Bu Gu Zhi
StarPsoralea corylifolia L. (syn. Cullen corylifolium (L.) Medik.)
☯ TCM Properties
Tonifies Kidney Yang; Secures Essence and Stops Enuresis; Warms the Middle Burner and Stops Diarrhea; Aids the Kidneys in Grasping Qi; Dispels Wind-Heat from the Skin
Traditional Chinese Uses
Bu Gu Zhi (psoralea fruit, broken dish bone herb) is a warm herb used in Chinese medicine to warm Kidney and Spleen Yang, astringe to stop deficiency-type diarrhea, and promote the absorption of calcium for bone health. It is used for lower back pain from Kidney Yang deficiency, early-morning diarrhea from Kidney-Spleen Yang deficiency, urinary frequency, bedwetting, and impotence. Applied externally, it is a classical treatment for vitiligo and patchy hair loss, for which modern research has identified its photosensitizing compounds.
Western Herbalism Properties
Botanical Description
Cullen corylifolium (syn. Psoralea corylifolia, Fabaceae), known as babchi or Bu Gu Zhi, is an erect annual herb 60-180 cm tall with glandular-pubescent stems and simple, broadly ovate to elliptic leaves 5-10 cm long bearing prominent dark resinous glands beneath. Dense axillary racemes 5-10 cm long carry numerous small pea-flowers with bluish-violet to whitish corollas. The single-seeded indehiscent pods are ovoid, 4-5 mm long, blackish-brown when ripe, and contain a flattened, kidney-shaped seed with a strongly aromatic, slightly bitter taste due to furanocoumarins (psoralen, isopsoralen) responsible for the herb's well-known phototoxic and pigmenting effects. Native to India and naturalized across China, Southeast Asia, and tropical Africa. (Sources: POWO; Wikipedia; Bensky)
Active Constituents
Psoralen
Linear furanocoumarinConcentration: Major coumarin; a Chinese Pharmacopoeia marker (with isopsoralen)
A photosensitising furanocoumarin underlying the herb's traditional topical use for vitiligo and psoriasis. It also activates the aryl-hydrocarbon receptor and induces CYP1A2, and is a principal contributor to dose- and duration-dependent hepatotoxicity.
Isopsoralen (angelicin)
Angular furanocoumarinConcentration: Major coumarin; co-marker with psoralen
Osteogenic and oestrogen-like activity reported; also implicated, with psoralen, in liver injury.
Bakuchiol
Meroterpene phenolConcentration: Major lipophilic constituent
Antibacterial, antioxidant and oestrogen-like; identified as a key hepatotoxic component acting through mitochondrial dysfunction and oxidative stress, particularly under immune/inflammatory stress.
Bavachin
FlavanoneConcentration: Major flavonoid
Phytoestrogenic and osteogenic (bone-forming) in preclinical models; can raise bilirubin and contributes to hepatotoxicity.
Isobavachalcone / bavachalcone
ChalconeConcentration: Characteristic flavonoid
Antibacterial, antioxidant and osteogenic; inhibits certain UDP-glucuronosyltransferases and contributes to the herb's hepatic effects.
Psoralidin
CoumestanConcentration: Characteristic constituent
Antioxidant and anticancer in vitro; also identified among the hepatotoxic constituents via mitochondrial dysfunction and apoptosis.
Corylifol A / corylin
Prenylated flavonoid / isoflavoneConcentration: Minor-to-moderate flavonoid
Osteogenic and oestrogen-modulating activity reported in preclinical bone and metabolic models.
Neobavaisoflavone
IsoflavoneConcentration: Minor flavonoid
Anti-inflammatory and osteogenic activity; investigated for CYP-mediated herb-drug interaction potential.
⚠ Drug Interactions
Hepatotoxic drugs (acetaminophen/paracetamol, methotrexate, isoniazid, statins)
Fructus Psoraleae is a recognised cause of drug-induced liver injury; psoralen, isopsoralen, bakuchiol, bavachin and psoralidin cause dose- and time-dependent hepatocellular damage and cholestasis via mitochondrial dysfunction, oxidative stress and CYP1A2 induction. Effects are amplified by overdose, prolonged use, raw (unprocessed) material and ethanol extracts, and under immune/inflammatory stress.
Clinical note: Avoid combining with other hepatotoxic agents; monitor liver function, limit duration, avoid high-dose raw/alcohol extracts, and stop at any sign of jaundice or transaminase rise.
Photosensitising agents and UV/PUVA therapy
The furanocoumarins psoralen and isopsoralen are potent photosensitisers that intercalate DNA and form cross-links on UVA exposure; combined with other photosensitising drugs or phototherapy they can cause severe phototoxic burns and increase long-term skin-cancer risk.
Clinical note: Counsel sun protection; avoid concurrent tetracyclines, fluoroquinolones, thiazides, retinoids and deliberate UV/PUVA unless supervised.
CYP3A4 substrates (e.g., midazolam, cyclosporine, certain statins)
Extracts and constituents (psoralen, isopsoralen) inhibit CYP3A4 in human recombinant enzyme and hepatocyte models, while psoralen also induces CYP1A2, so the herb can raise or lower plasma levels of CYP-metabolised drugs.
Clinical note: Monitor for altered response of narrow-therapeutic-index CYP3A4/CYP1A2 substrates.
Hormone-sensitive therapies (tamoxifen, aromatase inhibitors, oestrogens)
Bavachin, bakuchiol and corylin show oestrogen-like activity in preclinical models, which could theoretically oppose anti-oestrogen therapy or affect hormone-sensitive conditions.
Clinical note: Use caution in patients with hormone-sensitive cancers or on endocrine therapy.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 9-30g | Daily | — | — | — |
Preparation Methods
Decoction (Tang)
Parts: dried ripe fruit
Typical adult dose 6-10 g of dried fruit decocted in water. Because of established hepatotoxicity, avoid high doses and prolonged uninterrupted use, prefer water decoctions over alcohol extracts, and monitor liver function.
Salt-processed (Yan Zhi)
Parts: dried ripe fruit
Frying with salt-water is the classic processing to direct the herb to the Kidney and temper its acrid dryness; salt-processed fruit is standard in kidney-yang and diarrhoea formulas (e.g., Si Shen Wan, Qing E Wan).
Topical tincture with controlled UVA (traditional/dermatologic)
Parts: dried ripe fruit
Historically applied topically for vitiligo and psoriasis to exploit the psoralen-plus-UVA (PUVA) photosensitising effect. Because of phototoxic burn and skin-cancer risk this should only be done under specialist supervision, never with uncontrolled sun exposure.
Clinical Studies
Five Constituents Contributed to the Psoraleae Fructus-Induced Hepatotoxicity via Mitochondrial Dysfunction and Apoptosis
Identified bakuchiol, bavachin, isobavachalcone, psoralidin and neobavaisoflavone as hepatotoxic constituents that damage hepatocytes through mitochondrial dysfunction and apoptosis, clarifying the mechanism of Bu Gu Zhi liver injury.
Historical Texts
Kai Bao Ben Cao (Materia Medica of the Kaibao Era)
Northern Song dynasty (973 CE)Ben Cao Gang Mu (Compendium of Materia Medica), Li Shizhen
Ming dynasty (1578)Pu Ji Ben Shi Fang (Prescriptions of Universal Benefit), Xu Shuwei
Southern Song dynasty (1132)References
- Chen L, Chen S, Sun P, Liu X, Zhan Z, Wang J. Psoralea corylifolia L.: a comprehensive review of its botany, traditional uses, phytochemistry, pharmacology, toxicology, quality control and pharmacokinetics . Chinese Medicine (2023) [DOI]
- Wang Y, Zhang H, Jiang J, et al.. Five Constituents Contributed to the Psoraleae Fructus-Induced Hepatotoxicity via Mitochondrial Dysfunction and Apoptosis . Frontiers in Pharmacology (2021) [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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