Forsythia

Forsythia (Forsythia suspensa): A Comprehensive Reference

1. Identity, Botanical Classification, and Common Forms

Botanical and Pharmaceutical Names

Forsythia suspensa is defined as an ornamental shrub belonging to the Oleaceae family, whose fruits, known as Forsythiae Fructus (FF), are utilized in traditional Chinese medicine for their anti-inflammatory, antioxidant, antibacterial, and other pharmacological effects. The full scientific binomial is Forsythia suspensa (Thunb.) Vahl. Common names include Forsythia, Golden bells, Lian qiao (Lianqiao), Weeping forsythia, and Rengyo (in Japanese).

Forsythiae Fructus, the dried fruit of Forsythia suspensa (family Oleaceae), known as lianqiao in China, was first recorded in Shennong Bencao Jing, a prestigious monograph on traditional Chinese medicine (TCM), and subsequently listed in the pharmacopoeias of the People's Republic of China, Japan, and Korea. The plant is officially listed in the Pharmacopeia of the People's Republic of China, where forsythiaside A and phillyrin are designated as quality control markers.

Natural Source and Distribution

F. suspensa (Weeping Forsythia) is an ornamental deciduous shrub native to China, growing to a height of about 3 m. It has a long history of use in traditional Chinese medicine and is one of the most commonly used Chinese herbal medicines on the Chinese market, primarily distributed in Shanxi (40%), Henan (30%), and Shaanxi (approximately 20%), and is also widely distributed in South Korea, Japan, and many European countries.

Plant Parts Used

The dried fruit is the primary medicinal part. Forsythia is a bitter tasting and pungent herb, one of the 50 fundamental herbs in Chinese traditional medicine, used for clearing heat and detoxification in formulae for childhood fevers, acne and skin infections. Studies have shown that the chemical constituents in the leaves and fruits of Forsythia suspensa are very similar, and the content of phillyrin in the leaves of Forsythia is even 40 times higher than that in the fruits. Leaves, roots, stems, and seeds have all been subjects of phytochemical investigation, though the dried fruit (Forsythiae Fructus) remains the official pharmacopoeial material.

Harvest Forms and Preparations

Two forms of FF are available: the greenish fresh ripe fruit called Qingqiao and the yellow fully ripe one called Laoqiao. Both serve as official sources of FF; nevertheless, Qingqiao is used more frequently in TCM prescriptions. Qingqiao contains higher levels of forsythiaside, forsythoside C, cornoside, rutin, phillyrin, gallic acid and chlorogenic acid, and lower levels of rengyol, β-glucose and S-suspensaside methyl ether.

The source of earliest record is Shennong Bencao Jing. The fruit is steamed, dried in the sun, and its seeds separated from the flesh. Common modern preparations include water decoctions, standardized dried extracts, capsules, granules, and oral liquids. More than forty Chinese medicinal preparations containing Forsythiae Fructus are included in the Chinese Pharmacopoeia, Volume I.

---

2. Traditional and Historical Use

Origin and Earliest Records

Forsythiae Fructus was first recorded in Shennong Bencao Jing and has been used as a heat-clearing and detoxifying TCM for the treatment of infectious diseases, such as acute nephritis, erysipelas and ulcers, for over 2000 years. With at least 3000 years of continuous use, forsythia fruit is traditionally considered a detoxicant for treating so-called toxic and hot conditions.

Classical Chinese Medicine Traditions

In classical Chinese herbal texts, FF is recorded as useful in the treatment of rat fistula, scrofula, carbuncle, malignant ulcer, gall tumor, heat and poison (Shennong's Herbal, Bencao Chongyuan, Bencao Zhengyi, Zhenglei Bencao). According to many ancient classics, this medical herb is considerably effective on clearing the heat of heart channel and releasing the dampness-heat of spleen and stomach. It is also described as therapeutic for the treatment of stranguria, oedema, qi stagnancy and blood stasis.

Forsythiae Fructus is utilized as a common traditional medicine in China, Japan and Korea, and is traditionally used to treat pyrexia, inflammation, gonorrhea, carbuncle and erysipelas. The TCM characteristics of FF are summarized as a bitter flavor with a mildly cold nature and lung, heart, or intestinal meridian distribution; these characteristics are parallel to the characterization of anti-inflammatory TCM.

Forsythia suspensa leaf (FSL) comes from the Compendium of Materia Medica, has a bitter taste, cold nature, and the effect of heat-clearing and detoxification. In the Yuqiao Medical Order, it is written that FSL is bitter, slightly pungent, and cold in nature, and can be used to relieve fire, clear heat, and benefit the heart and lung meridians.

Use in Japan and Korea

F. suspensa (Oleaceae) is an important original plant of the crude drug "rengyo" (Forsythiae Fructus) which has been used for anti-inflammatory, diuretic, drainage, and antimicrobial purposes in Oriental medicine. Forsythia fruit (Forsythia suspensa Vahl (Oleaceae)) is a common component of Kampo medicines for treating the common cold, influenza, and allergies. Forsythia fruit, the dried fruit of F. suspensa, is listed in Japanese, Chinese, and Korean Pharmacopoeias.

Traditional Formulas and Pairings

Yinqiaosan (YQS), a classical formula first documented two hundred years ago, has been used for treating common cold, fever, coughing, and other respiratory diseases, and is one of the five TCM formulae found to have potent action against influenza. YQS consists of components from nine plants including Lonicera japonica Thunb. (honeysuckle flower) and Forsythia suspensa. The two herbs (Lonicera japonica and Fructus Forsythiae) are the basic components of Chinese herbal preparations such as Shuang-Huang-Lian tablet, Yin-Qiao-Jie-Du tablet, Fufang Jin-Huang-Lian Granule, and others, which are extensively used in clinical practice.

---

3. Phytochemistry: Key Constituents and Chemical Classes

Overall Chemical Profile

In modern research, more than 230 compounds were separated and identified from F. suspensa. At present, 321 chemical components have been isolated from FF, including phenylethanoid glycosides, lignans, flavonoids, terpenes and volatile oils. Identified compound classes include 42 phenylethanoid glycosides, 48 lignans, 22 terpenoids, 14 flavonoids, three steroids, 24 cyclohexyl ethanol derivatives, 14 alkaloids, 26 organic acids, 21 volatile oils, and 24 other compounds.

Principal Active Compound Classes

Recent studies have shown that phenylethanoid glycosides and lignans are the typical active constituents of FF, including forsythiaside A and phillyrin.

Phenylethanoid Glycosides

Forsythiaside A is the component at the highest level in Forsythia suspensa, which has been applied as one of the marker components to evaluate its quality. Forsythiaside A is a phenylethanoid glycoside; the skeleton of phenylethanoid glycosides includes three parts: phenylethyl alcohol, caffeic acid and a glycosyl group. The presence of phenolic hydroxyl groups enhances the antioxidant activity of these compounds. According to the different groups connected to the nucleus, forsythiasides can be divided into A–K; in recent years, numerous investigations have been carried out on forsythiasides A, B, C, D, E, and I, which have the effects of cardiovascular protection, anti-inflammation, anti-oxidation, and neuroprotection.

Forsythoside A is considered the main active index component of forsythia, thought to be responsible for its anti-inflammatory, antiviral, neuroprotective, antioxidant, hepatoprotective, and antibacterial activities. The Chinese Pharmacopoeia specifies that the immature fruit should not contain less than 2.0%, and the mature fruit not less than 0.25% forsythoside A.

Lignans

Phillyrin (C₂₇H₃₄O₁₁), a major lignan constituent of Forsythia suspensa, and its aglycone phillygenin (C₂₁H₂₄O₆) exhibit a broad spectrum of biological activities, including multi-target anti-inflammatory, antiviral, antioxidant, and anticancer effects. Phillyrin, also known as forsythin, is a major bioactive compound purified from Oleaceae Fructus Forsythiae with reported anti-inflammatory and antioxidant properties.

Phillyrin is described as a second index marker of forsythia, with anti-inflammatory, anti-aging, antiviral, antibacterial, hepatoprotective and anti-cancer effects. It may also have an anti-obesity effect through cyclic AMP phosphodiesterase 4 (PDE4) inhibitory activity. The Chinese Pharmacopoeia specifies that the immature fruit should not contain less than 0.3%, and the mature fruit not less than 0.09% phillyrin.

Regarding the content of phillyrin across plant parts: leaves (2.60%) > Qingqiao (0.91%) > Laoqiao (0.17%).

Flavonoids

Modern phytochemical studies reveal forsythia leaf as a rich source of active polyphenols (e.g., phillyrin), flavonoids (e.g., kaempferol), and terpenoids (e.g., oleanolic acid), which collectively mediate pleiotropic effects spanning antiviral, antioxidative, immunomodulatory, and metabolic regulatory functions.

Other Notable Compounds

Fifty compounds have been isolated from the fruits of Forsythia suspensa, including 13 new compounds characterized as eight new diterpenoids, three new lignans, a new iridoid, and a new triterpenoid. Active compounds isolated from Forsythiae Fructus include forsythoside A, arctigenin, arctiin, matairesinol, phillyrin/forsythin, and suspensine A.

---

4. Established and Proposed Mechanisms of Action

Anti-inflammatory Mechanisms

Mechanistically, forsythiasides regulate toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor kappaB (NF-κB), nuclear factor-erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) and other signaling pathways, as well as the expression of related cytokines and kinases. Forsythia leaf extract has been found to reduce the expression of TLR4, NF-κB (p65), TNF-α, and IL-6 genes in colon tissue.

Most isolated compounds were examined for their anti-inflammatory activity in vitro, with several compounds displaying significant inhibition of fMLP/CB-induced superoxide anion generation and elastase release, with IC₅₀ values ranging from 0.6 ± 0.1 to 8.6 ± 0.8 μg/mL and from 0.8 ± 0.3 to 7.3 ± 1.1 μg/mL, respectively.

Antiviral Mechanisms

Phillyrin and the reformulated preparation FS21 had potent antiviral effects against all six tested influenza A and B virus strains in a dose-dependent manner. Mechanistic studies showed that both suppressed influenza viral RNA polymerase with no effect on virus-mediated hemagglutination inhibition, viral binding or entry, endosomal acidification, or neuraminidase activity. The distinct antiviral mechanism is therefore inhibition of viral RNA polymerase.

In vitro experiments showed that phillyrin and rosmarinic acid could effectively improve the survival rate of RSV-infected cells, increase the expression level of PI3K, and decrease the expression level of AKT. The active ingredients of forsythia leaf, including phillyrin and rosmarinic acid, can play an anti-RSV role by inhibiting the PI3K/AKT signaling pathway.

Antioxidant Mechanisms

Some studies have revealed the anti-oxidative effect of the Forsythia Fructus extract and its compounds in the DPPH, ABTS and FRAP assays in vitro. Forsythoside A, isoforsythoside A, phillygenin, phillyrin, and forsythialan A exhibited strong antioxidant effects, with DPPH IC₅₀ values of 0.43, 2.74, 53.64, 351.14, and 29.86 μg/mL, respectively.

PDE4 Inhibitory Activity

Phillyrin was reported as a novel cyclic AMP phosphodiesterase 4 (PDE4) inhibitor derived from forsythia fruit. PDE4 inhibition is a mechanistic basis for anti-inflammatory, anti-obesity, and potential anti-asthma effects.

Neuroprotective Mechanisms

Forsythiae Fructus exerts neuroprotective effects by modulating various pathways, including oxidative stress, anti-inflammation, NF-κB signaling, 2-AG, Nrf2 signaling, acetylcholinesterase, PI3K-Akt signaling, ferroptosis, gut-brain axis, TLR4 signaling, endoplasmic reticulum stress, PI3K/Akt/mTOR signaling, and PPARγ signaling pathway.

In vitro, forsythoside A treatment significantly improved mitochondrial function and inhibited lipid peroxidation in Aβ1-42-exposed mouse neuroblastoma N2a cells. Forsythoside A treatment also suppresses erastin-stimulated ferroptosis and neuroinflammatory effects in HT22 cells mainly via the Nrf2/GPX4 axis. In vivo, forsythoside A treatment suppressed Aβ deposition and p-Tau levels and ameliorated memory and cognitive impairments in the male APP/PS1 mouse brain, significantly inhibiting iron deposition and lipid peroxidation.

---

5. Scientific Evidence by Health Area

5.1 Anti-inflammatory Activity

Heat-clearing actions of Forsythiae Fructus are based on the anti-inflammatory and antioxidant properties of lignans and phenylethanoid glycosides. Evidence for anti-inflammatory effects is primarily derived from in vitro cell-based experiments and animal models. FF from Shanxi and Shaanxi harvested in August showed marked anti-inflammatory and antioxidant activities, with differences that may be because of different contents of phillygenin and phillyrin of lignans in FF.

Preclinical studies reveal that phillyrin exerts potent anti-inflammatory effects across a broad spectrum of acute and chronic conditions, including viral pneumonia, acute lung injury, arthritis, colitis, and central nervous system injuries. Evidence strength: Anti-inflammatory evidence is robust at the in vitro and animal level; direct human RCT data for isolated Forsythia fruit as a sole agent are absent as of the time of these reviews.

5.2 Antiviral Activity

The antiviral effect of Forsythia Fructus has mainly focused on influenza A (H1N1) virus, respiratory syncytial virus (RSV), and infectious bronchitis virus (IBV). Previous studies suggested that the 80% ethanol extract of Forsythia Fructus protected H1N1-infected MDCK cells with a minimal inhibitory concentration (MIC) of 1:8192 mg/mL.

Four compounds from Forsythia Fructus, namely forsythoside A, calceolarioside B, phillyrin, and rengynic acid, also demonstrated significant antiviral activity.

FS21, a reformulated preparation composed of 90% purified phillyrin that has been approved for the treatment of fever, pyrexia, and other influenza-like symptoms in China since 2015, exhibits antiviral effects demonstrated through reduction of influenza virus-induced cytopathic effects (CPE) as well as suppression of viral genome RNA replication, mRNA transcription and protein expression, and infectious virus production.

Forsythia leaves are integral to Lianhua Qingwen granules, a WHO-recognized nutraceutical for viral respiratory diseases including COVID-19. These granules contain a mixture of components including Forsythia suspensa and are approved for the treatment of influenza virus. In a treated group, the application of these granules was shown to significantly reduce the duration of virus nucleic acid detection, as well as lead to a faster recovery from pneumonia, without the appearance of side effects. It is important to note, however, that these clinical findings relate to the multi-herb formulation Lianhua Qingwen and cannot be attributed to forsythia alone.

Evidence strength: Antiviral effects are well-established in vitro and in animal models. FS21 has achieved regulatory approval in China for influenza-related symptoms, providing some translational bridge. Direct, adequately-powered human RCTs using forsythia fruit as a single agent remain limited.

5.3 Antibacterial Activity

Lignans and phenylethanoid glycosides purified from Forsythia suspensa were reported to display antimicrobial activity in previous literature. Some of the purified principles were subjected to antimicrobial activity examinations against Escherichia coli to explore new natural lead compounds. Evidence strength: Primarily preclinical (in vitro); no well-powered clinical trials specifically examining forsythia's antibacterial efficacy in humans were identified.

5.4 Neuroprotection

Specific phenylethanoidglycoside compounds from the fruits of Forsythia suspensa exhibited significant neuroprotective activities with cell viability values of 75.24 ± 8.05% and 93.65 ± 10.17% for serum-deprivation and rotenone-induced PC12 cell injury. One compound also exhibited excellent anti-inflammatory activity against TNF-α expression in LPS-induced RAW264.7 cells with an IC₅₀ value of 1.30 μM. This study revealed that bioactive phenylethanoidglycosides may attenuate neuroinflammation through their neuroprotective and anti-inflammatory activities.

Evidence strength: Neuroprotective evidence is entirely preclinical (in vitro and animal models). No human clinical trials evaluating forsythia for neurological outcomes were identified.

5.5 Antioxidant Activity

Studies have revealed the anti-oxidative effect of the Forsythia Fructus extract and its compounds in the DPPH, ABTS, and FRAP assays in vitro. Evidence strength: In vitro evidence for antioxidant capacity is consistent. Translational significance to human health outcomes has not been established in clinical trials.

5.6 Anti-obesity Effects

It is known that polyphenolic compounds stimulate lipid catabolism in the liver and suppress dyslipidemia, thereby attenuating diet-induced obesity. Phillyrin was reported as a novel PDE4 inhibitor derived from forsythia fruit, which provides a mechanistic basis for anti-obesity effects. Research demonstrated that forsythia leaves have potential value as a health material for reducing obesity in SD rats fed a high-fat diet; however, anti-obesity effects in humans are still to be determined.

Evidence strength: Entirely animal and in vitro data. No human trials on forsythia for obesity outcomes were identified.

5.7 Antitumor / Anticancer Activity

The TCM characteristics of Forsythiae Fructus (bitter flavor, slightly cold nature and lung meridian) support its strong anti-inflammatory effects. The remarkable anti-inflammatory and antioxidant capacities of Forsythiae Fructus contribute to its anti-cancer and neuroprotective activities. Phillyrin, a major bioactive component of Forsythia suspensa, exhibits significant anti-inflammatory, neuroprotective, and antibacterial properties, offering potential for colorectal cancer (CRC) prevention and treatment. Studies have aimed to clarify the effects on CRC progression, focusing on epithelial-mesenchymal transition (EMT) and angiogenesis via CD147 molecular mechanisms.

Evidence strength: Anticancer evidence is exclusively preclinical (cell lines and some animal models). No human clinical trial data for forsythia in oncology were identified.

5.8 Hepatoprotective Effects

Crude extracts of F. suspensa fruit have reported protective activities against hepatic injury as well as antibacterial, antiviral, anti-inflammatory, and anti-allergy activities. Modern pharmacological studies have confirmed that forsythiaside A exhibits significant activities in treating various diseases, including inflammation, virus infection, neurodegeneration, oxidative stress, and liver injury.

Evidence strength: Preclinical only; no human clinical trial evidence identified.

5.9 Neuropathy (Chemotherapy-Induced)

It was demonstrated that the forsythoside A-containing organic fraction of F. suspensa fruit exerted neuroprotective effects against oxaliplatin-induced peripheral neuropathy. This work was conducted in cell culture and animal models. Evidence strength: Preclinical only.

5.10 Androgenic Alopecia

Research cited in the literature on forsythia includes a mouse model study examining the androgenic alopecia protective effects of forsythiaside-A and its molecular regulation. Modern pharmacology showed that Forsythiae Fructus has a variety of bioactivities including antiandrogenic alopecia activities. Evidence strength: Animal model only; no human RCT data identified.

---

6. Body Systems and Health Areas of Association

An overview of the pharmacology of Forsythiae Fructus (the dry fruits of Forsythia suspensa) reported its anti-inflammatory, antibacterial, antiviral, antioxidant, antitumor, antidiabetic, antihyperlipidemic, antiandrogenic alopecia, antivomiting, antiaging and anti-obesity activities, as well as neuroprotective, hepatoprotective and vasorelaxant effects.

Based on the published literature, the body systems with which Forsythiae Fructus is most prominently associated include:

• Respiratory system: Forsythia fruits are widely used in Chinese traditional medicine for antipyretic and anti-inflammatory activity in the treatment of bacterial infections and upper respiratory ailments.
• Immune system: Heat-clearing and detoxifying actions correspond to modulation of innate immune pathways, particularly NF-κB and TLR4 signaling.
• Central nervous system: Forsythiae Fructus, derived from the dried fruit of Forsythia suspensa, has numerous in vivo and ex vivo therapeutic effects including anti-inflammatory, antibacterial, and antiviral properties, with neuroprotective actions studied in models of neurodegeneration.
• Liver: Hepatoprotective activity is documented preclinically through antioxidant and anti-inflammatory mechanisms.
• Cardiovascular system: Forsythiasides have the effects of cardiovascular protection, anti-inflammation, anti-oxidation, and neuroprotection.
• Metabolic/endocrine: Potential antidiabetic, antihyperlipidemic, and anti-obesity effects studied in animal models via PDE4 inhibition and lipid metabolism pathways.
• Skin: Traditional use for skin infections, abscesses, and modern investigation in atopic dermatitis and androgenic alopecia.

---

7. Dosage Forms and Reported Dosages

Traditional Dosages

Daily administration dose of FF is recommended to be 6–15 g (PRC Pharmacopoeia, 2020). The green fruit gathered in the period of White Dew is considered better than the yellow fruit picked in the period of Cold Dew; the fruit is steamed, dried in the sun, and its seeds separated from the flesh. The TCM properties are described as bitter and slightly cold.

Forms of Administration

In traditional Chinese medicine, it is traditionally the fruit which is used in capsule form for the clearance of heat and resolution of toxicity, particularly in the upper body. Other documented forms include water decoctions, standardized dried extracts, granules, oral liquids, and injectable preparations (the latter used in combination with other herbs in some clinical settings in China). Clinical trials are lacking to support a place in therapy for forsythia as a single agent, and there are no recent clinical studies of forsythia alone to provide a basis for dosage recommendations.

Pharmacokinetics

The pharmacokinetic results of forsythiaside A vary due to the differences in administration routes, animal species, dosages, and detection methods. In general, pharmacokinetic studies showed a low absorption and bioavailability and a fast elimination of forsythiaside A in vivo. However, the bioavailability of forsythiaside A could be enhanced by improving the drug delivery system.

---

8. Safety, Toxicology, and Drug Interactions

General Safety Profile

Currently, there is no report on the toxicity of Forsythiae Fructus, despite slight toxicity of forsythiaside reported in local publications. Available toxicological data from animal studies and early-phase clinical trials indicate that phillyrin has a favorable safety profile, with only mild and transient adverse effects reported.

Animal Toxicology Studies

Relevant reports indicated no acute toxicity of water or ethanol extract of the leaves of F. suspensa in mice, even at a daily dose of 61.60 g/kg. No acute toxicity of phillyrin (from the leaves of F. suspensa) was found in NIH mice (18.1 g/kg/day, p.o., for 14 days), and no sub-chronic toxicity of phillyrin was found in SD rats (0.54, 1.62, and 6.48 g/kg/day, p.o., for 30 days). However, forsythiaside displayed cytotoxicity on PK-15, Marc-145 and CEK cell lines with IC₅₀ values of 0.138, 0.087, and 0.384 mg/mL, respectively.

Genotoxicity

A mutagenicity and teratogenicity evaluation found that forsythia leaf aqueous extract (FSLAE) was not mutagenic and did not induce unfavorable chromosomal events. The Ames test revealed FSLAE was not genotoxic and showed no mutagenic activity in histidine-dependent strains of Salmonella typhimurium at concentrations up to 5000 μg/plate. In vivo tests revealed no induced micronucleus of mouse bone marrow or chromosome aberration in spermatocytes up to the dose of 10.00 g/kg BW.

The toxicity of forsythiaside A mainly includes slight cytotoxicity and pseudoallergic reactions that only occur at excessively high doses, which suggest safety and effectiveness for clinical use at recommended doses.

Cytochrome P450 Interactions

Phillyrin and forsythoside, important constituents of Forsythia suspensa, showed in rats (in vitro and in vivo) significant effects on CYP1A2, CYP2C11, CYP2D1, and CYP3A1/2. Their human homologues are important for the metabolism of many clinically used drugs. Prior to the introduction of forsythia or its constituents into clinical use, it should be clarified whether CYP interactions are relevant in vivo in humans at the required doses. This is a particularly important consideration given that CYP3A4 (the human homologue of rat CYP3A1/2) metabolizes a large proportion of commonly prescribed medications.

Pregnancy

It is advised to avoid forsythia during pregnancy, as it has uterine stimulant and emmenagogue properties. One case of photodermatitis was traced to the topical application of forsythia fruit. Use during pregnancy is strictly contraindicated because of its emmenagogue/uterine stimulant properties.

Potential Effect on Blood Clotting

Because forsythia might slow blood clotting, there is a concern that it might cause extra bleeding during and after surgery. It is recommended to stop taking forsythia at least two weeks before a scheduled surgery.

Summary of Evidence Gaps

Despite an extensive body of preclinical data, the overall picture of forsythia's human clinical evidence base is limited. Clinical trials are lacking to support a place in therapy for forsythia as a single agent. Most pharmacological findings originate from in vitro cell assays and rodent models. Multi-herb formulations containing forsythia (e.g., Lianhua Qingwen, Yinqiaosan) have received more clinical study than forsythia in isolation, making it difficult to attribute observed clinical effects solely to forsythia. Future research must establish optimal dosing, long-term safety, and clinically meaningful efficacy in well-controlled human trials.

References

• Wang et al. (2018). Phytochemistry, pharmacology, quality control and future research of Forsythia suspensa (Thunb.) Vahl: A review. Journal of Ethnopharmacology. PubMed PMID 28887216.
• Xia et al. (2017). Forsythiae Fructus: A Review on its Phytochemistry, Quality Control, Pharmacology and Pharmacokinetics. Molecules. PMC6151565.
• Qu et al. (2014). Chemical Constituents from the Fruits of Forsythia suspensa and Their Antimicrobial Activity. PMC3972829.
• Law et al. (2017). Chemical Constituents and Anti-inflammatory Principles from the Fruits of Forsythia suspensa. Journal of Natural Products. PubMed PMID 28218000.
• Zhou et al. (2022). Review on the Pharmacological Properties of Phillyrin. Molecules. PMC9231344.
• Antiviral effect and mechanism of Phillyrin and its reformulated FS21 against influenza. PMC9975791.
• Comparative inhibitory effects of phillyrin and phillygenin on elastase: mechanisms and therapeutic potential. PMC12932445.
• Forsythiasides: A review of the pharmacological effects. PMC9357976.
• Forsythiaside A improves Influenza A virus infection through TLR7 signaling pathway in the lungs of mice. PMC9214192.
• Prediction of the Active Components and Mechanism of Forsythia suspensa Leaf against Respiratory Syncytial Virus Based on Network Pharmacology. PMC9328944.
• Review of the therapeutic potential of Forsythiae Fructus on the central nervous system: Active ingredients and mechanisms of action. Journal of Ethnopharmacology, 2023.
• Nishibe et al. (2021). The Biological Effects of Forsythia Leaves Containing the Cyclic AMP Phosphodiesterase 4 Inhibitor Phillyrin. Molecules. PMC8073696.
• The phytochemistry, pharmacology, pharmacokinetics, quality control, and toxicity of Forsythiae Fructus: An updated systematic review. Phytochemistry, 2024.
• Neuroprotective and anti-inflammatory phenylethanoidglycosides from the fruits of Forsythia suspensa. PubMed PMID 34082247.
• Comparative Evaluation of Forsythiae Fructus From Different Harvest Seasons and Regions. PMC8652199.
• Ameliorative effects of aqueous extract of Forsythiae suspensa fruits on oxaliplatin-induced neurotoxicity in vitro and in vivo. PMC6884752.
• Mutagenic and teratogenic toxicity evaluation of Forsythia suspensa leaves aqueous extract. PubMed PMID 33588684.
• Evaluating the safety of forsythin from Forsythia suspensa leaves by acute and sub-chronic oral administration in rodent models. Asian Pacific Journal of Tropical Medicine, 2016.
• Forsythia (Forsythia suspensa): Medicinal Benefits, Side Effects, Safety. Herbal Reality.
• Forsythia Uses, Benefits & Dosage. Drugs.com Natural Products Database.
• Forsythia suspensa – an overview. ScienceDirect Topics.
• Metabolome analysis of genus Forsythia related constituents in Forsythia suspensa leaves and fruits. PMC9239459.
• Integrated Metabolomics and Network Pharmacology to Reveal the Mechanisms of Forsythia suspensa Extract Against Respiratory Syncytial Virus. PMC12155444.
• Flavonoid compound from Forsythia suspensa leaves inhibits adenovirus infection related to cell cycle. PMC12408589.
• Phillyrin: A review of its pharmacokinetics and multi-target anti-inflammatory mechanisms for therapeutic potential. Phytomedicine, 2025.