Scutellaria baicalensis

Health Care Professional Information

Scientific Name
Scutellaria baicalensis
Common Name

Huang Qin, baikal skullcap, Chinese skullcap

Clinical Summary

Scutellaria baicalensis is an herb used in traditional Chinese medicine to treat a variety of conditions including epilepsy, hepatitis, infections, and cancer. It often is used in combination with other botanicals (e.g. PC-SPES and Sho-saiko-to).
In vitro and animal data suggest that its components cause apoptosis in various cancer cells (2) (3) (14), demonstrate neuroprotective (4) (5) and anti-inflammatory (17) effects, and protect against doxorubicin-induced cardiotoxicity (15). In addition, sedative and anticonvulsant effects have also been reported (6).

Although clinical trials have been conducted with formulas containing skullcap, it is not known if the herb would exert similar effects by itself.

Purported Uses
  • Atherosclerosis
  • Cancer treatment
  • Epilepsy
  • Hepatitis
  • Infections
  • Inflammation
  • Insomnia
Constituents
  • Flavonoids: Baicalin, baicalein, scutellarein, wogonin, apigenin, hispidulin, luteolin, scutellarein
  • Iridoids: Catalpol
  • Volatile oils: Limonene, terpineol, beta-humulene, caryophyllene
  • Others: Lignin, resin, tannin
    (1) (2)
Mechanism of Action

Baicalin exhibits anti-inflammatory, antioxidant, and gram-positive antibacterial activity in vitro (3). It was also shown to attenuate important features of asthma, possibly by reducing airway injury and restoring mitochondrial function (19). The neuroprotective effects of flavonoids were ameliorated by diazepam, a GABA receptor agonist, suggesting that the components influence GABA receptor activity (5). The flavonoids also prevent ethanol-induced hyperlipidemia, histamine release from mast cells, and catecholamine-induced lipolysis in animal models (8).

In vitro studies suggest that flavonoid components of S.baicalensis have anticancer activity. Induction of apoptosis in hepatoma G2, 3B, and SK-Hep1 cell lines occurs following 48 hours of exposure to baicalein, baicalin, and wogonin at concentrations of 25-100 mcg/ml. Wogonin causes arrest at G1 phase while baicalin and baicalein cause G2/M accumulation (2). Additional studies show that baicalin, at concentrations of 50-200 mcg/ml, activates caspase-3, resulting in apoptosis of Jurkat cells (leukemia-derived T cells).

Pharmacokinetics

Urinary pharmacokinetic analysis of baicalein, wogonin, and their glycosides in humans indicated that excretion of conjugated metabolites of wogonin was greater than those of baicalein (11.6 versus 7.2% of the dose) (10). The low recovery of both compounds may be due to bile excretion or metabolism by enteric bacteria. In addition, in vitro studies revealed that baicalein is capable of crossing the gut epithelium as well as the blood-brain barrier (11).

Warnings

Products containing S. baicalensis were found to be contaminated with a similar looking plant known as germander (Teucrium chamaedrys) that can cause hepatitis (8).

Adverse Reactions

Reported: Hepatotoxicity, pneumonitis (7)
Case Report: Acute liver injury has been reported in patients following consumption of a formula containing baicalin derived from S. baicalensis for osteoarthritis (18).

Herb-Drug Interactions
  • Anticoagulants / Antiplatelets: May cause additive effects (12).
  • Statins: Baicalin, an active constituent, can decrease the blood level of statin drugs used to lower cholesterol (13).
  • Cytochrome P450 substrates: Wogonin inhibits CYP1A2 and CYP2C19, and can affect the intracellular concentration of drugs metabolized by these enzymes (16).
  • Dextromethorphan: Baicalin was shown to inhibit metabolism of dextromethorphan in rats possibly via inhibition of hepatic CYP2D and CYP3A (20).
  • Solute carrier (SLC) transporters: Baicalein, baicalin, and wogonin inhibit uptake of specific substrates mediated by essential SLC transporters, which are important membrane proteins responsible for the cellular influx of various drugs (21).
Literature Summary and Critique

Scutellaria baicalensis has been studied in combination with other botanicals in formulations such as PC-SPES and sho-saiko-to.

Dosage (Inside MSKCC Only)
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References
  1. Bonham M, Posakony J, Coleman I, Montgomery B, Simon J, Nelson PS. Characterization of chemical constituents in Scutellaria baicalensis with antiandrogenic and growth-inhibitory activities toward prostate carcinoma. Clin Cancer Res 2005;11(10):3905-14.
  2. Chang WH, Chen CH, Lu, FJ. Different effects of baicalein, baicalin, and wogonin on mitochondrial function, glutathione content and cell cycle progression in human hepatoma cell lines. Planta Medica 2002;68:128-32.
  3. Ueda S, Nakamura H, Masutani H, et al. Baicalin induces apoptosis via mitochondrial pathway as prooxidant. Molecular Immunology 2002;38:781-91.
  4. Cheng Y, He G, Mu X, et al. Neuroprotective effect of baicalein against MPTP neurotoxicity: Behavioral, biochemical and immunohistochemical profile. Neurosci Lett. Aug 15 2008;441(1):16-20.
  5. Kim DH, Kim S, Jeon SJ, et al. The effects of acute and repeated oroxylin A treatments on Abeta(25-35)-induced memory impairment in mice. Neuropharmacology. Jul 10 2008.
  6. Park HG, Yoon SY, Choi JY, et al. Anticonvulsant effect of wogonin isolated from Scutellaria baicalensis. Eur J Pharmacol. Nov 28 2007;574(2-3):112-119.
  7. Takeshita K, Saisho Y, Kitamura K, et al. Pneumonitis induced by Ou-gon (scullcap). Internal Medicine 2001;40:764-8.
  8. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. 1st ed. London: Pharmaceutical Press; 1996.
  9. Huang KC. The Pharmacology of Chinese Herbs. 2nd ed. New York: CRC Press; 1999.
  10. Lai MY, Hsiu SL, Chen CC, Hou YC, Chao PD. Urinary pharmacokinetics of baicalein, wogonin and their glycosides after oral administration of Scutellariae Radix in humans. Biol Pharm Bull. Jan 2003;26(1):79-83.
  11. Tarrago T, Kichik N, Claasen B, Prades R, Teixido M, Giralt E. Baicalin, a prodrug able to reach the CNS, is a prolyl oligopeptidase inhibitor. Bioorg Med Chem. Apr 29 2008.
  12. Brinker F. Herb Contraindications and Drug Interactions. 3rd ed. Sandy (OR): Eclectic Medical Publications; 2001.
  13. Fan L, Zhang W, Guo D, et al. The effect of herbal medicine baicalin on pharmacokinetics of rosuvastatin, substrate of organic anion-transporting polypeptide 1B1. Clin Pharmacol Ther. 2008 Mar;83(3):471-6.
  14. Takahashi H, Chen MC, Pham H, et al. Baicalein, a component of Scutellaria baicalensis, induces apoptosis by Mcl-1 down-regulation in human pancreatic cancer cells. Biochim Biophys Acta. 2011 Aug;1813(8):1465-74.
  15. Chang WT, Li J, Huang HH, et al. Baicalein protects against doxorubicin-induced cardiotoxicity by attenuation of mitochondrial oxidant injury and JNK activation. J Cell Biochem. 2011 May 26. doi: 10.1002/jcb.23201.
  16. Li T, Li N, Guo Q, et al. Inhibitory effects of wogonin on catalytic activity of cytochrome P450 enzyme in human liver microsomes. Eur J Drug Metab Pharmacokinet. 2011 Jun 29.
  17. Li L, Bao H, Wu J, et al. Baicalin is anti-inflammatory in cigarette smoke-induced inflammatory models in vivo and in vitro: A possible role for HDAC2 activity. Int Immunopharmacol. 2012 May;13(1):15-22.
  18. Chalasani N, Vuppalanchi R, Navarro V, et al. Acute liver injury due to flavocoxid (Limbrel), a medical food for osteoarthritis: a case series.Ann Intern Med. 2012 Jun 19;156(12):857-60, W297-300.
  19. Mabalirajan U, Ahmad T, Rehman R, et al. Baicalein reduces airway injury in allergen and IL-13 induced airway inflammation. PLoS One. 2013 Apr 30;8(4):e62916.
  20. Tian X, Cheng ZY, He J, Jia LJ, Qiao HL. Concentration-dependent inhibitory effects of baicalin on the metabolism of dextromethorphan, a dual probe of CYP2D and CYP3A, in rats. Chem Biol Interact.2013 Apr 25;203(2):522-9.
  21. Xu F, Li Z, Zheng J, et al. The inhibitory effects of the bioactive components isolated from scutellaria baicalensis on the cellular uptake mediated by the essential solute carrier transporters. J Pharm Sci. 2013 Nov;102(11):4205-11.

Consumer Information

How It Works

Bottom Line: Scutellaria baicalensis has been used in traditional medicine to treat many medical conditions. Studies on its anticancer effects are underway.

Scutellaria baicalensis, also known as Huang Qin or Chinese skullcap, is a root extract used in traditional medicine, often in combination with other herbs. Scientists are not sure exactly how it works; it has been studied to some extent in the laboratory, but not in humans. Isolated liver cancer and leukemia cell lines, when exposed to extracts from this herb, undergo apoptosis (cell death). The extracts also reduce inflammation, act as antioxidants, and kill gram-positive bacteria in the laboratory setting. In animals, the extracts help lower blood cholesterol levels under certain conditions. However, it is not yet clear if any of these effects occur in the human body.

Purported Uses
  • To treat atherosclerosis
    Studies in animals show that extracts of this herb may help lower blood cholesterol levels under certain conditions, but human studies have not been conducted.
  • To treat cancer
    Extracts from this herb cause cell death in isolated liver cancer and leukemia cell lines in the laboratory setting, but human data are lacking.
  • To treat hepatitis
    The herbal formulation sho-saiko-to, which contains Huang Qin, has been studied for its possible liver-protectant effects.
  • To reduce inflammation
    Laboratory data support this use, but clinical data are lakcing.
Research Evidence

Scutellaria baicalensis has not been studied in clinical trials as a single agent, but only in combination with other herbs in formulations such as PC-SPES and sho-saiko-to. (Please see these monographs for more information).

Patient Warnings
  • Some products that contain scullcap have been found to be contaminated with a similar-looking plant known as germander (Teucrium chamaedrys), which can cause liver damage.
Do Not Take If
  • You are taking warfarin or other blood thinners (skullcap can increase the risk of bruising and bleeding).
  • You are on statins (skullcap can decrease the blood level of these drugs).
  • If you are taking drugs that are substrates of Cytochrome P450 (skullcap may increase the risk of side effects of these drugs).
Side Effects
  • Liver damage
  • Pneumonitis (inflammation of the lung due to bacterial or viral infection)
  • Case Report: Acute liver injury has been reported in patients following consumption of a formula containing baicalin derived from S. baicalensis for osteoarthritis.
E-mail your questions and comments to aboutherbs@mskcc.org.