Xylaria nigripes

Xylaria nigripes (Wu Ling Shen / Wulingshen)

1. Identity, Taxonomy, and Natural Source

Scientific name: Xylaria nigripes (Klotzsch) Cooke (synonym: Sphaeria nigripes Klotzsch, 1832). The species was originally described as Sphaeria nigripes by Klotzsch in 1832 and is classified within the kingdom Fungi, phylum Ascomycota, class Sordariomycetes, order Xylariales, and family Xylariaceae.

Xylaria nigripes (Klotzsch) Sacc. is a high-value medicinal fungus belonging to the family Xylariaceae, found growing in the wild around abandoned termite nests. It is part of a subgroup of Xylaria that grow specifically from the nests of termites. This Xylaria belongs to the monophyletic subgenus Pseudoxylaria, which are exclusively found associated with termite nests — they compete with the fungus that the termites cultivate, fruiting out of combs from deep underground.

Certain Xylaria species form massive sclerotia of several centimeters in diameter within the underground nests of macrotermitine termites after the termites abandon the nest. Vernacularly, the sclerotia are called Wulingshen in China or Nilamanga and Puttumanga in southern India. Xylaria nigripes was once commonly regarded as the sole producer of these massive sclerotia, which are in fact produced by at least six Xylaria species, including X. nigripes and close relatives. Wulingshen, massive Xylaria sclerotia, was originally reported from Chengdu Plain in western Sichuan, China for medicinal application; molecular studies have connected 54 Wulingshen samples procured from traditional Chinese medicine markets in Chengdu to six different Xylaria species, including X. nigripes, X. subescharoidea, and newly described species such as X. neonigripes and X. rogersionigripes.

Xylaria nigripes is a rare medicinal fungus known as Wulingshen in China. In the framework of Traditional Chinese Medicine (TCM), it is described as having a neutral and sweet nature, belonging to the heart and kidney meridians, and is rich in a variety of bioactive ingredients that allow it to serve as both a nutrient-dense food and a therapeutic agent.

Common Names

• Wulingshen (乌灵参) — principal Chinese name for the sclerotial/medicinal form
• Leizhenzi — an alternate Chinese name found in academic literature searches using keywords such as "Leizhenzi" and "Wulingshen."
• Wu Ling Shen — romanized TCM name, literally translatable as "black spirit mushroom"
• Nilamanga / Puttumanga — names used in southern India for related sclerotial forms vernacularly used in southern India.

Common Preparations and Dosage Forms

Xylaria sclerotia have been used in folk medicine for treating a wide range of ailments, whereas dried mycelia from cultures are used mainly for soothing anxiety, depression, insomnia, and some neurological disorders. In modern commercial contexts, several standardized preparations exist:

• Wuling Capsule (乌灵胶囊): A traditional Chinese medicine consisting of Wuling mycelia of Xylaria nigripes, used in China to treat major depressive disorders.
• Wuling Powder: Wuling powder is a fermented form of X. nigripes that leverages biotechnology to harness the fungus's health benefits.
• Aqueous extracts and ethanol extracts: Used in research settings, produced from both solid-state cultured and submerged-fermented mycelium.
• Zylaria™: A proprietary and standardized extract produced through a patented fermentation technology that grows the Xylaria nigripes mycelium in fermenting vats. The commercial ingredient Zylaria comprises a blend of botanical components, including Xylaria nigripes (mycelium), Cuscuta chinensis (seed), and Panax notoginseng (root).

In traditional Chinese medicine, a preparation of powdered mycelium of this fungus, known as Wuling Shen in these contexts, is taken several times a day for sleep regulation, depression, and anxiety.

2. Traditional and Historical Use

X. nigripes, commonly known as Wulingshen or Leizhenzi, possesses warm properties, a slightly bitter taste, and has been utilized in Chinese medicine for over 2,000 years. Its use dates back centuries, with references found in classical Chinese medical texts where it was considered valuable for promoting tranquility and improving sleep quality.

Xylaria nigripes has a long history of use in Traditional Chinese Medicine, particularly for calming the mind and addressing conditions such as insomnia, anxiety, and restlessness. In TCM, it is believed to "nourish the heart and calm the spirit."

Its pseudo-root, extending from the petiole base to the subterranean sclerotia (also known as the "seed seat"), is used medicinally to enhance brain function, reduce dampness, soothe nerves, clear collaterals, stimulate blood circulation, and boost immunity.

In traditional Chinese medicine, X. nigripes is known to enhance immunity and hematopoiesis; it is also used for treating insomnia, trauma, and as a diuretic and nerve tonic. In Chinese medicine, it was used in crude form as a nerve tonic, sedative, diuretic, and for the reduction of convulsions in infants and to discontinue heart palpitations. It was also said to promote lactation and prevent loss of blood in the nose and lungs following childbirth.

Xylaria sclerotia from termite nests have been called Wulingshen in China and Nilamanga and Puttumanga in southern India; X. nigripes was long considered the sole producer of these massive sclerotia, which are in fact produced by at least six Xylaria species. These sclerotia have been used in folk medicine for treating a wide range of ailments, whereas dried mycelia from cultures are used mainly for soothing anxiety, depression, insomnia, and some neurological disorders.

Despite being typically marketed primarily for sleep regulation, most of the clinical trials involving X. nigripes have focused on depression. XN mycelium capsules have been used and approved in China and are potentially effective for treatment of amnesia, neurosis, vertigo, exhaustion syndrome, depression, anemia, women's menstrual disorder, and insomnia.

3. Key Constituents and Active Compounds

The chemical composition of X. nigripes is exceptionally diverse, encompassing a wide array of compounds such as alkaloids, sterols, chromogenic ketones, terpenoids, isocoumarin derivatives, resorcinol derivatives, naphthalenone derivatives, and other miscellaneous compounds. Additionally, polysaccharides constitute a major component in the chemical composition of X. nigripes, particularly in their crude form.

A 2025 comprehensive review highlighted the chemical diversity and bioactivities of 82 compounds identified from X. nigripes between 2004 and October 2024. Among these, 26 compounds exhibit diverse pharmacological properties, including antioxidant, anti-inflammatory, neuroprotective, anti-tumor, and cholesteryl ester transfer protein (CETP) inhibitory activities.

The bioactivities of X. nigripes are attributed to different chemical compounds, including intracellular and extracellular polysaccharides, adenosine, total polyphenols, and triterpenoids in mycelia.

Major Compound Classes

Polysaccharides

Recent studies have shown that X. nigripes contains many valuable biological compounds such as polysaccharides, nucleosides, and sterols, which provide important biological effects, such as antioxidants, liver protection, immune system regulation, and diabetes treatment. Research on polysaccharides from different sources — including fruiting body polysaccharides, mycelium intracellular polysaccharides, and mycelium extracellular polysaccharides and their deproteinized products — found that the mycelium intracellular polysaccharide (XnIPS-1) showed the highest reducing power of antioxidant activity, with the lowest IC₅₀ values in all tested assays. The IC₅₀ values of chelating ferrous ion ability, ABTS radical scavenging activity, and DPPH free radical scavenging were 1412, 174.25, and 351.56 µg/mL, respectively.

Terpenoids / Sesquiterpenes

Six new sesquiterpenes, including nigriterpenes A–F with eremophilane skeletons, were obtained from the termite nest-derived Xylaria nigripes. Among them, nigriterpene C showed concentration-dependent inhibition of lipopolysaccharide-induced inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) expression, and nitric oxide (NO) production in murine brain microglial BV-2 cells, with IC₅₀ values of 8.1, 16.6, and 21.7 µM, respectively.

Naphthalenone Derivatives (Xylarinaps)

Five pairs of undescribed naphthalenone derivative enantiomers, xylarinaps A–E — including one pair of indole naphthalenones and four pairs of naphthalene-naphthalenone dimers — were isolated from the ethyl acetate extracts of the solid fermentation of Xylaria nigripes, which has been used as a traditional Chinese medicinal fungus for the treatment of insomnia, trauma, and depression. The results revealed that xylarinaps A, B, D, and E significantly enhanced cell viability, decreased the levels of malondialdehyde (MDA), increased the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px).

Novel Amino Acid Derivatives and Isovaleric Acid Esters

In the process of discovering more neural-system-related bioactive compounds from Xylaria nigripes, xylariamino acid A — a new amino acid derivative — and a new isovaleric acid phenethyl ester were isolated and identified. The isolated compounds were evaluated for their neuroprotective effects against damage to PC12 cells by oxygen and glucose deprivation (OGD). Both compounds can increase the viability of OGD-induced PC12 cells at all tested concentrations. Moreover, the isovaleric acid phenethyl ester at 1 µmol/L can significantly reduce the percentage of apoptotic cells.

Chromone Derivatives

A pair of new chromone derivatives, including (+)-xylarichromone A and (−)-xylarichromone A, were isolated from Xylaria nigripes collected from the Ailao Mountain, China.

Gamma-Aminobutyric Acid (GABA)

Xylaria nigripes is a source of a variety of amino acids, vitamins, minerals, GABA, and glutamic acid, and does contain high levels of GABA, an inhibitory neurotransmitter. The presence of GABA aligns conceptually with TCM descriptions of "nourishing the heart and calming the spirit," as GABA (gamma-aminobutyric acid) is the primary inhibitory neurotransmitter in the central nervous system and is associated with relaxation and reduced neuronal excitability.

4. Mechanisms of Action

The extracts of X. nigripes, along with its components and secondary metabolites, have shown a variety of biological activities, such as neuroprotection, anti-inflammatory effects, antioxidant capabilities, and acetylcholinesterase inhibitory action.

Neuroprotective and GABAergic Mechanisms

Investigations into the effects of X. nigripes extracts on rapid eye movement sleep deprivation (REMSD)-induced memory impairment in rats used the Morris water maze to assess effects on spatial learning and memory, and also examined the expression of cAMP-response element binding protein (CREB) and p-CREB in all groups. These molecular targets are relevant to memory consolidation.

In a model of ischemic brain insult (MCAO mice), X. nigripes (XN) reduced neuronal injury, neurobehavioral deficits, and reactive oxygen species (ROS) and malondialdehyde (MDA) contents. Moreover, XN treatment alleviated MCAO-induced reduction of the mRNA and protein levels of HO-1, Nrf2, and markers of neurons and astrocytes in ischemic brain. These results suggested that the Nrf2/HO-1 pathway mediates the neuroprotective effect of XN following ischemic insult.

Anti-Inflammatory Mechanisms

After treating macrophage cells with lipopolysaccharide (LPS) and different X. nigripes extracts, the immunomodulatory properties were determined by inflammatory mediators including nitric oxide (NO), prostaglandin E₂ (PGE₂), and cytokines (IL-1β, IL-6, TNF-α, and IFN-γ) production, iNOS, COX-2, and IκB-α expression, and NF-κB activation. Treatment of macrophages with 5–30 µg/mL of aqueous (XN-H) or ethanol (XN-E) extracts plus 1 µg/mL LPS exhibited no cytotoxic effect on cell viability; at these concentrations, both extracts showed a dose-dependent inhibitory effect on NO, PGE₂, IL-1β, IL-6, TNF-α, and IFN-γ production in LPS-stimulated macrophages.

Antioxidant Mechanisms

Compared to water extract, ethanol extract showed not only greater neuroprotective effects but also higher antioxidant activity by scavenging DPPH radicals, inhibiting lipid peroxidation, and reducing power. High phenolic content and antioxidant activity may provide the neuroprotective properties of X. nigripes ethanol extract.

5. Scientific Evidence by Area of Use

5.1 Depression

Despite being typically marketed primarily for sleep regulation, most clinical trials have focused on depression. Xylaria nigripes is included in reviews of traditional Chinese medicine treatments for depression, and the consensus is that there is evidence it works.

Randomized Controlled Trial: Depression in Epilepsy Patients (2015)

The comorbidity of depression in patients with epilepsy is common and treatment is still controversial. A pilot study aimed at evaluating the efficacy and safety of Xylaria nigripes for treating depressive symptoms in patients with epilepsy over 12 weeks used a multicenter, double-blind, placebo-controlled, randomized superiority design. A total of 104 patients with epilepsy were randomized 1:1 to receive Xylaria nigripes (the Wu Ling group) or placebo over 12 weeks, with visits at weeks 0, 2, 4, 8, and 12.

The primary efficacy endpoint — total effective rate for depression — was significantly greater in the Wu Ling group (51.3%, n=39) than in the placebo group (35.7%, n=42; 95% CI −0.06 to 0.37; P=0.002) after 12 weeks of treatment. No differences in seizure frequency or changes in severity were found between the Wu Ling and placebo groups. Additionally, quality of life and seizure worry subscale scores were improved more notably in the Wu Ling group than in the placebo group (P<0.05). Most of the adverse effects (AEs) in this study were mild and showed no differences between the Wu Ling and the placebo groups.

Evidence strength assessment: This is a properly randomized, double-blind, multicenter, placebo-controlled pilot trial. It is limited by its relatively small sample size (81 completers), by being conducted in a specialized population (epilepsy patients with comorbid depression), and by the fact that it is described as a pilot study. Generalization to the broader population is therefore constrained.

Meta-Analysis: Wuling Capsule for Major Depressive Disorder (2016)

A meta-analysis of randomised controlled trials was performed to compare the efficacy and safety of Wuling capsule alone with Wuling capsule-antidepressant combination in the treatment of major depressive disorders. Two assessors independently selected studies, extracted data, and conducted quality assessment and data synthesis, analyzing standard mean difference, risk ratio (RR) ± 95% CI, number needed to treat, and number needed to harm.

A total of 12 randomised controlled trials (880 patients; mean age 39.7 ± 12.5 years; 41% male) were identified, including 4 trials with Wuling capsule alone (n=340) and 8 with Wuling capsule-antidepressant combinations (using sertraline, mianserin, mirtazapine, and paroxetine). Meta-analysis of symptomatic improvement revealed no significant differences between Wuling capsule alone and antidepressant monotherapy. However, Wuling capsule-antidepressant co-treatment was superior to antidepressant monotherapy in symptomatic improvement (standard mean difference: −0.46, p=0.001) as well as study-defined response (68.4% vs. 56.0%, RR=1.23; p=0.03) and remission (46.5% vs. 34.5%, RR=1.35; p=0.05). Wuling capsule was associated with fewer adverse drug reactions than antidepressant monotherapy.

The conclusions indicated that adjunctive Wuling capsule may augment the effects of antidepressants and may be associated with fewer adverse drug reactions, but more large-scale and rigorously designed randomised controlled trials with large sample sizes are warranted to clarify the effectiveness of Wuling capsule for major depressive disorders.

Evidence strength assessment: The 2016 meta-analysis synthesized 12 RCTs covering 880 patients, representing the most substantial human evidence base for X. nigripes in depression to date. However, the authors themselves call for larger, more rigorously designed trials. The finding that Wuling capsule alone did not differ significantly from antidepressant monotherapy is notable but must be interpreted cautiously given variation in study quality across the included trials.

5.2 Insomnia

Clinical studies have further validated the efficacy of Wuling powder (dried mycelium product of X. nigripes) in regulating mental health, alleviating insomnia, and treating related disorders. Wuling capsule, a single herb formula from mycelia of Xylaria nigripes, was investigated for its efficacy and safety through a multicenter, randomized, double-blind, placebo-controlled trial in Chinese patients with insomnia. A 2022 systematic review and meta-analysis of randomized controlled trials focusing specifically on Wuling capsule for insomnia disorder was published in the journal Sleep Medicine.

Evidence strength assessment: While TCM use for insomnia represents the oldest and most consistent historical application of X. nigripes, the body of high-quality controlled trials dedicated specifically to insomnia endpoints in humans remains comparatively limited compared to the depression literature.

5.3 Sleep Deprivation and Spatial Memory (Preclinical)

Investigations into the effects of X. nigripes extracts on rapid eye movement sleep deprivation (REMSD)-induced memory impairment used male Sprague Dawley rats randomly divided into 6 groups (cage control, tank control, and sleep deprivation groups, each with and without X. nigripes). The rats were administered X. nigripes intragastrically, and the sleep deprivation group was deprived of REM sleep for 72 hours. The Morris Water Maze was used to assess effects on spatial learning and memory. Results showed that rats in the sleep deprivation-saline group had significantly longer mean escape latencies in finding the platform compared to control rats (p<0.05).

Evidence strength assessment: This is preclinical (rodent) evidence only. It demonstrates that X. nigripes may mitigate sleep deprivation-induced spatial memory impairment in rats, but no direct clinical translation to humans can be drawn from this study alone.

5.4 Neuroprotection (Preclinical)

The neuroprotective effects of xylarinaps A–E (naphthalenone derivatives) against damage to PC12 cells by oxygen and glucose deprivation were evaluated by an in vitro bioassay. Xylarinaps A, B, D, and E significantly enhanced cell viability, decreased the levels of malondialdehyde (MDA), and increased the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px).

Additional neuroprotective effects were demonstrated: the newly isolated xylariamino acid A and isovaleric acid phenethyl ester were evaluated for neuroprotective effects against OGD-induced damage in PC12 cells; both can increase the viability of OGD-induced PC12 cells at all tested concentrations, and the ester at 1 µmol/L can significantly reduce the percentage of apoptotic cells.

Evidence strength assessment: All neuroprotective evidence is currently preclinical — derived from in vitro cell-culture experiments and animal models. No human clinical trials specifically assessing neuroprotection have been published.

5.5 Immunomodulation and Anti-Inflammatory Activity

Significant health benefits of mushrooms, including immunomodulating effects, have been widely reported, and a study specifically examined the immunomodulatory properties of aqueous and ethanol extracts of X. nigripes in lipopolysaccharide-induced peritoneal macrophage cells of Balb/c mice.

In vivo and in vitro studies have demonstrated bioactivities of X. nigripes, including antioxidant, immunomodulatory, anti-inflammatory, hepatoprotective, anti-tumor, prevention of spatial memory impairment, anti-depressant activity in epileptic patients, enhancing insulin sensitivity, and neuroprotective activities.

Evidence strength assessment: Immunomodulatory and anti-inflammatory findings remain largely at the in vitro and animal model stage. The clinical relevance of these observations for human immune function has not been established in controlled human trials.

5.6 Hepatoprotection

It has been reported that Xylaria nigripes possesses good antioxidant and hepatoprotective activities. A published study examined the protective effects of Wu-Ling-Shen (Xylaria nigripes) against carbon tetrachloride-induced hepatotoxicity in mice. Previous studies have shown that X. nigripes possesses good antioxidant and hepatoprotective activities.

Evidence strength assessment: Evidence for hepatoprotection is preclinical (mouse models) only. No human clinical trial data on hepatoprotective outcomes is available in the published literature accessed.

5.7 Glucose Metabolism / Hypoglycemic Effects

A study explored the hypoglycemic effects of the aqueous extract of Xylaria nigripes in steroid-induced insulin-resistant rats and the role of serotonin in those effects. In vivo and in vitro studies suggest that X. nigripes enhances insulin sensitivity.

Evidence strength assessment: Evidence is preclinical (animal models). No human clinical data on glycemic outcomes is available in the published literature accessed.

5.8 Parkinson's Disease–Associated Depression

A randomized clinical trial examining the efficacy and safety of Wuling capsule for the treatment of mild depression in patients with early Parkinson's disease in China was published in BMC Complementary Medicine and Therapies in 2025.

Evidence strength assessment: Preliminary evidence from a single trial in a specialized population (early Parkinson's with mild depression). Replication and larger trials are needed.

5.9 Post-Stroke Depression

With a combination of several Western medicines, Wuling capsule could be helpful in strengthening efficacy and reducing the incidence of adverse events as an alternative choice in the treatment of post-stroke depression.

Evidence strength assessment: Evidence comes from a systematic review covering relatively small trials; this application requires further investigation in larger, well-controlled studies.

6. Body Systems and Health Areas Associated with Xylaria nigripes

• Central Nervous System / Neurological: Sleep regulation, antidepressant activity, anxiolytic effects, spatial memory support, neuroprotection against ischemic and oxidative damage, acetylcholinesterase inhibition. The extracts of X. nigripes, along with its secondary metabolites, have shown neuroprotection, anti-inflammatory effects, antioxidant capabilities, and acetylcholinesterase inhibitory action.
• Immune System: Wuling Shen is traditionally used to calm the spirit, nourish the heart, and support mental health, but is also cited for effects on the immune system.
• Hepatic System: Hepatoprotective activity documented in preclinical models using CCl₄-induced liver damage.
• Metabolic / Endocrine: Enhanced insulin sensitivity in steroid-induced insulin-resistant animal models.
• Hematopoietic: In traditional Chinese medicine, it is known to enhance immunity and hematopoiesis.

7. Dosage Forms and Dosages Reported in Studies

The following dosages are drawn directly from published study reports and should not be interpreted as recommended doses for any individual.

• Human clinical trial (Wuling capsule for depression in epilepsy, 2015): A multicenter, double-blind, placebo-controlled, randomized study enrolled 104 patients randomized 1:1 to receive Xylaria nigripes (Wu Ling group) or placebo for 12 weeks. The specific per-dose amount is not stated in the publicly accessible abstract.
• Human clinical trial (Wuling capsule for insomnia, multicenter RCT): A multicenter, randomized, double-blind, placebo-controlled trial investigated the efficacy and safety of Wuling capsule, a single herb formula from mycelia of Xylaria nigripes, in Chinese patients with insomnia. The per-dose specifics are not available in the accessed abstracts.
• Preclinical safety study (aqueous extract, 90 days in rats): A 90-day subchronic toxicity study used oral administration of a standardized aqueous extract (XNE) at daily doses of 20, 1000, and 2000 mg/kg body weight to Sprague-Dawley rats of both sexes.
• Preclinical safety study (Zylaria blend, 90 days in rats): One hundred Sprague Dawley rats of both sexes were divided into six study groups, with four main groups receiving different doses of Zylaria (0, 1000, 2750, and 4500 mg/kg body weight per day) and two recovery groups.
• Traditional preparation: In traditional Chinese medicine, a preparation of powdered mycelium is taken several times a day for sleep regulation, depression, and anxiety. Specific traditional dose quantities are not cited in available peer-reviewed sources.

8. Safety Considerations

Subchronic Toxicity (90-Day Animal Study — Aqueous Extract)

Oral administration of a standardized aqueous extract of X. nigripes (XNE) caused no treatment-induced adverse effects on general health, body weight gain, relative organ weights, and hematological and biochemical parameters. Histopathological results also showed no significant structural changes in organs even in high-dose XNE-treated animals. The study concludes that treatment with XNE for 90 days does not produce significant toxicity, even up to 100-fold (2000 mg/kg body weight/day) of the recommended daily intakes, and therefore its use as herbal medicine is considered relatively safe.

Subchronic Toxicity (90-Day Animal Study — Zylaria Blend)

Zylaria, a blend of Xylaria nigripes mycelium, Cuscuta chinensis seed, and Panax notoginseng root, was evaluated for potential toxicity via oral gavage in Sprague Dawley rats for 90 days continuously with a 28-day recovery period, at doses of 0, 1000, 2750, and 4500 mg/kg body weight per day. The no observed adverse effect level (NOAEL) of the test item Zylaria was concluded to be equal to or greater than 4500 mg/kg body weight/day.

Adverse Effects Observed in Human Clinical Trials

In the multicenter randomized double-blind clinical trial of Xylaria nigripes for depression in epilepsy patients, most of the adverse effects were mild and had no differences between the Wu Ling and the placebo groups. Xylaria nigripes was well tolerated in patients with epilepsy.

In the meta-analysis of 12 randomized controlled trials examining Wuling capsule for major depressive disorder, Wuling capsule was associated with fewer adverse drug reactions than antidepressant monotherapy. The authors concluded that adjunctive Wuling capsule may augment the effects of antidepressants and may be associated with fewer adverse drug reactions.

Taxonomic Identity Concerns Relevant to Safety

Wulingshen marketed in China is not derived exclusively from X. nigripes — it is in fact produced by at least six Xylaria species, including X. nigripes and close relatives. This multi-species reality introduces potential variability in chemical composition and bioactive content between commercial preparations, a factor with direct implications for reproducibility of efficacy and safety findings across studies.

Limitation of Safety Evidence

Its toxicity had never been systematically evaluated prior to a 2021 study, which aimed to evaluate the safety of a standardized aqueous extract prepared from solid-state cultured X. nigripes in rats. Systematic long-term human safety and pharmacovigilance data remain limited, and human drug interaction studies have not been published in the peer-reviewed literature accessed.

9. Limitations and Overall Evidence Assessment

The body of research on Xylaria nigripes has grown substantially in the 21st century, particularly in Chinese academic and clinical literature. Clinical studies have further validated the efficacy of Wuling powder in regulating mental health, alleviating insomnia, and treating related disorders. However, several major limitations apply to the existing evidence:

• The majority of pharmacological and mechanistic research is preclinical — conducted in vitro or in rodent models — and direct extrapolation to human biology requires caution.
• More large-scale and rigorously designed randomised controlled trials with large sample sizes are warranted to clarify the effectiveness of Wuling capsule for major depressive disorders.
• The most methodologically rigorous human trial (the 2015 multicenter RCT) was conducted in a specialized population — epilepsy patients — and explicitly described as a pilot study.
• The material sold as "Wulingshen" derives from at least six distinct Xylaria species, raising concerns about compositional standardization.
• No independent regulatory body (e.g., the European Medicines Agency, the U.S. FDA, or WHO) has issued a formal monograph or assessment for Xylaria nigripes as of the sources available.
• Only 82 compounds have been formally identified from X. nigripes across a 20-year literature survey, and the pharmacokinetics, bioavailability, and metabolic fate of key active constituents in humans have not been systematically characterized.

References

• NCBI Taxonomy Browser: Xylaria nigripes (Taxonomy ID: 490159)
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• 90-Day Subchronic Toxicological Evaluation of Zylaria in Sprague Dawley Rats. PMC.
• Divate RD et al. (2017). Protective effect of medicinal fungus Xylaria nigripes mycelia extracts against hydrogen peroxide-induced apoptosis in PC12 cells. PMC.
• Wuling Capsule for Major Depressive Disorder: A Meta-analysis of Randomised Controlled Trials. ResearchGate.
• Wulingshen, the massive Xylaria sclerotia used as traditional Chinese medicine, is produced by multiple species. ResearchGate.
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