Introduction
Ephedra plants are among the oldest and most popular herbs used in traditional medicine in
China and Japan [1 ], [2 ], [3 ]. Ephedrae herba has long been used as both medicine and food [4 ], [5 ]. It stands as an efficient anti-stroke herbal medicine [6 ]. Its use as a folk phytomedicine is mentioned in ancient medical books and traditional
prescriptions [3 ]. For example, the ancient Chinese medical book “Treatise on Febrile Diseases” refers
to the classic traditional Chinese medicine prescription Ge Gen decoction, which consists
of seven herbs, including an Ephedra species [7 ], and a Latin textbook from the roman naturalist Pliny the Elder (Gaius Plinius Secundus,
AD 23 – 79) underlined the use of Ephedra as follows: “it is given from
black austere wine, crushed, for coughs, sighs, convulsions, and drinking”
[8 ]. For decades, Ephedra species have provided herbal remedies to treat human diseases [9 ], [10 ]. These medicinal plants, largely distributed in arid and semiarid regions of the
world, also carry ecological and economic values [11 ], [12 ].
Over 60 Ephedra plants have been identified [4 ], [11 ]. The POWO database has listed 167 species, including 78 with accepted names (https://powo.science.kew.org/results?f = species_f%2Caccepted_names&q=Ephedra ). Ephedra species can be found in Europe, southern and eastern Asia (notably in China and Japan),
North America (southwestern United States and northern Mexico), the western part of
South America, and in Africa, from North Africa to the horn of Africa. Ephedra species grow in desert, arid, and semiarid conditions, most often on dry, rocky,
or sandy soil. They are often considered desert shrubs, but some species can be found
in riverbeds and grasslands [10 ], [13 ].
In traditional medicine, the uses of Ephedra species are extremely diversified. They are utilized to treat respiratory affections,
such as cough, symptoms of the common cold and asthma, or as a deobstruent or emollient.
These plants are also used to treat disorders of the cardiovascular and digestive
systems, ailments of the urinary tract, cancers, diabetes, as well as bacterial, viral,
and fungal infections [14 ], [15 ]. Other studies mention the use of Ephedra species for the treatment of edema, fever, and allergies [1 ], [2 ], [16 ], [17 ]. Ephedra extracts are also considered as dietary supplements, notably for weight loss [18 ], [19 ]. However, it is important to mention that despite the recognized benefits of Ephedra herbs on
human health, adverse effects have occasionally been recorded, such as excitation,
agitation, palpitation, dysuria, arrhythmia, elevated blood pressure, dizziness, and
insomnia [2 ], [20 ], [21 ]. These undesirable reactions were generally related to the presence of ephedrine-type
alkaloids [21 ], [22 ]. The alkaloid ephedrine, often present in Ephedra herb extracts, mediates sustained excitatory effects via activation of the α -2a adrenoceptor [23 ]. Over the past 10 years, the development of an ephedrine alkaloid-free Ephedra herb extract has been recommended for safer use by humans, with reduced side effects
[21 ], [22 ], [24 ], [25 ]. Ephedrine-free Ephedra herb extract and
derived products can be used to treat various diseases, including COVID-19, for example
[2 ], [26 ].
Ephedra species are used as medicinal plants in African and Mediterranean countries. For
example, the species Ephedra foeminea Forssk is a traditional medicinal plant in the Eastern Mediterranean region [27 ]. In Lebanon, this plant offers a popular remedy to treat inflammation and bacterial
infections [28 ]. The species Ephedra nebrodensis Tineo growing in Algeria is largely used to combat inflammatory and oxidative damage
[29 ], [30 ]. The two species Ephedra alata and Ephedra altissima growing in Tunisian arid zones are used traditionally to treat chills, coughs, fever,
and bronchial asthma [31 ]. In the present work, we have identified the Ephedra species used specifically in Morocco ([Fig. 1 ]). We inventoried their traditional medicinal uses by local populations
and the main bioactive products and associated pharmacological activities have been
analyzed. The aim of this analysis is to highlight the use of Ephedra species in Morocco, to encourage further studies on the plantʼs pharmacological activities,
and to try to provide a scientific rational for their medicinal usage.
Fig. 1 Illustrations of Ephedra species found in Morocco. a Ephedra alata , b Ephedra altissima , c Ephedra fragilis , and d Ephedra nebrodensis (by Jean-Paul Peltier, licensed under CC BY-NC 4.0.) e Ephedra distachya
[32 ]. Their traditional medicinal uses are either well described (+), not reported (−),
or remains questionable (*in the case of E. distachya ).
Results
Ephedra species around the world
Ephedra species are dispersed in arid and semiarid areas of Asia, Europe, Northern Africa,
southern North America, and South America [11 ]. The five species discussed in this paper are mainly present in North Africa and
Eurasia ([Fig. 2 ]). E. alata is located in North Africa and West Asia ([Fig. 2 a ]) [33 ], and was cited among the flora of Morocco [34 ], [35 ], [36 ], Algeria [37 ], Tunisia [38 ], [39 ], and Palestine [40 ]. E. altissima is limited to North Africa and the south of Europe [41 ] ([Fig. 2 b ]) [42 ], including countries such as Austria (botanical
garden) [43 ] and Morocco [44 ], [45 ], [46 ]. Ephedra distachya is the most abundant of these species and belongs to the extreme north of Africa
and Eurasia ([Fig. 2 c ]) [47 ]. Samples from China [48 ], Morocco [49 ], [50 ], Greece [51 ], Spain [52 ], Ukraine [53 ], and Austria [43 ] have been reported. Ephedra fragilis is distributed in North Africa and Europe ([Fig. 2 d ]) [54 ] as well as in Morocco [44 ], [55 ] and Austria [43 ]. Finally, Ephedra
nebrodensis, which has the lowest distribution, can be found in North Africa [56 ], Europe ([Fig. 2 e ]) [57 ], including Italy [58 ], [59 ] and Spain [52 ], Morocco [60 ], and Algeria [61 ]. Here, we will focus on Moroccan Ephedra species.
Fig. 2 Distribution of the five species of Ephedra around the world (maps defined from the Global Biodiversity Information Facility
[gbif.org]) [33 ], [42 ], [47 ], [54 ], [57 ].
Ephedra species found in Morocco and their medicinal uses
Several ethnobotanical surveys and floristic studies have been performed in different
regions of Morocco to take inventory of the flora species of the country. For example,
recent studies refer to the medicinal plants used traditionally in the Safi and Sefrou
provinces [62 ], [63 ] or the Ksar Elkebir [64 ] and Tafilalet regions [65 ]. Toxic plants found in northeastern Morocco have been inventoried as well [20 ]. Other studies cover different local areas or they are concerned with specific pathology
or disorders, such as the Moroccan plants used to treat cancers [14 ], [66 ], skin affections [67 ], kidney diseases [68 ], or cardiovascular diseases [69 ]. Some Moroccan plants have been largely
studied, such as the endemic argan [Argania spinosa (L.) Skeels], which is well known for its famous oil extracted from argan seeds [70 ]. However, there is no study focused on Moroccan Ephedra species and their medicinal uses. We performed this specific analysis.
We identified five medicinal Ephedra species present in Morocco, namely, E. alata, E. altissima, E. distachya, E. fragilis , and E. nebrodensis ([Fig. 1 ] and [Table 1 ]). They are essentially located in the southern part of the country, but also in
the Middle and High Atlas Mountains. The ethnobotanical information on Moroccan Ephedra is limited, probably because the density of the population is low in south Morocco
and because of the aridity of the region. Ephedra species are not abundant compared to other plants. For example, Abouri and coworkers
identified 163 plant species representing 134 genera in the Tata province (south-eastern
Morocco) but only one Ephedra species, E. alata Decne. (known locally as Tamatrt), which is used traditionally mainly to treat colds
and respiratory ailments. Ephedracea appeared to be rare in this part of the country,
in contrast to
Lamiaceae and Asteraceae, which are much more abundant [34 ]. The situation is a little more favorable in the Middle and High Atlas Range, with
a more frequent presence of Ephedra species, such as E. nebrodensis Guss. found on the rocky ecosystem (from 2200 meters) [56 ].
Table 1 Ephedra species of Morocco and their locations.
Ephedra species
Location in Morocco
Reference
Ephedra alata
Laâyoune Sakia El Hamra region
[35 ]
Tarfaya Province
[36 ]
Tata Province
[34 ]
Ephedra altissima
Atlas Mountains, Imouzzer region
[44 ], [45 ], [46 ]
Ephedra fragilis
Southern Morocco
[71 ], [72 ]
Oulad Teima, Taroudant
[44 ], [55 ]
Ephedra nebrodensis
Central Middle Atlas
[15 ]
High Atlas
[60 ]
Tichoukt Mountain, Middle Atlas
[56 ]
Ephedra distachya
Southern Morocco
[49 ], [50 ]
The five Ephedra species present in Morocco are used traditionally to treat different diseases ([Table 2 ]). Four of them are well referenced, but there is no published information on the
local (Moroccan) use of E. distachya L. to treat human diseases. However, this plant is cited as a medicinal plant in
other countries, owing to its content of catechins and other polyphenolic compounds
with antioxidant and anti-inflammatory properties [73 ], [74 ]. We choose to maintain this species in our analysis because the presence of the
plant in Morocco has been clearly mentioned [49 ], [50 ] and practitioners have cited this species also. Two other Ephedra species are present in Morocco, Ephedra foliata Boiss. ex C. A.Mey. and Ephedra major Host, but we did not identify any study pertaining to the traditional
medicinal use of these species. For this reason, we did not consider them in our study
([Fig. 1 ]). The most frequently cited species is E. alata Decne. followed by E. altissima Desf., E. fragilis Desf., and then E. nebrodensis Tineo. This latter species can be commonly found in other Mediterranean countries
such as Algeria and Italy [29 ], [58 ] and more rarely in other parts of the word, such as Pakistan [75 ]. Altogether, they are used locally to treat a variety of human diseases, such as
asthma, rheumatism, hypertension, diabetes, cancer, and other pathologies or conditions
([Table 2 ]). The aerial parts of the plants are used to make decoctions from the leaves or
stems. E. alata is the most frequently used Ephedra species in the form of decoction (powdered branches) or infusion (leaves) and
the preparations are used orally or inhaled to treat respiratory ailments. There is
also a mention of massage using a decoction to treat rheumatoid arthritis [34 ]. Decoctions made from the aerial parts of E. altissima are used to treat diabetes and cancer. However, this product should be used with
care because it can induce neurological damages, notably dizziness or vertigo [20 ]. E. alata is perhaps a safer species, with no major toxicity reported, in particular, no hallucinogenic
effect when a plant decoction is used for oral treatment of diabetes in the Zagora
region of Morocco [76 ]. However, caution is required because Ephedra preparations containing the alkaloid ephedrine may cause hypotension and spontaneous
abortion in pregnant women [77 ].
Table 2 Medicinal traditional uses of Ephedra species from Morocco.
Ephedra
species
Local vernacular name
Therapeutic traditional uses
Part of the plant used
Method of preparation
Moroccan study area
References
Ephedra nebrodensis
Timitrte
Antidiabetic
Leaves
Leaf decoction associated with Apium graveolens and Petroselinum sativum
Central Middle Atlas region
[15 ]
Ephedra alata
Daghmous
Cancer
Leaves, stems
Decoction (oral administration)
Greater Casablanca
[14 ]
Chdida
Rheumatism, colds
Leaves, stems
Oral powder
Tarfaya Province
[36 ]
Andla
Cancer
Leaves
Infusion, powder for internal or external uses
[66 ]
Amater
Asthma, arthritis/rheumatoid
Stems
Decoction (oral/ointment)
[78 ]
Tamatrt
To gain weight, calefacient, diabetes, asthma, hypertension, colds, influenza, respiratory
ailments, rheumatoid arthritis
Leaves, branches
Oral, inhalation, massage
Tata Province
[34 ]
Diabetes
Leaves
Decoction powder/oral
Zagora
[76 ]
Ephedra altissima
Tougel argan
Diabetes
Stems, leaves, and whole plant
Decoction/oral
Chtouka Ait Baha and Tiznit (Western Anti-Atlas)
[79 ]
Laâlenda
Abortion
Stems
[80 ]
Laâlenda
Cancer
Aerial part
Internal uses
Northeastern Morocco
[20 ]
Ephedra fragilis
Azrm
Hair care and diabetes
Aerial part
Decoction
Northeastern
[81 ]
Amater
Diabetes
Leafy stems
Decoction/oral
Taroudant Province
[82 ]
Pharmacological activities of Ephedra extracts and associated bioactive products
Experimental studies performed with plant extracts made from Moroccan Ephedra are rare, but there are a few useful reports ([Table 3 ]) that can be completed with studies using the same species collected from other
countries. Thereafter, the plant extract activities are discussed in turn.
Table 3 Studies about Ephedra species from Morocco.
Ephedra species
Plant part and preparation used
Main activity studied
Results
References
Ephedra alata
Aerial parts, ethanol extract
Enzyme inhibitory and antioxidant activities; extraction of isoquercetin
Antioxidant and inhibitory activities against diverse enzymes (acetyl- and butyryl-cholinesterase,
α -amylase, elastase, hyaluronidase). Optimization of the extraction process for isoquercetin
(recovery: 1034 µg/g of extract using optimized parameters: EtOH concentration, liquid-solid
ratio, extraction time, extraction temperature, and ultrasonic power).
[35 ]
Ephedra altissima
Roots, methanolic extract
Anti-staphylococcal activity
Antibacterial activities of the extract, notably against Staphylococcus epidermidis and two strains of Staphylococcus aureus .
[45 ]
Roots, methanolic extract
Antileishmanial activity
The alcoholic extract was found active against Leishmania infantum (IC50 = 490.8 µg/mL).
[46 ]
Ephedra fragilis
Aerial parts, several organic extracts
Antioxidant, anti-glycation activities; chemical composition
Marked antioxidant activity of the ethyl acetate fraction. Identification of rutin,
quercetin, caffeic, ferulic acid, gallic acid, and vanillic acid.
[55 ]
Aerial parts, ethyl acetate extract
Cytoprotective effect
Protection of Tetrahymena pyriformis cells from oxidative stress induced by hydrogen peroxide.
[83 ]
Ephedra alata Decne
The dried aerial parts of a sample of E. alata collected from the Laâyoune Sakia El Hamra region (Morocco) have been used to prepare
a plant extract via an ultrasound-assisted extraction process with the objective of
optimizing the yield of the main active ingredient from the extract, the flavonoid
glycoside isoquercetin [35 ]. The process afforded more than 1 mg of isoquercetin per gram of extract. The isoquercetin-enriched
extract was shown to display higher antioxidant and enzymatic effects than a classical
extract obtained with a conventional Soxhlet extraction. The enriched extract showed
a higher inhibitory efficiency against different enzymes, such as elastase and collagenase
implicated in skin aging, tyrosinase involved in hyperpigmentation, α- amylase playing a role in diabetes, hyaluronidase involved in inflammation processes,
and cholinesterase implicated in some neurodegenerative disorders. The content of
isoquercetin
was largely enhanced and the associated bioactivities reinforced [35 ]. Isoquercetin (quercetin 3-glucoside, also called isoquercitrin) ([Fig. 3 ]) is a major constituent of E. alata and a well-known flavonoid found in a variety of plants, with anti-neuroinflammatory
and anticancer activities [84 ], [85 ], [86 ], [87 ]. Recently, this compound has been characterized as a promising molecule for the
treatment of osteoporosis [88 ].
Fig. 3 E. alata with the extraction and purification process developed to efficiently extract isoquercetin
[35 ] (photo of the plant from POWO [https://powo.science.kew.org ]).
E. alata is one of the medicinal plants used to treat cancer in Morocco [14 ], [66 ] and in other countries, such as Algeria and Palestine (East Jerusalem) [89 ], [90 ]. Methanolic or ethanolic extracts made from the plant have revealed marked inhibitory
effects on the proliferation of breast cancer cell lines in vitro . The activity has been associated with the presence of diverse flavonoids, phenolic
acids, and proanthocyanidins [37 ], [91 ], [92 ], [93 ]. A recent study evidenced the induction of tumor cell apoptosis in a p53-dependent
manner by an ethanolic extract of E. alata (with a specimen from Algeria) [94 ]. Isoquercetin contributes to the anticancer effects in conjunction with other glycosylated
flavonoids, such as luteolin-7-O -glucuronide and myricetin-3-rhamnoside, which have been characterized in a sample
of a wild E. alata plant [40 ]. Other bioactivities have been characterized with E. alata extracts, including antioxidant and anti-inflammatory effects [16 ], notably associated with the presence of glycosylated flavonoids such as isorhamnetin-3-O -rutinoside, isoschaftoside, and kaempferol-3-O -rhamnoside [95 ]. There is also mention of antidiabetic and antibacterial activities with this plant
[96 ], [97 ], [98 ], [99 ]. Aqueous extracts of E. alata contain diverse flavonoids but also alkaloids, phenolic compounds, and steroids useful
to improve wound healing [100 ].
Ephedra altissima Desf.
This Ephedra species is native to the north of Africa (Morocco, Algeria, Tunisia, Libya, and Mauritania),
the Canary Islands, and Chad. A plant sample collected in the Atlas Mountains in the
Imouzzer region of Morocco has been used to prepare both aqueous and methanolic extracts
of E. altissima that were then tested for their antibacterial activities. The aqueous extracts were
found inactive, whereas methanolic extracts made from the plant roots revealed a modest
activity against Staphylococcus aureus [strain ATCC 29 213, which is a classical methicillin-resistant (MRSA) strain]. The
antibacterial activity was noticeable but weak compared to that measured with other
Moroccan plants, such as Berberis hispanica , for example [45 ]. The authors also evaluated the capacity of the plant extracts to inhibit the growth
of the promastigote forms of Leishmania parasites, responsible for cutaneous leishmaniasis. The
extract from E. altissima revealed a modest activity against Leishmania infantum (IC50 = 490.8 µg/mL) [46 ]. These are the only studies performed with samples of E. altissima collected in Morocco.
Other studies have evaluated the bioactivities of E. altissima extracts but with plant specimens collected from other countries. In particular,
a recent work evidenced the antibacterial effects of an ethyl acetate extract from
an Algerian sample of the plant (collected in Bouhmama County). It revealed inhibitory
activities against the two enzymes, α -amylase (IC50 = 8.07 µg/mL) and pancreatic lipase (IC50 = 289.1 µg/mL), coupled with an anti-inflammatory effect (IC50 = 126.4 µg/mL), possibly explaining the activity of the plant against type 2 diabetes
[101 ]. The activity has been associated with the presence of flavone glycosides, such
as isovitexin-2-O -rhamnoside, kaempferol-3-O -rhamnoside, and quercetin-3-O -rhamnoside found in the ethyl acetate extract [102 ]. The flavonoid content is higher in E. altissima compared to E. alata . This
has been evidenced when comparing the seeds of the two plants (both collected in Southern
Tunisia). The former contained significantly more flavonoids but also more polyphenols
and more condensed tannins than the latter species. As a result, the antioxidant potential
of an E. altissima seed extract was found to be markedly higher than that of an E. alata seed extract. The predominant bioactive natural products were gallic acid, quercetin,
epicatechin, naringin, and the atypical flavone cirsiliol (3′,4′,5-trihydroxy-6,7-dimethoxyflavone)
[31 ] ([Fig. 4 a ]). Cirsiliol is an interesting compound regulator of mitophagy in cancer cells [103 ], apparently acting as an inhibitor of tyrosine kinase TYK2 (KD = 0.8 µM) in cancer cells and tumors [104 ]. Its anticancer effects have been well evidenced using different cell lines and
tumor models in
recent years [105 ], [106 ]. It is also a potent antioxidant molecule capable of binding to the enzyme F1 Fo -ATP synthase [107 ] and a compound that can mitigate amyloid-β (Aβ ) aggregation, therefore being of potential interest to treat neurodegenerative disorders
[108 ]. This compound is probably a major contributor to the bioactivities of E. altissima .
Fig. 4 E. altissima with the extraction process used to extract various natural products from the seeds,
including the flavonoid cirsiliol or the glutamate uptake inhibitor L-CCG III (cis -α -(carboxycyclopropyl) glycine) from the fresh stems of the plant (photo of the plant
from https://www.teline.fr ; photo credit: Jean-Claude Thiaudière).
The plant contains many other compounds, including alkaloids, tannins, saponins, and
cardiac glycosides, identified after extraction with various organic solvents, notably
with the plant leaves extracted with ethanol [109 ]. Phenols, sterols, saponins, tannins, terpenoids, flavonoids, and alkaloids have
also been identified in an E. altissima stem methanolic extract, and this extract was found to affect male mice reproductive
functions [110 ]. The same methanolic extract was found to exhibit a dose-dependent (500 – 3000 mg/kg)
central nervous system depression and a mild antipsychotic activity without anxiolytic-like
effects in mice [111 ]. It is interesting to note that the fresh stems of this species contain neither
ephedrine nor pseudoephedrine, but they contain substantial amounts of the two cis -diastereoisomers of the L-glutamate analogue
(2S ,3S ,4R )-2-carboxycyclopropyl)-glycine (L-CCGIII) and (2S ,3R ,4S )-2-(carboxycyclopropyl) glycine (L-CCGIV) ([Fig. 4 b ]). These two rare 2-(carboxycyclopropyl)-glycine (CCG) derivatives (which constitute
about 1% of the stem dry weight in the plant) alter neurotransmission. They selectively
activate subgroups of glutamate receptors depending on stereochemistry. In mammalian
neurons, L-CCGIII potentiates responsiveness to L-glutamate and L-CCGIV activates
the N -methyl D-aspartate (NMDA) subtype of the L-glutamate receptor [112 ]. These compounds provided the foundation for the design of novel modulators of NMDA
receptors [113 ].
Ephedra nebrodensis Tineo (ex Guss.).
This Ephedra species is a Mediterranean medicinal plant well distributed in Morocco and Algeria
and is also found in Italy. It is a Macaronesian-Mediterranean nanophanerophyte growing
in dry and rocky places [114 ]. A 1 : 1 ethanolic : acetone crude extract prepared from the aerial parts of a plant
sample collected in Urzulei (Sardinia, Italy) has shown antioxidant and hypotensive
effects, as well as antinociceptive and anti-inflammatory activities. The presence
of ephredrine-type alkaloids was suspected [59 ]. The presence of ephedrine and pseudoephedrine ([Fig. 5 ]) was evidenced later when Hamoudi and coworkers performed a phytochemical screening
of the same plant (aerial parts) collected in Algeria. They identified the alkaloids
together with phenolic compounds and a large fraction of flavonoids with antioxidant
properties [29 ], [61 ]. They further characterized the antioxidant, anti-inflammatory, and analgesic effects
of a hydroalcoholic extract of E. nebrodensis , notably a marked dose-dependent capacity to reduce croton oil-induced ear edema
in mice. The antioxidant effect has been correlated to the high content of polyphenolics,
flavonoids, and tannins [30 ], [61 ]. Cell protective effects were also observed. A 1 : 1 ethanolic : acetone extract
from the aerial parts of the plant (collected from Arzana Province, Sardinia, Italy)
has shown a protective effect against cardiovascular damages induced by the anticancer
drug doxorubicin in rats. The level of the antioxidant defense enzymes (GSH and SOD)
was increased and lipid peroxidation was reduced [115 ]. A phytochemical analysis performed using an essential oil from the related species
E. nebrodensis Tineo ex Guss. subsp.
nebrodensis (from Italy) has shown the presence of numerous volatile sesquiterpene hydrocarbons
(citronellol, β -patchoulene, etc.) [116 ], [117 ]. Much the same type of terpenes have been found in other Ephedra -based volatile oils, such as (E)-phytol (10.1% in the oil of E. fragilis ), and benzaldehyde and cis -calamenene (8.0 and 3.6%, respectively, in the oil of E. distachya ) [118 ]. Two phenolic glycosides designated nebrodensides A and B ([Fig. 5 ]) have been isolated from the aerial parts of this plant, together with (−)-epicatechin
and (−)-ephedrine. The two compounds were found inactive against proliferation of
Madin-Darby canine kidney (MDCK) cells and the influenza A virus [58 ]. Nebrodenside A has been found in Dodonaea viscosa (L.) (Spindacea) and shown to exert
anti-inflammatory and analgesic properties [119 ]. The compound has been isolated from the herb Leontopodium leontopodioides (Willd.) Beauv. (Asteraceae) and characterized as a modest inhibitor of lipase and
α -glucosidase enzymes (IC50 = 12.3 and 6.1 µM, respectively) [120 ]. The same product was isolated from the aerial parts of Phagnalons ordidum L. (also Asteraceae) and shown to exert antioxidant activity [121 ]. Recently, a computational study has suggested that this compound could be used
as an inhibitor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible
for COVID-19, owing to its capacity to bind to the receptor-binding domain of the
virus Spike glycoprotein [122 ].
Fig. 5 E. nebrodensis and the chemical structures of alkaloids ephedrine and pseudoephedrine and the two
phenolic glycosides nebrodensides A – B (photo of the plant from https://www.teline.fr ; photo credit: Jean-Paul Peltier).
Ephedra fragilis Desf.
The evergreen species E. fragilis (vernacular name: joint pine) is a fleshy-fruited tall scrambling shrub (up to 1.8 m)
growing essentially on rocky hills and stone walls. It is native to the eastern Mediterranean
region of southern Europe and Northern Africa, and from Madeira and the Canary Islands
(Spain). It grows primarily in the subtropical biome. Small animals are important
contributors to the dispersion of the plant seeds, such as the frugivorous Balearic
lizard Podarcis lilfordi Günter (Lacertidae) [123 ], [124 ]. Through its intense frugivorous activity, this lizard plays a more important role
than insects in pollination and seed dispersal [125 ] ([Fig. 6 ]).
Fig. 6 E. fragilis (stems) with a representation of the frugivorous lizard Podarcis lilfordi , which consumes the plant seeds and importantly contributes to their dispersion.
The phenolic compound gallic acid (isolated from the stems) contributes to the antioxidant
properties of the extract through interaction with the receptor for advanced glycation
end products (RAGE; molecular structure from PDB: 2MOV) (photo of the plant from https://www.teline.fr ; photo credit: Jean-Paul Peltier).
In Morocco, the plant can be found in the Souss-Massa region (Taroudant Province).
An authenticated sample collected in the city of Oulad Teima, near Taroudant, has
led to the preparation of an ethanolic extract further fractionated using ethyl acetate
(EA). This EA fraction has revealed a high content of phenolic and flavonoid compounds
and strong antioxidant activity. The fraction protected cultured cells (from Tetrahymena pyriformis ) against oxidative stress injury induced by hydrogen peroxide, protecting these cells
from DNA damage and metabolic oxidation. The extract showed potent antioxidant activities
[55 ]. The extraction process has been optimized and several bioactive compounds were
isolated from the modified EA fraction, notably four phenolic compounds (caffeic acid,
ferulic acid, gallic acid, and vanillic acid) and two conventional flavonoids (rutin
and quercetin). The phenolic derivatives were characterized as the main
components responsible for both antioxidant and antiglycation activities of the extract
[83 ]. A complementary molecular modeling analysis (in silico ) suggested that gallic acid can form stable complexes with the receptor for advanced
glycation end product (RAGE) [83 ] ([Fig. 6 ]). This is not surprising because these phenolic derivatives present high affinities
for the different proteins of the HMGB1/RAGE/NF-κ B signaling pathway and gallic acid is known to reduce the risk of AGE-mediated cellular
complications, preventing fibrosis induced by advanced glycation end products [126 ], [127 ], [128 ].
Total organic carbon (TOC) is particularly high in E. fragilis compared to other plants growing on semiarid Mediterranean soils [129 ]. Nevertheless, this species contains many less phenolic compounds than the other
studied Ephedra species (notably 8-fold less phenols than E. alata ) and less flavonoids as well, but a high content in ephedrine alkaloids [43 ]. The main characteristic of E. fragilis is the presence of the two alkaloids, pseudoephedrine and ephedrine, in the different
parts of the plants. Pseudoephedrine is a stereoisomer of ephedrine ([Fig. 5 ]) that is commonly used as a nasal decongestant in combination with other anti-inflammatory
drugs for the symptomatic treatment of some common pathologies such as the common
cold. The alkaloid content is very high in E. fragilis flowers, which contain both alkaloids (1.86%) whereas the seeds
essentially contain pseudoephedrine (0.62%) and the branches a little quantity of
ephedrine (0.054%), as determined with a specimen of E. fragilis from Malta [130 ]. Ephedrine and pseudoephedrine can exert immunomodulatory activities. Notably, pseudoephedrine
has been shown to modulate T cell activation, via the inhibition of interleukin-2
(IL-2) and TNF-α gene transcription in stimulated Jurkat T cells, thereby inhibiting the transcriptional
activity of proteins JNK and AP-1 (activator protein-1) [131 ]. Similar T cell deactivation effects have been reported with caffeic acid [132 ]. It is therefore not surprising to observe that a plant extract containing the same
type of phenolic compounds and alkaloids (with α -adrenoceptor activity) can also affect lymphocyte activities. Ephedrine has been
shown to attenuate oxidative damages in epithelial cells, through
regulation of endoplasmic reticulum (ER) stress [133 ].
Several studies have underlined the anti-inflammatory action of ephedrine and ephedrine-containing
extracts from various Ephedra species [16 ], [134 ], [135 ], [136 ]. An extract of E. fragilis made from a Tunisian specimen revealed dose-dependent anti-inflammatory effects,
with inhibition of the production of nitric oxide (NO) in lipopolysaccharide-stimulated
RAW 264.7 macrophages. The ethanolic extract contained high levels of both caffeic
acid and hydroxycinnamic acid [137 ]. This latter compound notoriously exerts antioxidant activity and modulates proinflammatory
cytokines [138 ].
Ephedra distachya L.
This shrub species (also known as Ephedra vulgaris Rich. or sea grape) is a major component of desert vegetation. It can be found in
North Africa (Morocco, Algeria) but also in sand dunes of temperate deserts, such
as the Gurbantünggüt desert in the Junggar Basin (northwestern China), and in Central
Asia, for example [139 ], [140 ]. It can be found as well in clay steppes of the Ulyanovsk region in Russia [141 ], the Balkan Peninsula in Serbia [142 ], and the dunes of Letea in Romania [143 ], [144 ].
From a phytochemical viewpoint, this species has been less investigated than the other
aforementioned species. This herb is rich in catechins, which possess antioxidant
activities [145 ], and also contains large amounts of pseudoephedrine (1.25 – 1.59% of dry weight),
a sympathomimetic used to treat symptoms of the common cold and flu, sinusitis, asthma,
and bronchitis [74 ]. The subspecies E. distachya subsp. helvetica (from Vienna, Austria) was shown to contain 20.8 mg of (pseudo)ephedrine per gram
of dry weight, which is less than the content in E. fragilis (27.1 mg/g) [43 ]. However, the ephedrine content may vary substantially from one plant to another
because another study indicated that ephedrine was not detected in the species E. distachya subsp. helvetica
[146 ]. Its content in phenolic and flavonoid compounds is not
particularly high (largely inferior to that found in E. alata , for example), but this species does present a high content of total alkaloids (15.8 mg/g
compared to 0.2 mg/g in E. fragilis ) [43 ]. These alkaloids have not been characterized formally but the phylogenetic similarities
between E. distachya and the well-studied analogous species Ephedra sinica
[147 ] suggest that it may contain similar alkaloids such as the ephedrannins largely present
in E. sinica
[148 ]. Cell suspension cultures (callus) of E. distachya have been developed and used to elicit the production of phytoalexin p -coumaroylamino acids by the addition of a yeast extract to the culture [149 ], [150 ], [151 ].
A characteristic of E. distachya is the content in glycans called ephedrans A, B, C, D, and E, with hypoglycemic and
antioxidant activities [48 ] ([Fig. 7 ]). They have a different molecular mass (from 6.6 × 103 to 1.5 × 106 Da) and varied monosaccharide compositions, with the presence of trehalose and xylose
in ephedrans A and B, and various proportion of rhamnose and arabinose [148 ]. These polysaccharides also display anti-inflammatory activity [152 ]. Similar polysaccharides with antihypertensive and antioxidant activities have been
characterized in other species, such as E. alata
[153 ].
Fig. 7 E. distachya (stems) from which the polysaccharides ephedrans A – E can be isolated. These water-soluble
polymers exhibit antioxidant and hypoglycemic properties [35 ] (photo of the plant from https://inpn.mnhn.fr ; photo credit: P. Rouveyrol).
Clinical trials with Ephedra -based products
Medicinal products containing Ephedra extracts or ephedrine are not frequently used nowadays due to the adverse effects
reported with Ephedra preparations in the past (see Discussion below). However, there are rare clinical
trials that concern Ephedra , notably with Chinese medicines containing Mahuang (Ephedrae herba). For example,
trial NCT03733873 has evaluated the Ephedra -containing Chinese medicine Suoquan for the treatment of nocturnal enuresis [154 ]. Trial NCT00432991 evaluated the effect of intramuscular ephedrine on the incidence
of nausea and vomiting in women during and after a Cesarean section. The objective
was to reduce or prevent hypotension [155 ]. Ephedrine and phenylephrine can be safely used to counteract hypotension after
spinal anesthesia in obstetric patients, but the safety of the product administration
requires careful monitoring [156 ], [157 ]. We will not discuss further ephedrine-based trials so as to maintain a focus on
Ephedra plants and extracts.
Discussion
Plants of the Ephedraceae family and Ephedra species in particular are used in many countries all over the world to treat human
diseases. One of the most popular Ephedra -based medicinal herbs is the one called Mahuang in Chinese, which corresponds to
the herbaceous stem of E. sinica Stapf, Ephedra intermedia Schrenk et C. A. Mey., and Ephedra equisetina Bge. [158 ]. Mahuang decoctions (Ephedrae herba) are largely used in China to treat asthma,
liver disease, skin disease, and other diseases [4 ], [5 ]. Ephedrae herba (Maoto) is also used in traditional Japanese medicine (Kampo) [159 ], [160 ], based notably on the cultivation of E. sinica
[161 ]. The same species is also used in the Republic of Korea, notably to combat obesity
[162 ], [163 ]. Ephedra species can be found on all continents and many of them are associated with traditional
medicinal usage. The bracts of Ephedra cones have played a crucial role in long-distance seed dispersal that is responsible
for a wide distribution of the genus in semiarid and arid areas of Eurasia, North
Africa, North America, and South America [164 ]. Ephedra species are commonly exploited for their anti-inflammatory, anticancer, antibacterial,
antioxidant, hepatoprotective, anti-obesity, antiviral, and diuretic activities [11 ], [148 ]. To our knowledge, seven Ephedra species are present in Morocco, including five used traditionally to treat diverse
symptoms and/or pathologies (Fig. [1 ]). Four species are clearly listed as being used to treat inflammatory diseases (such
as rheumatism) or
other pathologies: E. alata (the most frequently used species), E. altissima, E. fragilis , and E. nebrodensis . The ethnobotanical use of E. distachya in Morocco is very likely, but firm evidence is lacking. Nevertheless, this species
is with no doubt a medicinal plant used in the surrounding Mediterranean area.
The medicinal activities of Moroccan Ephedra extracts can be linked to the presence of diverse bioactive products, in particular
ephedrine-type alkaloids and glycosylated flavonoids. Among the many beneficial flavonoids,
one can underline the anti-inflammatory action of isoschaftoside found in E. alata , for example [95 ]. This compound is a potent antioxidant and an anti-inflammatory agent with an anti-steatosis
activity useful to combat metabolic liver disease [165 ], [166 ]. Other flavonol glycosides, such as isorhamnetin-3-O -rutinoside, contribute similarly to the antioxidant and anti-inflammatory effects
[16 ]. This compound is also a proapoptotic agent, useful to limit the growth of cancer
cells [167 ]. It would be interesting to apply network pharmacology approaches to determine how
these different metabolites
participate and cooperate to promote the activity of the plant extract. This type
of approach has proved useful to predict the combinatorial effects of Ephedrae herba
components [162 ], [168 ], [169 ], [170 ].
Evidently, alkaloids are essential components of the extracts, most of them containing
either ephedrine and/or pseudoephedrine. Their content varies from one Ephedra species to another, depending on diverse plant growth parameters, such as altitude.
It has been observed recently with another species (Ephedra saxatilis ) that the ephedrine content increased as the altitude gradient increased, and pseudoephedrine
decreased as the altitude gradient decreased [171 ]. There is also a seasonal variation of the alkaloid content [161 ]. Their concentrations vary greatly according to plant species, the collection location,
and cultivation conditions [172 ], [173 ]. Both ephedrine and pseudoephedrine are key medicinal components of almost all Ephedra , and their contents in Ephedra formulations can be precisely estimated from the compounding
amount of the starting Ephedra plant [160 ]. They are useful medications to prevent or treat hypotension, for example, owing
to their indirect sympathomimetic pharmacodynamic properties [174 ] but their use remains controversial, because they can also induce cardiovascular
side effects, including stroke and heart attack [175 ], [176 ]. Pseudoephedrine was considered potentially more useful than ephedrine due to its
anorexigenic effect and its capacity to influence lipolysis and thermogenesis. But
the use of this product is also associated with effects on the cardiovascular and
central nervous systems. Its prescription to obese patients is not at all recommended
[177 ]. These considerations have prompted the development of ephedrine alkaloid-free Ephedra herb extracts [21 ], [24 ], [178 ]. Beyond flavonoids and alkaloids, Ephedra extracts also contain useful terpenoids, carboxylic acids, tannins, and other types
of constituents such as unsaturated fatty acids [55 ], [97 ], [179 ], [180 ]. The polysaccharides found in the stems of E. alata are particularly interesting
products due to their contribution to the antihypertensive and antioxidant activities
of the extracts [153 ]. Ephedra polysaccharides warrant further consideration to improve their identification and
contribution to extract activities [181 ], [182 ].
Ephedrine was well recognized as a dependable asthma treatment in the Western world
by the mid-1930 s. Primitive inhalers were created to provide ephedrine alkaloids,
and they become the main oral asthma medications in the 1940 s and 1950 s [3 ]. Ephedrine was widely used and readily available, but over time, it was realized
that the alkaloid was more toxic than initially thought.
Ephedra was appointed as a weight-loss and energy-enhancement supplement in the US in the
1990 s and early 2000 s. It was categorized as an herbal supplement under the Dietary
Supplement Health and Education 1994 [183 ], [184 ]. No evidence proved Ephedra’ s effectiveness other than short-term weight loss. However, the number of reported
adverse events increased [185 ]. In 2004, the Food and Drug Administration (FDA) in the United States received over
18 000 reports of harmful events associated with Ephedra , and banned dietary supplements with ephedrine alkaloids [4 ], [185 ]. The same ban of Ephedra was imposed in the European Union by the European Commission in 2015. Among the toxic
responses to Ephedra use are increased blood pressure, excitement, sweating, and dysuria, in addition
to more serious
events like arrhythmia, nephritis, gallstones, and possibly death due to myocardial
infarction and stroke or respiratory failure [4 ], [183 ], [184 ].
Altogether, our analysis identified the Ephedra species used traditionally in Morocco and provided useful information to establish
links between the pharmacological effects observed with the plant extracts and the
nature of bioactive natural products identified in those preparations. Moroccan Ephedra plants, notably the two most frequently used regional species E. alata and E. altissima , represent key medicinal plants for the country. Their traditional use can be encouraged,
but always with caution due the presence of potentially harmful ephedrine-type alkaloids
[18 ], [183 ], [185 ]. Their use should be accompanied with health information whenever possible. In this
respect, the danger of using Arabic YouTube videos regarding herbal cancer treatment
has been pointed out recently [186 ]. There is no reason to ban the traditional use of
Moroccan Ephedra extracts to treat some human infections, notably inflammatory symptoms, making profit
of the abundance, relative safety, and beneficial functional attributes of the products.
But it would be useful to assess the toxicological profile of such extracts in parallel,
so as to better understand the efficacy, safety, and quality of the available products.
Finally, beyond the health benefits, it is interesting to note that the same type
of Moroccan Ephedra extracts can be used in the field of green chemistry. An aqueous plant extract of
E. alata has proved efficient when used as a reducing and capping agent for the synthesis
of copper oxide nanoparticles [187 ]. Similarly, other Ephedra extracts have been used to prepare various types of composite nanoparticles [187 ], [188 ], [189 ], [190 ]. A bright future may be anticipated in front of Ephedra plant extracts in medicine, green chemistry, and the food industry.
