Forsythoside B

Forsythoside B at a Glance

Forsythoside B is a caffeoyl phenylethanoid glycoside (PhG) — the same structural family as verbascoside (acteoside) and echinacoside. It is built on the verbascoside scaffold — a hydroxytyrosol unit esterified with caffeic acid on a rhamnose–glucose disaccharide — carrying an additional branched pentose (apiose) sugar (molecular formula C34H44O19).

Its best-known botanical source is the dried fruit of weeping forsythia (Forsythia suspensa), called lian qiao (连翘) in traditional Chinese medicine, a classic “heat-clearing” antimicrobial herb. It also occurs in the Tibetan painkiller herb Lamiophlomis rotata, in black horehound (Ballota nigra) and wood betony (Stachys officinalis).

The honest headline for this molecule is that all of its pharmacology is preclinical — cell assays and rodent models, with no human trials. Within that limit, its most developed and distinctive signal is anti-inflammatory: repeated rodent work in sepsis and acute lung injury points to suppression of the TLR4/NF-κB pathway, alongside a broader neuroprotective and antioxidant story.

The Anti-Sepsis & Acute Lung Injury Signal

The strongest and most repeated finding for forsythoside B is an anti-inflammatory action in models of systemic and pulmonary inflammation, and it is the reason the molecule is worth its own page rather than a footnote under verbascoside.

In a mouse model of experimental sepsis, forsythoside B lowered serum TNF-α, IL-6 and HMGB1 (a late-phase mediator of lethal sepsis), reduced TREM-1 and circulating endotoxin, raised the anti-inflammatory cytokine IL-10, and cut myeloperoxidase in lung, liver and intestine; in LPS-stimulated macrophages it suppressed the same cytokines by inhibiting the IκB kinase (IKK) → NF-κB cascade ^{1Reference 1Jiang WL et al. · 2012Forsythoside B protects against experimental sepsis by modulating inflammatory factorsView study →}.

In LPS-induced acute lung injury (ALI), forsythoside B pre-treatment suppressed lung oedema, inflammatory-cell infiltration and cytokine expression by attenuating TLR4/NF-κB signalling in vivo and in vitro — leading the authors to propose it as a candidate for sepsis-associated ALI ^{2Reference 2Liu JX et al. · 2019Protective effect of forsythoside B against lipopolysaccharide-induced acute lung injury by attenuating the TLR4/NF-κB pathwayView study →}.

This is a coherent mechanistic thread — TLR4 → IKK/NF-κB → pro-inflammatory cytokines and HMGB1 — but it is entirely animal- and cell-based. No human sepsis or ALI data exist.

What It's Used For

Beyond the anti-inflammatory core, forsythoside B has been tested for neuroprotection, antioxidant activity and antibacterial effects. The evidence is uniformly preclinical, and — unusually for a plant PhG — a good share of it uses the isolated molecule in defined rodent models rather than whole extract.

Evidence by IndicationStrength of support · Beta

Support is an experimental score — weighted by study type (human > animal > in vitro) and volume. A beta, not a validated metric. Every row here is preclinical; the scores rank rodent-model depth, not clinical proof.

01Anti-inflammatory / anti-sepsis & ALIShaky40%Multiple rodent sepsis/ALI models + macrophage mechanism (TLR4/NF-κB) ^{1,2Reference 1Jiang WL et al. · 2012Forsythoside B protects against experimental sepsis by modulating inflammatory factorsView study →Reference 2Liu JX et al. · 2019Protective effect of forsythoside B against lipopolysaccharide-induced acute lung injury by attenuating the TLR4/NF-κB pathwayView study →}

02NeuroprotectionShaky34%Rat ischaemia–reperfusion, spinal-cord injury, cognitive-dysfunction models ^{3,4,5,6Reference 3Jiang WL et al. · 2010AnimalNeuroprotective efficacy and therapeutic window of Forsythoside B: in a rat model of cerebral ischemia and reperfusion injuryView study →Reference 4Xia M et al. · 2022Forsythoside B attenuates neuro-inflammation and neuronal apoptosis by inhibition of NF-κB and p38-MAPK signaling pathways through activating Nrf2 post spinal cord injuryView study →Reference 5Kong F et al. · 2020Forsythoside B attenuates memory impairment and neuroinflammation via inhibition on NF-κB signaling in Alzheimer’s diseaseView study →Reference 6Nan X et al. · 2022AnimalForsythoside B ameliorates diabetic cognitive dysfunction by inhibiting hippocampal neuroinflammation and reducing synaptic dysfunction in ovariectomized miceView study →}

03Antioxidant / LDL protectionShaky26%In-vitro LDL-peroxidation inhibition as a Ballota PhG constituent ^{7Reference 7Seidel V et al. · 2000In vitroPhenylpropanoids from Ballota nigra L. inhibit in vitro LDL peroxidationView study →}

04AntibacterialShaky22%In-vitro; the founding activity from Forsythia koreana / Ballota ^{8Reference 8Didry N et al. · 1999Isolation and antibacterial activity of phenylpropanoid derivatives from Ballota nigraView study →}

Mechanisms

The through-line is anti-inflammatory: nearly every beneficial result traces back to damping TLR4–IKK/NF-κB signalling, with Nrf2 activation as the antioxidant counterpart. This is the same mechanistic vocabulary as its PhG siblings verbascoside and echinacoside.

Pharmacokinetics

Forsythoside B is a large, highly polar polyphenolic glycoside (C34H44O19, molecular weight ~756), a physical profile that predicts poor oral absorption — the general weakness of the phenylethanoid-glycoside class. Consistent with this, the rodent efficacy studies that show the clearest effects give it by intravenous injection ^{1,3Reference 1Jiang WL et al. · 2012Forsythoside B protects against experimental sepsis by modulating inflammatory factorsView study →Reference 3Jiang WL et al. · 2010AnimalNeuroprotective efficacy and therapeutic window of Forsythoside B: in a rat model of cerebral ischemia and reperfusion injuryView study →}, and pharmacokinetic/metabolite work in Lamiophlomis rotata extracts finds the molecule extensively phase-II conjugated (glucuronide, sulfate and amino-acid conjugates) after oral dosing ^{10Reference 10Li Y et al. · 2021Lamiophlomis herba: a comprehensive overview of its chemical constituents, pharmacology, clinical applications, and quality controlView study →}. No human pharmacokinetic data and no reliable oral-bioavailability figure exist. This poor-oral-absorption caveat is important: it undercuts any assumption that eating Forsythia fruit delivers the intravenous-dose effects seen in the models.

Clinical Trials

There are no clinical trials of forsythoside B as an isolated compound. Human exposure is only indirect, as one constituent of traditional Forsythia-based (lian qiao) preparations, whose clinical use is not attributable to this molecule.

Last checked: July 2026.

Isolate vs. Plant Studies

Forsythoside B sits on the stronger side of the usual isolate-vs-plant caveat: much of its evidence uses the purified molecule in defined rodent models — the sepsis, acute-lung-injury and cerebral-ischaemia studies all dose isolated forsythoside B ^{1,2,3Reference 1Jiang WL et al. · 2012Forsythoside B protects against experimental sepsis by modulating inflammatory factorsView study →Reference 2Liu JX et al. · 2019Protective effect of forsythoside B against lipopolysaccharide-induced acute lung injury by attenuating the TLR4/NF-κB pathwayView study →Reference 3Jiang WL et al. · 2010AnimalNeuroprotective efficacy and therapeutic window of Forsythoside B: in a rat model of cerebral ischemia and reperfusion injuryView study →}. That is a genuine methodological strength over molecules known only from whole-extract assays.

The offsetting weaknesses are that (a) the studies are preclinical, with no human arm; (b) the most convincing results are parenteral, sidestepping the poor oral absorption that a Forsythia-fruit user would face ^{10Reference 10Li Y et al. · 2021Lamiophlomis herba: a comprehensive overview of its chemical constituents, pharmacology, clinical applications, and quality controlView study →}; and (c) the antioxidant and antibacterial data come from whole-PhG fractions (Ballota, Forsythia) where forsythoside B is one active among several ^{7,8Reference 7Seidel V et al. · 2000In vitroPhenylpropanoids from Ballota nigra L. inhibit in vitro LDL peroxidationView study →Reference 8Didry N et al. · 1999Isolation and antibacterial activity of phenylpropanoid derivatives from Ballota nigraView study →}. So the isolate is well-characterised in animals but unproven in people, and its whole-herb relevance is limited by pharmacokinetics.

Prevalence in Nature

Forsythoside B is a caffeoyl phenylethanoid glycoside distributed across several plant families, most notably the Oleaceae and Lamiaceae. Its signature source is the dried fruit (Fructus Forsythiae, lian qiao) of weeping forsythia (Forsythia suspensa), where it belongs to a large family of forsythosides (A, B, C, D, E, I…) that are characteristic markers of the herb ^{11Reference 11Yang HX et al. · 2022ReviewForsythiasides: a review of the pharmacological effectsView study →}. It was first obtained from the closely related Forsythia koreana ^{9Reference 9Endo K · 1982Structure of forsythoside B, an antibacterial principle of Forsythia koreana stems}.

Outside Forsythia, forsythoside B is a constituent of the Tibetan medicinal herb Lamiophlomis rotata (leaves) ^{10Reference 10Li Y et al. · 2021Lamiophlomis herba: a comprehensive overview of its chemical constituents, pharmacology, clinical applications, and quality controlView study →}, of black horehound (Ballota nigra) — where it co-occurs with verbascoside, arenarioside and ballotetroside ^{7,8Reference 7Seidel V et al. · 2000In vitroPhenylpropanoids from Ballota nigra L. inhibit in vitro LDL peroxidationView study →Reference 8Didry N et al. · 1999Isolation and antibacterial activity of phenylpropanoid derivatives from Ballota nigraView study →} — and of wood betony (Stachys officinalis), from which it was co-isolated with the betonyosides and verbascoside ^{12Reference 12Miyase T et al. · 1996Phenylethanoid glycosides from Stachys officinalisView study →}. It is also reported from marshmallow (Althaea officinalis). Quantitative concentrations across these sources are not well documented in the literature.

Discovery & Synthesis

Forsythoside B was first isolated and structurally characterised in 1982 by Endo and Hikino, who identified it as an antibacterial principle of the stems of Forsythia koreana (published in Heterocycles) — the name derives directly from the Forsythia genus ^{9Reference 9Endo K · 1982Structure of forsythoside B, an antibacterial principle of Forsythia koreana stems}. Structurally it is the verbascoside (acteoside) scaffold bearing an additional apiose sugar: a 3,4-dihydroxyphenylethyl (hydroxytyrosol) aglycone glycosylated with a rhamnose–glucose–apiose oligosaccharide and esterified with caffeic acid.

Manufacture today is by extraction from plant material rather than synthesis — it is obtained from Forsythia suspensa fruit or Lamiophlomis by solvent extraction and chromatographic purification (counter-current and preparative HPLC methods are documented for the forsythoside series). As a large, densely glycosylated and acylated natural product, forsythoside B is not a practical total-synthesis target, and commercial reference material is plant-derived.

Patents: not yet researched.

Toxicity & Safety

Forsythoside B carries a low toxicity flag. It is a dietary-type polyphenol from a food/medicine herb (Forsythia fruit is a long-used traditional remedy), the class is generally well tolerated, and no specific toxicity signal has been reported for the isolate. That said, the safety record is thin and preclinical — there is no dedicated toxicology package, and the caveats below reflect what has not been established rather than a demonstrated hazard.

Safety at a Glance

✅ Low / no toxicity

• No specific toxicity signal. A polyphenolic glycoside from a traditionally consumed herb; not flagged as toxic in the available preclinical work.
• Human safety unstudied. No clinical safety, repeat-dose, genotoxicity or drug-interaction data exist for the isolated molecule.
• Efficacy data are by injection. The protective effects were shown mostly intravenously in animals; oral relevance and any high-dose oral effects are uncharacterised.
• Reproductive/developmental data absent. No reproductive-toxicity dataset exists for the isolate; intake decisions belong on the source-herb or product page, not here.

No drug-interaction studies (CYP or transporter) have been performed on forsythoside B, so interaction potential is simply unknown; this is an absence of data, not evidence of safety.

Dosage

There is no established human dose for forsythoside B — it has not been used as a stand-alone human therapeutic, and all figures come from animal research:

Human exposure is only indirect, as a minor constituent of traditional Forsythia (lian qiao) preparations, which are dosed as whole-herb decoctions and not standardised to forsythoside B. These are doses studied in research and are not a personal recommendation.

References

1. Jiang WL, et al. (2012). Forsythoside B protects against experimental sepsis by modulating inflammatory factors. Phytotherapy Research. https://pubmed.ncbi.nlm.nih.gov/22147417/
2. Liu JX, et al. (2019). Protective effect of forsythoside B against lipopolysaccharide-induced acute lung injury by attenuating the TLR4/NF-κB pathway. International Immunopharmacology. https://pubmed.ncbi.nlm.nih.gov/30521962/
3. Jiang WL, et al. (2010). Neuroprotective efficacy and therapeutic window of Forsythoside B: in a rat model of cerebral ischemia and reperfusion injury. European Journal of Pharmacology. https://pubmed.ncbi.nlm.nih.gov/20470770/
4. Xia M, et al. (2022). Forsythoside B attenuates neuro-inflammation and neuronal apoptosis by inhibition of NF-κB and p38-MAPK signaling pathways through activating Nrf2 post spinal cord injury. International Immunopharmacology. https://pubmed.ncbi.nlm.nih.gov/35944463/
5. Kong F, et al. (2020). Forsythoside B attenuates memory impairment and neuroinflammation via inhibition on NF-κB signaling in Alzheimer’s disease. Journal of Neuroinflammation. https://pubmed.ncbi.nlm.nih.gov/33059746/
6. Nan X, et al. (2022). Forsythoside B ameliorates diabetic cognitive dysfunction by inhibiting hippocampal neuroinflammation and reducing synaptic dysfunction in ovariectomized mice. Frontiers in Aging Neuroscience. https://pubmed.ncbi.nlm.nih.gov/36389075/
7. Seidel V, et al. (2000). Phenylpropanoids from Ballota nigra L. inhibit in vitro LDL peroxidation. Phytotherapy Research. https://pubmed.ncbi.nlm.nih.gov/10685104/
8. Didry N, et al. (1999). Isolation and antibacterial activity of phenylpropanoid derivatives from Ballota nigra. Journal of Ethnopharmacology. https://pubmed.ncbi.nlm.nih.gov/10619384/
9. Endo K, Hikino H (1982). Structure of forsythoside B, an antibacterial principle of Forsythia koreana stems. Heterocycles, 19(2), 261–264.
10. Li Y, et al. (2021). Lamiophlomis herba: a comprehensive overview of its chemical constituents, pharmacology, clinical applications, and quality control. Biomedicine & Pharmacotherapy. https://pubmed.ncbi.nlm.nih.gov/34656063/
11. Yang HX, et al. (2022). Forsythiasides: a review of the pharmacological effects. Frontiers in Cardiovascular Medicine. https://pubmed.ncbi.nlm.nih.gov/35958429/
12. Miyase T, et al. (1996). Phenylethanoid glycosides from Stachys officinalis. Phytochemistry. https://pubmed.ncbi.nlm.nih.gov/8862039/

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