Scutellaria lateriflora

Botany

Native to North America.
Skullcap thrives in damp environments such as on riverbanks, in woods and thickets (2,4).
A perennial herbaceous plant, which typically grows 30-60 cm in height. The stem is slender and branched and the leaves are opposite serrate-crenate and covered in fine glandular hairs.
Appearing in one-sided terminal racemes, the helmet-shaped flowers are blue to violet with a small, bilaterally symmetrical lipped corolla (2,5,6,7).

The native people of North America used skullcap in women’s medicines to relieve breast pain, as a stimulant for menstruation and placenta expulsion (2,4).
In 1773 Skullcap was introduced into mainstream American medicine for the treatment of the hysteria and hydrophobia associated with rabies (2,4,6).
In the 19th century the Physiomedicalists acknowledged the deeper action of Skullcap as a nervine, additionally using it in the treatment of convulsions, epilepsy and mental illness (4).

Major Active Constituents

Flavonoids - predominantly baicalein and its glycoside baicalin as well as scutellarein, scutellarin and wogonin. In addition, skullcap contains apigenin, hispidulin and luteolin (2,4,7).
(Human neurohormones –) serotonin and lesser amounts of melatonin (8).
Iridoid glycoside – catalpol (2,7).
Volatile oil and tannins (2,4).

Actions

Nervine tonic (1,3,4,5,6,10,11)
Sedative (1,7,11,12)
Anti-spasmodic (1,4,5,6,10)
Anti-convulsant (3,7,12)
Anti-psychotic (3)
Anti-inflammatory (4,7)
Anxiolytic (3,4)
Antioxidant (8,9)
Trophorestorative (15)

Pharmacology

An in vivo behavioural test measuring the anxiolytic responses in rats administered aqueous extracts of skullcap showed a significant difference between treated and control rats (n=21, p<0.05) (17).
In vitro aqueous extracts of skullcap induced release of [3H] GABA in rat brain synaptosomes. Inhibition of GABA reuptake in cells explains the in vivo mechanism by which skullcap has an inhibitory effect on neurotransmission (17).
In vitro studies with baicalin and the aglycone baicalein from Scutellaria baicalensis demonstrate binding with high affinity to the benzodiazepine site of GABAA, contributing to the anxiolytic properties (17).
The discovery of relatively high quantities of serotonin in skullcap may explain the in vitro study, which found that skullcap extracts bind to the serotonin 5-HT7 receptor (8,18).

Clinical Outcome Studies

A double blind, placebo controlled crossover study measured the effects of various skullcap preparations on healthy volunteer’s energy, cognition and anxiety levels (n = 19).
3 active preparations were used: One 350mg capsule of organic, freeze dried skullcap (Eclectic Institute, Oregon), One 100mg capsule of organic, freeze dried skullcap extract (Phytos, California) and Two 100mg capsules of organic, freeze dried skullcap extract (Phytos, California)
Placebo: 2 capsules of inert substance undistinguishable from active substance.
3 outcome variables (anxiety, cognition and energy) were subjectively measured at baseline and over 30-minute intervals up to 120 minutes after administration.

Results - An obvious effect on reduction of anxiety was consistent in the 19 volunteers with only a mild impact on energy and cognition in the single dose preparations. Results for the doubled dose indicate an impact on cognition ratings, suggesting that Skullcap is sedative in higher doses (3).

Indications

Restlessness (2)
Nervousness with fatigue and depression (2)
Anxiety (4)
States of nervous tension (12)
Epilepsy (7,12)
Grand mal (7,12)
Petit mal when sleeping (13,14)
Tension, anxiety, insomnia (7)
Nervousness with or after acute or chronic disease or with physical or mental exhaustion (5)
Nervousness or hysteria causing muscle tremor or cardiac disorders (5,15)
Chorea, convulsions, tremors, intermittent fever, neuralgia (5)
St. Vitus’s dance (6)
Neurological damage from bacterial infections (8)
Withdrawal from tranquillisers or barbiturates (8)
Kidney or urinary system disorders (9)
Typhoid delirium and nervous dyspepsia (10)
Spasmodic conditions (10,15)
Herpes, pre eruption nerve pain (13)
Multiple sclerosis and pain worse for stress and fear (13)
Ease premenstrual tension (14)
Gastrooesophageal reflux and IBS linked to stress (15)

Contra-indications and Cautions

Overdose can cause confusion and stupor, with twitches, pulse irregularities and symptoms similar to epilepsy (6)
Reports of hepatotoxicity are not supported by experimental data or with skullcap definitively. Some cases have involved European mistletoe (Viscum album) or wood germander (Teucrium chamaedrys) (2,3,16).
Research has shown skullcap extracts to inhibit CYP3A4 enzyme. When herbs that inhibit this enzyme are combined with drugs that are metabolised by the same enzyme, caution should be taken (19).
In pregnancy – category B2: Limited use in women causes no increase in frequency of malformation or side effects (11)
In lactation – category C: compatible with breast feeding (11)

Posology

1 cup boiling water with 1-2 teaspoons dried herb, infused 10-15 mins tds (1).
Half an ounce of recently dried leaves with half a pint of boiling water. Take 1 to 60 drops (5).
1 oz. of the powdered herb to a pint of boiling water. Give in half-teacup doses, every few hours (6).
3-6 g/day dried aerial part (11).
6-12 mL/day of a 1:1 liquid extract (11).
2-4.5 mL/day of a 1:2 liquid extract or equivalent capsule or tablet form (11,20).
3-6 mL/day of a 1:5 tincture (11).

References

1. Hoffman D. 2003.The Holistic Herbal. London: Element.

2. Wohlmuth H. Skullcap (Scutellaria lateriflora): the herb with an identity crisis. Botanical Pathways 2001;13:115-119.

3. Wolfson P, Hoffman DL. An investigation into the efficacy of Scutellaria lateriflora in healthy volunteers. Alternative Therapies in Health and Medicine 2003;9:74-78.

4. Chevallier A. 2000. Encyclopaedia of Herbal Medicine.2nd edition. London: DK Natural Health.

5. Felter HW, Lloyd JU. 1898-1900. King’s American dispensatory Vol II. Oregon: Eclectic Medical Publications.

6. Grieve M. 1931. A Modern Herbal. London: Tiger Books International.

7. van Wyk BE, Wink M. 2004. Medicinal Plants of the World. Oregon: Timber Press.

8. Cole IB, Cao J, Alan AR, Saxena PK, Murch SJ. Comparisons of Scutellaria baicalensis, Scutellaria lateriflora and Scutellaria racemosa: Genome Size, Antioxidant Potential and Phytochemistry. Planta Medica 2008;74:474-481.

9. Wojcikowski K, Stevenson L, Leach D, Wohlmuth H, Gobe G. Antioxidant capacity of 55 medicinal herbs traditionally used to treat the urinary system: A comparison using a sequential three-solvent extraction process. Journal of Alternative and Complementary Medicine. 2007;13:103-109.

10. Lyle TJ. 1897. Physio-medical therapeutics, materia medica and pharmacy. London: The National Association of Medical Herbalists of Great Britain, Ltd.

11. Mills S, Bone K. 2005. The Essential Guide To Herbal Safety. Missouri: Elsevier.

12. Anonymous. 1990. British Herbal Pharmacopoeia. Bournemouth: British Herbal Medicine Association.

13. Scutellaria lateriflora. 1997. Specific Indications For Herbs in General Use. 3rd edition. Michael Moore. Arizona. Accessed 19 September 2008. <http://www.swsbm.com/homepage/>

14. Hoffmann D. 2003. Medical Herbalism. Rochester, Vt: Healing Arts Press.

15. Mills S, Bone K. 2000. Principles and Practice of Phytotherapy. Edinburgh: Churchill Livingstone.

16. Boon H, Smith M. 1999. The Botanical Pharmacy. Ontario: Quarry Health Books.

17. Awad R, Amason JT, Trudeau V, Bergeron C, Budzinski JW, Foster BC et al. Phytochemical and biological analysis of skullcap (Scutellaria lateriflora L.): A medicinal plant with anxiolytic properties. Phytomedicine. 2003;10:640-649.

18. Gafner S, Bergeron C, Batcha LL, Reich J, Arnason JT, Burdette JE et al. Inhibition of [3H]-LSD binding to 5-HT7 receptors by flavonoids from Scutellaria lateriflora. Journal of Natural Products. 2003;66:535-537.

19. Herr SM. 2005. Herb-Drug Interaction Handbook. 3rd edition. Castleton, NY: Church St. Books.

20. Bone K. 2003. A Clinical Guide to Blending Liquid Herbs: herbal formulations for the individual patient. St. Louis, Missouri: Churchill Livingstone.

This monograph was authored in 2008 by Dale Amanda Savins, a student in Southern Cross University’s Bachelor of Naturopathy programme, and edited by Nena Aleschewski BNat. While the author and editor have strived to cite published information accurately, Southern Cross University will not be responsible for any inaccuracies that may have occurred.

This information is provided for educational purposes only and does not constitute medical advice. If you wish to use herbal medicine as part of your health care, seek the advice of an appropriately qualified practitioner.