Juan Bai
StarSelaginella tamariscina (P.Beauv.) Spring
Traditionally used for
- Bowel health
- Menstrual & women's health
Cautions & contraindications
- Pregnancy
☯ TCM Properties
Invigorates Blood and Regulates Menstruation; Invigorates Blood and Dispels Stasis; Reduces Swelling and Alleviates Pain; Stops Bleeding
Traditional Chinese Uses
Juan Bai (selaginella or spikemoss) is used in two preparations with different actions. The raw herb circulates Blood and clears Damp-Heat to stop bleeding from Heat in the Blood, addressing bloody dysentery, hemorrhoidal bleeding, and uterine bleeding. When charred, its astringent properties are greatly enhanced for stopping bleeding. It is a versatile hemostatic herb applicable to various bleeding conditions.
Western Herbalism Properties
Relationships
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Botanical Description
Selaginella tamariscina is a resurrection spike-moss in the family Selaginellaceae, native to East and Southeast Asia where it grows in dense rosette-like cushions on dry rocks and cliff faces. The plant is a lycophyte (fern-ally), not a true moss, reaching 5–15 cm tall with a short woody caudex bearing tightly imbricate, scale-like microphylls arranged in four ranks along branched stems. During drought the fronds curl inward into a tight ball and turn brown, then unfurl and green again upon rewetting — hence the name “resurrection plant.” Reproduction is by heterosporous strobili borne at branch tips. In traditional Chinese medicine the whole dried plant (Juan Bai) is harvested year-round and used as a hemostatic and blood-invigorating herb.
Active Constituents
Amentoflavone
Biflavonoid (apigenin dimer)Concentration: 5.63-9.18 mg/g of dried herb across 10 batches, distinctly higher than in the co-official Selaginella pulvinata (0.82-7.13 mg/g)
The principal biflavone of the drug and the compound behind most of its documented pharmacology, including vasorelaxant and anti-inflammatory effects. It is also a very strong inhibitor of CYP3A4 and of CYP2C8/2C9, and a broad-spectrum inhibitor of human UDP-glucuronosyltransferases, which makes it the main source of interaction risk with this herb.
Hinokiflavone
BiflavonoidOne of the four biflavones routinely quantified alongside amentoflavone in quality control of Juan Bai.
Isocryptomerin
BiflavonoidA biflavone of the drug, quantified together with amentoflavone, sequoiaflavone and hinokiflavone in HPLC assays; reported among the anti-inflammatory biflavonoids acting through ERK 1/2 signalling.
Sequoiaflavone
BiflavonoidA methylated amentoflavone derivative measured as one of the standard biflavone markers of the herb.
Robustaflavone
BiflavonoidA Selaginella biflavone; in human liver microsomes it belongs to the group of biflavonoids that inhibit CYP2C8-mediated metabolism at sub-micromolar concentrations.
Selamariscina A
BiflavonoidThe most potent of five biflavonoids tested against human liver microsomal P450s, inhibiting CYP2C8-mediated amodiaquine N-dealkylation strongly and selectively, with the series spanning IC50 values of 0.019-0.123 microM.
Selaginellin
Selaginellin-type alkylphenol pigmentConcentration: 0.067-0.133 mg/g of dried herb, lower than in Selaginella pulvinata (0.123-0.593 mg/g)
A pigment class essentially restricted to Selaginella. Its content runs the opposite way to amentoflavone between the two co-official species, so the two markers together distinguish S. tamariscina from S. pulvinata.
Dihydrocaffeic acid
Phenolic acidReported to be enriched after the herb is stir-fried to carbon, and proposed as a contributor to the haemostatic activity that the charred drug shows but the raw drug does not.
⚠ Drug Interactions
CYP3A4 substrates (e.g. midazolam, simvastatin, tacrolimus, ciclosporin, nifedipine)
In a screen of close to a hundred herbal medicines against CYP3A4, Selaginella tamariscina was one of the strongest inhibitors, and its biflavone components, amentoflavone in particular, were identified as the responsible constituents. The same study showed inhibition of the CYP3A4-dependent metabolism of clinically used drugs. The evidence is in vitro and no human interaction study has been done, but the potency is high enough that the risk should be treated as real.
Clinical note: Avoid combining Juan Bai with narrow-therapeutic-index CYP3A4 substrates such as tacrolimus, ciclosporin and everolimus; separate dosing does not solve enzyme inhibition.
CYP2C9 and CYP2C8 substrates (warfarin, phenytoin, repaglinide, amodiaquine)
Five biflavonoids from S. tamariscina, headed by selamariscina A and including amentoflavone and robustaflavone, non-competitively inhibited CYP2C8 in human liver microsomes with IC50 values of 0.019-0.123 microM, with strong CYP2C9 inhibition as well. Warfarin is a special concern because the pharmacokinetic effect adds to the herb's own blood-moving action.
Clinical note: If a patient on warfarin is given Juan Bai, arrange earlier and more frequent INR checks; consider avoiding the combination altogether.
UGT substrates (e.g. mycophenolate, raloxifene, morphine, paracetamol at high dose)
Amentoflavone is a potent broad-spectrum inhibitor of human UDP-glucuronosyltransferases in vitro, affecting multiple isoforms rather than one. Because glucuronidation is the main clearance route for a number of drugs that also have narrow margins, the theoretical scope of this interaction is wide, though it has not been tested in people.
Clinical note: Bear this in mind for transplant and oncology patients in particular, where UGT-cleared drugs are common.
Anticoagulants and antiplatelet drugs (the direction depends on whether the drug is raw or charred)
Raw and carbonised Juan Bai act in opposite directions on the coagulation system. In Sprague-Dawley rats the 75% methanol extract of the raw herb and of the stir-fried carbonised product (S. tamariscina carbonisatus) were compared on haemorheology and coagulation, and only the carbonised drug showed haemostatic activity, matching the classical rule that raw it breaks Blood and charred it stops bleeding. A prescription that specifies charred Juan Bai therefore carries a different interaction profile from one that specifies the raw herb.
Clinical note: Read the prescription for the processing state before assessing bleeding risk, and record which form was dispensed.
Selaginella pulvinata and Selaginella doederleinii (substitution)
Two things happen with this pinyin name. First, the Chinese Pharmacopoeia admits both S. tamariscina and S. pulvinata as Juan Bai, and they are not chemically equivalent: S. tamariscina carries roughly 5.6-9.2 mg/g amentoflavone against 0.8-7.1 mg/g in S. pulvinata, while selaginellin runs the other way, so the CYP-inhibition load of the batch depends on which species was collected. Second, Selaginella doederleinii is a separate drug, Shi Shang Bai, used mainly as an antitumour herb; it is not Juan Bai and should not be dispensed against a Juan Bai prescription. The Juan Bai of the Shen Nong Ben Cao Jing is S. tamariscina.
Clinical note: Ask the supplier which Selaginella species the batch is, and treat any material sold as Shi Shang Bai as a different medicine entirely.
Oral antidiabetic drugs and insulin
Three previously undescribed biflavonoids from S. tamariscina, involvenflavones H, I and J, increased glucose consumption in normal and insulin-resistant HepG2 cells and upregulated glucokinase and adenylate cyclases. This is a cell-culture finding at compound level with no animal or human confirmation for the crude drug.
Clinical note: No action needed beyond the usual advice to diabetic patients to keep monitoring when starting any new herb.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 5–10 g | Daily | — | — | 中国药典 2020 【用法与用量】5～10g。 【注意】孕妇慎用。 【性味与归经】辛，平。归肝、心经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Evidence Tier
Moderate evidence · 6 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
6
1 verified · 5 unverified
Show 6 studies
- Comparing coagulation activity of Selaginella tamariscina before and after stir-frying process and determining the possible active constituents based on compositional variation
- Potent Inhibition of Human Cytochrome P450 3A4 by Biflavone Components from Ginkgo Biloba and Selaginella Tamariscina
- Strong and Selective Inhibitory Effects of the Biflavonoid Selamariscina A against CYP2C8 and CYP2C9 Enzyme Activities in Human Liver Microsomes
- Amentoflavone is a potent broad-spectrum inhibitor of human UDP-glucuronosyltransferases
- Hypoglycemic flavonoids from Selaginella tamariscina (P.Beauv.) Spring
- Biflavonoids Isolated from Selaginella tamariscina and Their Anti-Inflammatory Activities via ERK 1/2 Signaling
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Comparing coagulation activity of Selaginella tamariscina before and after stir-frying process and determining the possible active constituents based on compositional variation
Male Sprague-Dawley rats received 75% methanol extracts of raw S. tamariscina or of the carbonised product for 72 hours, with Yunnan Baiyao as positive control, and haemorheology and coagulation parameters were measured. The carbonised drug showed haemostatic activity while the raw drug did not, and compositional profiling was used to identify the constituents that shift during charring. This is the experimental basis for treating raw and charred Juan Bai as two different medicines.
Potent Inhibition of Human Cytochrome P450 3A4 by Biflavone Components from Ginkgo Biloba and Selaginella Tamariscina
A visual high-throughput screen of close to a hundred herbal medicines against CYP3A4 picked out Selaginella tamariscina and Ginkgo biloba as strong inhibitors, and traced the activity to biflavones: bilobetin, ginkgetin, isoginkgetin and amentoflavone. The inhibitory effect extended to clinical drugs cleared mainly by CYP3A4.
Strong and Selective Inhibitory Effects of the Biflavonoid Selamariscina A against CYP2C8 and CYP2C9 Enzyme Activities in Human Liver Microsomes
Five biflavonoids, selamariscina A, amentoflavone, robustaflavone, cupressuflavone and taiwaniaflavone, were tested against nine P450 activities in human liver microsomes by cocktail incubation with LC-MS/MS. CYP2C8-mediated amodiaquine N-dealkylation was the most strongly inhibited activity, with IC50 values of 0.019-0.123 microM and non-competitive kinetics; CYP2C9 was also strongly inhibited.
Amentoflavone is a potent broad-spectrum inhibitor of human UDP-glucuronosyltransferases
Amentoflavone inhibited a broad panel of human UGT isoforms rather than a single enzyme, marking phase II glucuronidation as a second interaction route for amentoflavone-rich herbs such as Juan Bai, alongside the P450 effects.
Hypoglycemic flavonoids from Selaginella tamariscina (P.Beauv.) Spring
Six flavonoids, including three previously undescribed biflavonoids and one 8-aryl flavonoid, were isolated from S. tamariscina and tested in HepG2 cells. Involvenflavones H, I and J increased glucose consumption in both normal and insulin-resistant cells and upregulated glucokinase and adenylate cyclases.
Biflavonoids Isolated from Selaginella tamariscina and Their Anti-Inflammatory Activities via ERK 1/2 Signaling
Biflavonoids isolated from S. tamariscina suppressed inflammatory mediator production in cell models, with ERK 1/2 signalling identified as the pathway involved. Supports the traditional use for swelling and pain but at compound level only.
⚠ Safety & Contraindications
- Pregnancy
Contraindications
Its use is cautious in pregnant women.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, p. 244.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyRi Hua Zi Ben Cao
Five Dynasties periodMing Yi Bie Lu
Han to Six Dynasties periodReferences
- Christian Bailly. The traditional and modern uses of Selaginella tamariscina (P.Beauv.) Spring, in medicine and cosmetic: Applications and bioactive ingredients . Journal of Ethnopharmacology (2021) [DOI]
- Yuan Cao, Yan Wu, Xin Zhou, Feng Qian, Hui Fan, Qiang Wang. Simultaneous determination of selaginellins and biflavones in Selaginella tamariscina and S. pulvinata by HPLC . China Journal of Chinese Materia Medica (2012) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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