Phthalides

Other Names

1(3H)-Isobenzofuranone1,3-Dihydro-2-benzofuran-1-one1,3-Dihydrobenzo[c]furan-1-one1,3-Dihydroisobenzofuran-1-one1-Isobenzofuranone1-Oxophthalan1-Phthalanone2-Benzofuran-1(3H)-one2-Hydroxymethylbenzoic acid, gamma-lactone3-Oxo-1,3-dihydro-isobenzofuran3-Oxo-1,3-dihydroisobenzofuran3H-2-Benzofuran-1-one3H-Isobenzofuran-1-one3nBalpha-Hydroxy-o-toluic acid lactoneBenzo-fused gamma-lactoneBenzo[c]furan-2-oneButylphthalideE-LigustilideIsobenzofuran-1(3H)-oneIsobenzofuranoneLigustiliden-Butylphthalideo-Hydroxymethylbenzoic acid lactoneOxophthalanePhthalanonePhthalidPhthalidePhthalolactoneSedanenolideSedanolideSenkyunolide AZ-Ligustilide

Synopsis

Phthalides: A Comprehensive Reference

1. Identity, Chemistry, and Natural Sources

Chemical Definition and Structure

Phthalides are a group of compounds possessing a basic skeleton of 3H-isobenzofuran-1-one, on which chemical research has a history of more than 100 years. Structurally, phthalides can be classified into monomers, dimers, and trimers. The phthalide monomers are further classified into simple phthalides, mono-alkyl-substituted phthalides, bis-alkyl-substituted phthalides, and tri-alkyl-substituted phthalides, according to the number of substituent groups linked via carbon-carbon bonds. They are thus bicyclic lactone compounds, with the lactone ring fused to a benzene ring, forming the characteristic isobenzofuranone nucleus. This core structure admits a wide variety of side-chain substitutions—particularly alkyl chains at the 3-position—which give rise to the diverse family of naturally occurring phthalides and largely determine their biological activity and physical properties (e.g., volatility, lipophilicity).

Phthalides are widely present in plants, fungi, and liverworts. Up to date, hundreds of phthalide monomers and polymers have been reported from plants, fungi, lichens, and liverworts. In one major review, the chemical structures, classifications, and plant sources of approximately 137 natural phthalides of plant origin were described.

Botanical Sources

Most known phthalides have been obtained from plants belonging to Ligusticum and Angelica species in the Apiaceae family. The most referenced bioactive natural phthalides were identified from species of the genera Ligusticum (12 species) and Angelica (9 species). Other phthalide-enriched species belong to Apium, Cnidium, Levisticum, and Petroselinum genera.

The Apiaceae (synonym: Umbelliferae), which includes several economically important vegetables, herbs, and spices, is one of the most numerous plant families. Umbelliferous crops (namely anise, fennel, carrot, coriander, parsley, etc.) are also valuable sources of botanical flavoring agents and fragrances. In addition, Apiaceae species yield a wide variety of distinctive specialized metabolites, including volatile phenylpropanoids, furanocoumarins, sesquiterpene coumarins, polyacetylenes, and phthalides, some of them described as uncommon natural phytochemicals exclusive to the family.

Throughout the second part of the twentieth century, phthalides were characterized from several plant families, namely Asteraceae, Leguminosae, Orchidaceae, and Rutaceae, among others, but mainly from the Umbelliferae (Apiaceae) family; the major contributors were the following species used in traditional medicine: Ligusticum chuanxiong (Chinese name: Chuanxiong), Angelica sinensis (Chinese name: Danggui), Cnidium officinale (Japanese name: Senkyu), Angelica acutiloba (Japanese name: Toki), and Ligusticum porteri (Hispanic name: Oshá).

The first reports on the chemistry of phthalides appeared at the end of the nineteenth century, in which they were identified as odor constituents of the essential oil of celery (Apium graveolens) by Ciamician and Silber (1897). In the first half of the last century, phthalides were isolated from Cnidium officinale and Ligusticum acutilobum, species widely used in Asian traditional medicine, and from Levisticum officinale, a species used as food and condiment.

Phthalides are also constituents of several genera of fungi, such as Penicillium, Alternaria, and Pestalotiopsis, and some liverworts.

Principal Individual Compounds

Several specific phthalides have been isolated and subjected to scientific study. The most pharmacologically investigated include:

3-n-Butylphthalide (NBP; DL-3-n-butylphthalide) — the most extensively studied single compound; originally isolated from celery seed oil and subsequently synthesized; the basis of an approved pharmaceutical drug in China.
Ligustilide (Z-ligustilide) — the main pharmacologically active ingredient in the volatile oils of umbelliferous plants such as Angelica sinensis, Ligusticum wallichii, and other traditional Chinese medicines; its content is up to approximately 1%, and it has significant cardiovascular and cerebrovascular pharmacological activities.
Senkyunolide A, B, C … I — a series of butylphthalides first isolated from Ligusticum chuanxiong; associated with antiplatelet and analgesic activities.
Butylidenephthalide (E and Z forms), levistolide A, riligustilide, tokinolide B, and neocnidilide — key components isolated from Angelica species.
Sedanolide — an important aroma constituent of celery seed. Celery seeds are rich in flavonoids, phthalides (e.g., sedanolide, 3-n-butylphthalide), and monoterpenes (e.g., limonene), whereas celery stalks and leaves contain higher levels of phenolic acids, furanocoumarins, and flavonoids.

Phthalides, which contain a phthalide parent nucleus, constitute a type of active compound in A. sinensis. Thirty compounds have been isolated from Angelica species, including non-alkaloid phthalides and phthalide derivatives.

Common Preparations and Forms

Phthalides reach consumers and clinical settings in several forms:

Whole food / dietary source: celery stalk, celery seed, lovage root, and angelica root consumed as food, spice, or tea.
Essential oil / volatile oil extracts: used in food flavoring and traditional herbal preparations; phthalides contribute the characteristic aroma.
Standardized plant extracts: typically produced from celery seed (Apium graveolens) or lovage, standardized to a defined phthalide percentage, and formulated into capsules or tablets for dietary supplement use.
Pharmaceutical drug formulation (NBP): in the clinical trial literature, fifty-seven RCTs involving 8,747 participants were included, of which twenty trials examined NBP as a capsule, twenty-nine as an injection, and eight as sequential injection-capsule therapy. The capsule form (soft-gel capsules of DL-3-n-butylphthalide) is approved and marketed as a prescription pharmaceutical in China.

2. Traditional and Historical Use

Ancient and Pre-Modern History

Phthalides are responsible for the characteristic odor of celery. Since ancient times, phthalide-containing plants have been used in Asia, Europe, and North America as traditional medicines and food flavoring agents.

Phthalides are a group of structurally specific constituents naturally distributed in several important medicinal herbs in Asia, Europe, and North Africa.

Traditional Chinese Medicine (TCM)

Ligusticum chuanxiong Hort. and Angelica sinensis (Oliv.) Diels, frequently used in traditional Chinese medicine to invigorate the circulation of qi and the blood, both contain a high level of phthalide components, typically exceeding 1% in their rhizome or root.

Known as Dang Gui (in Chinese), Angelica sinensis is a traditional medicinal and edible plant that has long been used for tonifying, replenishing, and invigorating blood as well as relieving pain. Ligusticum chuanxiong (Chuanxiong, or Sichuan lovage) has been a cornerstone herb in TCM cardiovascular and gynecological formulae for at least a thousand years, often combined with Danggui in preparations for blood disorders.

Accumulating evidence demonstrates that natural phthalides have various pharmacological activities, including analgesic, anti-inflammatory, antithrombotic, and antiplatelet activities, mostly consistent with the traditional medicinal uses of their natural plant sources.

In the case of compounds isolated from the Apiaceae, the bioactivities correlate with the traditional medicinal uses of the natural sources.

Japanese Kampo Medicine

Cnidium officinale (Japanese name: Senkyu) and Angelica acutiloba (Japanese name: Toki) are major sources of phthalides used in Japanese Kampo (traditional herbal medicine), employed in formulations aimed at blood circulation disorders, menstrual irregularities, and pain syndromes—uses that closely parallel the TCM indications of their Chinese botanical counterparts.

European and Western Folk Traditions

In the first half of the last century, phthalides were also isolated from Levisticum officinale, a species used as food and condiment. Lovage (Levisticum officinale), a culinary herb native to southern Europe, has long been employed in European folk medicine as a digestive aid, diuretic, and carminative. Celery seed (Apium graveolens var. dulce) similarly figured in European herbal practice as a remedy for rheumatic complaints, kidney disorders, and blood pressure support.

Ligusticum porteri (Hispanic name: Oshá) has been used by Native American and Hispanic communities of the American Southwest and Mexico as a root medicine for respiratory infections, pain, and digestive complaints.

Many phthalide-containing plants have been used worldwide as herbal remedies in traditional and folk medicines, dietary supplements, and food flavorings.

3. Key Constituents and Mechanisms of Action

Overview of Pharmacological Activities

Phthalides, mainly isolated from Ligusticum and Angelica of the Apiaceae family, are thought to be potent natural compounds with many therapeutic effects, such as antiplatelet, antitussive, antinociceptive, anti-inflammatory, antibacterial, antiviral, and immunosuppressive activities. They also have antifungal, antioxidant, and anticancer activities.

A wide range of biological activities for natural phthalides have been reported, including regulation of the cardio-cerebrovascular system and central nervous system, hemorheological improvement, antioxidation, anti-inflammation, analgesia, anti-cancer, organ and bone-related protection.

Cardiovascular and Vascular Mechanisms

Advances in the biological activities of phthalides include actions on the central nervous system, anti-platelet aggregation and anti-thrombosis, cardiac function modulation and anti-angina, inhibition of smooth muscle cell proliferation, protection against cerebral ischemia, and smooth muscle relaxation.

Celery phthalides lead to expansion of smooth muscle in the blood vessels, which lowers blood pressure. The smooth muscle relaxant effect is considered one of the primary mechanisms by which phthalides exert their antihypertensive and vasodilatory actions.

Over 100 chemical metabolites have been isolated from Ligusticum chuanxiong, including phthalides, terpenes and their enol derivatives, alkaloids, polysaccharides, and organic acids. These metabolites exhibit multiple pharmacological activities, such as vasodilation, blood circulation enhancement, antiplatelet aggregation, antioxidant, and anti-inflammatory effects.

Phthalides including senkyunolide A and ligustilide show immunomodulatory effects in improving atherosclerosis, through inhibiting AP-1 and NF-κB expression.

Neuroprotective Mechanisms

DL-3-n-butylphthalide (NBP) can increase regional cerebral blood flow, reconstruct microcirculation at the ischemic area, inhibit neuronal apoptosis and autophagy, regulate brain energy metabolism, and enhance post-ischemic neuronal recovery.

A large number of experiments and clinical studies have confirmed that NBP and its derivatives can reduce infarct size, protect against mitochondrial damage, exhibit anti-apoptotic activity, reduce antioxidant stress, and promote neurogenesis of newborn neurons. Preclinical studies reveal that NBP exerts neuroprotective effects in ischemic stroke both in vivo and in vitro, partially by promoting angiogenesis, increasing BDNF expression, promoting dendrite development, protecting mitochondrial function, inhibiting neuroinflammation, and improving brain metabolism.

NBP plays a role in different pathophysiological processes in the treatment of ischemic stroke, including antioxidant, anti-inflammatory, anti-apoptotic, anti-thrombosis, and mitochondrial protective mechanisms.

Ligustilide has been shown to inhibit aging-induced cognitive impairment via modulating mitochondrial-associated disorders; it also protects the blood-brain barrier from oxygen-glucose deprivation (OGD)-triggered increases in permeability mainly through potentiation of tight junction proteins (ZO-1 and occludin) and the blockage of HIF-1α/VEGF signaling pathways.

NBP exerts neuroprotective effects by safeguarding mitochondria, reducing oxidative stress, combating inflammation, and decreasing neuronal apoptosis. Animal studies have shown that NBP soft capsules can effectively improve cholinesterase activity, activate mitochondrial enzymes, and enhance mitochondrial function in rats with hypoperfusion dementia, thus improving memory in Alzheimer's disease animal models.

Senkyunolide A, a 3-butylphthalide from L. chuanxiong, could inhibit the progression of osteoarthritis by inhibiting the NLRP3 signaling pathway.

Phthalides were found to mediate angiogenesis in the improvement of vascular disorders.

Pharmacological properties of plant-derived phthalides are associated with hemorheological improvement, vascular function modulation, and central nervous system protection.

4. Scientific Evidence by Area of Use

4.1 Ischemic Stroke Treatment

The most robust clinical evidence for phthalides concerns DL-3-n-butylphthalide (NBP) as a pharmaceutical agent for ischemic stroke. According to the results of multicenter phase 2 and phase 3 randomized controlled clinical trials, NBP was approved by the State Food and Drug Administration of China as a drug for the treatment of ischemic stroke in 2002, which showed good safety and tolerance.

DL-3-n-butylphthalide is widely used as a neuroprotective drug in stroke patients in China. A systematic review in 2010 suggested NBP to be safe and effective at promoting neurological recovery, but could not conclude whether it decreased risk of long-term death or disability. Since numerous randomized controlled trials have been conducted on NBP since 2010, an updated systematic review and meta-analysis of safety and efficacy data was performed.

The updated review included fifty-seven RCTs involving 8,747 participants. The key quantitative findings from this meta-analysis were substantial:

Meta-analyses showed that NBP treatment was associated with a reduction in composite outcome of death and dependency (risk ratio 0.59, 95% CI 0.42 to 0.83; 260 participants; 2 studies), death (risk ratio 0.32, 95% CI 0.13 to 0.75; 2,287 participants; 10 studies), modified Rankin Scale score (mean difference −0.80, 95% CI −0.88 to −0.72; 568 participants; 4 studies), and an increase in Barthel Index, assessing ability to engage in basic activities of daily living (mean difference 11.08, 95% CI 9.10 to 13.05; 2,968 participants; 22 studies).
Meta-analyses found that NBP significantly reduced neurological deficit based on National Institute of Health Stroke Scale (mean difference −3.39, 95% CI −3.76 to −3.03; 7,283 participants; 46 studies) and Chinese Stroke Scale (mean difference −4.16, 95% CI −7.60 to −0.73; 543 participants; 4 studies).

The updated review confirmed that NBP can help acute ischemic stroke patients regain the ability to perform activities of daily living, reduce their neurological deficit, and reduce short-term death rates. However, the available evidence on whether NBP reduces risk of long-term death or dependence after ischemic stroke remains insufficient.

A notable randomized clinical trial examined NBP specifically in stroke patients receiving modern reperfusion therapy: NBP was associated with a higher proportion of patients achieving a favorable functional outcome at 90 days compared with placebo among patients with acute ischemic stroke receiving intravenous thrombolysis and/or endovascular treatment. This randomized clinical trial assessed the efficacy and safety of DL-3-n-butylphthalide in patients with acute ischemic stroke receiving reperfusion therapy. Of 1,216 enrolled patients, 827 (68.0%) were men, and the median age was 66 (IQR 56–72) years.

Many randomized, double-blind, placebo-controlled, multicenter clinical trials suggest that NBP is a safe and effective treatment for ischemic stroke. However, it is important to note that the bulk of this clinical evidence is generated in China, using Chinese-market drug formulations, and a substantial proportion of the underlying trials carry methodological limitations including incomplete blinding and reporting. The evidence base, while large in aggregate participant numbers, should be interpreted with appropriate attention to these design considerations.

4.2 Post-Stroke Cognitive Impairment and Vascular Dementia

The efficacy of multitarget neuroprotective drug DL-3-n-butylphthalide (NBP) in improving cognitive function has been confirmed in patients with vascular cognitive impairment without dementia. However, its efficacy in patients in the symptomatic predementia phase of Alzheimer's disease remains uncertain.

One randomized controlled trial of note examined cognitive outcomes: Jia et al. (2016) found that NBP significantly increased cognitive scores compared with placebo in patients with subcortical vascular cognitive impairment without dementia in China, after treatment with NBP 200 mg three times daily for 24 weeks.

One trial evaluated the efficacy and safety of NBP in improving cognitive function in patients with mild cognitive impairment (MCI) through a 12-month, randomized, double-blind, placebo-controlled, multicentric trial, involving 270 patients with MCI.

Butylphthalide is widely used for the adjunctive treatment of vascular dementia; however, the clinical evidence has not been well synthesized. At the preclinical level, evidence suggests that l-3-n-butylphthalide may be a potentially beneficial and promising drug for the treatment and prevention of vascular dementia. The overall evidence for cognitive indications is more preliminary than for acute ischemic stroke, and the translation to Alzheimer's-type dementia remains to be established in rigorous trials.

4.3 Blood Pressure and Cardiovascular Function

Previous studies have demonstrated the efficacy of phthalides in improving blood circulation, reducing blood stasis, and providing progressive stimulation, particularly for cardiovascular and cerebrovascular diseases, as well as dysmenorrhea.

Some early research, mainly in animal models and in vitro studies, has explored phthalides' vasodilatory effects, particularly focusing on 3-n-butylphthalide (NBP). These studies suggest potential mechanisms, such as calcium-channel modulation and antioxidant activity, but robust human clinical evidence remains limited. While there are promising findings, the translation to established arterial health benefits in humans is not firmly supported by clinical trials.

Pharmacological properties of plant-derived phthalides are associated with hemorheological improvement, vascular function modulation, and central nervous system protection. Potential treatments for a variety of diseases mainly including cardio-cerebrovascular disorders and neurological complications such as Alzheimer's disease have been proposed. However, the blood pressure–lowering evidence in human subjects, outside of mechanistic plausibility and animal data, remains preliminary and calls for well-designed clinical trials specifically targeting hypertension endpoints.

4.4 Anti-Inflammatory and Analgesic Effects

Scientific reports on crude extracts and pure compounds and formulations have revealed a wide range of pharmacological activities, including anti-inflammatory activity, antifibrotic action, antispasmodic activity, antioxidant activities, and neuroprotective action, as well as cardio- and cerebrovascular effects. The current evidence for phthalide-mediated anti-inflammatory and analgesic effects is primarily preclinical (animal models and cell-based assays), with NF-κB inhibition, prostaglandin pathway modulation, and cytokine suppression among the documented molecular mechanisms. Controlled clinical data specifically examining pain or inflammatory endpoints for phthalides as dietary supplements are lacking.

4.5 Hemorheology and Antiplatelet Effects

Biological activities including anti-platelet aggregation and anti-thrombosis have been identified as significant properties of natural phthalides. These effects are mechanistically important and have contributed to the rationale for using phthalide-containing herbs and drugs in cardiovascular medicine. The antiplatelet activity is both a therapeutic property and a safety consideration (see Section 7).

4.6 Intracerebral Hemorrhage (Hemorrhagic Stroke)

A randomized, double-blind, double-dummy trial suggested that 90-day treatment with NBP could improve outcomes at the third month after acute ischemic stroke. A meta-analysis revealed that the combination of NBP and standard anti-ischemic stroke drugs is more effective than standard drugs alone. Evidence for NBP in hemorrhagic stroke (intracerebral hemorrhage) is still at a preclinical stage, with animal models providing supporting mechanistic data but human data not yet available in mature form.

5. Body Systems and Health Areas of Association

Based on the published pharmacological and clinical literature, phthalides are primarily investigated in relation to the following body systems and conditions:

Cerebrovascular and neurological system: Ischemic stroke, vascular dementia, post-stroke cognitive impairment, mild cognitive impairment, Alzheimer's disease (animal models), Parkinson's disease (preclinical). In addition to ischemic stroke, NBP has been assessed in dementia and Parkinson's disease.
Cardiovascular system: Blood pressure regulation, antiplatelet/antithrombotic effects, angina modulation, smooth muscle relaxation, and atherosclerosis. Metabolites exhibit vasodilation, blood circulation enhancement, antiplatelet aggregation, antioxidant, and anti-inflammatory effects.
Blood and hematology: Hemorheological improvement (blood viscosity, microcirculation), anticoagulation modulation.
Gynecological system: Traditional use for dysmenorrhea and menstrual blood stasis, supported in part by smooth muscle–relaxing properties documented in TCM practice.
Musculoskeletal system: Preclinical investigation for osteoarthritis inhibition via NLRP3 pathway suppression.
Immune and inflammatory system: Modulation of NF-κB and AP-1 signaling, inhibition of pro-inflammatory cytokines.
Antioxidant defense: Free radical scavenging, mitochondrial protection, reduction of oxidative stress markers.

6. Dosage Forms and Dosages Reported in Studies

Dosage data in the phthalide literature is almost entirely concentrated on the pharmaceutical compound DL-3-n-butylphthalide (NBP), and refers to that drug rather than to unprocessed botanical supplements. The following dosages are reported directly in peer-reviewed clinical literature:

Oral capsule (NBP soft capsules) — ischemic stroke: Hospital patients with acute cerebral infarction were randomized into either standard medical therapy alone or standard medical therapy combined with NBP treatment at a dose of 200 mg, three times per day for 24 weeks.
Oral capsule (NBP) — cognitive impairment: In a trial by Jia et al. (2016), patients with subcortical vascular cognitive impairment received NBP 200 mg three times daily for 24 weeks.
Dosage forms studied across 57 RCTs: Twenty trials examined NBP as a capsule, 29 as an injection, and 8 as sequential injection-capsule therapy.
Phase IV safety trial (injection): A phase IV, multicenter, prospective, open-label trial showed that NBP injection was safe and associated with an overall adverse event rate of 3.28% in patients with acute ischemic stroke.

Dosage information for celery seed extract or other botanical phthalide-containing supplements — as used in the context of dietary supplementation rather than pharmaceutical treatment — is not established through peer-reviewed clinical trials to the standard that would allow precise recommendations. Clinical data are insufficient to specify doses for prevention or general wellness indications.

7. Safety Considerations and Drug Interactions

General Safety Profile

The safety profile of butylphthalide is well-characterized and generally favorable. The most common adverse events are mild to moderate gastrointestinal discomfort and elevations in liver transaminases, which necessitate clinical monitoring.

Of adverse events reported in 31 trials, elevated transaminase (incidence 1.39–17.53%), rash (0–1.96%), and gastrointestinal discomfort (1.09–6.15%) were the most frequent, and no serious adverse events were reported.

Hepatotoxicity Signal

Serum levels of alanine transaminase (ALT) and aspartate transaminase (AST), two liver function indices, are increased in patients after long-term use of NBP. A meta-analysis confirmed that DL-3-n-butylphthalide, while appearing to have better efficacy in the treatment of ischemic stroke, is more detrimental to patients' liver function. This hepatotoxicity signal means that liver enzyme monitoring is recommended during sustained use.

DL-3-n-butylphthalide is clinically approved as an anti-ischemic drug in China, but its potential hepatotoxicity limits its use.

Antiplatelet and Bleeding Risk

The primary safety concern stems directly from its therapeutic mechanism: NBP's antiplatelet activity creates a heightened risk of bleeding, especially when co-administered with other anticoagulant or antiplatelet medications. Individuals taking anticoagulants (such as warfarin or direct oral anticoagulants), antiplatelet drugs (such as aspirin or clopidogrel), or other herbs with blood-thinning properties would face additive risk when combining these with phthalide-containing preparations.

Real-World Comparative Safety

In a large real-world population of acute ischemic stroke patients, NBP was found to have a lower incidence of adverse events and a better safety profile than edaravone or other usual medications. Prescription sequence symmetry analysis showed that NBP had a weak correlation with abnormal platelet count.

Long-Term Safety Gaps

Even though NBP injections have been used in the clinic for more than a decade, the evidence base still needs to examine adverse events over much longer periods. This is particularly relevant for dietary supplement users who may take phthalide-containing products over months or years without clinical oversight.

Evidence Quality and Applicability Caveats

The safety data summarized above derive almost entirely from clinical studies of the pharmaceutical compound NBP (DL-3-n-butylphthalide) in Chinese hospital settings for stroke treatment. The degree to which these findings apply to phthalides in botanical dietary supplement form — where concentrations, bioavailability, and the accompanying phytochemical matrix differ substantially — has not been directly established in clinical literature. Despite promising findings, extensive human clinical evidence remains limited. Most studies to date have been preliminary or have focused on isolated compounds rather than whole food sources or complex supplements.

References

Health Conditions

Health conditions that Phthalides may help support.

No conditions available.

Body Systems

Body systems that Phthalides may help support.

No body systems available.