Compound Monograph
Syringic acid
Syringic acid is a dimethoxy hydroxybenzoic (phenolic) acid — the 3,5-dimethoxy relative of gallic and vanillic acid — found across fruits, whole grains, honey and wine. A well-characterised dietary antioxidant with broad but entirely preclinical antidiabetic and organ-protective activity, moderate native oral bioavailability, and no human trials of the isolate.
Classification
Syringic acid is a hydroxybenzoic acid (phenolic acid), part of the phenolics class. Antioxidant compounds built around one or more phenol rings — the flavonoids, tannins, phenolic acids, coumarins, and pigments behind much of a plant's protective chemistry.
Where Does It Come From? (6)
Syringic acid is a naturally occurring hydroxybenzoic acid (phenolic acid), found in Chickweed, Marshmallow, Yerba maté and 3 other sources. It is well tolerated orally (low toxicity).
Pharmacology & Research
Syringic acid is a dimethoxy phenolic acid — the 3,5-dimethoxy sibling of gallic acid and vanillic acid — and a ubiquitous dietary compound found in fruits, whole grains, honey and wine. Its best-substantiated property is antioxidant activity: the dimethoxy-phenol ring is a direct radical scavenger, and in cell and animal models it raises endogenous defences (SOD, catalase, glutathione) via Nrf2 1,2Reference 1ReviewSyringic acid — a review of its occurrence, biosynthesis, and pharmacological importanceView study →Reference 2Antioxidant and anti-inflammatory potential of syringic acid: mechanistic insights and pathway interactionsView study →. Everything downstream of that — antidiabetic, organ-protective, anticancer — is entirely preclinical, and there are no human trials of the isolate.
- A well-characterised dietary antioxidant: direct scavenging plus Nrf2-mediated induction of antioxidant enzymes across cell and rodent models 1,2Reference 1ReviewSyringic acid — a review of its occurrence, biosynthesis, and pharmacological importanceView study →Reference 2Antioxidant and anti-inflammatory potential of syringic acid: mechanistic insights and pathway interactionsView study →.
- The honest headline: every disease claim (diabetes, organ protection, cancer) is rodent, cell-line or whole-extract; native oral bioavailability is only moderate, so much “efficacy” work used enhanced-delivery formulations 1,10Reference 1ReviewSyringic acid — a review of its occurrence, biosynthesis, and pharmacological importanceView study →Reference 10Improved oral bioavailability and hypolipidemic effect of syringic acid via a self-microemulsifying drug-delivery systemView study →.
1. Antioxidant
The dimethoxy-phenol ring neutralises ROS directly, and in cell/animal models syringic acid raises SOD, catalase and glutathione via Nrf2 — the property under all the disease claims below 1,2Reference 1ReviewSyringic acid — a review of its occurrence, biosynthesis, and pharmacological importanceView study →Reference 2Antioxidant and anti-inflammatory potential of syringic acid: mechanistic insights and pathway interactionsView study →.
Gap: mechanism, not outcome — no human antioxidant-biomarker trial of the isolate; all data in-vitro or rodent 1Reference 1ReviewSyringic acid — a review of its occurrence, biosynthesis, and pharmacological importanceView study →.
2. Antidiabetic / metabolic
In diabetic rodents, syringic acid lowers hyperglycaemia and protects heart, kidney, liver and nerve tissue from chronic-hyperglycaemia damage 3Reference 3AnimalSyringic acid ameliorates cardiac, hepatic, renal and neuronal damage induced by chronic hyperglycaemia in Wistar ratsView study →, and accelerates diabetic wound healing 4Reference 4AnimalAcceleration of wound-healing activity with syringic acid in streptozotocin-induced diabetic ratsView study →.
Gap: entirely rodent; no human glycaemic trial, and effect sizes and dose translation are unestablished 3,4Reference 3AnimalSyringic acid ameliorates cardiac, hepatic, renal and neuronal damage induced by chronic hyperglycaemia in Wistar ratsView study →Reference 4AnimalAcceleration of wound-healing activity with syringic acid in streptozotocin-induced diabetic ratsView study →.
3. Anti-inflammatory
Syringic acid suppresses pro-inflammatory signalling (NF-κB, NLRP3/caspase-1/IL-1β) while activating PPARγ/Nrf2 — shown in keratinocytes 5Reference 5Syringic acid suppresses Cutibacterium acnes-induced inflammation in keratinocytes via NLRP3/caspase-1/IL-1β by activating PPARγ/Nrf2View study → and as a recurring secondary readout across the organ-protection studies 2Reference 2Antioxidant and anti-inflammatory potential of syringic acid: mechanistic insights and pathway interactionsView study →.
Gap: no isolated-compound human anti-inflammatory data; supports mechanism, not a treatment claim 2,5Reference 2Antioxidant and anti-inflammatory potential of syringic acid: mechanistic insights and pathway interactionsView study →Reference 5Syringic acid suppresses Cutibacterium acnes-induced inflammation in keratinocytes via NLRP3/caspase-1/IL-1β by activating PPARγ/Nrf2View study →.
4. Organ-protective (hepato/cardio/neuro)
Syringic acid reduces CCl₄-induced liver injury 6Reference 6Hepatoprotective effect of syringic acid and vanillic acid on CCl₄-induced liver injuryView study →, mitigates myocardial ischaemia-reperfusion injury via PI3K/Akt/GSK-3β 7Reference 7Syringic acid mitigates myocardial ischaemia-reperfusion injury by activating the PI3K/Akt/GSK-3β pathwayView study →, and is protective in neuronal oxygen-glucose-deprivation models 8Reference 8Neuroprotective effects of syringic acid against OGD/R-induced injury in cultured hippocampal neuronsView study →.
Gap: all rodent/in-vitro; these benefits are downstream antioxidant/anti-inflammatory effects, not demonstrated clinical uses 6,7,8Reference 6Hepatoprotective effect of syringic acid and vanillic acid on CCl₄-induced liver injuryView study →Reference 7Syringic acid mitigates myocardial ischaemia-reperfusion injury by activating the PI3K/Akt/GSK-3β pathwayView study →Reference 8Neuroprotective effects of syringic acid against OGD/R-induced injury in cultured hippocampal neuronsView study →.
5. Anticancer
Syringic acid induces apoptosis and inhibits proliferation (AKT/mTOR) in colorectal and gastric cancer models, in vitro and in vivo 9Reference 9In-vitro and in-vivo anticancer effects of syringic acid on colorectal cancerView study →.
Gap: cell-line and rodent only, often at supraphysiologic concentrations — not evidence for human cancer therapy 9Reference 9In-vitro and in-vivo anticancer effects of syringic acid on colorectal cancerView study →.
Mechanisms
| Target / pathway | Effect | Relevant to |
|---|---|---|
| Direct radical scavenging (dimethoxy-phenol) | neutralises ROS | antioxidant (all uses) |
| Nrf2 / antioxidant enzymes | ↑ SOD, catalase, glutathione | antioxidant, organ protection |
| NF-κB / NLRP3–caspase-1–IL-1β | suppressed | anti-inflammatory, organ protection |
| PPARγ | activated (↑ insulin sensitivity, anti-inflammatory) | metabolic |
| PI3K/Akt/GSK-3β | ↓ myocardial ischaemia-reperfusion injury | cardioprotective |
| AKT/mTOR → apoptosis | pro-apoptotic in tumour cells | anticancer (preclinical) |
Pharmacokinetics
Syringic acid is orally absorbed as a small phenolic acid and undergoes phase-II conjugation (methylation, glucuronidation, sulfation) typical of hydroxybenzoic acids, giving moderate but limited native oral bioavailability. That ceiling is why much of the recent literature is formulation work — self-microemulsifying systems, liposomes and micelles — aimed at raising exposure and antioxidant/hepatoprotective efficiency over the free acid 10Reference 10Improved oral bioavailability and hypolipidemic effect of syringic acid via a self-microemulsifying drug-delivery systemView study →. No dedicated human single-dose pharmacokinetic study of the isolate exists; human exposure is inferred from general dietary-phenolic handling.
Clinical trials
There are no human trials of isolated syringic acid for any indication. All efficacy evidence is in-vitro, rodent, or whole-extract (where syringic acid is one marker phenolic).
| Completed | Planned | Terminated | Preclinical |
|---|---|---|---|
| —(none, isolate) | — | — | Extensive |
Last checked: July 2026.
Toxicity & Safety
Syringic acid is a ubiquitous dietary phenolic — present in many fruits and berries, whole grains, honey and wine, and in herbs such as chickweed, marshmallow and yerba maté — and is regarded as low-toxicity at dietary and studied preclinical doses; it has even been co-administered as a protective agent against drug-induced liver injury. As with other polyphenols, high-concentration pro-oxidant behaviour and competition at conjugation enzymes are theoretically possible but not clinically documented for the isolate. No verified human interaction, contraindication or overdose dataset exists.
Pregnancy & lactation
Dietary amounts fine; avoid isolated supplements. Syringic acid as a normal food constituent is presumed safe, but there are no reproductive-safety or human data for isolated/supplemental use — so supraphysiologic supplementation is best avoided in pregnancy and lactation.
Dosage
There is no established therapeutic dose. Rodent studies typically used ~25–100 mg/kg/day orally, which does not translate to a human dose, and there is no human isolate dose. Because native oral bioavailability is only moderate, any biological effect likely depends on repeated intake or enhanced-delivery formulations rather than a single dose 10Reference 10Improved oral bioavailability and hypolipidemic effect of syringic acid via a self-microemulsifying drug-delivery systemView study →.
References
- Srinivasulu C, et al. (2018). Syringic acid — a review of its occurrence, biosynthesis, and pharmacological importance. Biomedicine & Pharmacotherapy. https://pubmed.ncbi.nlm.nih.gov/30243088/
- (2025). Antioxidant and anti-inflammatory potential of syringic acid: mechanistic insights and pathway interactions. Frontiers in Pharmacology. https://pubmed.ncbi.nlm.nih.gov/40703347/
- (2022). Syringic acid ameliorates cardiac, hepatic, renal and neuronal damage induced by chronic hyperglycaemia in Wistar rats. Molecules. https://pubmed.ncbi.nlm.nih.gov/36235257/
- (2019). Acceleration of wound-healing activity with syringic acid in streptozotocin-induced diabetic rats. Life Sciences. https://pubmed.ncbi.nlm.nih.gov/31386877/
- (2024). Syringic acid suppresses Cutibacterium acnes-induced inflammation in keratinocytes via NLRP3/caspase-1/IL-1β by activating PPARγ/Nrf2. International Immunopharmacology. https://pubmed.ncbi.nlm.nih.gov/39033661/
- (2010). Hepatoprotective effect of syringic acid and vanillic acid on CCl₄-induced liver injury. Biological & Pharmaceutical Bulletin. https://pubmed.ncbi.nlm.nih.gov/20522963/
- (2020). Syringic acid mitigates myocardial ischaemia-reperfusion injury by activating the PI3K/Akt/GSK-3β pathway. Biochemical and Biophysical Research Communications. https://pubmed.ncbi.nlm.nih.gov/32798018/
- (2016). Neuroprotective effects of syringic acid against OGD/R-induced injury in cultured hippocampal neurons. International Journal of Molecular Medicine. https://pubmed.ncbi.nlm.nih.gov/27278454/
- (2021). In-vitro and in-vivo anticancer effects of syringic acid on colorectal cancer. Chemico-Biological Interactions. https://pubmed.ncbi.nlm.nih.gov/33548266/
- (2021). Improved oral bioavailability and hypolipidemic effect of syringic acid via a self-microemulsifying drug-delivery system. AAPS PharmSciTech. https://pubmed.ncbi.nlm.nih.gov/33439366/