Labiatae (Plant Family)
Scutellaria lateriflora is one of 90 species in the genus
Scutellaria distributed throughout temperate and tropical regions.
Most Scutellaria species thrive in garden soils (particularly soils with
sunny, open borders) and generally die off after two or three years. Many of the
closely related species in this genus are found in the United States. Although
Scutellaria lateriflora is native to North America, it is now widely
cultivated in Europe. This particular species is also called mad-dog skullcap
because of its traditional use in treating hydrophobia.
Scutellaria lateriflora is slightly astringent and widely touted as a
nervine. Its tonic, sedative, and antispasmodic activities are reportedly so
pronounced that it has long been hailed as an effective therapy for hysteria,
convulsions, hydrophobia, and epilepsy. Among its other varied uses are as a
treatment for rickets, neuralgia, pain, hiccough, nervous headaches, and
headaches associated with incessant coughing.
Despite these popular uses, precise structure-activity relationships have not
been determined for skullcap. Even though flavonoids are presumably responsible
for many of its purported pharmacological effects, therapeutic claims for
Scutellaria lateriflora have not been fully substantiated scientifically.
Skullcap has in the past been frequently adulterated with Teucrium
species, a group of plants known to contain potential liver toxins. Because of
its possibility for causing serious adverse side effects, including
hepatotoxicity and hepatitis, skullcap should not be used unless taken under the
direct supervision of a qualified health care practitioner knowledgeable about
this plant, and care should be taken to buy the herb from a reliable
Scutellaria lateriflora is a slender, perennial, herbaceous plant that
grows to a height of 60 cm. Although its erect stem is heavily branched, it is
rarely shrubby. Skullcap is distinguished by a thick cover of simple and
glandular hairs. Its leaves are typically ovate to lanceolate and petioled, with
either complete or scalloped margins.
Skullcap blooms in July, giving rise to barely conspicuous blue and sometimes
pink flowers that take the form of short lateral false spikes. The fluffy calyx
(sepals) is flattened with two rounded, complete lips. The upper and lower sides
of the calyx have different appearances. The flowers have four ascending
stamens, each with a pair of cilated anthers. The fruit consists of a warty nut
that is globular to flattened-ovoid in shape.
Herb (1 to 2 year-old plant harvested in early summer).
Flavonoids (apigenin, hispidulin, luteolin, scutellarein, scutellarin [bitter
glycoside]); catalpol; volatile oils (limonen, terpineol [monoterpenes],
d-cadinene, caryophyllene, trans-B-farnesene, B-humulene [sesquiterpenes]);
other constituents (lignin, resin, tannin).
Note: Published findings on the constituents of Scutellaria
lateriflora are quite limited.
Available for internal use as a powder or liquid extract made from the
Traditional uses: epilepsy, chorea, hysteria, nervous tension, convulsions,
hydrophobia, grand mal or St. Vitus's dance (epileptic seizure), nervous
headaches, neuralgia, pain, hiccough, rickets, headache arising from incessant
Uses of Scutellaria baicalensis roots in Traditional Chinese Medicine:
inflammation, suppurative dermatitis, allergic diseases, hyperlipidemia,
Conditions: historically used to treat hysteria, nervous tension, epilepsy,
chorea, and other nervous disorders; also once used as bitter tonic and
febrifuge (for fever).
Clinical applications: nervousness, anxiety, muscle spasm, nervous tics,
restless legs syndrome, and mild Tourette's syndrome
Scutellaria latiflora reportedly possesses sedative, antispasmodic,
and anti-inflammatory activities as well as inhibitory effects against lipid
peroxidation. However, relatively little research has been conducted on
Scutellaria lateriflora, and no in vivo data have been located for
Pharmacological studies have been conducted on the root of a related species,
Scutellaria baicalensis. Flavonoid compounds in Scutellaria
baicalensis are responsible for several in vitro effects, including blockage
of mast cell histamine release comparable to that of disodium cromoglycate;
inhibition of lipid peroxidation; and inactivation of lipoxygenase and
Flavonoids may also account for certain in vivo activities of
Scutellaria baicalensis such as hypocholesterolemia in rats. This latter
activity has been associated with flavonoid-induced in vitro prevention
of experimentally-induced hyperlipidemia and lipolysis, as well as
flavonoid-induced in vitro lipogenesis in adipose tissues.
In certain animal investigations, Scutellaria baicalensis did not
elicit a marked effect on blood pressure in cats and rabbits. Nor did it exert
CNS depressant or antispasmodic action on test animals. However, Scutellaria
baicalensis did exhibit antibacterial effects against several strains of
Gram-positive bacteria. It is not clear, however, if these findings are relevant
to the pharmacological effects of Scutellaria lateriflora.
In clinical trials conducted in China, scutellarin, the active constituent in
several Scutellaria species, was administered i.m., i.v., or p.o.
to over 600 patients diagnosed with cerebral thrombosis, cerebral embolism, and
paralysis. An overall rate of efficacy of 88% was reported for this treatment.
|Dosage Ranges and Duration of
- Dried herb: 1 to 2 g or by infusion tid
- Fluid extract (1:1 in 25% alcohol): 2 to 4 ml tid
- Tincture (1:2 in 35% alcohol): 2 to 5 ml tid
According to some authorities, skullcap is devoid of side effects when taken
in recommended therapeutic dosages. However, other experts warn that because of
the possibility of adulteration, skullcap should be used with caution.
Overdosage of skullcap tincture produces symptoms of giddiness, stupor,
mental confusion, seizure, twitching of the limbs, intermission of the pulse,
and epileptic-related manifestations. Oral intake of skullcap may be associated
with hepatotoxic reactions, probably attributable to adulteration with
Teucrium species, for example, Teucrium chamaedrys (germander).
Skullcap should be avoided under all circumstances during pregnancy and
lactation due to potential adulteration and subsequent liver
While no clinically significant interactions between this herb and
conventional medications are known to have been reported in the literature to
date, skullcap does possess sedative properties; therefore, it should be used
with caution, if at all, in patients taking benzodiazepines, barbiturates, or
other medications with sedative potential.
|Regulatory and Compendial
Skullcap is an entry on the General Sales List in Great Britain. In the USA,
the FDA designates skullcap as herb of undefined safety. This plant is not used
in food products.
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CommunicationsThis publication contains
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