Skullcap: Potential Medicinal Crop

Abstract

The English name "skullcap" describes the shape of the calyx at the base of the flowers, which resemble miniature medieval helmets. During the 19th century, the common name used in America was "mad dog." Other popular names include scullcap, hoodwort, quaker bonnet, helmet flower, European skullcap, greater skullcap, American skullcap, blue skullcap, blue pimpernel, hoodwart, hooded willow herb, side-flowering skullcap, mad dog weed, and mad weed. Scutellaria is a large genus, about 300 species, growing from Siberia to Sri Lanka. It is well adapted to the North American climate where it has over 90 species. Plants are herbaceous, slender, rarely shrubby, scattered over temperate regions and tropical mountains around the globe. They flourish under full sunlight, limited feeding, and well-drained soil. BOTANY The skullcap (scullcap) is a North American perennial. It grows in wet places in Canada and the north- ern and the eastern United States. Its generic name is derived from the Latin scutella (little dish), from the lid of the calyx. The fibrous, yellow root system supports a branching stem 30 to 90 cm tall, with opposite, ovate, and serrate leaves. The root is a short creeper which supports hairy, square, and branched stems from 15 to 45 cm tall, or in small plants, nearly simple, with opposite leaves, heart-shaped at the base, 1 to 6 cm long with scal- loped or toothed margins. The blue to lavender flowers are in racemes and grow from the leaf axils. The flowers are tube shaped, hooded, with two lips, the upper lip being the hood and the lower lip having two shallow lobes. Flower- ing generally occurs from May to August. Above ground plant parts are collected during summer around bloom time, dried in shade and stored for later use as medicinal herb. Skullcaps are now becoming popular in southern gardens owing to their drought tolerance as well as bright and showy blooms (Fig. 1) (E. McDowell, pers. commun.).

Full text

580
Reprinted from: Trends in new crops and new uses. 2002. J. Janick
and A. Whipkey (eds.). ASHS Press, Alexandria, VA.
Skullcap: Potential Medicinal Crop
Nirmal Joshee, Thomas S. Patrick, Rao S. Mentreddy, and Anand K Yadav*
INTRODUCTION
Scutellaria species, Lamiaceae, popularly known as skullcaps have been extensively used in traditional
medical systems of China, India, Korea, Japan, European countries, and North America. The most exten-
sively used and documented species is baical skullcap (Scutellaria baicalensis) although other species such as
S. amoena, S. hypericifolia, S. tenax, S. rehderiana, and S. viscidula have been substituted (Song 1981). Baicalin,
baicalein, and wogonin are major ingredients and have been studied in S. rivularis (Chou 1978; Tomimori et
al. 1984, 1986a, 1990), S. discolor (Tomimori et al. 1985, 1986b), S. indica (Chou and Lee 1986; Miyaichi et
al. 1987, 1989), and S. scadens (Miyaichi et al. 1988a,b).
The English name “skullcap” describes the shape of the calyx at the base of the flowers, which resemble
miniature medieval helmets. During the 19th century, the common name used in America was “mad dog.”
Other popular names include scullcap, hoodwort, quaker bonnet, helmet flower, European skullcap, greater
skullcap, American skullcap, blue skullcap, blue pimpernel, hoodwart, hooded willow herb, side-flowering
skullcap, mad dog weed, and mad weed.
Scutellaria is a large genus, about 300 species, growing from Siberia to Sri Lanka. It is well adapted to
the North American climate where it has over 90 species. Plants are herbaceous, slender, rarely shrubby,
scattered over temperate regions and tropical mountains around the globe. They flourish under full sunlight,
limited feeding, and well-drained soil.
BOTANY
The skullcap (scullcap) is a North American perennial. It grows in wet places in Canada and the north-
ern and the eastern United States. Its generic name is derived from the Latin scutella (little dish), from the lid
of the calyx. The fibrous, yellow root system supports a branching stem 30 to 90 cm tall, with opposite, ovate,
and serrate leaves. The root is a short creeper which supports hairy, square, and branched stems from 15 to 45
cm tall, or in small plants, nearly simple, with opposite
leaves, heart-shaped at the base, 1 to 6 cm long with scal-
loped or toothed margins. The blue to lavender flowers are
in racemes and grow from the leaf axils. The flowers are
tube shaped, hooded, with two lips, the upper lip being the
hood and the lower lip having two shallow lobes. Flower-
ing generally occurs from May to August. Above ground
plant parts are collected during summer around bloom time,
dried in shade and stored for later use as medicinal herb.
Skullcaps are now becoming popular in southern gardens
owing to their drought tolerance as well as bright and showy
blooms (Fig. 1) (E. McDowell, pers. commun.).
FOLKLORE AND USES IN ALTERNATIVE
MEDICINE
Skullcap is a powerful medicinal herb and it is used
in alternative medicine as an anti-inflammatory, abortifa-
cient, antispasmodic, slightly astringent, emmenagogue, feb-
rifuge, nervine, sedative, and a strong tonic. Skullcap is
* The authors thank Ed McDowell (President, Georgia Plant Rescue Society), Bonaire, Georgia, for allowing us to use
photographs of S. ocmulgee. We thank Carol Helton, Conservation Coordinator, Atlanta Botanical Gardens, Atlanta, for
providing plants of S. montana.
Fig. 1. Scutellaria ocmulgee.

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Herbs, Medicinals, and Aromatics
also utilized in treating a wide range of nervous conditions including epilepsy, insomnia, hysteria, anxiety,
delerium tremens, and withdrawal from barbiturates and tranquilizers. A medicinal infusion of this plant is
used to promote menstruation. It should not be given to a pregnant woman since it can induce miscarriage.
Scutellaria infusion is also used for treating neuralgia, headaches in general as well as those arising from
incessant coughing, without any unpleasant side effects. Normally, it should be used with extra caution since
an overdose of this medicinal herb can cause giddiness, stupor, confusion, and twitching.
Skullcap is well known among the Cherokee and other Native American tribes, as a strong emmenag-
ogue and medicinal herb for females. It is used in some tribes as a ceremonial plant to induct young girls into
womanhood. Native Americans used skullcap to promote menstruation, and it was reputed to be effective
against rabies, hence some of its common names. Cherokee women use skullcap to maintain healthy men-
strual cycles, and a root decoction is taken after the birth of a child to stimulate the reproductive system.
Skullcap is also used in purification ceremonies if menstrual taboos are broken. The Iroquois use an infusion
of the root to keep the throat clear. Other Native American tribes use closely related species as bitter tonics
for the kidneys. The herb is used to induce visions and as a ceremonial plant to be smoked as tobacco by some
Native Indians.
Wogon Scutellariae Radix, a well known ancient drug in the traditional Chinese medicine, is prepared
from S. baicalensis roots (dry and without exodermis), which is conventionally collected in spring and fall
(Tang and Eisenbrand 1992). It is officially listed in the Japanese Pharmacopeia JPXIII and Chinese Pharma-
copeia. It is one of the most widely used crude drugs for the treatment of bronchitis, hepatitis, diarrhea, and
tumors. Chinese physicians use the root of S. baicalensis or “huang qin,” as an antibacterial, diuretic, antis-
pasmodic, and promoter of bile flow. In Nepal, S. discolor leaves are used as a folk remedy for common cold,
cuts, and insect stings (Sinha et al. 1999).
Scutellaria is a traditional treatment for epilepsy in European countries. Homeopaths have reported some
success in the use of this plant to treat chronic fatigue syndrome. It is helpful for skin and urinary tract infec-
tions and is also used where hypertension is related to over-heated conditions. Note that serious health prob-
lems could arise from incomplete and/or misleading information on the use of traditional medicines. For
example, misidentification of a Chinese herb resulted in the loss of renal function in more than 100 patients
(Betz 1998). Potential problems with herbal preparations are: (a) contamination with bacteria, fungi, insects,
and pollutants, (b) seasonal variation in bioactive compounds, (c) degradation of active ingredients in pro-
cessing and storage of plant materials, and (d) a lack of understanding of the unique physiology of medicinal
plants (Li et al. 2000).
BIOACTIVE COMPOUNDS
Hattori (1930) was first to isolate wogonin
from S. baicalensis roots and determined its chemi-
cal structure (Fig. 2). Wogonin is present only in
small amounts in roots while baicalin, a flavone gly-
coside, pervades the entire plant (Shibata et al.
1923). Upon acid hydrolysis, baicalin from roots
yields glucuronic acid plus baicalein (Fig. 2), a fla-
vone aglycone. There are over 50 flavones isolated
from S. baicalensis (Tang and Eisenbrand 1992;
Miyaichi and Tomimori 1994, 1995; Zhang et al.
1994; Ishimaru et al. 1995; Zhou et al. 1997). Other
Scutellaria phytochemicals include flavones, fla-
vonoids, chrysin, iridoids, neo-clerodanes,
scutapins, and isoscutellarein. Shin and Lee (1995),
successfully produced baicalin in callus cultures of
S. baicalensis. Using the hairy root culture system,
Hirotani (1999), isolated a brand new flavone glu-
coside, along with 15 known flavones and five Fig. 2. Structure of compounds isolated from S.
baicalensis Georgi roots.

582
Trends in New Crops and New Uses
phenylethanoids from S. baicalensis. Thus it is suggested that hairy root cultures could possibly be used in
herbal medicine as a substitute for Scutellaria Radix (Zhou et al. 1997; Hirotani 1999).
MEDICAL STUDIES
Sato et al. (2000) showed antibacterial properties of apigenin and luteolin in the crude extracts of S.
barbata. Constituents were selectively toxic to Staphylococcus aureus, including both methicillin-resistant
and sensitive strains. Flavones isolated from S. baicalensis roots were found inhibitory to HIV-1 (human
immunodeficiency virus) by Li et al. (1993), to HTLV-I (human T cell leukemia virus type I) by Baylor et al.
(1992), and to mouse skin tumor promotion (Konoshima et al. 1992). Plant extracts of S. rivularis have shown
anti-inflammatory and hepatoprotective activity in test animals (Ching and Den 1996). Akishiro et al. (1992)
were awarded a patent for therapeutic use of a flavone from S. baicalensis, as sialidase enzyme inhibitor of
the influenza virus. It has been suggested that baicalin may play a significant role in lipid metabolism through
lipogenic and lipolytic pathways of adipose cells (Eun et al. 1994; Chung et al. 1995). Scutalpin C, one of the
diterpenoids from Scutellaria, has shown strong insect antifeedant bioactivity against the Spodoptera littoralis
larvae (Munoz et al. 1997). Studies have shown that reactive oxygen species (ROS) including superoxide,
hydrogen peroxide, and hydroxyl radicals, contribute to myocardial ischemia-reperfusion injury (Halpern et
al. 1995). In vitro studies revealed that baicalein can directly scavenge ROS (Shieh et al. 2000; Shao et al.
1999) protecting cells from lethal damage.
CULTIVATION
Major species of medicinal Scutellaria grow in the wild, and systematic cultivation methods for crop
production have not been worked out. Skullcaps used for ornamental purposes are established by seeds or
cuttings in sunny garden locations with good drainage. Seeds are sown in early spring when there is no more
danger of late frosts. Although there are no major insect-pests or diseases reported for Scutellaria, it is sus-
ceptible to two virus pathogens: tomato spotted wilt virus (TSWV) and impatiens necrotic spot virus (INSV).
PROPAGATION
Efforts in Scutellaria propagation have been underway at Fort Valley State University. Mature seeds of
S. montana and S. integrifolia were collected in late summer from the Wildlife Resources Division of the
Georgia Department of Natural Resources, Social Circles, Georgia. Seeds of two species were planted for
germination in the greenhouse but only S. integrifolia germinated. Some success in micropropagation of
Scutellaria has been reported (Sinha et al. 1999; Stojakowska et al. 1999; Li et al. 2000). Shoot growth from
the S. montana and S. integrifolia plants were cultured in vitro in basal MS (Murashige and Skoog 1962)
medium supplemented with 0.5 mg L-1 BA (6-benzylamino purine) and 0.1 mg L-1 NAA (naphthaleneacetic
acid). Multiple shoot clumps were allowed to elongate in the basal MS medium to reach 4–6 cm length.
Microshoots rooted when cultured in MS basal, rooting medium (M527) from Phytotechnology Laboratories
(Shawnee Mission, Kansas), or MS + 1 mg L-1 IBA (Joshee and Yadav 2002).
FUTURE PROSPECTS AND CONCLUSION
Numerous herbal formulations including PC SPES from BotanicLab, Brea, California, Zyflamend PM
and Zyflamend Creme from New Chapter, and Migra-Profen from Gaia Herbs, all of which contain Scutellaria
as an ingredient, are currently available in the market. In recent years, Scutellaria-based herbal formulations
have been employed to establish its medical/scientific value using in vitro cell culture systems (Li et al. 1993;
Shao et al. 1999; Sato et al. 2000; Chen 2001). Scutellaria baicalensis and S. lateriflora are the two species
which have been used in most of the herbal formulations. Since there are over 300 Scutellaria species distrib-
uted all over the world other Scutellaria species need to be evaluated. Our current research here at FVSU
focuses on the Scutellaria species found in and around the state of Georgia (Table 1). Some of these species
are becoming rare or threatened because of population pressure, environmental pollution, and destruction of
their natural habitat (Patrick et al. 1995). Future studies are planned to include propagation, cultivation, and
conservation of native Scutellaria germplasm. Many of the skullcaps have showy, beautiful blooms and there
is a great potential for these species as ornamentals.

583
Herbs, Medicinals, and Aromatics
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Scutellaria baicalensis and its flavonoids on human gingival fibroblast. Planta Medica 61:150–153.
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from Scutellaria baicalensis on Epstein-Barr virus activation and their anti-tumor-promoting activities.
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Miyaichi, Y., Y. Imoto, H. Kizu, and T. Tomimori. 1988a. Studies on the Nepalese crude drugs. X. On the
flavonoid constituents of the root of Scutellaria scadens Buch.-Ham. D. Don. Chem. Pharm. Bul.
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Miyaichi, Y., Y. Imoto, H. Kizu, and T. Tomimori. 1988b. Studies on the Nepalese crude drugs. X. On the
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Table 1. Different species of Scutellaria that are native to and growing in and around the state of Georgia.
Flower size
Scutellaria species Flower color (mm) Bloom period Plant description and habitat Distribution and status
S. alabamensis Violet blue 20–22 June–July Hairy leaves averaging 50 mm long and Georgia, Florida, South Carolina
Alexander 20 mm wide.
S. arenicola Small Violet blue 25 June–July Bracts under the flowers are as long as N Florida, Georgia, South Carolina
the calyx. Thrives in sandy woods.
S. arguta Buckley Violet and white 15–20 June–Aug. Weak stemmed plant that spreads by Delaware to Indiana and southward
runners. Flowers on 5–15 cm long to South Carolina and Tennessee.
racemes. Near mountain woods.
S. australis Blue 8–10 May–July Gland tipped hairy stems, narrow ovate Texas to Nebraska and most regions
(Fassett) Epling hairy leaves. Thrives in dry woods further east.
and on prairies.
S. elliptica Muhl. Light violet 15–21 May–Aug. Soft hairy stems. Leaves 4–7 cm long by Southern New York to Missouri and
ex Spreng. 2–3.5 cm wide. Flowers in 3–10 cm southward to Florida and Texas.
racemes. Thrives in dry woods and thickets.
S. floridana Chapm. Pale violet, blue, -- April–July Leaves up to 3 mm wide and 26 mm long. A threatened species in Florida
white Thrives in pineland swamps.
S. glabriuscula Pale blue to white 18–27 April–July Slender hairy stems, ovate to Florida
Fernald elliptical leaves on petioles 5
mm long. Thrives in sandy soils.
S. incana Biehler Blue 18–25 June–Sept. Ovate leaves. Flowers are in New Jersey, W New York to Iowa,
racemes at or near the tip in a south to Florida, Alabama,
branched inflorescence. Found Arkansas, Kansas
in dry woods, thickets and clearings.
S. integrifolia L. Violet blue white or 23 May–June Densely hairy, slender stems bearing New York to Missouri and
pale pink streaked narrow lanceolate to oblong leaves with southward from Texas to Florida
lower lip almost no petiole. Flowers in 5–10 cm
long racemes. Grows on edges
of woods and fields on coastal plains.
S. lateriflora L. Violet pink to white 7–8 June–Sept. Smooth, often glossy leaves vary from Widespread in US and parts of
ovate to lanceolate. Flowers are in one western Canada
sided racemes. Found in swampy woods,
thickets and meadows.
S. leonardi Epling Blue 8–10 May–July Square stems bear lanceolate hairless North Dakota to Oklahoma.
Leaves. Flowers arises from pedicels,
and thrives in dry woods and prairies.

585
Herbs, Medicinals, and Aromatics
S. mellichampii Small Violet blue 25 June–July Inflorescence 5–15 cm long. Grows in Georgia, South Carolina
sandy woods.
S. montana Chapm. Blue and white 26–35 May–June 10–15 cm racemes, habitat is dry soil on Endangered species found in
rocky slopes in undisturbed mature oak Georgia and Tennessee
and hickory woodlands where trees range
from 70–200+ years old.
S. multiglandulosa Pale blue to white 20–23 April–July One or two capitate glandular stems Wide Florida, Georgia
(Kearn.) Small lanceolate leaves grows in dry pine lands,
bog type fields, and peat laden terrain or
shores.
S. nervosa Pursh. Pale blue 10 May–July Weak slender stems bear deltoid to ovate New Jersey to Ontario and Iowa
leaves, sessile except for some lower southward to North Carolina and
leaves. Flowers arise singularly from Tennessee
pedicel. Found in moist woods and thickets.
S. ocmulgee Small Violet blue 23 June–Oct. Stem clothed throughout with capitate Threatened species in Georgia
glands and curled hairs in upper parts.
Leaves round to ovate, crenate, hairy.
S. ovata Hill Blue violet with 13–25 May–July 10 cm racemes, hairy stems and ovate Maryland to Minnesota to Texas,
whitish lip leaves up to 10 cm long. Grows more South Carolina, ssp. pseudoarguta
abundant on westward facing terrain and threatened in West Virginia
often associated with limestone or
calcium bearing rocks.
S. parvula Michx. Blue with darker 8–10 May–July Slim horizontal square stems swollen at North Dakota to Oklahoma
spots on lower lip intervals into tubers. Ovate leaves on short
petioles. Found in dry woods and prairies
associated with mainly calcareous soils.
S. pseudoserrata -- -- -- Perhaps a natural hybrid of S. serrata, S. Alabama, North Carolina,
montana, and/or S. ovalifolia. Most similar Tennessee
to S. montana but has glabrous foliage and
elongated internodes. Found in Mesic
hardwood forests.
S. saxatilis Riddell Violet and white 14–19 June–Aug. 5–15 cm racemes, weak stemmed plant Delaware to Indiana and southward
spreads by runners, stem is nearly smooth to South Carolina and Tennessee
but glands in the inflorescence. Leaf
triangular, sparsely hairy. Found along
rocky woods, talus slopes, bluffs.
S. serrata Andrews Blue 23–26 May–June Glabrous plant with smooth ovate leaves. New York to West Virginia, to
Flowers in racemes 8–10 cm long. Likes Missouri South Carolina,
rich woods and bluffs. Alabama

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