Introduction
Natural products have been an important source of medicinal agents throughout history and
modern medicine continues to rely on traditional knowledge for treatment of human maladies [1].
Traditional medicines such as Traditional Chinese Medicine [2], Ayurvedic [3], and medicinal plants
from Latin America [4] have proven to be rich resources of biologically active compounds and potential
new drugs. Several plant-derived drugs are in use today, including, for example, vinblastine (from
Catharanthus roseus (L.) G. Don, used to treat childhood leukemia); paclitaxel (from Taxus brevifolia Nutt., used to treat ovarian cancer); morphine (from Papaver somniferum L., used to treat pain); and quinine (from Cinchona spp., used to treat malaria) [5]. Not only are phytochemicals useful medicines in their own right, but compounds derived from them or inspired by them have become useful medicines [6,7].
For example, Artemisia annua L., a plant originally used in Traditional Chinese Medicine to treat fever,
is the source of artemisinin, a clinically-useful antimalarial sesquiterpenoid [8]; the antihypertensive
drug reserpine, isolated from the roots of Rauvolfia serpentina (L.) Benth. ex Kurz., has been used
in Ayurveda to treat insanity, epilepsy, insomnia, hysteria, eclampsia, as well as hypertension [9];
Dysphania ambrosioides (L.) Mosyakin and Clemants (syn. Chenopodium ambrosioides L.) is used in several Latin American cultures as an internal anthelmintic and external antiparasitic [4] and has shown
promise for treatment of cutaneous leishmaniasis [10].
The biological activity of D. ambrosioides has been attributed to the monoterpenoid endoperoxide ascaridole.
Unfortunately, much of the traditional medicine knowledge of Native North American peoples
has been lost due to population decimation and displacement from their native lands by European
conquerors (see, for example: [11–14]). Nevertheless, there are still some remaining sources of information about Native American ethnobotany [15,16]. In addition, there are several sources of
Cherokee ethnobotany [17–22].
The Cherokee Native Americans are a tribe of Iroquoian-language people who lived in the
southern part of the Appalachian Mountain region in present-day northern Georgia, eastern Tennessee, and western North Carolina and South Carolina at the time of European contact [13] (Figure 1A).
During and after the American Revolution, Cherokee wars with European settlers resulted in the
surrender of vast amounts of territory. Gold was discovered on Cherokee land in north Georgia
and the Treaty of New Echota (1835) ceded all Cherokee land east of the Mississippi River to the
United States. Congress passed the Indian Removal Act in 1830, and the forced eviction of as many as
16,000 Cherokee took place during the fall and winter of 1838–1839 to a new territory in north-eastern Oklahoma (Fibure 1B). During this “Trail of Tears”, an estimated one-fourth of the Cherokee died.
However, at the time of the removal, a few hundred Cherokee successfully escaped to the mountains
of western North Carolina, forming what is now the Eastern Band of Cherokee Indians.
In this review, I have consulted the ethnobotanical sources for plants used in Cherokee
traditional medicine [15–24] and I have carried out a literature search using Google Scholar, PubMed,
ResearchGate, and Science Direct for phytochemical analyses on the plant species. Note that in many
instances, the phytochemistry was determined by plants not collected in the south-eastern United
States; many of the species have been introduced to other parts of the world and some species are native to other continents besides North America. The phytochemistry, therefore, may be affected by the different geographical and climatic conditions [25]. Sources reporting the phytochemical constituents, regardless of geographical origin, have been included.
Medicines 2018, 5, x FOR PEER REVIEW 2 of 90
Unfortunately, much of the traditional medicine knowledge of Native North American peoples
has been lost due to population decimation and displacement from their native lands by European
conquerors (see, for example: [11–14]). Nevertheless, there are still some remaining sources of
information about Native American ethnobotany [15,16]. In addition, there are several sources of
Cherokee ethnobotany [17–22].
The Cherokee Native Americans are a tribe of Iroquoian-language people who lived in the
southern part of the Appalachian Mountain region in present-day northern Georgia, eastern
Tennessee, and western North Carolina and South Carolina at the time of European contact [13]
(Figure 1A). During and after the American Revolution, Cherokee wars with European settlers
resulted in the surrender of vast amounts of territory. Gold was discovered on Cherokee land in north
Georgia and the Treaty of New Echota (1835) ceded all Cherokee land east of the Mississippi River to
the United States. Congress passed the Indian Removal Act in 1830, and the forced eviction of as many
as 16,000 Cherokee took place during the fall and winter of 1838–1839 to a new territory in north-eastern Oklahoma (Fibure 1B). During this “Trail of Tears”, an estimated one-fourth of the Cherokee died.
However, at the time of the removal, a few hundred Cherokee successfully escaped to the mountains
of western North Carolina, forming what is now the Eastern Band of Cherokee Indians.
In this review, I have consulted the ethnobotanical sources for plants used in Cherokee
traditional medicine [15–24] and I have carried out a literature search using Google Scholar, PubMed,
ResearchGate, and Science Direct for phytochemical analyses on the plant species. Note that in many
instances, the phytochemistry was determined by plants not collected in the south-eastern United
States; many of the species have been introduced to other parts of the world and some species are
native to other continents besides North America. The phytochemistry, therefore, may be affected by
the different geographical and climatic conditions [25]. Sources reporting the phytochemical
constituents, regardless of geographical origin, have been included
Figure 1.(A)
Cherokee territorial lands [26]. (A) ′′Map of the former territorial limits of the Cherokee ′Nation of′ Indians′′, i.e., prior to displacement of Euro-Americans.
Cherokee Aromatic Medicinal Plants and Their Phytochemical Constituents
The plants used by the Cherokee people for traditional medicines for which the phytochemistry
has been investigated are summarized in Table 1.
Figure 1.(B)
"Map showing the territory originally assigned Cherokee ′Nation of′ Indians′′, i.e., after the forcible relocation known as the ′′Trail of Tears”
Achillea millefolium L
Achillea millefolium (yarrow) is native to temperate regions of the Northern Hemisphere but
has been introduced worldwide [510]. The traditional medical uses of A. millefolium have been
reviewed and the plant has been used since ancient times as a wound-healing agent and to treat
gastrointestinal complaints [510–512]. Consistent with this, the Cherokee have also used A. millefolium as an antihemorrhagic; for healing wounds, treating bloody hemorrhoids and bloody urine, and for bowel complaints [15,17,510]. In addition, infusions of A. millefolium have been used as a treatment for fever [15,17,510]. Yarrow extract has shown spasmogenic effects on murine and human gastric antrum, consistent with its traditional use to treat dyspepsia [513]. In a double-blind clinical trial, A. millefolium ointment was shown to reduce pain, inflammation, and ecchymosis in episiotomy wound healing [514].
The essential oils of A. millefolium have shown wide variation depending on geographical location
and growing season. Volatile oil samples from Turkey [48] and Macedonia [51] were dominated by
1,8-cineole and camphor, whereas the essential oil from Lavras, Brazil, was rich in chamazulene [49].
The essential oil from Lithuania showed wide variation in composition depending on morphological
type (flower color) as well as plant phenology [50]; γ-terpinene and cadinene (isomer not identified)
were the major components during the flowering phase, but β-pinene was abundant during the
vegetative phase. Conversely, A. millefolium leaf essential oil from Portugal was rich in 1,8-cineole
during the flowering phase, but germacrene D dominated the oil during the vegetative phase [53].
The non-volatile chemical components of A. millefolium are generally dominated by phenolics
(e.g., chlorogenic acid and other quinic acid derivatives) and flavonoids and flavonoid glycosides (e.g.,
luteolin, apigenin, and quercetin, and their glycosides) [38–42,44,46,47]. Chlorogenic acid has shown
in vivo wound-healing properties in rat models [515,516]. Likewise, the flavonoid apigenin [517,518]
as well as an apigenin glycoside [519] have shown in vivo wound-healing effects in rodent models.
Similarly, luteolin [520–522], luteolin-7-O-glucoside [523], quercetin [524–526] and several quercetin
glycosides [527–531] have shown wound-healing effects.
Caulophyllum thalictroides (L.) Michx.
A decoction of the roots of C. thalictroides (blue cohosh) has been used by the Cherokee as an
anticonvulsive (to treat “fits and hysterics”) and antirheumatic [15]. The plant is also used as a
gynecological aid, to promote childbirth and to treat womb inflammation [15].
These traditional uses are in apparent contrast to the observed toxic effects (convulsions, respiratory paralysis) of the plant observed in range animals such as sheep [108]. The rhizome of C. thalictroides contains several quinolizidine alkaloids, including N-methylcytisine (also known as caulophylline), baptifoline, anagyrine, and lupanine [108,110,112]. N-Methylcytisine is known to stimulate the central nervous system, and in high doses causes convulsions followed by paralysis [532]. Acute lupanine toxicity is characterized by neurotoxic effects including decreased cardiac contractility, blocking of ganglionic transmission and contraction of uterine smooth muscle [533].
This latter effect explains the traditional Cherokee use to promote childbirth. Apparently, lupanine, in lower doses, does not exhibit sub-chronic, chronic, reproductive, or mutagenic toxic effects [533].
Both N-methylcytisine [110] and anagyrine [534] have been shown to be teratogenic, however. The aporphine alkaloid magnoflorine, on the other hand, has shown sedative and anxiolytic effects [535] and may be responsible for the anti-convulsive and sedative uses of C. thalictroides in Cherokee traditional medicine.
Lee and co-workers [115] have shown that the oleanolic acid glycosides caulosides A–D exert
anti-inflammatory effects by way of inhibiting expression of inducible nitric oxide synthase (iNOS)
and the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6).
The anti-inflammatory effects of C. thalictroides triterpene saponins are consistent with the Cherokee
traditional uses to treat rheumatism and inflammation.
Cimicifuga racemosa (L.) Nutt. (syn. Actaea racemosa L.)
Black cohosh (C. racemosa) has been a popular herbal supplement for many years [536]. The plant
is reputed to possess anti-inflammatory, diuretic, sedative, and antitussive activities [511], and the root
has been reported to have estrogenic activity [537–539]. Fukinolic acid [137] and formononetin [511]
have been reported to be estrogenic constituents of C. racemosa rhizome.
The traditional Cherokee
use of C. racemosa rhizome to stimulate menstruation [15] is consistent with the reported estrogenic
activity. There have been conflicting reports regarding the estrogenic activity of C. racemosa rhizome,
however [540–542], and a survey of 13 populations of C. racemosa in the eastern United States failed
to detect the presence of formononetin [543]. Molecular docking studies have suggested that C.
racemosa triterpenoids are unlikely estrogen receptor binding agents, but any estrogenic activity of C.
racemosa extract is probably due to phenolic components such as cimicifugic acid A, cimicifugic acid B,
cimicifugic acid G, cimiciphenol, cimiciphenone, cimiracemate A, cimiracemate B, cimiracemate C,
cimiracemate D, and fukinolic acid [544]. Although recent evidence suggests the estrogen receptor not
to be a target of C. racemosa phytochemical constituents, other biomolecular targets may be involved.
Rhizome extracts of C. racemosa have been shown to interact with the serotonin receptor [545], the
µ-opioid receptor [546,547] as well as the γ-aminobutryic acid type A (GABAA) receptors [548].
Modulation of these receptors may contribute to some of the biological effects of C. racemosa extracts.
Reviews of several randomized clinical trials have failed to demonstrate efficacy of C. racemosa on
menopausal symptoms [549,550]. However, one randomized, placebo-controlled double-blind clinical
trial with menopausal women, concluded that C. racemosa extract showed superiority over a placebo
in ameliorating menopausal disorders [551]. Clinical studies have generally suggested C. cimicifuga
use to be safe, but there have been some case reports indicating safety concerns [552].
The Cherokee have also used infusions of C. racemosa rhizome to treat rheumatism, coughs,
and colds [15]. Aqueous extracts of C. racemosa have demonstrated reduction of the release
of pro-inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and
interferon-gamma (IFN-γ) in whole blood, and the prominent active component responsible was
isoferulic acid [553]. The ethyl acetate fraction of the aqueous extract of C. racemosa was also shown
to suppress the release of TNF-α, due to cimiracemate A [554]. Aqueous extracts reduced inducible
nitric oxide synthase (iNOS) protein expression as well as iNOS mRNA levels, but did not inhibit
iNOS enzymatic activity; the triterpenoid glycoside 23-epi-26-deoxyactein was found to be the active
principle in the extract [555]. These effects likely explain the anti-inflammatory activities of C. racemosaand their traditional uses to treat rheumatism and other inflammatory diseases.
Hamamelis virginiana L.
Hamamelis virginiana, American witch hazel, is a shrub or small tree, native to eastern North
America. Several Native American tribes have used the plant for numerous medicinal purposes.
Decoctions of the bark or the stems of witch hazel have been used as a topical lotion for cuts, bruises,
insect bites, external inflammations, and other skin problems [15]. In addition, the Cherokee people
took infusions of witch hazel for periodic pains, to treat colds, sore throats, and fevers. Modern
uses of witch hazel include treatment of hemorrhoids, inflammation of the mouth and pharynx
(leaf only), inflammation of the skin, varicose veins, wounds and burns [537]. Hamamelis virginiana
leaves contain up to 10% tannins, including gallic acid, polygalloylglucose, hamamelitannin and
analogs, flavonoids, and proanthocyanidins [511], which are responsible for the observed astringent,
anti-inflammatory, and hemostatic effects [537]. The bark also contains hamamelitannin and analogs,
and proanthocyanidins [511].
The aqueous ethanol extract of H. virginiana showed anti-inflammatory activity in the croton
oil mouse ear edema test [556] as well as the induced rat paw edema assay, confirming its use
as an anti-inflammatory agent [557]. The extract also showed notable antiviral activity against
Herpes simplex virus type 1 (HSV-1) [556]. Hamamelitannin and galloylated proanthocyanidins
from H. virginiana were found to be potent inhibitors of 5-lipoxygenase (5-LOX) [558]. Hamamelis
proanthocyanidins were found to stimulate cell growth of keratinocytes, enhancing cell growth, and
are likely responsible for the dermatological use of tannin-containing witch hazel preparations [559].
Hamamelis tannins have also shown cytotoxic activity against HT-29 human colorectal adenocarcinoma cells [223] and antiviral activity against influenza A virus and human papillomavirus [560].
The anti-inflammatory activity of witch hazel was demonstrated in a clinical study using a lotion
prepared from H. virginiana distillate, which showed suppression of erythema after ultraviolet (UVB)
light exposure [561]. Similarly, in a clinical trial with patients suffering from atopic eczema, a cream
containing H. virginiana distillate significantly reduced skin desquamation, itching and redness [562].
Of course, H. virginiana distillate will not contain tannins.
Hydrastis canadensis L.
Goldenseal (Hydrastis canadensis), a perennial herb in the Ranunculaceae, is native to eastern
North America from Ontario, Canada, south to Alabama and Georgia [563]. The Cherokee used the
root decoction of goldenseal as a tonic and wash for local inflammations; took the root decoction orally
to treat cancer, dyspepsia, and general debility [15]. Goldenseal is still used in herbal medicine to
control muscle spasms, treat cancer, increase blood pressure, treat gastrointestinal disorders, manage
painful and heavy menstruation, treat infections topically, and reduce swelling [537,564].
The major components in goldenseal root are isoquinoline alkaloids hydrastine, berberine, and
canadine, and berberine likely accounts for the biological activities of goldenseal. Berberine has
shown in vitro cytotoxic activity to HeLa human epitheloid cervix carcinoma, SK-OV-3 human
ovarian carcinoma, HEp2 human laryngeal carcinoma, HT-29 human colorectal adenocarcinoma,
MKN-45 human gastric cancer, HepG2 human hepatocellular carcinoma, MCF-7 and MDA-MB-231
human breast adenocarcinoma cell lines [565–568]. The cytotoxicity of berberine can be attributed
to DNA intercalation [569–571] and modulation of the human epidermal growth factor receptor 2
(HER2)/phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway [572,573].
Berberine has also shown antibacterial activity against Staphylococcus aureus [238,574], and Helicobacter pylori [453]; antiparasitic activity against Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis, Trypanosoma brucei, Trypanosoma congolense, Leishmania braziliensis panamensis, Leishmania major, and Plasmodium falciparum [575–578]; and anti-inflammatory activity in a serotonin-induced mouse paw edema assay [579]. In a randomized, double-blind, placebo-controlled clinical trial with patients suffering from acute watery diarrhea due to cholera, berberine showed a significant reduction in stool volume compared to the placebo [580]. Several clinical studies have demonstrated antihyperlipidemic effects of berberine in humans [581]
Juncus effusus L
Juncus effusus (common rush) is native to North and South America, Europe, Asia, and
Africa [563]. There are numerous varieties and subspecies of J. effusus with at least two in eastern
North America [582]. The Cherokee took a decoction of the plant as an emetic, while an infusion was
used to wash babies to strengthen them and prevent lameness [15]. In Chinese Traditional Medicine
(TCM), J. effusus is used as a sedative, anxiolytic, antipyretic, and to reduce swelling. Extracts of
J. effusus have revealed several cinnamoylglycerides [252,253], cycloartane triterpenoids [255–257],
phenanthrenes [258–264,266,267,269–272,583,584], and pyrenes [265,268]. Dehydroeffusol, effusol,
and juncusol, phenanthrenes isolated from J. effusus, have shown anxiolytic and sedative effects in a
mouse model [264,271], likely due to modulation of the gamma-amino butyric acid type A (GABAA)
receptor [272]. The GABAA modulatory activity may account for the TCM use of J. effusus as a sedative
and anxiolytic agent. Several J. effusus phenanthrenes have shown inhibition of NO production in
lipopolysaccharide (LPS)-activated murine macrophage RAW 264.7 cells, indicating anti-inflammatory
activity [270].
Panax quinquefolius L
American ginseng (Panax quinquefolius) is a member of the Araliaceae and is native to eastern
North America [585]. Ginseng root from P. ginseng or P. notoginseng, has been used for thousands
of years in the Asian traditional medicine. Panax quinquefolius is currently cultivated in the United
States, Canada, and China, and is used as a medical tonic worldwide. Native Americans have used P.
quinquefolius for numerous medical problems as well as a general tonic [15], and European settlers had
also utilized this plant for similar purposes [586]. The Cherokee used the root as an expectorant, to
treat colic, oral thrush, and as a general tonic [15].
The phytochemistry and pharmacology of P. quinquefolius has been reviewed several
times [333,339,341,342]. The major components in P. quinquefolius roots are triterpenoid glycosides,
the ginsenosides, as well as several polyacetylenes. The ginsenosides have shown anti-inflammatory,
antiproliferative, hepatoprotective, cardioprotective, neuroprotective, cholesterol-lowering, and
cognitive improvement [340].
Several clinical trials have been carried out using P. quinquefolius extracts. In terms of cognitive
function, a randomized, double-blind, placebo-controled crossover trial, P. quinquefolius extract showed significant improvement in working memory, choice reaction time and “calmness” [587]. A clinical trial to study the effects of P. quinquefolius extract on cancer-related fatigue showed a promising significant trend in relieving fatigue [588]. Panax quinquefolius extracts were found to be clinically effective in preventing upper respiratory infections in healthy adult senior citizens [589,590].
Sanguinaria canadensis L.
Bloodroot (Sanguinaria canadensis, Papaveraceae) is native to eastern North America [591]. The
plant has been used by Native Americans as a traditional medicine for a variety of ailments [455].
The Cherokee used a decoction of the root, in small doses, for coughs, lung inflammations, and
croup, and a root infusion was used as a wash for ulcers and sores [15]. The roots are rich in
isoquinoline alkaloids, including sanguinarine, chelerythrine, sanguilutine, chelilutine, sanguirubine,
chelirubine, protopine, and allocryptopine [455]. The traditional Cherokee uses of bloodroot as a cough
medicine/respiratory aid as well as for treating ulcers and sores can be attributed to the antimicrobial
activities of the isoquinoline alkaloids [592]. Thus, for example, sanguinarine has shown antimicrobial
activity against methicillin-resistant Staphylococcus aureus (MRSA) [593], biofilm-forming Candida
spp. [594], Mycobacterium spp. [452], and Helicobacter pylori [453].
Scutellaria lateriflora L
Infusions of the roots of blue skullcap (Scutellaria lateriflora, Lamiaceae) were used by the Cherokee
for monthly periods and to treat diarrhea; root decoctions were used as an emetic to expel afterbirth
and to remedy breast pains [15]. Interestingly, the aerial parts, rather than the roots, are currently used
as an herbal medicine as an anxiolytic, sedative and antispasmodic [511,537,595,596].
The phytochemistry and pharmacology of S. lateriflora have been reviewed [469].
The secondary metabolites from the aerial parts of S. lateriflora are dominated by flavonoid glycosides (baicalin, dihydrobaicalin, lateriflorin, ikonnikoside I, scutellarin (scutellarein-7-O-glucuronide), and oroxylin A-7-O-glucuronide, and 2-methoxy-chrysin-7-O-glucuronide), flavonoid aglycones (baicalein, oroxylin A, wogonin, and lateriflorein), phenylpropanoids (caffeic acid, cinnamic acid, p-coumaric acid, and ferulic acid), and clerodane diterpenoids (scutelaterin A, scutelaterin B, scutelaterin C, ajugapitin,
and scutecyprol A) [469]. The essential oil from the aerial parts of S. lateriflora (collected in northern
Iran) was composed largely of sesquiterpene hydrocarbons, δ-cadinene (27%), calamenene (15.2%),
β-elemene (9.2%), α-cubenene (4.2%), α-humulene (4.2%), and α-bergamotene (2.8%) [470].
The flavonoids scutellarin and baicalin and the phenylpropanoid ferulic acid have shown in vitro
estrogenic effects [597,598], and may be responsible for the traditional Cherokee uses of S. lateriflora.
Consistent with the current herbal medicinal use of S. lateriflora, the plant has shown
anti-convulsant activity in rodent models of acute seizures, attributable to the flavonoid
constituents [474]. Baicalin has shown anti-convulsant activity in pilocarpine-induced epileptic
model in rats [599], and wogonin has shown anti-convulsant effects on chemically-induced and
electroshock-induced seizures in rodents [600]. In addition, scutellarin has shown relaxant activity
using rodent aorta models [601,602], while wogonin showed smooth muscle relaxant activity in rat
aorta [603] and rat uterine smooth muscle [604]. On the other hand, both baicalin and baicalein
inhibited NO-mediated relaxation of rat aortic rings [605]. Baicalein and baicalin have shown
anxiolytic activity [606]. Apparently, baicalin and wogonin exert their anxiolytic effects through
allosteric modulation of the GABAA receptor by way of interaction at the benzodiazepine site [607,608].
Conversely, baicalein promotes anxiolytic effects via interaction with non-benzodiazepine sites of the
GABAA receptor [609]. There have apparently been no clinical trials on the root extracts of S. lateriflora.
However, in randomized, double-blind, placebo-controlled crossover clinical trials, the anxiolytic
effects of S. lateriflora herbal treatments significantly enhanced overall mood without reducing cognition
or energy [610,611]