clinical evidence.

### Are there any drug interactions or safety concerns with forsythin?

Forsythin's human safety profile is not formally established, but preclinical pharmacological data indicate that Forsythia suspensa constituents can modulate cytochrome P450 enzymes (including CYP2C9, CYP3A4, and CYP1A2), raising the theoretical concern of pharmacokinetic interactions with drugs metabolized by these enzymes, such as warfarin, statins, and certain antiviral medications. Its immunomodulatory properties also suggest potential interactions with immunosuppressive drugs, though no human case reports or interaction studies confirm this. Forsythin-containing products should be avoided during pregnancy and lactation, and individuals taking prescription medications should consult a healthcare provider before use.

### How does forsythin compare to other herbal antivirals like elderberry or andrographis?

Forsythin from Forsythia suspensa works through distinct mechanisms—disrupting viral replication machinery and activating NF-κB/interferon pathways—which differs from elderberry's primarily immune-stimulating effects and andrographis's anti-inflammatory focus. While all three have traditional antiviral use, forsythin's mechanism appears more directly targeted at viral replication inhibition, though head-to-head clinical comparisons in humans remain limited. The choice between them depends on whether you prioritize direct viral suppression versus general immune support.

### What is the bioavailability of forsythin, and does extraction method affect how well it's absorbed?

Forsythin's bioavailability is influenced by its classification as a phenylethanoid glycoside, which typically have moderate absorption rates that can be enhanced through standardized extraction methods and co-occurring compounds in Forsythia suspensa. Standardized extracts that preserve the full spectrum of Forsythia constituents (rather than isolated forsythin alone) may offer superior bioavailability since related glycosides work synergistically. Most clinical benefit has been observed with whole-plant or polyphenol-rich extracts rather than single-compound isolates.

### Who would benefit most from forsythin supplementation—acute viral illness, prevention, or chronic immune support?

Forsythin appears most beneficial for acute viral support, as preclinical evidence shows strong inhibition of viral replication machinery and rapid immune activation via interferon signaling pathways. While prevention and chronic immune support are theoretically supported by its anti-inflammatory effects on TLR4/MyD88 signaling, the strongest traditional use and mechanistic evidence points to early intervention during active viral exposure or infection. Those with recurrent viral infections may also benefit from chronic use, though optimal timing and duration require further human clinical research.

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