Wise Mind Herbs

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Skullcap - Scutellaria baicalensis

Skullcap refers to plants from the genus Scutellaria in the mint family (Lamiaceae), with over 350 species worldwide. The two most researched species for medicinal purposes are Scutellaria lateriflora (American skullcap) and Scutellaria baicalensis (Chinese skullcap, Huang-qin). Despite sharing a genus, these species contain different bioactive compounds and traditional uses. Other less common medicinal species include Scutellaria barbata and Scutellaria racemosa.

Image source and license: https://commons.wikimedia.org/wiki/File:Scutellaria_baicalensis_Tarczyca_bajkalska_2020-09-20_02.jpg.
Modified by Peter Jorgensen.

Common Names and Botanical Classification

American skullcap (Scutellaria lateriflora) is also known as blue skullcap, mad dog skullcap, and hoodwort. Chinese skullcap (Scutellaria baicalensis) is commonly called Huang-qin or Baikal skullcap. These should not be confused with Scutellaria galericulata (marsh skullcap) or plants from other genera sometimes incorrectly called "skullcap," such as Scroftylaria nodosa (figwort) or certain Teucrium species.

Active Compounds

The therapeutic properties of skullcap are attributed to various bioactive compounds. American skullcap contains flavonoids (primarily scutellarin, baicalin, and wogonin), phenolic acids, essential oils, and amino acids. Chinese skullcap is rich in flavones including baicalin, baicalein, and wogonin, which are its primary active compounds. Research indicates these compounds have anti-inflammatory, antioxidant, and neuroprotective properties.

Evidence-Based Therapeutic Applications

• Anxiety and Stress Disorders: American skullcap shows modest anxiolytic effects in human clinical trials. Use of S. lateriflora extract has significantly reduced anxiety scores using the Beck Anxiety Inventory when compared to placebo.
• Neurological Protection: Baicalein and wogonin from Chinese skullcap show neuroprotective properties in preclinical models of neurodegenerative diseases, with mechanisms involving antioxidant activity and modulation of GABA receptors.
• Anti-inflammatory Effects: Multiple studies demonstrate that flavones from Chinese skullcap inhibit pro-inflammatory cytokines and NF-κB signaling pathways.
• Cancer Research: Preclinical studies suggest potential anticancer activity, particularly with baicalein and wogonin from Chinese skullcap, showing apoptotic and anti-proliferative effects in various cancer cell lines.
• Cardiovascular Protection: Animal models show Chinese skullcap extracts may offer protection against atherosclerosis and cardiac injury through antioxidant and anti-inflammatory mechanisms.
• Antimicrobial Properties: In vitro studies demonstrate activity against certain bacteria and viruses, though clinical evidence remains limited.

Recommended Dosages

Clinical evidence for standardized dosing remains limited. For American skullcap (S. lateriflora), studies typically use 100-350mg of dried herb extract standardized to contain 30% flavonoids, taken 1-3 times daily. For Chinese skullcap (S. baicalensis), clinical trials have used 400-1200mg daily of root extract standardized to contain 80% baicalin. Traditional Chinese Medicine typically uses 3-9g of dried root in decoctions. Currently, there is no universally accepted standardization of skullcap products.

Safety Profile and Side Effects

• Common Side Effects: Mild gastrointestinal discomfort, dizziness, and drowsiness.
• Drug Interactions: Potential interactions with sedatives, anticoagulants, and drugs metabolized by cytochrome P450 enzymes.
• Hepatotoxicity Concerns: Rare cases of liver injury have been reported, though evidence suggests these may be due to misidentification or adulteration with hepatotoxic plants.
• Contraindications: Not recommended during pregnancy, breastfeeding, or for individuals with hormone-sensitive conditions due to potential estrogenic effects of certain flavonoids.

High-Dose Investigations

Limited research exists on doses exceeding standard therapeutic recommendations. Up to 5 times the therapeutic dose of S. baicalensis extract did not produce significant adverse effects in rodent models, but produced mild sedation and decreased motor coordination at very high doses. There remains a significant knowledge gap regarding long-term effects of high-dose administration in humans. No established upper limit of safe consumption has been definitively determined.

Chinese medicine has a number of formulations that include skullcap, and Scutellaria injections are used in some Chinese hospitals for acute inflammatory conditions

In Western markets, skullcap is primarily available as dietary supplements rather than regulated pharmaceuticals. No FDA-approved drugs currently contain skullcap as an active ingredient. Several pharmaceutical companies are investigating synthetic derivatives of baicalein and wogonin for potential drug development, particularly for neurodegenerative and inflammatory conditions.

Research Limitations and Knowledge Gaps

Despite promising preclinical research, high-quality human clinical trials remain limited. Most studies use varying extraction methods, dosages, and standardization protocols, making direct comparisons difficult. Long-term safety data and pharmacokinetic studies in diverse populations are lacking. There is also a need for better quality control in commercial products to address issues of adulteration and misidentification.

References

Ahmadi, A., Mortazavi, Z., Mehri, S., & Hosseinzadeh, H. (2022). Protective and therapeutic effects of Scutellaria baicalensis and its main active ingredients baicalin and baicalein against natural toxicities and physical hazards: A review of mechanisms. DARU Journal of Pharmaceutical Sciences, 30(2), 351-366.

Brock, C., Whitehouse, J., Tewfik, I., & Towell, T. (2014). American skullcap (Scutellaria lateriflora): A randomised, double‐blind placebo‐controlled crossover study of its effects on mood in healthy volunteers. Phytotherapy research, 28(5), 692-698.

Choi, E. O., Jeong, J. W., Park, C., Hong, S. H., Kim, G. Y., Hwang, H. J., ... & Choi, Y. H. (2016). Baicalein protects C6 glial cells against hydrogen peroxide-induced oxidative stress and apoptosis through regulation of the Nrf2 signaling pathway. International Journal of Molecular Medicine, 37(3), 798-806.

Gasiorowski, K., Lamer-Zarawska, E., Leszek, J., Parvathaneni, K., Bhushan Yendluri, B., Blach-Olszewska, Z., & Aliev, G. (2011). Flavones from root of Scutellaria baicalensis Georgi: drugs of the future in neurodegeneration?. CNS & Neurological Disorders-Drug Targets (Formerly Current Drug Targets-CNS & Neurological Disorders), 10(2), 184-191.

Jeong, J. Y., Cha, H. J., Choi, E. O., Kim, C. H., Kim, G. Y., Yoo, Y. H., ... & Choi, Y. H. (2019). Activation of the Nrf2/HO-1 signaling pathway contributes to the protective effects of baicalein against oxidative stress-induced DNA damage and apoptosis in HEI193 Schwann cells. International journal of medical sciences, 16(1), 145.

Li, X., Wang, L., Li, Y., Bai, L., & Xue, M. (2011). Acute and subacute toxicological evaluation of scutellarin in rodents. Regulatory Toxicology and Pharmacology, 60(1), 106-111.

Sowndhararajan, K., Deepa, P., Kim, M., Park, S. J., & Kim, S. (2018). Neuroprotective and cognitive enhancement potentials of baicalin: a review. Brain Sciences, 8(6), 104.

Wang, Z. L., Wang, S., Kuang, Y., Hu, Z. M., Qiao, X., & Ye, M. (2018). A comprehensive review on phytochemistry, pharmacology, and flavonoid biosynthesis of Scutellaria baicalensis. Pharmaceutical biology, 56(1), 465-484.

Zhao, Q., Chen, X. Y., & Martin, C. (2016). Scutellaria baicalensis, the golden herb from the garden of Chinese medicinal plants. Science bulletin, 61, 1391-1398.