Japanese St. Johnswort Herb

Chinese
地耳草
Pinyin
Di Er Cao
Latin
Herba Hyperici Japonici

TCM Properties

Taste
bitter, sweet
Temperature
cool
Channels
Lung, Liver, Kidney, Bladder

Traditional Use

Primary Actions

  • Clears Heat and resolves toxicity
  • Promotes urination and treats Damp-Heat jaundice
  • Disperses Blood stasis and reduces swelling
  • Clears Lung Heat — used for cough, hemoptysis, and lung abscess

Secondary Actions

  • Anti-inflammatory for hepatitis and cholecystitis — key clinical use
  • External application for traumatic injury, furuncles, snakebite, and infected wounds

Classical References

  • Also known as Tian Ji Huang (田基黄); commonly used in Lingnan (Guangdong/Guangxi) folk medicine for infectious hepatitis and jaundice
  • Ben Cao Tui Chen: 'Di Er Cao resolves toxicity, cools blood, and promotes urination — applicable to jaundice, dysentery, and sores'
  • Note: Di Er Cao (地耳草, Hypericum japonicum) is NOT the same plant as Guan Ye Lian Qiao (贯叶连翘, Hypericum perforatum, Western St John's Wort) — different species with distinct pharmacology and safety profiles; the Western species carries significant drug interactions (CYP3A4 inducer) that do NOT apply to H. japonicum

Modern Research

Active Compounds

  • Quercetin
  • Quercitrin (quercetin-3-rhamnoside)
  • Isoquercitrin (quercetin-3-glucoside)
  • Kaempferol
  • Tetramethoxyluteolin (5,7,3′,4′-tetramethoxyflavone; hepatoprotective)
  • Hypericin and pseudohypericin (trace levels; much lower than H. perforatum)
  • Chlorogenic acid
  • Xanthones (trace)

Studied Effects

  • Hepatoprotective in cholestatic hepatitis: network pharmacology identified quercetin as a central multi-target node acting on PTGS2 (COX-2), BCL2, CYP7A1, and FXR pathways; molecular docking confirmed direct binding — provides mechanistic basis for classical Damp-Heat jaundice indication (PMID 33657087)
  • Anti-hepatitis B: Di Er Cao extract and isolated flavonoids inhibit HBsAg and HBeAg secretion in HepG2.2.15 cells; tetramethoxyluteolin identified as the most active compound with IC50 comparable to lamivudine in cell assays
  • Anti-inflammatory and antioxidant: total flavonoids reduce LPS-induced NO, IL-6, and TNF-α in RAW264.7 macrophages; DPPH radical scavenging IC50 comparable to ascorbic acid

PubMed References

Safety & Interactions

Contraindications

  • Cold-Damp jaundice or diarrhea (no fever, pale jaundice, cold limbs)
  • Spleen-Stomach Deficiency Cold

Cautions

  • Standard dose 15–60g fresh herb; 15–30g dried in decoction
  • IMPORTANT: Do not confuse with Hypericum perforatum (Western St John's Wort, Guan Ye Lian Qiao 贯叶连翘) — H. perforatum is a potent CYP3A4 inducer with major drug interactions; H. japonicum does NOT share this pharmacology and has a separate safety and interaction profile
  • Hypericin content in H. japonicum is trace-level compared with H. perforatum; photosensitisation risk is negligible at standard oral doses

Conditions